A Critical Look at Prebiotics Within the Dietary Fiber Concept.
Verspreet Joran,Damen Bram,Broekaert Willem F,Verbeke Kristin,Delcour Jan A,Courtin Christophe M
Annual review of food science and technology
This article reviews the current knowledge of the health effects of dietary fiber and prebiotics and establishes the position of prebiotics within the broader context of dietary fiber. Although the positive health effects of specific fibers on defecation, reduction of postprandial glycemic response, and maintenance of normal blood cholesterol levels are generally accepted, other presumed health benefits of dietary fibers are still debated. There is evidence that specific dietary fibers improve the integrity of the epithelial layer of the intestines, increase the resistance against pathogenic colonization, reduce the risk of developing colorectal cancer, increase mineral absorption, and have a positive impact on the immune system, but these effects are neither generally acknowledged nor completely understood. Many of the latter effects are thought to be particularly elicited by prebiotics. Although the prebiotic concept evolved significantly during the past two decades, the line between prebiotics and nonprebiotic dietary fiber remains vague. Nevertheless, scientific evidence demonstrating the health-promoting potential of prebiotics continues to accumulate and suggests that prebiotic fibers have their rightful place in a healthy diet.
Dietary Fiber Intake in Young Adults and Breast Cancer Risk.
Farvid Maryam S,Eliassen A Heather,Cho Eunyoung,Liao Xiaomei,Chen Wendy Y,Willett Walter C
OBJECTIVE:We evaluated fiber intake during adolescence and early adulthood in relation to breast cancer (BC) risk in the Nurses' Health Study II. METHODS:Among 90,534 premenopausal women who completed a dietary questionnaire in 1991, we documented 2833 invasive BC cases during 20 years of follow-up. In 1998, 44,263 of these women also completed a questionnaire about their diet during high school; among these women, we documented 1118 cases of BC by end of follow-up. Multivariable-adjusted Cox proportional hazards regression was used to model relative risks (RRs) and 95% confidence intervals (CIs) for BC across categories of dietary fiber. RESULTS:Among all women, early adulthood total dietary fiber intake was associated with significantly lower BC risk (RR for highest versus lowest quintile 0.81; 95% CI 0.72-0.91; Ptrend = .002). Higher intakes of soluble fiber (RR for highest versus lowest quintile 0.86; 95% CI 0.77-0.97; Ptrend = .02) and insoluble fiber (RR for highest versus lowest quintile 0.80; 95% CI 0.71-0.90; Ptrend < .001) were each associated with lower BC risk. Total dietary fiber intake in adolescence was also associated with lower BC risk (RR for highest versus lowest quintile 0.84; 95% CI 0.70-1.01; Ptrend = .04). For the average of fiber intake during adolescence and early adult life, the RR comparing highest with lowest quintiles was 0.75 (95% CI 0.62-0.91, Ptrend = .004). CONCLUSIONS:Our findings support the hypothesis that higher fiber intakes reduce BC risk and suggest that intake during adolescence and early adulthood may be particularly important.
Dietary fiber and blood pressure control.
Aleixandre A,Miguel M
Food & function
In the past few years, new strategies to control blood pressure levels are emerging by developing new bioactive components of foods. Fiber has been linked to the prevention of a number of cardiovascular diseases and disorders. β-Glucan, the main soluble fiber component in oat grains, was initially linked to a reduction in plasma cholesterol. Several studies have shown afterward that dietary fiber may also improve glycaemia, insulin resistance and weight loss. The effect of dietary fiber on arterial blood pressure has been the subject of far fewer studies than its effect on the above-mentioned variables, but research has already shown that fiber intake can decrease arterial blood pressure in hypertensive rats. Moreover, certain fibers can improve arterial blood pressure when administered to hypertensive and pre-hypertensive subjects. The present review summarizes all those studies which attempt to establish the antihypertensive effects of dietary fiber, as well as its effect on other cardiovascular risk factors.
A Prospective Study of Different Types of Dietary Fiber and Risk of Cardiovascular Disease: Tehran Lipid and Glucose Study.
Mirmiran Parvin,Bahadoran Zahra,Khalili Moghadam Sajad,Zadeh Vakili Azita,Azizi Fereidoun
BACKGROUND AND AIM:This study was designed to examine the hypothesis that dietary of intake different types of fiber could modify the risk of cardiovascular disease (CVD) in a large prospective cohort among Iranian adults. METHODS:In 2006-2008, we used a validated food frequency questionnaire to assess dietary fiber intake among 2295 health professionals with no previous history of heart disease. Subjects were subsequently followed until 2012 for incidence of CVD events. Multivariate Cox proportional hazard regression models, adjusted for potential confounders were used to estimate the risk of CVD across tertiles of total dietary fiber and different types of fiber. Linear regression models were also used to indicate the association of dietary fiber intakes with changes of cardiovascular risk factors during the follow-up. RESULTS:Mean age of participants (42.8% men) was 38.2 ± 13.4, at baseline. Mean (SD) dietary intake of total fiber was 23.4 (8.9) g/day. After adjustment for cardiovascular risk score and dietary confounders, a significant inverse association was observed between intakes of total, soluble and insoluble dietary fiber and CVD risk, in the highest compared to the lowest tertiles (HR = 0.39, 95% CI = 0.18-0.83, HR = 0.19, 95% CI = 0.09-0.41, and HR = 0.31, 95% CI = 0.14-0.69, respectively). Inverse relations were observed between risk of CVD and dietary fiber from legumes, fruits and vegetables; however, dietary fiber intake from grain and nut sources was not related to risk of CVD. CONCLUSION:Our findings confirmed that higher intakes of dietary fiber from different sources is associated with CVD events and modify its major risk-related factors.
The Interaction between Dietary Fiber and Fat and Risk of Colorectal Cancer in the Women's Health Initiative.
Navarro Sandi L,Neuhouser Marian L,Cheng Ting-Yuan David,Tinker Lesley F,Shikany James M,Snetselaar Linda,Martinez Jessica A,Kato Ikuko,Beresford Shirley A A,Chapkin Robert S,Lampe Johanna W
Combined intakes of specific dietary fiber and fat subtypes protect against colon cancer in animal models. We evaluated associations between self-reported individual and combinations of fiber (insoluble, soluble, and pectins, specifically) and fat (omega-6, omega-3, and docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), specifically) and colorectal cancer (CRC) risk in the Women's Health Initiative prospective cohort ( = 134,017). During a mean 11.7 years (1993-2010), 1952 incident CRC cases were identified. Cox regression models computed multivariate adjusted hazard ratios to estimate the association between dietary factors and CRC risk. Assessing fiber and fat individually, there was a modest trend for lower CRC risk with increasing intakes of total and insoluble fiber ( 0.09 and 0.08). An interaction ( = 0.01) was observed between soluble fiber and DHA + EPA, with protective effects of DHA + EPA with lower intakes of soluble fiber and an attenuation at higher intakes, however this association was no longer significant after correction for multiple testing. These results suggest a modest protective effect of higher fiber intake on CRC risk, but not in combination with dietary fat subtypes. Given the robust results in preclinical models and mixed results in observational studies, controlled dietary interventions with standardized intakes are needed to better understand the interaction of specific fat and fiber subtypes on colon biology and ultimately CRC susceptibility in humans.
Dietary Fiber Is Independently Related to Blood Triglycerides Among Adults with Overweight and Obesity.
Hannon Bridget A,Thompson Sharon V,Edwards Caitlyn G,Skinner Sarah K,Niemiro Grace M,Burd Nicholas A,Holscher Hannah D,Teran-Garcia Margarita,Khan Naiman A
Current developments in nutrition
BACKGROUND:Metabolic syndrome (MetS), a cluster of visceral adiposity-related risk factors, affects approximately 35% of the United States population. Although improvement in diet quality is an important approach to reducing MetS risk, the role of particular dietary components remains unclear, especially among younger adults. Individual dietary components have been implicated in ameliorating or exacerbating MetS risk; however, the extent to which these factors contribute to MetS prevention has received little attention. OBJECTIVE:This cross-sectional study aimed to assess relations between diet and individual MetS components in young to middle-aged adults who are overweight and/or obese. METHODS:Participants aged 25-45 y ( = 117) with overweight and obesity, but no other diagnosed metabolic disease, recorded dietary intake over 7 d. MetS components (waist circumference, blood pressure, glucose, triglycerides [TGs], and high-density lipoprotein cholesterol [HDL]) were measured. Visceral adipose tissue was measured by dual-energy X-ray absorptiometry. Linear regression was used to assess relations between diet and MetS risk factors, adjusting for age, sex, and visceral adipose tissue. RESULTS:MetS prevalence in this sample was 32%. Energy-adjusted total fiber intake (β = -0.21, = 0.02) was inversely associated with TG concentrations. No significant relations were observed between other dietary factors and MetS components. These findings indicate that among MetS components, TG concentrations are potentially sensitive to fiber consumption. CONCLUSIONS:These results provide cross-sectional evidence supporting the protective influence of dietary fiber on MetS components among young to middle-aged adults. Additional, well-designed clinical trials are needed to assess the causal relations between various types of dietary fiber and metabolic disease.
Dietary Fiber and the Risk of Pancreatic Cancer.
Koulouris Andreas I,Luben Robert,Banim Paul,Hart Andrew R
OBJECTIVES:High dietary fiber may protect against pancreatic ductal adenocarcinoma (PDAC). We investigated associations between fiber intake and the risk of PDAC using for the first time 7-day food diaries. METHODS:Participants in the European Prospective Investigation Into Cancer-Norfolk completed the 7-day food diaries at recruitment. The cohort was followed up for 17 years to identify those who developed PDAC. Participants were divided into quintiles of fiber intake, and hazard ratios (HR) were estimated with their 95% confidence intervals (CIs). Fiber was tested for effect modification of high red and processed meat intake and smoking and the risk of PDAC. RESULTS:No significant associations for any quintiles of intake (HR Q5 vs Q1, 1.08; 95% CI, 0.56-2.08) were detected with no trend across quintiles. A high-fiber diet modified positive associations between red and processed meats with the development of PDAC (HR trends, 0.89 [95% CI, 0.47-1.69] and 1.02 [95% CI, 0.55-1.88], respectively) but not those with lower fiber intake. Fiber intake did not modify the risk of PDAC in past and current smokers. CONCLUSION:The findings do not suggest that fiber protects against PDAC, although it may decrease potential deleterious effects of meats.
Low intakes of dietary fiber and magnesium are associated with insulin resistance and hyperandrogenism in polycystic ovary syndrome: A cohort study.
Food science & nutrition
BACKGROUND:Women with polycystic ovary syndrome (PCOS) often have insulin resistance (IR) which may be worsened by obesity. The roles of dietary intake and activity are unclear. Our objectives were to determine whether (a) high caloric intake or inactivity explains obesity in PCOS, and (b) dietary composition is associated with PCOS phenotypes. METHODS:Eighty-seven women with PCOS and 50 women without PCOS participated in this cohort study at a reproductive medicine center. Data collected included 3-day food and physical activity records, anthropometrics, and metabolic and hormonal assays. RESULTS:Women with PCOS had increased body mass index (BMI) but similar caloric intake and activity to women without PCOS. There were no differences in protein, carbohydrates, fat, or glycemic load consumption, but women with PCOS consumed less fiber (medians: 19.6 vs. 24.7 g) and less magnesium (medians: 238.9 vs. 273.9 mg). In women with PCOS, those with IR consumed less fiber, less magnesium, and greater glycemic load than those without IR (medians: 18.2 vs. 22.1 g, 208.4 vs. 264.5 mg, 89.6 vs. 83.5). Fiber intake of women with PCOS was negatively correlated with IR, fasting insulin, glucose tolerance, testosterone, and dehydroepiandrosterone sulfate. Magnesium intake was negatively correlated with IR, C-reactive protein, and testosterone, but positively correlated with HDL cholesterol. Fiber intake and BMI accounted for 54.0% of the variance observed in IR. CONCLUSIONS:Obesity in women with PCOS could not be explained by overeating or inactivity. Increasing dietary fiber and magnesium intakes may assist in reducing IR and hyperandrogenemia in women with PCOS.
Impact of dietary fiber supplementation on modulating microbiota-host-metabolic axes in obesity.
Mayengbam Shyamchand,Lambert Jennifer E,Parnell Jill A,Tunnicliffe Jasmine M,Nicolucci Alissa C,Han Jay,Sturzenegger Troy,Shearer Jane,Mickiewicz Beata,Vogel Hans J,Madsen Karen L,Reimer Raylene A
The Journal of nutritional biochemistry
Low dietary fiber intake is associated with higher rates of microbiota-associated chronic diseases such as obesity. Low-fiber diets alter not only microbial composition but also the availability of metabolic end products derived from fermentation of fiber. Our objective was to examine the effects of dietary fiber supplementation on gut microbiota and associated fecal and serum metabolites in relation to metabolic markers of obesity. We conducted a 12-week, single-center, double-blind, placebo-controlled trial with 53 adults with overweight or obesity. They were randomly assigned to a pea fiber (PF, 15 g/d in wafer form; n=29) or control (CO, isocaloric amount of wafers; n=24) group. Blood and fecal samples were collected at baseline and 12 weeks. Serum metabolomics, gut microbiota and fecal short-chain fatty acids (SCFAs) and bile acids (BAs) were examined. Within-group but not between-group analysis showed a significant effect of treatment on serum metabolites at 12 weeks compared to baseline. Fiber significantly altered fecal SCFAs and BAs with higher acetate and reduced isovalerate, cholate, deoxycholate and total BAs content in the PF group compared to baseline. Microbiota was differentially modulated in the two groups, including an increase in the SCFA producer Lachnospira in the PF group and decrease in the CO group. The change in body weight of participants showed a negative correlation with their change in Lachnospira (r=-0.463, P=.006) abundance. The current study provides insight into the actions of pea fiber and its impact on modulating microbiota-host-metabolic axes in obesity.
Dietary Fiber Intake (Supplemental or Dietary Pattern Rich in Fiber) and Diabetic Kidney Disease: A Systematic Review of Clinical Trials.
Carvalho Cláudia Mesquita de,Gross Luiza Azevedo,de Azevedo Mirela Jobim,Viana Luciana Verçoza
Fiber intake is associated with better glycemic control being an important nonpharmacologicaltreatment for diabetes (DM). We hypothesize that a dietary fiber intake can bringbenefits to diabetic kidney disease (DKD), improving renal outcomes. This systematic review aimedto evaluate the effect of dietary fiber (supplemental or dietary pattern rich in fiber) on DKD. Wesearched six databases to identify clinical trials that reported fiber intake and renal outcomes(albuminuria, proteinuria, estimated glomerular filtration rate (eGFR) dialysis) in patients with DM.From 1814 studies, 48 papers were fully evaluated. In the end, seven trials (161 patients, aged 58.3years, 49% females) were included. The studies were organized into three categories (vegetarian,Dietary Approaches to Stop Hypertension (DASH) diet, and fiber supplement), two evaluatedsupplements and five dietary patterns. Vegetarian diet reduced albuminuria in three trials, two inpatients with type 1 DM and one in patients with type 2 DM; and one study demonstrated a change inthe eGFR in type 1 DM. The individual quality of the studies was low/uncertain. A vegetarian dietarypattern may have a beneficial effect on these renal outcomes. However, the individual effect of theintake of fiber on DKD not was possible to be evaluated.
Dietary Fiber Intake: Its Relation With Glycation End Products and Arterial Stiffness in End-Stage Renal Disease Patients.
Demirci Bahar Gürlek,Tutal Emre,Eminsoy Irem O,Kulah Eyup,Sezer Siren
Journal of renal nutrition : the official journal of the Council on Renal Nutrition of the National Kidney Foundation
OBJECTIVE:We aimed to analyze the relationship between the effect of total dietary fiber intake on C-reactive protein (CRP) and on oxidative stress parameters such as serum advanced glycation end products (AGEs), superoxide dysmutase (SOD), malondialdehyde, and arterial stiffness by pulse wave velocity (PWv) in maintanace hemodialysis (MHD) patients. METHODS:Among 650 MHD patients, 128 were selected according to inclusion criteria. The dietary survey was performed with a 3-day dietary history. Dietary fiber level was adjusted for total energy intake by the residual method. Patients were stratiﬁed by quartiles of adjusted dietary ﬁber (ADF) level as group 1 (n = 32) (ADF: <8.86 g/day), group 2 (n = 35) (ADF: 8.86-12.50 g/day), group 3 (n = 31) (ADF: 12.51-15.90 g/day), and group 4 (n = 30) (ADF: ≥15.91 g/day). Monthly assessed biochemical parameters including serum hemoglobin, albumin, CRP, calcium, phosphorus, and lipid profile levels were recorded. Serum AGEs, SOD, and malondialdehyde levels were determined by ELISA method. The PWv was determined from pressure tracing over carotid and femoral arteries. RESULTS:Patients in group 3 and 4 had significantly lower CRP and AGE than those in group 1 and 2. Mean serum SOD level and PWv were significantly higher in group 4. In regression analysis, ADF intake was the unique predictor for both AGE (r = 0.164, P = 0.017) and CRP levels (r = 0.238, P = 0.01). CONCLUSION:Present data show that dietary fiber intake is independently correlated with inflammation and oxidative stress. In addition, decreased fiber intake results in impaired arterial stiffness. Thus, adequate fiber intake could prevent cardiovascular events and inflammatory processes in patients undergoing MHD.
Dietary fiber intake and glycemic control: coronary artery calcification in type 1 diabetes (CACTI) study.
Basu Arpita,Alman Amy C,Snell-Bergeon Janet K
BACKGROUND:Dietary fiber has been recommended for glucose control, and typically low intakes are observed in the general population. The role of fiber in glycemic control in reported literature is inconsistent and few reports are available in populations with type 1 diabetes (T1D). METHODS:Using data from the Coronary Artery Calcification in Type 1 Diabetes (CACTI) study [n = 1257; T1D: n = 568; non-diabetic controls: n = 689] collected between March 2000 and April 2002, we examined cross-sectional (baseline) and longitudinal (six-year follow-up in 2006-2008) associations of dietary fiber and HbA1c. Participants completed a validated food frequency questionnaire, and a physical examination and fasting biochemical analyses (12 h fast) at baseline visit and at the year 6 visit. We used a linear regression model stratified by diabetes status, and adjusted for age, sex and total calories, and diabetes duration in the T1D group. We also examined correlations of dietary fiber with HbA1c. RESULTS:Baseline dietary fiber intake and serum HbA1c in the T1D group were 16 g [median (IQ): 11-22 g) and 7.9 ± 1.3% mean (SD), respectively, and in the non-diabetic controls were 15 g [median (IQ): 11-21 g) and 5.4 ± 0.4%, respectively. Pearson partial correlation coefficients revealed a significant but weak inverse association of total dietary fiber with HbA1c when adjusted for age, sex, diabetes status and total calories (r = - 0.07, p = 0.01). In the adjusted linear regression model at baseline, total dietary fiber revealed a significant inverse association with HbA1c in the T1D group [β ± SE = - 0.32 ± 0.15, p = 0.034], as well as in the non-diabetic controls [- 0.10 ± 0.04, p = 0.009]. However, these results were attenuated after adjustment for dietary carbohydrates, fats and proteins, or for cholesterol and triglycerides. No such significance was observed at the year 6 follow-up, and with the HbA1c changes over 6 years. CONCLUSION:Thus, at observed levels of intake, total dietary fiber reveals modest inverse associations with poor glycemic control. Future studies must further investigate the role of overall dietary quality adjusting for fiber-rich foods in T1D management.
Dietary fiber, glycemic index, glycemic load and renal cell carcinoma risk.
Xu Xin,Zhu Yi,Li Jiangfeng,Wang Song
Several epidemiological studies have investigated the potential association between dietary fiber, glycemic index (GI) or glycemic load (GL), and renal cell carcinoma (RCC) risk with inconsistent results. The aim of this study was to systematically evaluate this issue with a meta-analysis approach. A comprehensive literature search up to March 2018 was performed in PubMed and Web of Science databases. Summary relative risks (RRs) and 95% confidence intervals (CIs) were estimated with a random-effects model. Twelve studies were finally included in this study (eight for fiber analysis, five for GI and five for GL). A significant positive association was observed between GI and the risk of RCC (summary RR 1.16, 95% CI 1.02-1.32), and no significant heterogeneity was detected among studies (I2 = 22.8%, P = 0.262). A significant inverse association was found between fiber intake and the risk of RCC (summary RR 0.82, 95% CI 0.72-0.92), and no significant heterogeneity was observed across studies (I2 = 27.6%, P = 0.218). GL was not significantly associated with RCC risk (summary RR 1.14, 95% CI 0.81-1.60), and significant heterogeneity was found across studies (I2 = 78.6%, P < 0.001). In conclusion, this systematic review and meta-analysis suggests that dietary GI and fiber may be associated with the risk of RCC. Further large prospective cohort studies are still warranted to confirm our preliminary findings.
Dietary Fiber, Atherosclerosis, and Cardiovascular Disease.
Soliman Ghada A
Observational studies have shown that dietary fiber intake is associated with decreased risk of cardiovascular disease. Dietary fiber is a non-digestible form of carbohydrates, due to the lack of the digestive enzyme in humans required to digest fiber. Dietary fibers and lignin are intrinsic to plants and are classified according to their water solubility properties as either soluble or insoluble fibers. Water-soluble fibers include pectin, gums, mucilage, fructans, and some resistant starches. They are present in some fruits, vegetables, oats, and barley. Soluble fibers have been shown to lower blood cholesterol by several mechanisms. On the other hand, water-insoluble fibers mainly include lignin, cellulose, and hemicellulose; whole-grain foods, bran, nuts, and seeds are rich in these fibers. Water-insoluble fibers have rapid gastric emptying, and as such may decrease the intestinal transit time and increase fecal bulk, thus promoting digestive regularity. In addition to dietary fiber, isolated and extracted fibers are known as functional fiber and have been shown to induce beneficial health effects when added to food during processing. The recommended daily allowances (RDAs) for total fiber intake for men and women aged 19-50 are 38 gram/day and 25 gram/day, respectively. It is worth noting that the RDA recommendations are for healthy people and do not apply to individuals with some chronic diseases. Studies have shown that most Americans do not consume the recommended intake of fiber. This review will summarize the current knowledge regarding dietary fiber, sources of food containing fiber, atherosclerosis, and heart disease risk reduction.
Association of Intake of Whole Grains and Dietary Fiber With Risk of Hepatocellular Carcinoma in US Adults.
IMPORTANCE:Increased intake of whole grain and dietary fiber has been associated with lower risk of insulin resistance, hyperinsulinemia, and inflammation, which are known predisposing factors for hepatocellular carcinoma (HCC). Therefore, we hypothesized that long-term intake of whole grains and dietary fiber may be associated with lower risk of HCC. OBJECTIVE:To assess the associations of whole grain and dietary fiber intake with the risk of HCC. DESIGN, SETTING, AND PARTICIPANTS:Cohort study of the intake of whole grains, their subcomponents (bran and germ), and dietary fiber (cereal, fruit, and vegetable) in 125 455 participants from 2 cohorts from the Nurses' Health Study and the Health Professionals Follow-up Study. EXPOSURES:Intake of whole grains, their subcomponents (bran and germ), and dietary fiber (cereal, fruit, and vegetable) were collected and updated almost every 4 years using validated food frequency questionnaires. MAIN OUTCOMES AND MEASURES:Multivariable hazard ratios (HRs) and 95% CIs were estimated using Cox proportional hazards regression model after adjusting for most known HCC risk factors. RESULTS:After an average follow-up of 24.2 years, we identified 141 patients with HCC among 125 455 participants (77 241 women and 48 214 men (mean [SD] age, 63.4 [10.7] years). Increased whole grain intake was significantly associated with lower risk of HCC (the highest vs lowest tertile intake: HR, 0.63; 95% CI, 0.41-0.96; P = .04 for trend). A nonsignificant inverse HCC association was observed for total bran (HR, 0.70; 95% CI, 0.46-1.07; P = .11 for trend), but not for germ. Increased intake of cereal fiber (HR, 0.68; 95% CI, 0.45-1.03; P = .07 for trend), but not fruit or vegetable fiber, was associated with a nonsignificant reduced risk of HCC. CONCLUSIONS AND RELEVANCE:Increased intake of whole grains and possibly cereal fiber and bran could be associated with reduced risk of HCC among adults in the United States. Future studies that carefully consider hepatitis B and C virus infections are needed to replicate our findings, to examine these associations in other racial/ethnic or high-risk populations, and to elucidate the underlying mechanisms.
Beneficial Effect of Dietary Fiber on Hyperuricemia in Rats and Humans: A Review.
Koguchi Takashi,Tadokoro Tadahiro
International journal for vitamin and nutrition research. Internationale Zeitschrift fur Vitamin- und Ernahrungsforschung. Journal international de vitaminologie et de nutrition
Hyperuricemia is recognized as a lifestyle-related disease and the prevalence is increasing in many parts of the world. Excessive intake of purines increases serum uric acid concentration and is thought to be one factor causative of hyperuricemia. Therefore, it is thought that prevention of hyperuricemia by dietary control may be very important. This is an article of our basic research regarding the role of dietary fiber in the suppression of hyperuricemia induced by dietary purines in rats; in addition, clinical research suggesting the possibility that dietary fiber intake has a beneficial effect on the prevention or suppression of hyperuricemia in humans is discussed. Our own studies reveal that the test dietary fiber significantly suppresses the elevation of serum uric acid concentration induced by dietary RNA (12.3-46.2%), adenosine-5'-monophosphate (9.5-23.2%), adenosine (10.7-20.4%), or adenine (16.3-38.9%) and suppresses experimental hyperuricemia in rats. The mechanism is presumed to be mediated by suppression of the digestion and/or absorption of dietary purines by dietary fiber. In clinical studies, intake of dietary fiber decreases serum uric acid concentrations. Reports of recent epidemiological studies indicate that higher levels of hyperuricemia increase the prevalence of its comorbidities (e.g., chronic kidney disease, obesity, hypertension, diabetes, and cardiovascular disease) and dietary fiber intake is associated with significantly lower risk for hyperuricemia and its comorbidities. We wish to emphasize the importance of recognizing the validity of increased dietary fiber intake as a preventive or suppressive method for hyperuricemia and its comorbidities.
Exploring the Role of Cereal Dietary Fiber in Digestion.
Gouseti O,Lovegrove A,Kosik O,Fryer P J,Mills C,Gates F,Tucker G,Latty C,Shewry P,Bakalis S
Journal of agricultural and food chemistry
Increasing the dietary fiber of staple foods such as bread is an attractive way to promote healthy eating in a large part of the population, where dietary fiber consumption is reportedly below the recommended values. However, many consumers prefer white breads, which are typically low in dietary fiber. In this work, white bread was made from two wheat cultivars with differing fiber contents. The resulting breads showed similar quality parameters (volume, specific volume, firmness, inner structure characteristics) with any differences maintained below 7%. Bread digestibility was evaluated using a novel dynamic in vitro digestion model. Reduced digestion rates of 30% were estimated for the high-fiber white bread compared to that in the control. Overall, this work demonstrates the potential to produce healthy, high-fiber white breads that are acceptable to consumers, with a reduced rate of starch digestion, by exploiting a genetic variation in the dietary fiber content of wheat cultivars.
Long-term dietary fiber intake and risk of chronic obstructive pulmonary disease: a prospective cohort study of women.
Szmidt Maria Karolina,Kaluza Joanna,Harris Holly Ruth,Linden Anders,Wolk Alicja
European journal of nutrition
PURPOSE:Until now, only two prospective cohort studies have investigated dietary fiber intake in relation to risk of chronic obstructive pulmonary disease (COPD), but neither examined long-term fiber intake. Both studies reported that total fiber intake was associated with decreased COPD risk; however, results for specific fiber sources were inconsistent. Thus, we prospectively evaluated the association between baseline and long-term intake of dietary fiber and COPD risk in a population-based prospective cohort of 35,339 Swedish women. METHODS:Dietary fiber intake was assessed in 1987 and 1997 with a food frequency questionnaire. Cox proportional hazard regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS:During follow-up (2002-2014), 1557 COPD cases were identified via linkage to the Swedish National Patient Register. Long-term high dietary fiber intake (≥ 26.5 vs. < 17.6 g/day) was associated with a 30% (95% CI 17-41%) lower risk of COPD. For specific fiber sources, cereal (≥ 16.3 vs. < 9.4 g/day; HR 0.67, 95% CI 0.55-0.81) and fruit fiber (≥ 7.6 vs. < 2.6 g/day; HR 0.65, 95% CI 0.5-0.81), but not vegetable fiber intake (≥ 5.4 vs. < 2.2 g/day; HR 1.03, 95% CI 0.81-1.28) were associated with lower COPD risk. Current and ex-smokers with low long-term total fiber intake (< 17.6 g/day) compared to never smokers with high intake (≥ 26.5 g/day) had a 33-fold (95% CI 23.6-46.6) and tenfold (95% CI 7.0-16.3), respectively, higher risk of COPD. CONCLUSIONS:Our findings indicate that high fiber intake is a modifiable lifestyle factor which may decrease COPD risk primarily in current and ex-smokers.
Intake of Dietary Fiber, Fruits, and Vegetables and Risk of Diverticulitis.
Ma Wenjie,Nguyen Long H,Song Mingyang,Jovani Manol,Liu Po-Hong,Cao Yin,Tam Idy,Wu Kana,Giovannucci Edward L,Strate Lisa L,Chan Andrew T
The American journal of gastroenterology
OBJECTIVES:Although low fiber intake has been considered a risk factor for diverticulitis, prospective evidence is limited in women despite having a disproportionate burden of disease, with little known about variation in the protective effects according to food sources. We assessed the associations of intakes of fiber and major food sources of fiber including fruits and vegetables with risk of diverticulitis in a large cohort of women. METHODS:We followed 50,019 women in the Nurses' Health Study (1990-2014) who were aged 43-70 years and free of diverticulitis, cancer, and inflammatory bowel disease at baseline. Incident diverticulitis was identified through self-report with validity confirmed by review of medical records. RESULTS:We documented 4,343 incident cases of diverticulitis, encompassing 1,106,402 person-years of follow-up. Compared with participants in the lowest quintile, the multivariable hazard ratio of diverticulitis in the highest quintile of total fiber intake was 0.86 (95% confidence interval: 0.78-0.95; P-trend = 0.002). Fiber from fruits and cereals, but not vegetables, was associated with a decreased risk of diverticulitis. Furthermore, intake of total whole fruit intake and specific fruits such as apples/pears and prunes were associated with reduced risk of diverticulitis with a multivariable hazard ratio for diverticulitis of 0.95 (0.92-0.98; P-trend < 0.001) for every serving increase of total whole fruit intake per day. DISCUSSION:Higher intake of dietary fiber and fiber from different food sources, except for vegetable fiber, are associated with a lower risk of diverticulitis in women. A greater intake of whole fruit is also associated with reduced risk.
Whey Protein Combined with Low Dietary Fiber Improves Lipid Profile in Subjects with Abdominal Obesity: A Randomized, Controlled Trial.
Rakvaag Elin,Fuglsang-Nielsen Rasmus,Bach Knudsen Knud Erik,Landberg Rikard,Johannesson Hjelholt Astrid,Søndergaard Esben,Hermansen Kjeld,Gregersen Søren
Abdominal obesity is associated with elevated postprandial triglycerides (TG), an independent risk factor for cardiovascular diseases. Previous studies show that whey protein (WP) and dietary fiber may separately reduce postprandial TG. However, few studies have investigated the long-term effects of WP and dietary fiber on postprandial TG. We aimed to investigate the separate and combined long-term effects of WP and dietary fiber from wheat bran on postprandial TG and markers of lipid metabolism in subjects with abdominal obesity. We conducted a 12-week, double-blind, randomized, controlled, parallel intervention study. In a 2 × 2 factorial design, 73 adults were randomized to receive 60 g/day of either WP hydrolysate or maltodextrin (MD) combined with high-fiber wheat bran products (HiFi; 30 g dietary fiber/day) or low-fiber refined wheat products (LoFi; 10 g dietary fiber/day). A high-fat meal test was conducted before and after the intervention. Sixty-five subjects were included in the final analyses. There were no differences between intervention groups in postprandial TG assessed as incremental area under the curve (iAUC). WP-LoFi had reduced postprandial TG assessed as total area under the curve (tAUC) and reduced fasting TG compared with all other groups, and reduced fasting apolipoprotein B-48 compared with MD-LoFi. There were no changes in lipoprotein lipase activity. Total cholesterol and apolipoprotein B-100 were reduced after WP intake compared with MD. Total cholesterol was increased after HiFi intake compared with LoFi. In conclusion, intake of WP in combination with low-fiber cereal products for 12 weeks had beneficial effects on postprandial TG tAUC and fasting TG, but not on postprandial TG iAUC in subjects with abdominal obesity. Combining WP with high-fiber wheat bran products did not improve lipid profile.
Dietary Fiber and Gut Microbiota in Renal Diets.
Camerotto Carla,Cupisti Adamasco,D'Alessandro Claudia,Muzio Fulvio,Gallieni Maurizio
Nutrition is crucial for the management of patients affected by chronic kidney disease (CKD) to slow down disease progression and to correct symptoms. The mainstay of the nutritional approach to renal patients is protein restriction coupled with adequate energy supply to prevent malnutrition. However, other aspects of renal diets, including fiber content, can be beneficial. This paper summarizes the latest literature on the role of different types of dietary fiber in CKD, with special attention to gut microbiota and the potential protective role of renal diets. Fibers have been identified based on aqueous solubility, but other features, such as viscosity, fermentability, and bulking effect in the colon should be considered. A proper amount of fiber should be recommended not only in the general population but also in CKD patients, to achieve an adequate composition and metabolism of gut microbiota and to reduce the risks connected with obesity, diabetes, and dyslipidemia.
Association between dietary fiber and endometrial cancer: a meta-analysis.
Li Hengjie,Mao Hui,Yu Yi,Nan Yong
Nutrition and cancer
To explore a potential relationship between dietary fiber consumption and risk of endometrial cancer (EC), eligible studies published up to 30 June 2018 were retrieved via computer searches and manual review of references. Random-effects models were used to calculate summary relative risk (RR) estimates based on contrasting high- and low-fiber intake values. Sensitivity analysis was conducted, and heterogeneity among study results was explored through stratified analyses by study design, geographic region, Newcastle-Ottawa Scale (NOS) score, impact factor, and adjustment for several confounders (age, body mass index, smoking, energy intake, and education). We extracted data from 16 studies (involving 6,563 cases). There was a significant association between dietary fiber intake and EC (RR = 0.86, 95% confidence interval [CI]: 0.78, 0.93). In stratified analysis, this trend was more pronounced in the case-control studies, and in studies conducted in the Americas and Asia. The relationship was further confirmed after adjusting for education level (RR = 0.74; 95% CI: 0.60, 0.88) and age (RR = 0.70; 95% CI: 0.57, 0.83), and NOS scores of 6 (RR = 0.81; 95% CI: 0.67, 0.95) and 7 (RR = 0.75; 95% CI: 0.62, 0.88). In conclusion, our meta-analysis revealed an inverse association between dietary fiber consumption and EC risk. Further efforts should be made to confirm these findings.
The Role of Dietary Fiber in Rheumatoid Arthritis Patients: A Feasibility Study.
Häger Julian,Bang Holger,Hagen Melanie,Frech Michael,Träger Pascal,Sokolova Maria V,Steffen Ulrike,Tascilar Koray,Sarter Kerstin,Schett Georg,Rech Jürgen,Zaiss Mario M
Short-chain fatty acids are microbial metabolites that have been shown to be key regulators of the gut-joint axis in animal models. In humans, microbial dysbiosis was observed in rheumatoid arthritis (RA) patients as well as in those at-risk to develop RA, and is thought to be an environmental trigger for the development of clinical disease. At the same time, diet has a proven impact on maintaining intestinal microbial homeostasis. Given this association, we performed a feasibility study in RA patients using high-fiber dietary supplementation with the objective to restore microbial homeostasis and promote the secretion of beneficial immunomodulatory microbial metabolites. RA patients ( = 36) under routine care received daily high-fiber bars or cereals for 28 days. Clinical assessments and laboratory analysis of immune parameters in blood and stool samples from RA patients were done before and after the high-fiber dietary supplementation. We observed an increase in circulating regulatory T cell numbers, favorable Th1/Th17 ratios, as well as decreased markers of bone erosion in RA patients after 28 days of dietary intervention. Furthermore, patient-related outcomes of RA improved. Based on these results, we conclude that controlled clinical studies of high-fiber dietary interventions could be a viable approach to supplement or complement current pharmacological treatment strategies.
Association of Dietary Fiber and Yogurt Consumption With Lung Cancer Risk: A Pooled Analysis.
Yang Jae Jeong,Yu Danxia,Xiang Yong-Bing,Blot William,White Emily,Robien Kim,Sinha Rashmi,Park Yikyung,Takata Yumie,Lazovich DeAnn,Gao Yu-Tang,Zhang Xuehong,Lan Qing,Bueno-de-Mesquita Bas,Johansson Ingegerd,Tumino Rosario,Riboli Elio,Tjønneland Anne,Skeie Guri,Quirós J Ramón,Johansson Mattias,Smith-Warner Stephanie A,Zheng Wei,Shu Xiao-Ou
Importance:Dietary fiber (the main source of prebiotics) and yogurt (a probiotic food) confer various health benefits via modulating the gut microbiota and metabolic pathways. However, their associations with lung cancer risk have not been well investigated. Objective:To evaluate the individual and joint associations of dietary fiber and yogurt consumption with lung cancer risk and to assess the potential effect modification of the associations by lifestyle and other dietary factors. Design, Setting, and Participants:This pooled analysis included 10 prospective cohorts involving 1 445 850 adults from studies that were conducted in the United States, Europe, and Asia. Data analyses were performed between November 2017 and February 2019. Using harmonized individual participant data, hazard ratios and 95% confidence intervals for lung cancer risk associated with dietary fiber and yogurt intakes were estimated for each cohort by Cox regression and pooled using random-effects meta-analysis. Participants who had a history of cancer at enrollment or developed any cancer, died, or were lost to follow-up within 2 years after enrollment were excluded. Exposures:Dietary fiber intake and yogurt consumption measured by validated instruments. Main Outcomes and Measures:Incident lung cancer, subclassified by histologic type (eg, adenocarcinoma, squamous cell carcinoma, and small cell carcinoma). Results:The analytic sample included 627 988 men, with a mean (SD) age of 57.9 (9.0) years, and 817 862 women, with a mean (SD) age of 54.8 (9.7) years. During a median follow-up of 8.6 years, 18 822 incident lung cancer cases were documented. Both fiber and yogurt intakes were inversely associated with lung cancer risk after adjustment for status and pack-years of smoking and other lung cancer risk factors: hazard ratio, 0.83 (95% CI, 0.76-0.91) for the highest vs lowest quintile of fiber intake; and hazard ratio, 0.81 (95% CI, 0.76-0.87) for high vs no yogurt consumption. The fiber or yogurt associations with lung cancer were significant in never smokers and were consistently observed across sex, race/ethnicity, and tumor histologic type. When considered jointly, high yogurt consumption with the highest quintile of fiber intake showed more than 30% reduced risk of lung cancer than nonyogurt consumption with the lowest quintile of fiber intake (hazard ratio, 0.67 [95% CI, 0.61-0.73] in total study populations; hazard ratio, 0.69 [95% CI, 0.54-0.89] in never smokers), suggesting potential synergism. Conclusions and Relevance:Dietary fiber and yogurt consumption was associated with reduced risk of lung cancer after adjusting for known risk factors and among never smokers. Our findings suggest a potential protective role of prebiotics and probiotics against lung carcinogenesis.
Dietary fiber intake and the risk of bladder cancer in the Prostate, Lung, Colorectal and Ovarian (PLCO) cohort.
Luo Jindan,Xu Xin
Dietary fiber intake has been implicated as a protective factor for several human cancers in multiple epidemiologic studies. However, little is known about the effect of fiber intake on bladder cancer. This study examines the association between dietary fiber intake and bladder cancer risk among participants in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. A total of 101 721 participants were included in this study as they completed both the baseline questionnaire and the diet history questionnaire (cancer free before completion of the diet history questionnaire). Hazard ratios (HRs) and the corresponding 95% confidence intervals (CIs) were estimated using the Cox proportional hazards regression model. After a median of 12.5 years of follow-up, 776 new cases of bladder cancer were identified. Higher intake of total fiber, insoluble fiber and soluble fiber were not significantly associated with a reduced risk of bladder cancer. The multi-adjusted HRs (95 CIs) of highest versus lowest tertile of intake were 0.83 (0.66-1.04) for total fiber (P for trend = 0.098), 0.83 (95% CI: 0.67-1.03) for insoluble fiber (P for trend = 0.092) and 0.86 (95% CI: 0.68-1.08) for soluble fiber (P for trend = 0.168), respectively. There was no significant interaction of potential confounders, including education, body mass index and smoking status, with total fiber intake on bladder cancer risk. In summary, the findings of this prospective study show that there is no obvious evidence for a link between dietary fiber consumption and bladder cancer risk. Further large cohort studies are warranted to confirm these findings.
Effects of Low-Fat and High-Fat Meals, with and without Dietary Fiber, on Postprandial Endothelial Function, Triglyceridemia, and Glycemia in Adolescents.
Whisner Corrie M,Angadi Siddhartha S,Weltman Nathan Y,Weltman Arthur,Rodriguez Jessica,Patrie James T,Gaesser Glenn A
The consumption of fiber-rich foods may negate the deleterious effects of high-fat meals on postprandial triglyceridemia and endothelial function. Despite supportive data in adults, little is known about the effects of high-fat and high-fiber foods on cardiovascular health parameters in pediatric populations. In this crossover trial, male and female adolescents ( = 10; 14.1 + 2.6 years; range 10-17 years) consumed (1) low-fat, low-fiber, (2) low-fat, high-fiber, (3) high-fat, low-fiber, and (4) high-fat, high-fiber breakfast meals in randomized order, each following an overnight fast. Baseline and 4 h post-meal blood was obtained for determination of glucose, insulin and triglyceride concentrations. Endothelial function was assessed via brachial artery flow-mediated dilation (FMD). Postprandial FMD was not significantly changed after any meal. However, regression analyses revealed a significant inverse relationship between the change in 4 h triglyceride concentration and change in 4 h FMD for the high-fat, low-fiber meal (β = -0.087; 95% CI = -0.138 to -0.037; = 0.001) that was no longer significant in the high-fat, high-fiber meal (β = -0.044; 95% CI = -0.117 to 0.029; = 0.227). Interpretation of these analyses must be qualified by acknowledging that between-meal comparison revealed that the two regression lines were not statistically different ( = 0.226). Addition of high-fiber cereal to the high-fat meal also reduced 4 h postprandial triglyceride increases by ~50% ( = 0.056). A high-fiber breakfast cereal did not attenuate postprandial glucose and insulin responses after consumption of a low-fat meal. While further work is needed to confirm these results in larger cohorts, our findings indicate the potential importance of cereal fiber in blunting the inverse relationship between postprandial hypertriglyceridemia and FMD after consumption of a high-fat meal in adolescents.
Effect of Dietary Fiber on Serum Leptin Level: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.
Hassanzadeh-Rostami Zahra,Faghih Shiva
Experimental and clinical endocrinology & diabetes : official journal, German Society of Endocrinology [and] German Diabetes Association
BACKGROUND:Dietary fibers may induce satiety through affecting gastro-intestinal and peripheral appetite regulating hormones. Thus, we aimed to investigate the effect of dietary fiber consumption on serum leptin level compared to control diet, in short- and long- term trials, through a systematic review and meta-analysis. METHODS:We searched PubMed, web of science, Scopus, ProQuest, EMBASE, and Cochrane Library to find randomized controlled clinical trials that evaluated effect of any type of dietary fiber on serum leptin level compared to control diet, until April 2019. Both short-term (1-4 days) and long-term (longer than 2 weeks) studies were selected. Mean differences (MD) of changes in serum leptin level and 95% confidence intervals were extracted from eligible studies, and random effects model was used to analyze data. RESULTS:Thirteen studies included the systematic review and 11 entered in the meta-analysis. No significant change was seen in serum leptin level in short-term (MD=0.02, 95% CI; -0.15, 0.20, Tau=0.0) and long-term studies (MD=-0.10, 95% CI; -0.28, 0.08, Tau=0.0), followed by fiber consumption. However, this effect was statistically significant in obese participants (MD=-0.36, 95% CI; -0.71, -0.02, Tau=0.0) in long-term studies. Moreover, we found no significant results in subgroups of baseline serum leptin level, intervention duration, fiber dose, and fiber type. CONCLUSIONS:This meta-analysis found that taking dietary fiber for long term could lower serum leptin level, just in obese persons. However, further clinical trials are needed in this field to clarify this issue.
A prospective analysis of dietary fiber intake and mental health quality of life in the Iowa Women's Health Study.
Ramin Seth,Mysz Margaret A,Meyer Katie,Capistrant Benjamin,Lazovich DeAnn,Prizment Anna
OBJECTIVE:Recent studies have reported associations between dietary intake and mental health. Dietary fiber is one nutrient that may modulate mental health, specifically depression risk, through the gut microbiome. We prospectively examined the association between dietary fiber intake and mental health-related quality of life (QOL) scores, a proxy for depressive symptoms, in a cohort of 14,129 post-menopausal women in the Iowa Women's Health Study. METHODS:Dietary intake was assessed at baseline  using a 127-item food frequency questionnaire. Mental health-related QOL scores were assessed at the follow-up questionnaire  using the Mental Health (MH) component and Mental Health Composite (MCS) scales derived from the SF-36 Health Survey. The association between dietary fiber intake and mean QOL scores was examined using linear regression, with adjustment for age, alcohol intake, energy intake, waist-to-hip ratio, physical activity, smoking status, and education. RESULTS:The median dietary fiber intake was 19.0 g/day, ranging from 1.1 to 89.4 g/day. Multivariable-adjusted mean MH scores were higher among those with higher fiber intake (P = 0.02). For MCS score, the association with fiber intake observed in a model adjusted for age and energy intake became insignificant after multivariable adjustment. CONCLUSIONS:Our study is one of the first prospective analyses of the association between higher dietary fiber intake and increased MH QOL scores later in life. Given a plausible biological mechanism underlying the association between fiber intake and mental health, additional studies are warranted.
Relationship Between Dietary Fiber Intake and Short-Chain Fatty Acid-Producing Bacteria During Critical Illness: A Prospective Cohort Study.
Fu Yichun,Moscoso Dagmara I,Porter Joyce,Krishnareddy Suneeta,Abrams Julian A,Seres David,Chong David H,Freedberg Daniel E
JPEN. Journal of parenteral and enteral nutrition
BACKGROUND:Dietary fiber increases short-chain fatty acid (SCFA)-producing bacteria yet is often withheld in the intensive care unit (ICU). This study evaluated the safety and effect of fiber in ICU patients with gut microbiome sampling. METHODS:This was a retrospective study nested within a prospective cohort. Adults were included if newly admitted to the ICU and could receive oral nutrition, enteral feedings, or no nutrition. Rectal swabs were performed at admission and 72 hours later. The primary exposure was fiber intake over 72 hours, classified in tertiles and adjusted for energy intake. The primary outcome was the relative abundance (RA) of SCFA producers via 16S RNA sequencing and the tolerability of fiber. RESULTS:In 129 patients, median fiber intake was 13.4 g (interquartile range 0-35.4 g) over 72 hours. The high-fiber group had less abdominal distension (11% high fiber vs 28% no fiber, P < .01) and no increase in diarrhea (15% high fiber vs 13% no fiber, P = .94) or other adverse events. The median RA of SCFA producers after 72 hours was 0.40%, 0.50%, and 1.8% for the no-, low-, and high-fiber groups (P = .05 for trend). After correcting for energy intake, the median RA of SCFA producers was 0.41%, 0.32%, and 2.35% in the no-, low-, and high-corrected-fiber categories (P < .01). These associations remained significant after adjusting for clinical factors including antibiotics. CONCLUSIONS:During the 72 hours after ICU admission, fiber was well tolerated, and higher fiber intake was associated with more SCFA-producers.
The impact of dietary fiber and probiotics in infectious diseases.
Yang Huan,Sun Yiran,Cai Rui,Chen Ying,Gu Bing
Although antibiotics are commonly used to treat infectious diseases, emergence of antibiotic resistant strains highlights the necessity for developing novel alternative approaches. Meanwhile, clinically, antibiotics can destroy the gut microbes balance, which is not conducive to the recovery of infectious disorders. As a result, recent studies have begun to explore potential prevention and treatment methods for infectious diseases, starting with more readily available dietary fiber and probiotics. Moreover, researches have shown the personalized nature of host responses to dietary fiber intervention, with outcomes being dependent on individual pre-treatment gut microbes. In this review, we will focus on the roles of dietary fiber and probiotics on infectious diseases, how probiotics and dietary fiber work on infectious diseases and then explore their mechanisms, so as to guide clinical consideration of new therapies for infectious diseases.
Dietary fiber intake is inversely associated with risk of pancreatic cancer: a meta-analysis.
Mao Qi-Qi,Lin Yi-Wei,Chen Hong,Qin Jie,Zheng Xiang-Yi,Xu Xin,Xie Li-Ping
Asia Pacific journal of clinical nutrition
BACKGROUND AND OBJECTIVES:The association between fiber intake and pancreatic cancer risk is conflicting and poorly explored. The aim of study was to investigate the association between dietary fiber intake and the risk of pancreatic cancer by conducting a meta-analysis of epidemiological studies. METHODS AND STUDY DESIGN:Systematic search of PubMed and Embase databases up to April 2015 were conducted to identify relevant studies. Adjusted odds ratios (ORs) were combined using random-effects models to assess the risk of pancreatic cancer when comparing extreme categories of fiber intake. Dose-response meta-analysis was performed for studies reporting categorical risk estimates for at least 3 exposure levels. RESULTS:One cohort and thirteen case-control studies were identified. The overall analysis revealed a strong inverse association between risk of pancreatic cancer and high fiber intake (OR 0.52; 95% CI 0.44-0.61). No publication bias was detected by Egger's or Begg's test. The dose-response analyses showed that the summary OR for an increment of 10 g daily intake of fiber was 0.88 (0.84 to 0.92). CONCLUSION:A high intake of dietary fiber was associated with a reduced risk of pancreatic cancer. Further well-designed prospective studies are warranted to confirm the inverse association and to identify the dietary fiber types involved.
Dietary fiber and prebiotics and the gastrointestinal microbiota.
Holscher Hannah D
The gastrointestinal microbiota has an important role in human health, and there is increasing interest in utilizing dietary approaches to modulate the composition and metabolic function of the microbial communities that colonize the gastrointestinal tract to improve health, and prevent or treat disease. One dietary strategy for modulating the microbiota is consumption of dietary fiber and prebiotics that can be metabolized by microbes in the gastrointestinal tract. Human alimentary enzymes are not able to digest most complex carbohydrates and plant polysaccharides. Instead, these polysaccharides are metabolized by microbes which generate short-chain fatty acids (SCFAs), including acetate, propionate, and butyrate. This article reviews the current knowledge of the impact of fiber and prebiotic consumption on the composition and metabolic function of the human gastrointestinal microbiota, including the effects of physiochemical properties of complex carbohydrates, adequate intake and treatment dosages, and the phenotypic responses related to the composition of the human microbiota.
IMPACT OF FOOD ENRICHED WITH DIETARY FIBER ON PATIENTS WITH CONSTIPATION PREDOMINANT IRRITABLE BOWEL SYNDROME.
Sulaberidze G,Okujava M,Liluashvili K,Tughushi M,Abramashvili M
Georgian medical news
The causes of motility disorder of gastrointestinal tract and in particular Irritable Bowel Syndrome IBS are multifold, leading to complexity of treatment and requirement of more precise investigation of different pharmacological and non-pharmacological approaches. The aim of the study was investigation and comparison of the dietary fiber intake among women with constipation-predominant irritable bowel syndrome (IBS-C) and without, improvement of the dietary fiber intake using interventions with less rough changes of food related behavior and study of its effects on the bowel function, general wellbeing and compliance of patients. In total 100 healthy women, without any clinical signs of gastrointestinal disorders and 98 women who met Rome III criteria of IBS-C were enrolled in the dietary fiber intake assessment survey. The dietary habits of all participants, as well as bowel function, digestive feelings and general wellbeing of patients at baseline, on the 7th and 14th day of dietary intervention was assessed by the means of adopted questionnaires. The dietary supplementation was provided during the breakfast with fiber enriched food - bread and muesli. Research data reviled significantly lower daily intake of dietary fiber among patients with IBS-C compared with healthy group. The main source of dietary fiber in IBS-C group was bread and cereals, therefore introduction of dietary fiber rich bread and muesli in the breakfast didn't affect diet-related habits and determined high compliance of patients. Two week long intervention significantly improved the bowel function and irritation related complains, the feeling of general wellbeing was considerably better on the endpoint as well.
Effects of Higher Dietary Protein and Fiber Intakes at Breakfast on Postprandial Glucose, Insulin, and 24-h Interstitial Glucose in Overweight Adults.
Amankwaah Akua F,Sayer R Drew,Wright Amy J,Chen Ningning,McCrory Megan A,Campbell Wayne W
Dietary protein and fiber independently influence insulin-mediated glucose control. However, potential additive effects are not well-known. Men and women ( = 20; age: 26 ± 5 years; body mass index: 26.1 ± 0.2 kg/m²; mean ± standard deviation) consumed normal protein and fiber (NPNF; NP = 12.5 g, NF = 2 g), normal protein and high fiber (NPHF; NP = 12.5 g, HF = 8 g), high protein and normal fiber (HPNF; HP = 25 g, NF = 2 g), or high protein and fiber (HPHF; HP = 25 g, HF = 8 g) breakfast treatments during four 2-week interventions in a randomized crossover fashion. On the last day of each intervention, meal tolerance tests were completed to assess postprandial (every 60 min for 240 min) serum glucose and insulin concentrations. Continuous glucose monitoring was used to measure 24-h interstitial glucose during five days of the second week of each intervention. Repeated-measures ANOVA was applied for data analyses. The HPHF treatment did not affect postprandial glucose and insulin responses or 24-h glucose total area under the curve (AUC). Higher fiber intake reduced 240-min insulin AUC. Doubling the amount of protein from 12.5 g to 25 g/meal and quadrupling fiber from 2 to 8 g/meal at breakfast was not an effective strategy for modulating insulin-mediated glucose responses in these young, overweight adults.
Dietary fiber and digestive health in children.
Korczak Renee,Kamil Alison,Fleige Lisa,Donovan Sharon M,Slavin Joanne L
Digestive health is an expanding area in nutrition research due to the interest in how food components such as fiber affect gastrointestinal tolerance, stool form, defecation frequency, transit time, and gut microbial composition and metabolic activity. In children, however, digestive health studies that intervene with dietary fiber are limited due to legal and ethical concerns. To better understand if fiber improves digestive health in children, a literature review was conducted to answer the following research question: What are the effect(s) of fiber-containing foods and/or supplements on digestive health outcomes in children? A search of the PubMed database identified a total of 12 studies that fit the inclusion criteria established for this review. Most of the evidence in children shows beneficial effects of partially hydrolyzed guar gum, glucomannan, and bran on digestive health outcomes; however, the existing evidence is not conclusive. Furthermore, limited data exists on the effect of whole-grain sources of dietary fiber, such as oats. Additional well-designed intervention trials are needed to determine whether outcomes of digestive health such as stool form, gastrointestinal tolerance, and stool frequency are improved by increasing the fiber content of children's diets with whole-grain sources.
Dietary fiber intake reduces risk for Barrett's esophagus and esophageal cancer.
Sun Lingli,Zhang Zhizhong,Xu Jian,Xu Gelin,Liu Xinfeng
Critical reviews in food science and nutrition
BACKGROUND:Observational studies suggest an association between dietary fiber intake and risk of Barrett's esophagus and esophageal cancer. However, the results are inconsistent. OBJECTIVE:To conduct a meta-analysis of observational studies to assess this association. DESIGN:All eligible studies were identified by electronic searches in PubMed and Embase through February 2015. Dose-response, subgroup, sensitivity, and publication bias analyses were performed. RESULTS:A total of 15 studies involving 16,885 subjects were included in the meta-analysis. The pooled odds ratio for the highest compared with the lowest dietary fiber intake was 0.52 (95% CI, 0.43-0.64). Stratified analyses for tumor subtype, study design, geographic location, fiber type, publication year, total sample size, and quality score yielded consistent results. Dose-response analysis indicated that a 10-g/d increment in dietary fiber intake was associated with a 31% reduction in Barrett's esophagus and esophageal cancer risk. Sensitivity analysis restricted to studies with control for conventional risk factors produced similar results, and omission of any single study had little effect on the overall risk estimate. CONCLUSIONS:Our findings indicate that dietary fiber intake is inversely associated with risk of Barrett's esophagus and esophageal cancer. Further large prospective studies are warranted.
Dietary Fiber Intake in Relation to Knee Pain Trajectory.
Dai Zhaoli,Lu Na,Niu Jingbo,Felson David T,Zhang Yuqing
Arthritis care & research
OBJECTIVE:Dietary fiber may reduce knee pain, in part by lowering body weight and reducing inflammation. In this study, we assessed whether fiber intake was associated with patterns of knee pain development. METHODS:In a prospective, multicenter cohort of 4,796 men and women ages 45-79 years with or at risk of knee osteoarthritis, participants underwent annual followups for 8 years. Dietary fiber intake was estimated using a validated food frequency questionnaire at baseline. Group-based trajectory modeling was used to identify Western Ontario and McMaster Universities Osteoarthritis Index pain trajectories, which were assessed for associations with dietary fiber intake using polytomous regression models. RESULTS:Of the eligible participants (4,470 persons and 8,940 knees, mean ± SD age 61.3 ± 9.1 years, 58% women), 4.9% underwent knee replacement and were censored at the time of surgery. Four distinct knee pain patterns were identified: no pain (34.5%), mild pain (38.1%), moderate pain (21.2%), and severe pain (6.2%). Dietary total fiber was inversely related to membership in the moderate or severe pain groups (P ≤ 0.006 for trend for both). Subjects in the highest versus those in the lowest quartile of total fiber intake had a lower risk of belonging to the moderate pain pattern group (odds ratio [OR] 0.76 [95% confidence interval (95% CI) 0.61-0.93]) and severe pain pattern group (OR 0.56 [95% CI 0.41-0.78]). Similar results were found with grain fiber and these 2 pain pattern groups. CONCLUSION:Our findings suggest that a high intake of dietary total or grain fiber, particularly the recommended daily fiber average intake of 25 gm per day, is associated with a lower risk of developing moderate or severe knee pain over time.
Dietary fiber in irritable bowel syndrome (Review).
El-Salhy Magdy,Ystad Synne Otterasen,Mazzawi Tarek,Gundersen Doris
International journal of molecular medicine
Irritable bowel syndrome (IBS) is a common chronic gastrointestinal disorder. It is widely believed that IBS is caused by a deficient intake of dietary fiber, and most physicians recommend that patients with IBS increase their intake of dietary fiber in order to relieve their symptoms. However, different types of dietary fiber exhibit marked differences in physical and chemical properties, and the associated health benefits are specific for each fiber type. Short-chain soluble and highly fermentable dietary fiber, such as oligosaccharides results in rapid gas production that can cause abdominal pain/discomfort, abdominal bloating/distension and flatulence in patients with IBS. By contrast, long-chain, intermediate viscous, soluble and moderately fermentable dietary fiber, such as psyllium results in a low gas production and the absence of the symptoms related to excessive gas production. The effects of type of fiber have been documented in the management of IBS, and it is known to improve the overall symptoms in patients with IBS. Dietary fiber acts on the gastrointestinal tract through several mechanisms, including increased fecal mass with mechanical stimulation/irritation of the colonic mucosa with increasing secretion and peristalsis, and the actions of fermentation byproducts, particularly short-chain fatty acids, on the intestinal microbiota, immune system and the neuroendocrine system of the gastrointestinal tract. Fiber supplementation, particularly psyllium, is both safe and effective in improving IBS symptoms globally. Dietary fiber also has other health benefits, such as lowering blood cholesterol levels, improving glycemic control and body weight management.
Effect of Functional Oligosaccharides and Ordinary Dietary Fiber on Intestinal Microbiota Diversity.
Cheng Weiwei,Lu Jing,Li Boxing,Lin Weishi,Zhang Zheng,Wei Xiao,Sun Chengming,Chi Mingguo,Bi Wei,Yang Bingjun,Jiang Aimin,Yuan Jing
Frontiers in microbiology
Functional oligosaccharides, known as prebiotics, and ordinary dietary fiber have important roles in modulating the structure of intestinal microbiota. To investigate their effects on the intestinal microecosystem, three kinds of diets containing different prebiotics were used to feed mice for 3 weeks, as follows: GI (galacto-oligosaccharides and inulin), PF (polydextrose and insoluble dietary fiber from bran), and a GI/PF mixture (GI and PF, 1:1), 16S rRNA gene sequencing and metabolic analysis of mice feces were then conducted. Compared to the control group, the different prebiotics diets had varying effects on the structure and diversity of intestinal microbiota. GI and PF supplementation led to significant changes in intestinal microbiota, including an increase of and a decrease of in the GI-fed, but those changes were opposite in PF fed group. Intriguing, in the GI/PF mixture-fed group, intestinal microbiota had the similar structure as the control groups, and flora diversity was upregulated. Fecal metabolic profiling showed that the diversity of intestinal microbiota was helpful in maintaining the stability of fecal metabolites. Our results showed that a single type of oligosaccharides or dietary fiber caused the reduction of bacteria species, and selectively promoted the growth of or bacteria, resulting in an increase in diamine oxidase (DAO) and/or trimethylamine N-oxide (TMAO) values which was detrimental to health. However, the flora diversity was improved and the DAO values was significantly decreased when the addition of nutritionally balanced GI/PF mixture. Thus, we suggested that maintaining microbiota diversity and the abundance of dominant bacteria in the intestine is extremely important for the health, and that the addition of a combination of oligosaccharides and dietary fiber helps maintain the health of the intestinal microecosystem.
The behavior of dietary fiber in the gastrointestinal tract determines its physiological effect.
Critical reviews in food science and nutrition
A diet rich in dietary fiber (DF) is considered healthy and recommended dietary intake of DF is established all over the world. The physiological effect of DF is mostly related to its behavior during digestion. In this review, the behavior of DF in the human digestive tract is discussed and linked to its physiological effect with special attention to four aspects of such behavior: (i) the modulation of bioavailability by the plant cell walls, (ii) the effect of DF on the rheological and colloidal state of digesta, (iii) the binding of DF with phenolic compounds, bile salts, mineral ions, and digestive enzymes, and (iv) DF fermentation in the large intestine and the corresponding effect on microbiota composition. It is stressed that the detailed chemical characterization of DF is crucial to explain its effect on health and that DF behavior in the digestive tract can be modulated by interactions with other food and meal components so that information of the bare content in DF of food is not sufficient to predict its physiological effect.
Dietary Fiber and Metabolic Syndrome: A Meta-Analysis and Review of Related Mechanisms.
Chen Jia-Ping,Chen Guo-Chong,Wang Xiao-Ping,Qin Liqiang,Bai Yanjie
(1) Background: Dietary fiber intake may provide beneficial effects on the components of metabolic syndrome (MetS); however, observational studies reported inconsistent results for the relationship between dietary fiber intake and MetS risk. We conducted a meta-analysis to quantify previous observational studies and a narrative review to summarize mechanisms involved in the potential relationship. (2) Methods: The literature was searched on PubMed and Web of Science until 28 November 2017. A random-effects model was used to calculate the summary risk estimates. Eleven cross-sectional studies and three cohort studies were included in the meta-analysis. Results from the original studies were reported as odds ratios (ORs) or relative ratios (RRs) of the MetS associated with different levels of dietary fiber intake, and the ORs/RRs comparing the highest with lowest categories of the intake were pooled. (3) Results: For the cross-sectional studies, the pooled OR was 0.70 (95% confidence interval (CI): 0.61-0.82) with evidence of high heterogeneity (² = 74.4%, < 0.001) and publication bias ( for Egger's test < 0.001). After removing four studies, results remained significant (OR = 0.67, 95% CI: 0.58-0.78) and the heterogeneity was largely reduced (² = 32.4%, = 0.181). For the cohort studies, the pooled RR was 0.86 (95% CI: 0.70-1.06). (4) Conclusion: Although the meta-analysis suggests an inverse association between dietary fiber intake and risk of MetS, and the association was supported by a wide range of mechanism studies, the findings are limited by insufficient cohort data. More prospective studies are needed to further verify the association between dietary fiber intake and the risk of MetS.
Dietary Fiber Is Beneficial for the Prevention of Cardiovascular Disease: An Umbrella Review of Meta-analyses.
McRae Marc P
Journal of chiropractic medicine
OBJECTIVE:The purpose of this study was to review previously published meta-analyses on the effectiveness of dietary fiber on cardiovascular disease. METHODS:An umbrella review of all published meta-analyses was performed. A PubMed search from January 1, 1980, to January 31, 2017, was conducted using the following search strategy: (fiber OR glucan OR psyllium OR fructans) AND (meta-analysis OR systematic review). Only English-language publications that provided quantitative statistical analysis on cardiovascular disease, lipid concentrations, or blood pressure were retrieved. RESULTS:Thirty-one meta-analyses were retrieved for inclusion in this umbrella review, and all meta-analyses comparing highest versus lowest dietary fiber intake reported statistically significant reductions in the relative risk (RR) of cardiovascular disease mortality (RR = 0.77-0.83), as well as the incidences of cardiovascular disease (RR = 0.72-0.91), coronary heart disease (RR = 0.76-0.93), and stroke (RR = 0.83-0.93). Meta-analyses on supplementation studies using β-glucan or psyllium fibers also reported statistically significant reductions in both total serum and low-density lipoprotein cholesterol concentrations. CONCLUSION:This review suggests that individuals consuming the highest amounts of dietary fiber intake can significantly reduce their incidence and mortality from cardiovascular disease. Mechanistically, these beneficial effects may be due to dietary fibers' actions on reducing total serum and low-density lipoprotein cholesterol concentrations between 9.3 to 14.7 mg/dL and 10.8 to 13.5 mg/dL, respectively.
Impact of Dietary Fiber Consumption on Insulin Resistance and the Prevention of Type 2 Diabetes.
Weickert Martin O,Pfeiffer Andreas F H
The Journal of nutrition
Large prospective cohort studies consistently show associations of a high dietary fiber intake (>25 g/d in women and >38 g/d in men) with a 20-30% reduced risk of developing type 2 diabetes (T2D), after correction for confounders. It is less well recognized that these effects appear to be mainly driven by high intakes of whole grains and insoluble cereal fibers, which typically are nonviscous and do not relevantly influence postprandial glucose responses [i.e., glycemic index (GI)] or are strongly fermented by the gut microbiota in the colon. In contrast, a dietary focus on soluble, viscous, gel-forming, more readily fermentable fiber intakes derived from fruit and certain vegetables yields mixed results and generally does not appear to reduce T2D risk. Although disentangling types of fiber-rich foods and separating these from possible effects related to the GI is an obvious challenge, the common conclusion that key metabolic effects of high-fiber intake are explained by mechanisms that should mainly apply to the soluble, viscous type can be challenged. More recently, studies in humans and animal models focused on gaining mechanistic insights into why especially high-cereal-fiber (HCF) diets appear to improve insulin resistance (IR) and diabetes risk. Although effects of HCF diets on weight loss are only moderate and comparable to other types of dietary fibers, possible novel mechanisms have emerged, which include the prevention of the absorption of dietary protein and modulation of the amino acid metabolic signature. Here we provide an update of our previous review from 2008, with a focus on mechanistic insights of how HCF diets may improve IR and the risk of developing T2D.
Dietary fiber and risk of irritable bowel syndrome: a case-control study.
Hosseini Oskouie Fatemeh,Vahedi Homayoun,Shahrbaf Mohammad Amin,Sadeghi Amir,Rashidkhani Bahram,Hekmatdoost Azita
Gastroenterology and hepatology from bed to bench
AIM:The purpose of this study was to determine the relationship between dietary fiber intake and risk of irritable bowel syndrome (IBS). BACKGROUND:Patients with IBS are usually concerned about their diet, which can exacerbate or relieve their symptoms. METHODS:In this case-control study, ninety cases and 355 controls were selected from a gastroenterology clinic. Dietary intakes of participants were assessed using a validated and reliable food frequency questionnaire (FFQ). Dietary fiber was calculated according to United States Department of Agriculture (USDA) food composition table. RESULTS:Dietary total fiber intake was significantly associated with lower risk of IBS. The adjusted odds ratio (OR) comparing the highest tertile of dietary total fiber with the lowest tertile was 0.14 (95% CI = 0.71-0.28; P-test for trend <0.001); however, there was no significant association or dose-response trend for higher intakes of soluble, and insoluble fiber separately with risk of IBS. CONCLUSION:Our data indicate that dietary fiber is inversely associated with the risk of IBS. Further prospective studies are needed to confirm these data.
Health Effects and Sources of Prebiotic Dietary Fiber.
Carlson Justin L,Erickson Jennifer M,Lloyd Beate B,Slavin Joanne L
Current developments in nutrition
Prebiotic dietary fibers act as carbon sources for primary and secondary fermentation pathways in the colon, and support digestive health in many ways. Fructooligosaccharides, inulin, and galactooligosaccharides are universally agreed-upon prebiotics. The objective of this paper is to summarize the 8 most prominent health benefits of prebiotic dietary fibers that are due to their fermentability by colonic microbiota, as well as summarize the 8 categories of prebiotic dietary fibers that support these health benefits. Although not all categories exhibit similar effects in human studies, all of these categories promote digestive health due to their fermentability. Scientific and regulatory definitions of prebiotics differ greatly, although health benefits of these compounds are uniformly agreed upon to be due to their fermentability by gut microbiota. Scientific evidence suggests that 8 categories of compounds all exhibit health benefits related to their metabolism by colonic taxa.
Dietary Fiber Treatment Corrects the Composition of Gut Microbiota, Promotes SCFA Production, and Suppresses Colon Carcinogenesis.
Bishehsari Faraz,Engen Phillip A,Preite Nailliw Z,Tuncil Yunus E,Naqib Ankur,Shaikh Maliha,Rossi Marco,Wilber Sherry,Green Stefan J,Hamaker Bruce R,Khazaie Khashayarsha,Voigt Robin M,Forsyth Christopher B,Keshavarzian Ali
Epidemiological studies propose a protective role for dietary fiber in colon cancer (CRC). One possible mechanism of fiber is its fermentation property in the gut and ability to change microbiota composition and function. Here, we investigate the role of a dietary fiber mixture in polyposis and elucidate potential mechanisms using TS4Cre×cAPC° mice. Stool microbiota profiling was performed, while functional prediction was done using PICRUSt. Stool short-chain fatty acid (SCFA) metabolites were measured. Histone acetylation and expression of SCFA butyrate receptor were assessed. We found that SCFA-producing bacteria were lower in the polyposis mice, suggesting a decline in the fermentation product of dietary fibers with polyposis. Next, a high fiber diet was given to polyposis mice, which significantly increased SCFA-producing bacteria as well as SCFA levels. This was associated with an increase in SCFA butyrate receptor and a significant decrease in polyposis. In conclusion, we found polyposis to be associated with dysbiotic microbiota characterized by a decline in SCFA-producing bacteria, which was targetable by high fiber treatment, leading to an increase in SCFA levels and amelioration of polyposis. The prebiotic activity of fiber, promoting beneficial bacteria, could be the key mechanism for the protective effects of fiber on colon carcinogenesis. SCFA-promoting fermentable fibers are a promising dietary intervention to prevent CRC.
The Need to Reassess Dietary Fiber Requirements in Healthy and Critically Ill Patients.
O'Keefe Stephen J D
Gastroenterology clinics of North America
This article provides evidence that current dietary fiber intake levels may be insufficient to maintain colonic mucosal health and defense, and reduce inflammation and cancer risk in otherwise healthy people. Current commercial tube feeds generally overlook the metabolic needs of the colon and may predispose patients to dysbiosis, bacterial overgrowth with pathogens such as Clostridium difficile, and acute colitis. These results raise concern about the wide-scale use of prophylactic antibiotics in the intensive care unit and the use of elemental, fiber-depleted tube feeds. Nutrition support is not complete without the addition of sufficient fiber to meet colonic nutritional needs.
Soluble dietary fiber improves energy homeostasis in obese mice by remodeling the gut microbiota.
Wang Haiyuan,Hong Tao,Li Na,Zang Bin,Wu Xingmao
Biochemical and biophysical research communications
Intervention with dietary fibers is an important strategy to combat the global epidemic of obesity which is a consequence of energy imbalance. However, a possible role of the gut microbiota in effects of dietary fibers on energy homeostasis remains unclear. Here, we treated a high fat diet-induced obese (DIO) mouse model with soluble dietary fiber. Our results showed that soluble dietary fiber reduced body weight gain and the excessive accumulation of white fat tissue in DIO mice. Notably, soluble dietary fiber increased energy expenditure, but not change energy intake in DIO mice. In accordance, 16S rRNA sequencing revealed that the diversity of the gut microbiota was restored by soluble dietary fiber. Moreover, compared with controls, soluble dietary fiber resulted in a decreased ratio of Firmicutes/Bacteroidetes at the phylum level, and an increased relative abundance of the genera Roseburia at the genus level. Taken together, these findings indicate that soluble dietary fiber improves energy homeostasis and prevents obesity by increasing the diversity of the gut microbiota and the colonization of beneficial bacteria.
Complementary effects of cereal and pulse polyphenols and dietary fiber on chronic inflammation and gut health.
Awika Joseph M,Rose Devin J,Simsek Senay
Food & function
Cereal grains and grain pulses are primary staples often consumed together, and contribute a major portion of daily human calorie and protein intake globally. Protective effects of consuming whole grain cereals and grain pulses against various inflammation-related chronic diseases are well documented. However, potential benefits of combined intake of whole cereals and pulses beyond their complementary amino acid nutrition is rarely considered in literature. There is ample evidence that key bioactive components of whole grain cereals and pulses are structurally different and thus may be optimized to provide synergistic/complementary health benefits. Among the most important whole grain bioactive components are polyphenols and dietary fiber, not only because of their demonstrated biological function, but also their major impact on consumer choice of whole grain/pulse products. This review highlights the distinct structural differences between key cereal grain and pulse polyphenols and non-starch polysaccharides (dietary fiber), and the evidence on specific synergistic/complementary benefits of combining the bioactive components from the two commodities. Interactive effects of the polyphenols and fiber on gut microbiota and associated benefits to colon health, and against systemic inflammation, are discussed. Processing technologies that can be used to further enhance the interactive benefits of combined cereal-pulse bioactive compounds are highlighted.
Dietary Fiber Pectin Directly Blocks Toll-Like Receptor 2-1 and Prevents Doxorubicin-Induced Ileitis.
Sahasrabudhe Neha M,Beukema Martin,Tian Lingmin,Troost Berit,Scholte Jan,Bruininx Erik,Bruggeman Geert,van den Berg Marco,Scheurink Anton,Schols Henk A,Faas Marijke M,de Vos Paul
Frontiers in immunology
Dietary carbohydrate fibers are known to prevent immunological diseases common in Western countries such as allergy and asthma but the underlying mechanisms are largely unknown. Until now beneficial effects of dietary fibers are mainly attributed to fermentation products of the fibers such as anti-inflammatory short-chain fatty acids (SCFAs). Here, we found and present a new mechanism by which dietary fibers can be anti-inflammatory: a commonly consumed fiber, pectin, blocks innate immune receptors. We show that pectin binds and inhibits, toll-like receptor 2 (TLR2) and specifically inhibits the proinflammatory TLR2-TLR1 pathway while the tolerogenic TLR2-TLR6 pathway remains unaltered. This effect is most pronounced with pectins having a low degree of methyl esterification (DM). Low-DM pectin interacts with TLR2 through electrostatic forces between non-esterified galacturonic acids on the pectin and positive charges on the TLR2 ectodomain, as confirmed by testing pectin binding on mutated TLR2. The anti-inflammatory effect of low-DM pectins was first studied in human dendritic cells and mouse macrophages and was subsequently tested in TLR2-dependent ileitis in a mouse model. In these mice, ileitis was prevented by pectin administration. Protective effects were shown to be TLR2-TLR1 dependent and independent of the SCFAs produced by the gut microbiota. These data suggest that low-DM pectins as a source of dietary fiber can reduce inflammation through direct interaction with TLR2-TLR1 receptors.
Dietary Fiber and Telomere Length in 5674 U.S. Adults: An NHANES Study of Biological Aging.
Tucker Larry A
The relationship between fiber intake and telomere length was evaluated using a cross-sectional design and an NHANES sample of 5674 U.S. adults. Another purpose was to test the impact of potential confounders on the association. Fiber consumption was measured using a 24 h recall and telomere length was indexed using the quantitative polymerase chain reaction method. Overall, the U.S. adults had low fiber intake (median: 6.6 g per 1000 kcal)-less than one-half the recommendation of the Dietary Guidelines for Americans. With age, gender, race, housing status, and misreported energy intake controlled, the relationship between fiber intake per 1000 kcal and telomere length was linear ( = 9.5, = 0.0045). Specifically, for each 1 g increment in fiber intake per 1000 kcal, telomeres were 8.3 base pairs longer. Because each additional year of chronological age was associated with telomeres that were 15.5 base pairs shorter, results suggest that a 10 g increase in fiber intake per 1000 kcal would correspond with telomeres that are 83 base pairs longer. On average, this would equate to 5.4 fewer years of biologic aging (83 ÷ 15.5). With smoking, BMI, alcohol use, and physical activity controlled, as well as the other covariates, each 10 g increment in fiber accounted for telomeres that were 67 base pairs longer ( = 7.6, = 0.0101), a biologic aging difference of about 4.3 years. In conclusion, significant fiber consumption accounts for longer telomeres and less biologic aging than lower levels of fiber intake.
Dietary Fiber Intake and Type 2 Diabetes Mellitus: An Umbrella Review of Meta-analyses.
McRae Marc P
Journal of chiropractic medicine
OBJECTIVE:The purpose of this study was to review previously published meta-analyses on the effectiveness of dietary fiber on type 2 diabetes. METHODS:An umbrella review of all published meta-analyses was performed. A PubMed search from January 1, 1980, to April 30, 2017, was conducted using the following search strategy: (fiber OR glucan OR psyllium) AND (meta-analysis OR systematic review). Only English-language publications that provided quantitative statistical analysis on type 2 diabetes, fasting blood glucose concentrations, or glycosylated hemoglobin were retrieved. RESULTS:Sixteen meta-analyses were retrieved for inclusion in this umbrella review. In the meta-analyses comparing highest versus lowest dietary fiber intake, there was a statistically significant reduction in the relative risk (RR) of type 2 diabetes (RR = 0.81-0.85), with the greatest benefit coming from cereal fibers (RR = 0.67-0.87). However, statistically significant heterogeneity was observed in all of these meta-analyses. In the meta-analyses of supplementation studies using β-glucan or psyllium fibers on type 2 diabetic participants, statistically significant reductions were identified in both fasting blood glucose concentrations and glycosylated hemoglobin percentages. CONCLUSION:This review suggests that those consuming the highest amounts of dietary fiber, especially cereal fiber, may benefit from a reduction in the incidence of developing type 2 diabetes. There also appears to be a small reduction in fasting blood glucose concentration, as well as a small reduction in glycosylated hemoglobin percentage for individuals with type 2 diabetes who add β-glucan or psyllium to their daily dietary intake.
Dietary Fiber Intake and Risk of Chronic Obstructive Pulmonary Disease: A Prospective Cohort Study of Men.
Kaluza Joanna,Harris Holly,Wallin Alice,Linden Anders,Wolk Alicja
Epidemiology (Cambridge, Mass.)
BACKGROUND:The limited literature suggests that dietary fiber intake from whole grains, fruits, and vegetables is negatively associated with chronic obstructive pulmonary disease (COPD) via fiber's anti-inflammatory properties. Therefore, we investigated the association between total fiber and fiber sources and risk of COPD in the population-based prospective Cohort of Swedish Men (45,058 men, ages 45-79 years) with no history of COPD at baseline. METHODS:Dietary fiber intake was assessed with a self-administered questionnaire in 1997 and was energy adjusted using the residual method. Cox proportional hazard regression models were used to estimate hazard ratios (HRs) with 95% confidence intervals (95% CIs) adjusted for potential confounders. RESULTS:During a mean follow-up of 13.1 years (1998-2012), 1,982 incident cases of COPD were ascertained via linkage to the Swedish health registers. A strong inverse association between total fiber intake (≥36.8 vs. <23.7 g/day) and COPD was observed in current smokers (hazard ratio [HR] = 0.54; 95% confidence interval [CI] = 0.43, 0.67) and ex-smokers (HR = 0.62; 95% CI = 0.50, 0.78) but not in never smokers (HR = 0.93; 95% CI = 0.60, 1.45; P interaction = 0.04). For cereal fiber, HRs for highest versus lowest quintile were 0.62 (95% CI = 0.51, 0.77; P trend < 0.001) in current smokers and 0.66 (95% CI = 0.52, 0.82; P trend < 0.001) in ex-smokers; for fruit fiber, the HR was 0.65 (95% CI = 0.52, 0.81; P trend < 0.001) in current smokers and 0.77 (95% CI = 0.61, 0.98; P trend = 0.17) in ex-smokers; and for vegetable fiber, it was 0.71 (95% CI = 0.57, 0.88; P trend = 0.003) in current smokers and 0.92 (95% CI = 0.71, 1.19; P trend = 0.48) in ex-smokers. CONCLUSIONS:Our findings indicate that high fiber intake was inversely associated with COPD incidence in men who are current or ex-smokers.
Dietary Fiber, C-Reactive Protein, and Leisure-Time Physical Activity Among U.S. Adults.
Richardson M Ryan,Arikawa Andrea Y,Churilla James R
Metabolic syndrome and related disorders
BACKGROUND:Some evidence suggests an inverse association between increased fiber intake and C-reactive protein (CRP). However, few studies have examined the associations among CRP, dietary fiber, and leisure-time physical activity (LTPA) in a nationally representative sample of U.S. adults. METHODS:Sample (n = 8372) included adults (≥20 years of age) who participated in the 2007-2010 National Health and Nutrition Examination Survey. Tertiles of reported fiber intake were created. The dependent variable was elevated CRP (>3-10 mg/L). Logistic regression models were stratified by LTPA participation and adjusted for age, gender, race, waist circumference (WC), and standing height. RESULTS:In adults reporting any volume of LTPA participation, increased fiber intake was significantly (P < 0.05 for the upper tertile of fiber intake) associated with lower odds of having an elevated CRP concentration when compared with the lowest tertile. Similar associations were not revealed in analyses limited to adults reporting no LTPA participation. After additional adjustment for WC and standing height, this protective association was no longer statistically significant. CONCLUSIONS:Results suggest that WC and standing height may mediate the beneficial association between increased fiber intake and lower odds of elevated CRP in adults reporting LTPA participation.
Dietary fiber and health outcomes: an umbrella review of systematic reviews and meta-analyses.
Veronese Nicola,Solmi Marco,Caruso Maria Gabriella,Giannelli Gianluigi,Osella Alberto R,Evangelou Evangelos,Maggi Stefania,Fontana Luigi,Stubbs Brendon,Tzoulaki Ioanna
The American journal of clinical nutrition
Background:Several studies have suggested that higher consumption of dietary fiber is beneficial for a variety of health outcomes. However, many results have been inconclusive and, to our knowledge, there has been no attempt to systematically capture the breadth of outcomes associated with dietary fiber intake or to systematically assess the quality and the strength of the evidence on the associations of dietary fiber intake and different health outcomes or medical conditions. Objective:The aim of this study was to describe the diverse health outcomes convincingly associated with dietary fiber consumption. Design:This was an umbrella review of systematic reviews with meta-analysis of observational studies. For each association, random-effects summary effect size, 95% CIs, and 95% prediction intervals were estimated. We also assessed heterogeneity, evidence for small-study effect, and evidence for excess significance bias. We used these metrics to evaluate the credibility of the identified evidence. Results:Our literature search identified 1351 abstracts. Of these, 18 meta-analyses including a total of 298 prospective observational studies and 21 outcomes were included. Outcomes studied included cancer and precancer lesions (n = 12), cardiovascular diseases (CVDs; n = 3), all-cause and specific-cause mortality (n = 4), type 2 diabetes (n = 1), and Crohn disease (n = 1). Overall, 6 (29%) of the 21 eligible outcomes reported highly significant summary results (P < 1 × 10-6); these included CVD and CVD mortality, coronary artery disease, pancreatic cancer, and gastric cancer. Overall, 3 of 21 (14%) outcomes presented convincing evidence (pancreatic cancer, CVD mortality, and all-cause mortality), but only CVD and all-cause mortality were based on prospective studies. Two other outcomes (10%), CVD and coronary artery disease, presented highly suggestive evidence based on prospective studies. Conclusion:Our results support dietary recommendations that promote higher fiber intake as part of a healthy diet.
Dietary Fiber Intake in Children With Inflammatory Bowel Disease.
Pituch-Zdanowska Aleksandra,Albrecht Piotr,Banasiuk Marcin,Banaszkiewicz Aleksandra
Journal of pediatric gastroenterology and nutrition
OBJECTIVES:The aim of the study was to estimate intake of total dietary fiber, and its soluble and insoluble fractions, by children with inflammatory bowel disease (IBD) in comparison with healthy controls. METHODS:This was a prospective controlled study on children with IBD. Food consumption data were collected by using the 3-day diet record. For intake of soluble and insoluble fibers author's questionnaire was used. RESULTS:The study included 50 children with IBD (80% in clinical remission) and 50 healthy controls. There were no statistically significant differences in age, weight, height, and BMI percentiles between both groups. The mean disease duration was 3.5 ± 2.5 years. The daily median dietary fiber intake in patients was 15.3 ± 4.2 g, whereas controls consumed about 14.1 ± 3.6 g/day; differences were not statistically significant. The median intake of soluble fiber in the study group was 5.0 g/day and in controls 4.7 g/day, whereas the intake of insoluble fractions was 10.2 versus 9.7 g/day, respectively. The total fiber intake significantly increased with age and it was higher among boys in each age group. The boys better achieved adequate intake recommendations (P = 0.003). Both, children with IBD and healthy controls, did not meet the adequate intake recommendations. CONCLUSIONS:Intake of fiber in patients with IBD and healthy controls was comparable; however, in both groups, it was lower than recommended.
Dietary Fiber Intake and Metabolic Syndrome Risk Factors among Young South African Adults.
Sekgala Machoene D,Mchiza Zandile J,Parker Whadi-Ah,Monyeki Kotsedi D
This study attempts to bridge the research gap regarding the importance of dietary fiber in reducing metabolic syndrome (MetS) risk factors in young rural South Africans. A total of 627 individuals (309 males and 318 females) aged 18–30 years participated in the study. Dietary intake was measured using a validated 24-h recall method. The consumption of different types of dietary fiber (total, soluble, and insoluble) was calculated and presented as grams. Anthropometrics, blood pressure, fasting blood glucose, and lipid profiles were measured according to standard protocols. According to the definition of the International Diabetes Federation (IDF), the prevalence of MetS was 23.1%. Overall, the total median [interquartile range (IQR)] values for total, insoluble, and soluble fiber consumed were 4.6 g [0.0–48.9], 0.0 g [0.0–18.0], and 0.0 g [0.0–15.0], respectively. Females had a higher median [IQR] intake of total (5.1 g [0.0–48.9] vs. 4.3 g [0.0–43.9]), insoluble (0.0 g [0.0–18.0] vs. 0.0 g [0.0–12.0]), and soluble fiber (0.0 g [0.0–14.9] vs. 0.0 g [0.0–7.3]) than males, respectively. The mean values for waist circumference, fasting blood glucose, and total cholesterol were higher in females than males (82.20 cm vs. 75.07 cm; 5.59 mmol/L vs. 5.44 mmol/L; and 4.26 mmol/L vs. 4.03 mmol/L, respectively), with significant differences observed for waist circumference and total cholesterol ( < 0.001 and = 0.005, respectively). More than 97% of participants had fiber intakes below the recommended levels. After adjusting for all potential confounders (age, gender, and energy), log total fiber was inversely associated with fasting blood glucose (β = −0.019, 95% CI [−0.042 to 0.003], < 0.05), systolic blood pressure (β = −0.002, 95% CI [−0.050 to 0.002], < 0.05) and high-density lipoprotein cholesterol (β = −0.085, 95% CI [−0.173 to 0.002], = 0.051) This study may be of public health relevance, providing a potential link between less dietary fiber intake and fasting blood glucose (FBG) and both systolic and diastolic blood pressure. Therefore, this observational data encourages public health policy measures to increase the consumption of dietary fiber in rural communities in order to lower the burden of MetS and its associated risk factors.
Effect of Dietary Fiber and Metabolites on Mast Cell Activation and Mast Cell-Associated Diseases.
Folkerts Jelle,Stadhouders Ralph,Redegeld Frank A,Tam See-Ying,Hendriks Rudi W,Galli Stephen J,Maurer Marcus
Frontiers in immunology
Many mast cell-associated diseases, including allergies and asthma, have seen a strong increase in prevalence during the past decades, especially in Western(ized) countries. It has been suggested that a Western diet may contribute to the prevalence and manifestation of allergies and asthma through reduced intake of dietary fiber and the subsequent production of their metabolites. Indeed, dietary fiber and its metabolites have been shown to positively influence the development of immune disorders changes in microbiota composition and the regulation of B- and T-cell activation. However, the effects of these dietary components on the activation of mast cells, key effector cells of the inflammatory response in allergies and asthma, remain poorly characterized. Due to their location in the gut and vascularized tissues, mast cells are exposed to high concentrations of dietary fiber and/or its metabolites. Here, we provide a focused overview of current findings regarding the direct effects of dietary fiber and its various metabolites on the regulation of mast cell activity and the pathophysiology of mast cell-associated diseases.
The Association of Dietary Fiber Intake with Cardiometabolic Risk in Four Countries across the Epidemiologic Transition.
Lie Louise,Brown Laquita,Forrester Terrence E,Plange-Rhule Jacob,Bovet Pascal,Lambert Estelle V,Layden Brian T,Luke Amy,Dugas Lara R
The greatest burden of cardiovascular disease is now carried by developing countries with cardiometabolic conditions such as metabolic syndrome, obesity and inflammation believed to be the driving force behind this epidemic. Dietary fiber is known to have protective effects against obesity, type 2 diabetes, cardiovascular disease and the metabolic syndrome. Considering the emerging prevalence of these cardiometabolic disease states across the epidemiologic transition, the objective of this study is to explore these associations of dietary fiber with cardiometabolic risk factors in four countries across the epidemiologic transition. We examined population-based samples of men and women, aged 25⁻45 of African origin from Ghana, Jamaica, the Seychelles and the USA. Ghanaians had the lowest prevalence of obesity (10%), while Jamaicans had the lowest prevalence of metabolic syndrome (5%) across all the sites. Participants from the US presented with the highest prevalence of obesity (52%), and metabolic syndrome (22%). Overall, the Ghanaians consumed the highest dietary fiber (24.9 ± 9.7 g), followed by Jamaica (16.0 ± 8.3 g), the Seychelles (13.6 ± 7.2 g) and the lowest in the USA (14.2 ± 7.1 g). Consequently, 43% of Ghanaians met the fiber dietary guidelines (14 g/1000 kcal/day), 9% of Jamaicans, 6% of Seychellois, and only 3% of US adults. Across all sites, cardiometabolic risk (metabolic syndrome, inflammation and obesity) was inversely associated with dietary fiber intake, such that the prevalence of metabolic syndrome was 13% for those in the lowest quartile of fiber intake, compared to 9% those in the highest quartile of fiber intake. Notably, twice as many of participants (38%) in the lowest quartile were obese compared to those in the highest quartile of fiber intake (18%). These findings further support the need to incorporate strategies and policies to promote increased dietary fiber intake as one component for the prevention of cardiometabolic risk in all countries spanning the epidemiologic transition.
High fiber dietary and sodium butyrate attenuate experimental autoimmune hepatitis through regulation of immune regulatory cells and intestinal barrier.
Hu En-De,Chen Da-Zhi,Wu Jin-Lu,Lu Feng-Bin,Chen Lu,Zheng Ming-Hua,Li Hui,Huang Yu,Li Ji,Jin Xiao-Ya,Gong Yue-Wen,Lin Zhuo,Wang Xiao-Dong,Xu Lan-Man,Chen Yong-Ping
Autoimmune hepatitis (AIH) is chronic autoimmune liver disease accompanied with the imbalance of Treg/Th17 and increased intestinal permeability. We investigated the effects of a high fiber diet and sodium butyrate on the Treg/Th17 and intestinal barrier function in an experimental autoimmune hepatitis. Intraperitoneal injection of hepatic antigen (S100) was used to induce experimental autoimmune hepatitis mice model and mice were divided into normal control, S100 model control, S100 plus high fiber diet and S100 plus sodium butyrate. Serum aminotransferases and liver histology were examined. Short chain fatty acids in feces were determined by HPLC. The ratio of CD4 + C25 + Foxp3+ Treg and CD4 + IL-17 + Th17 were evaluated by flow cytometry. Tight junction proteins Zonula ocluden, Occludin and Claudin-1 were used to assess intestinal barrier function, so does Escherichia coli protein in the liver. Mice fed with either high fiber diet or sodium butyrate showed significantly lower levers of serum aminotransferases and minor liver injury compared to that of model control. Moreover, the ratio of Treg/Th17 was significantly higher in high fiber diet and sodium butyrate fed mice than that in model control. Furthermore, high fiber diet and sodium butyrate significantly increased intestinal tight junction proteins and decreased Escherichia Coli protein in the liver. In conclusion, high fiber diet and sodium butyrate can attenuate development of autoimmune hepatitis through regulation of immune regulatory cells and intestinal barrier function.
Epigenome-Wide Association Study of Dietary Fiber Intake in African American Adolescents.
Chen Li,Dong Yanbin,Wang Xiaoling,Hao Guang,Huang Ying,Gutin Bernard,Zhu Haidong
Molecular nutrition & food research
SCOPE:Low fiber intake is associated with increased risk for cardiovascular disease (CVD) and cancer. However, the underlying mechanisms are not well understood. Two hypotheses are tested: 1) dietary fiber would be associated with DNA methylation levels; 2) those DNA methylation changes would be associated with visceral adiposity and inflammation. Also the possibility that the associations between fiber and DNA methylation levels might be confounded with folic acid intake as sensitivity analysis are explored. METHODS AND RESULTS:An epigenome-wide association study is conducted using Illumina 450K Bead-Chip on leukocyte DNA in 284 African American adolescents. Linear regression is performed to identify differentially methylated CpG sites associated with fiber. The methylation levels of 3 CpG sites (cg15200711, cg19462022, and cg07035602) in LPCAT1 and RASA3 genes are associated with fiber (false discovery rate [FDR] < 0.05) after adjustment for covariates including folic acid. The methylation levels of cg07035602 and cg19462022 are also associated with visceral adiposity and inflammation. CONCLUSIONS:The data show that DNA methylation levels at LPCAT1 and RASA3 genes are associated with dietary fiber intake as well as with adiposity and inflammation. Future studies are warranted to determine whether epigenetic regulation may underlie the beneficial effects of fiber intake on adiposity and inflammation.
Dietary fiber intervention on gut microbiota composition in healthy adults: a systematic review and meta-analysis.
So Daniel,Whelan Kevin,Rossi Megan,Morrison Mark,Holtmann Gerald,Kelly Jaimon T,Shanahan Erin R,Staudacher Heidi M,Campbell Katrina L
The American journal of clinical nutrition
Background:Dysfunction of the gut microbiota is frequently reported as a manifestation of chronic diseases, and therefore presents as a modifiable risk factor in their development. Diet is a major regulator of the gut microbiota, and certain types of dietary fiber may modify bacterial numbers and metabolism, including short-chain fatty acid (SCFA) generation. Objective:A systematic review and meta-analysis were undertaken to assess the effect of dietary fiber interventions on gut microbiota composition in healthy adults. Design:A systematic search was conducted across MEDLINE, EMBASE, CENTRAL, and CINAHL for randomized controlled trials using culture and/or molecular microbiological techniques evaluating the effect of fiber intervention on gut microbiota composition in healthy adults. Meta-analyses via a random-effects model were performed on alpha diversity, prespecified bacterial abundances including Bifidobacterium and Lactobacillus spp., and fecal SCFA concentrations comparing dietary fiber interventions with placebo/low-fiber comparators. Results:A total of 64 studies involving 2099 participants were included. Dietary fiber intervention resulted in higher abundance of Bifidobacterium spp. (standardized mean difference (SMD): 0.64; 95% CI: 0.42, 0.86; P < 0.00001) and Lactobacillus spp. (SMD: 0.22; 0.03, 0.41; P = 0.02) as well as fecal butyrate concentration (SMD: 0.24; 0.00, 0.47; P = 0.05) compared with placebo/low-fiber comparators. Subgroup analysis revealed that fructans and galacto-oligosaccharides led to significantly greater abundance of both Bifidobacterium spp. and Lactobacillus spp. compared with comparators (P < 0.00001 and P = 0.002, respectively). No differences in effect were found between fiber intervention and comparators for α-diversity, abundances of other prespecified bacteria, or other SCFA concentrations. Conclusions:Dietary fiber intervention, particularly involving fructans and galacto-oligosaccharides, leads to higher fecal abundance of Bifidobacterium and Lactobacillus spp. but does not affect α-diversity. Further research is required to better understand the role of individual fiber types on the growth of microbes and the overall gut microbial community. This review was registered at PROSPERO as CRD42016053101.
Synbiotic Effects of the Dietary Fiber Long-Chain Inulin and Probiotic Lactobacillus acidophilus W37 Can be Caused by Direct, Synergistic Stimulation of Immune Toll-Like Receptors and Dendritic Cells.
Lépine Alexia,de Vos Paul
Molecular nutrition & food research
SCOPE:Synbiotic effects of dietary fibers and lactobacilli are usually explained by synergistic modulation of gut microbiota. New insight, however, has demonstrated that both dietary fibers and lactobacilli can directly stimulate immune cells and benefit consumer immunity. Here, the synergistic effects of immune active long-chain inulin (lcITF) and Lactobacillus acidophilus W37 (LaW37) on dendritic cells (DCs) are investigated. METHODS AND RESULTS:Effects of lcITF and LaW37 alone or combined were studied on Toll-like receptor (TLRs) signaling and cytokine secretion by DCs in the presence and absence of media of intestinal epithelial cell (IEC) exposed to the ingredients. Also, the effects of DC responses against Salmonella Typhimurium (STM) were investigated. Synergistic effects were observed on TLR2 and 3. Synergistic effects were not always pro-inflammatory. LaW37 was strongly pro-inflammatory, while cytokine responses were regulatory when combined with lcITF. Exposure of DCs to IECs medium changed the DCs' response, which revealed synergistic enhancing effects of lcITF/LaW37 on production of IL-6 and IL-8. DCs' response in the presence of STM and LaW37 were so strong that lcITF had no additional effect. CONCLUSION:It is demonstrated that synbiotic effects of dietary fibers and bacteria are not limited to the effects on gut microbiota but can also occur by synergistically directly stimulating IECs and/or immune cells.
The Impact of Dietary Fiber on Gut Microbiota in Host Health and Disease.
Makki Kassem,Deehan Edward C,Walter Jens,Bäckhed Fredrik
Cell host & microbe
Food is a primordial need for our survival and well-being. However, diet is not only essential to maintain human growth, reproduction, and health, but it also modulates and supports the symbiotic microbial communities that colonize the digestive tract-the gut microbiota. Type, quality, and origin of our food shape our gut microbes and affect their composition and function, impacting host-microbe interactions. In this review, we will focus on dietary fibers, which interact directly with gut microbes and lead to the production of key metabolites such as short-chain fatty acids, and discuss how dietary fiber impacts gut microbial ecology, host physiology, and health. Hippocrates' notion "Let food be thy medicine and medicine be thy food" remains highly relevant millennia later, but requires consideration of how diet can be used for modulation of gut microbial ecology to promote health.
The Benefits of Dietary Fiber Intake on Reducing the Risk of Cancer: An Umbrella Review of Meta-analyses.
McRae Marc P
Journal of chiropractic medicine
OBJECTIVE:The purpose of this study was to review previously published meta-analyses on the effectiveness of dietary fiber on reducing the incidence of cancer. METHODS:An umbrella review of all published meta-analyses was performed. A PubMed search from January 1, 1980 to June 30, 2017 was conducted using the following search strategy: (fiber OR fibre) AND (meta-analysis OR systematic review) AND (cancer OR carcinoma). Only English-language publications that provided quantitative statistical analysis on cancer were retrieved. RESULTS:Nineteen meta-analyses comparing highest vs lowest dietary fiber intake were retrieved for inclusion in this umbrella review. There was a statistically significant reduction in the relative risk (RR) of colorectal, esophageal, gastric, and pancreatic cancer (RR = 0.52-0.88); however, statistically significant heterogeneity was observed in the meta-analyses on esophageal, gastric, and pancreatic cancer. There was a statistically significant reduction in the RR of breast cancer (RR = 0.85-0.93). CONCLUSION:This review suggests that those consuming the highest amounts of dietary fiber may benefit from a reduction in the incidence of developing colorectal cancer, and there also appears to be a small reduction in the incidence of breast cancer.
Dietary Fiber Intake and Endometrial Cancer Risk: A Systematic Review and Meta-Analysis.
Chen Kangning,Zhao Qianyu,Li Xiaofan,Zhao Jing,Li Peiqin,Lin Shuchun,Wang Hongwei,Zang Jiajie,Xiao Ying,Xu Wanghong,Chen Fuxue,Gao Ying
Epidemiological studies are inconclusive regarding the association between dietary fiber intake and endometrial cancer risk. Thus, we aimed to conduct a meta-analysis to clarify the association between dietary fiber and endometrial cancer risk. We searched the PubMed and ISI Web databases for relevant studies through March 2018. The association between dietary fiber and endometrial cancer risk was evaluated by conducting a meta-analysis including 3 cohort and 12 case⁻control studies. A significant negative association was observed between total dietary fiber intake and endometrial cancer risk in 11 case⁻control studies (odds ratios (OR) 0.76, 95% confidence interval (CI): 0.64⁻0.89, ² = 35.2%, = 0.117), but a marginal positive association was observed in three cohort studies (relative risk (RR) 1.22, 95% CI: 1.00⁻1.49, ² = 0.0%, = 0.995). Particularly, a negative association was observed in North America (OR = 0.70, 95% CI: 0.59⁻0.83, ² = 8.9%, = 0.362). In addition, a positive association was observed in cereal fiber (RR = 1.26, 95% CI: 1.03⁻1.52, ² = 0.0%, = 0.530, 3 cohort studies) and a negative association was observed in vegetable fiber (OR = 0.74, 95% CI: 0.58⁻0.94, ² = 0.0%, = 0.445, 3 case⁻control studies). In conclusion, negative associations with endometrial cancer risk were observed for higher total dietary fiber intake and higher vegetable fiber intake in the case⁻control studies. However, results from the cohort studies suggested positive relationships of higher total fiber intake and higher cereal fiber intake with endometrial cancer risk.
Dietary non-fermentable fiber prevents autoimmune neurological disease by changing gut metabolic and immune status.
Berer Kerstin,Martínez Inés,Walker Alesia,Kunkel Birgit,Schmitt-Kopplin Philippe,Walter Jens,Krishnamoorthy Gurumoorthy
The autoimmune neurological disease, Multiple Sclerosis (MS), have increased at alarming rates in the Western society over the last few decades. While there are numerous efforts to develop novel treatment approaches, there is an unmet need to identify preventive strategies. We explored whether central nervous system (CNS) autoimmunity can be prevented through dietary manipulation using a spontaneous autoimmune encephalomyelitis mouse model. We report that the nutritional supplementation of non-fermentable fiber, common components of a vegetarian diet, in early adult life, prevents autoimmune disease. Dietary non-fermentable fiber alters the composition of the gut microbiota and metabolic profile with an increase in the abundance of long-chain fatty acids. Immune assays revealed that cecal extracts and a long chain fatty acid but not cecal lysates promoted autoimmune suppressive T2 immune responses, demonstrating that non-fermentable fiber-induced metabolic changes account for the beneficial effects. Overall, these findings identify a non-invasive dietary strategy to prevent CNS autoimmunity and warrants a focus on nutritional approaches in human MS.
Dietary fiber intake is associated with a reduced risk of ovarian cancer: a dose-response meta-analysis.
Xu Hui,Ding Yu,Xin Xueling,Wang Weijing,Zhang Dongfeng
Nutrition research (New York, N.Y.)
Dietary fiber may reduce the bioavailability of steroid hormones and favorably regulate insulin-like growth factor 1, and therefore may be associated with ovarian cancer risk. Current evidence on the association between dietary fiber intake and risk of ovarian cancer is inconsistent. Therefore, we conducted a meta-analysis to explore the association. We hypothesized that dietary fiber intake might be associated with a reduced risk of ovarian cancer. PubMed, Web of Science, Embase, China National Knowledge Infrastructure, and Wanfang databases were searched for relevant articles up to September 2017. Summary relative risks (RRs) with 95% confidence intervals (CIs) were calculated using random-effects model. Dose-response relationship was assessed by restricted cubic spline. A total of 19 studies involving 567 742 participants were included in this meta-analysis. The summary RR of the association between dietary fiber intake and ovarian cancer risk was 0.70 (95% CI, 0.57-0.87; I = 83.5%, P < .001). In subgroup analyses, the above-mentioned significant inverse association was found among studies conducted in North America, case-control studies, and studies assessing the association of total fiber intake with ovarian cancer risk. Dose-response analysis suggested that ovarian cancer risk decreased by 3% (RR, 0.97; 95% CI, 0.95-0.99) for each 5-g/d increment in dietary fiber intake. This meta-analysis suggests that dietary fiber intake is associated with a reduced risk of ovarian cancer. Future intervention trials are needed to test the associations between different types of fiber (including soluble, insoluble, vegetable, fruit, cereal, and legumes fiber) and ovarian cancer risk.
Postprandial glucose-lowering effect of premeal consumption of protein-enriched, dietary fiber-fortified bar in individuals with type 2 diabetes mellitus or normal glucose tolerance.
Bae Jae Hyun,Kim Lee Kyung,Min Se Hee,Ahn Chang Ho,Cho Young Min
Journal of diabetes investigation
AIMS/INTRODUCTION:Protein preload improves postprandial glycemia by stimulating secretion of insulin and incretin hormones. However, it requires a large dose of protein to produce a significant effect. The present study was carried out to investigate the postprandial glucose-lowering effect of a premeal protein-enriched, dietary fiber-fortified bar (PFB), which contains moderate amounts of protein, in individuals with type 2 diabetes mellitus or normal glucose tolerance (NGT). MATERIALS AND METHODS:The participants (15 type 2 diabetes mellitus and 15 NGT) were randomly assigned to either a premeal or postmeal PFB group and underwent two mixed meal tolerance tests, 1 week apart in reverse order. Plasma levels of glucose, insulin, glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide were measured. RESULTS:During the mixed meal tolerance tests, the incremental area under the curve from 0 to 180 min of plasma glucose levels was lower with premeal PFB than with postmeal PFB in the type 2 diabetes mellitus (14,723 ± 1,310 mg min/dL vs 19,642 ± 1,367 mg min/dL; P = 0.0002) and NGT participants (3,943 ± 416 mg min/dL vs 4,827 ± 520 mg min/dL, P = 0.0296). In the type 2 diabetes mellitus participants, insulinogenic index and the incremental area under the curve from 0 to 180 min of plasma total glucagon-like peptide-1 levels were higher with premeal PFB than with postmeal PFB, but not in the NGT participants. There was no difference in postprandial glucose-dependent insulinotropic polypeptide levels between premeal and postmeal PFB in both groups. CONCLUSIONS:Acute administration of premeal PFB decreased postprandial glucose excursion in both type 2 diabetes mellitus and NGT participants. In the type 2 diabetes mellitus participants, premeal PFB augmented the early-phase insulin secretion, possibly through enhancing glucagon-like peptide-1 secretion.
Increased Long-term Dietary Fiber Intake Is Associated With a Decreased Risk of Fecal Incontinence in Older Women.
Staller Kyle,Song Mingyang,Grodstein Francine,Whitehead William E,Matthews Catherine A,Kuo Braden,Chan Andrew T
BACKGROUND & AIMS:Fiber supplements are frequently used as treatment for fecal incontinence (FI), but little is known about the role of dietary fiber in the prevention of FI. METHODS:We performed a prospective study to examine the association between long-term dietary fiber intake and risk of FI in 58,330 older women (mean age, 73 years) in the Nurses' Health Study who were free of FI in 2008. Energy-adjusted long-term dietary fiber intake was determined using food frequency questionnaires starting in 1984 and updated through 2006. We defined incident FI as at least 1 liquid or solid FI episode per month during the past year during 4 years of follow-up using self-administered biennial questionnaires. We used Cox proportional hazards models to calculate multivariable-adjusted hazard ratios and 95% CIs for FI according to fiber intake, adjusting for potential confounding factors. RESULTS:During 193,655 person-years of follow-up, we documented 7,056 incident cases of FI. Compared with women in the lowest quintile of fiber intake (13.5 g/day), women in the highest quintile (25 g/day) had an 18% decrease in risk of FI (multivariable hazard ratio, 0.82; 95% CI, 0.76-0.89). This decrease appeared to be greatest for risk of liquid stool FI, which was 31% lower in women with the highest intake of fiber compared with women with the lowest intake (multivariable hazard ratio, 0.69; 95% CI, 0.62-0.75). Risk of FI was not significantly associated with fiber source. CONCLUSIONS:In an analysis of data from almost 60,000 older women in the Nurses' Health Study, we found higher long-term intake of dietary fiber was associated with decreased risk of FI. Further studies are needed to determine the mechanisms that mediate this association.
Dietary fiber intake and risks of proximal and distal colon cancers: A meta-analysis.
Ma Yu,Hu Mingyue,Zhou Lingna,Ling Sunkai,Li Yuan,Kong Bo,Huang Peilin
The purpose of this study was to conduct a systematic review and meta-analysis of studies investigating the relationship between dietary fiber intake and subsite-specific colon cancer.The PubMed database was searched to identify relevant cohort studies published from inception to August 2016 in order to examine individually the association between dietary fiber intake and the risk of proximal colon cancer (PCC), and that between dietary fiber intake and the risk of distal colon cancer (DCC). We searched the reference lists of the studies included in our analysis as well as those listed in the published meta-analyses. A random-effects model was used to compute summary risk estimates. Heterogeneity was assessed using I and Q statistics. Publication bias was assessed with the Egger's and Begg's tests, with a P value of P < .10 indicating publication bias. All statistical tests were 2-sided.We identified and included 11 prospective cohort studies in the final meta-analysis. The risks of PCC and DCC among individuals in the highest dietary fiber intake quartile/quintile were 14% (relative risk [RR] = 0.86, 95% confidence interval [CI] = 0.78-0.95) and 21% (RR = 0.79, 95% CI = 0.71-0.87) lower, respectively, than those among individuals with the lowest dietary fiber intake. In a subgroup analysis, the inverse association observed in the sex-based subgroup was apparent only for men with PCC. Dietary fiber intake was inversely associated with DCC for both men and women. In addition, dietary fiber intake appeared to be inversely associated with PCC only in European countries, whereas this association was observed for DCC in both European countries and the United States.Our findings reveal that dietary fiber intake is associated inversely with the risk of both PCC and DCCs.
Exploration of the association between dietary fiber intake and depressive symptoms in adults.
Xu Hui,Li Suyun,Song Xingxing,Li Zongyao,Zhang Dongfeng
Nutrition (Burbank, Los Angeles County, Calif.)
OBJECTIVE:Current evidence on the association between dietary fiber intake and the risk of depressive symptoms is inconsistent. Thus, the purpose of the present study was to explore their association. METHODS:Data from the National Health and Nutrition Examination Survey 2007 to 2014 were used in this cross-sectional study. Dietary data were obtained through two 24-h dietary recall interviews. Depressive symptoms were assessed using Patient Health Questionnaire. Logistic regression models and restricted cubic spline models were applied to evaluate the associations among dietary intakes of total, cereal, vegetable, and fruit fiber and depressive symptoms. RESULTS:A total of 16 807 adults ages 20 y or older were included in this study. Dietary intakes of total, cereal, vegetable, and fruit fiber were inversely associated with depressive symptoms in unadjusted model and multivariate-adjusted model 1. In multivariate-adjusted model 2, the odds ratios (95% confidence intervals) of depressive symptoms were 0.59 (0.44-0.79), 0.90 (0.69-1.19), 0.58 (0.45-0.76), and 0.64 (0.45-0.92) for the highest versus lowest quartile of total, cereal, vegetable, and fruit fiber intakes, respectively. Dose-response analyses found that the risk of depressive symptoms was associated with total fiber intake in a nonlinear manner, whereas the relationships were linear with cereal, vegetable, and fruit fiber intakes. CONCLUSIONS:Our study suggested that intakes of total fiber, vegetable fiber, and fruit fiber were inversely associated with depressive symptoms. Further larger prospective studies are needed to confirm our findings.
The association among diet, dietary fiber, and bowel preparation at colonoscopy.
Leszczynski Anna M,MacArthur Kristin L,Nelson Kerrie P,Schueler Samuel A,Quatromoni Paula A,Jacobson Brian C
BACKGROUND AND AIMS:Pre-colonoscopy dietary restrictions vary widely and lack evidence-based guidance. We investigated whether fiber and various other foods/macronutrients consumed during the 3 days before colonoscopy are associated with bowel preparation quality. METHODS:This was a prospective observational study among patients scheduled for outpatient colonoscopy. Patients received instructions including split-dose polyethylene glycol, avoidance of vegetables/beans 2 days before colonoscopy, and a clear liquid diet the day before colonoscopy. Two 24-hour dietary recall interviews and 1 patient-recorded food log measured dietary intake on the 3 days before colonoscopy. The Nutrition Data System for Research was used to estimate dietary exposures. Our primary outcome was the quality of bowel preparation measured by the Boston Bowel Preparation Scale (BBPS). RESULTS:We enrolled 201 patients from November 2015 to September 2016 with complete data for 168. The mean age was 59 years (standard deviation, 7 years), and 90% of colonoscopies were conducted for screening/surveillance. Only 17% and 77% of patients complied with diet restrictions 2 and 1 day(s) before colonoscopy, respectively. We found no association between foods consumed 2 and 3 days before colonoscopy and BBPS scores. However, BPPS was positively associated with intake of gelatin, and inversely associated with intake of red meat, poultry, and vegetables on the day before colonoscopy. CONCLUSIONS:Our findings support recent guidelines encouraging unrestricted diets >1 day before colonoscopy if using a split-dose bowel regimen. Furthermore, we found no evidence to restrict dietary fiber 1 day before colonoscopy. We also found evidence to promote consumption of gelatin and avoidance of red meat, poultry, and vegetables 1 day before colonoscopy.
Association between dietary fiber intake and risk of ovarian cancer: a meta-analysis of observational studies.
Huang Xiumin,Wang Xuelian,Shang Jing,Lin Yanzhen,Yang Ying,Song Youyi,Yu Shengnan
The Journal of international medical research
Objective To evaluate the associations between dietary fiber intake and ovarian cancer risk. Methods A literature survey was conducted by searching the PubMed, Web of Science, and Wanfang Med Online databases up to March 1st, 2018. The effect of dietary fiber intake on ovarian cancer risk was evaluated by calculating relative risks with 95% confidence intervals (95%CI) using Stata 12.0 software. Results A total of 17 articles with 149,177 participants including 7609 ovarian cancer patients were included in this analysis. The summarized relative risk for ovarian cancer in participants with the highest compared with the lowest fiber intake was 0.760 (95%CI=0.702-0.823), with no significant between-study heterogeneity ( I=12.4%). Subgroup analysis according to study design demonstrated positive associations in both cohort studies and case-control studies. Moreover, the results were consistent among populations from America, Europe, and Asia. No publication bias was found by Egger's test or funnel plots. Conclusion This meta-analysis concluded that a high intake of dietary fiber could significantly reduce the risk of ovarian cancer compared with a low fiber intake.
Increasing Dietary Fiber Intake Is Associated with a Distinct Esophageal Microbiome.
Nobel Yael R,Snider Erik J,Compres Griselda,Freedberg Daniel E,Khiabanian Hossein,Lightdale Charles J,Toussaint Nora C,Abrams Julian A
Clinical and translational gastroenterology
INTRODUCTION:There is increasing evidence that the microbiome contributes to esophageal disease. Diet, especially fiber and fat intake, is a known potent modifier of the colonic microbiome, but its impact on the esophageal microbiome is not well described. We hypothesized that dietary fiber and fat intake would be associated with a distinct esophageal microbiome. METHODS:We collected esophageal samples from 47 ambulatory patients scheduled to undergo endoscopy who completed a validated food frequency questionnaire quantifying dietary fiber and fat intake. Using 16S high-throughput sequencing, we determined composition of the esophageal microbiome and predicted functional capacity of microbiota based on fiber and fat intake. RESULTS:Among all samples, the most abundant phyla were Firmicutes (54.0%), Proteobacteria (19.0%), Bacteroidetes (17.0%), Actinobacteria (5.2%), and Fusobacteria (4.3%). Increasing fiber intake was significantly associated with increasing relative abundance of Firmicutes (p = 0.04) and decreasing relative abundance of Gram-negative bacteria overall (p = 0.03). Low fiber intake was associated with increased relative abundance of several Gram-negative bacteria, including Prevotella, Neisseria, and Eikenella. Several predicted metabolic pathways differed between highest and lowest quartile of fiber intake. Fat intake was associated with altered relative abundance of few taxa, with no alterations at the phylum level and no changes in microbiome functional composition. CONCLUSIONS:Dietary fiber, but not fat, intake was associated with a distinct esophageal microbiome. Diet should be considered an important modifier of the esophageal microbiome in future studies. Studies are also needed to elucidate how the effects of dietary fiber on the esophageal microbiome may contribute to esophageal disease.
Dietary fiber intake and reduced risk of ovarian cancer: a meta-analysis.
Zheng Bowen,Shen Hui,Han Hedong,Han Ting,Qin Yonghong
BACKGROUND:Epidemiological studies regarding the association between dietary fiber intake and ovarian cancer risk are still inconsistent. We aimed to review the available evidence and conduct a dose-response meta-analysis to investigate the relationship between dietary fiber intake and ovarian cancer risk. METHODS:Relevant studies were identified by searching PubMed, EMBASE, and the Cochrane Library databases before August 2017. Studies that reported relative risk (RR) estimates with 95% confidence intervals (CIs) for the association between dietary fiber intake and risk of ovarian cancer were included. Random-effects models were used to combine the estimated effects extracted from individual study. RESULTS:Thirteen studies, with a total of 5777 ovarian cancer cases and 142,189 participants, met the inclusion criteria. The pooled multivariable RRs of ovarian cancer for the highest vs. the lowest category of dietary fiber intake was 0.78 (95% CI: 0.70, 0.88) with no evidence of heterogeneity (I = 4.20%, P = 0.40). Our dose-response analysis also showed a significant inverse association between dietary fiber intake and ovarian cancer risk (an increment of 10 g/day; combined RR: 0.88; 95% CI: 0.82, 0.93). There was no evidence for a nonlinear association (P for nonlinearity = 0.83). CONCLUSIONS:This meta-analysis suggests a significant inverse dose-response association between dietary fiber intake and ovarian cancer risk. Further studies with prospective design that take account of more potential confounders are warranted to confirm this association.
Gut Permeability Might be Improved by Dietary Fiber in Individuals with Nonalcoholic Fatty Liver Disease (NAFLD) Undergoing Weight Reduction.
Krawczyk Marcin,Maciejewska Dominika,Ryterska Karina,Czerwińka-Rogowska Maja,Jamioł-Milc Dominika,Skonieczna-Żydecka Karolina,Milkiewicz Piotr,Raszeja-Wyszomirska Joanna,Stachowska Ewa
(1) Introduction: Zonulin (ZO) has been proposed as a marker of intestinal permeability. Only a few studies have analyzed to date how diet influences the serum concentration of ZO among patients with non-alcoholic fatty liver disease (NAFLD). We performed a six-month dietetic intervention to evaluate the association between fiber intake and ZO concentration in 32 individuals with NAFLD. (2) Methods: Fiber content in the diet was estimated by Food Frequency Questionnaire (FFQ) and by analyzing 72-h nutritional diaries. ZO concentrations in serum were measured before and after the intervention by immunoenzymatic assay (ELISA). Fatty liver was quantified using the Hamaguchi score before and after the dietetic intervention. (3) Results: During the intervention, the dietary fiber intake increased from 19 g/day to the 29 g/day concomitant with an increase in the frequency of fiber consumption. All patients experienced significant (all < 0.05) improvements in serum aspartate aminotransferase (AST), alanine aminotransferase (ALT) and gamma-glutamyltransferase (GGTP) activities. We also detected decreased serum triglycerides ( = 0.036), homeostatic model assessment insulin resistance (HOMA-IR ( = 0.041) and insulin content ( = 0.34), and improvement of fatty liver status according to the Hamaguchi score ( = 0.009). ZO concentration in serum decreased by nearly 90% (7.335 ± 13.492 vs. 0.507 ± 0.762 ng/mL, = 0.001) and correlated with the amount of dietary fiber intake ( = 0.043) as well as the degree of fatty liver ( = 0.037). (4) Conclusion: Increasing nutritional fiber results in reduced serum ZO levels, reduced liver enzymes and improved hepatic steatosis in patients with NAFLD, possibly by altering intestinal permeability. Increased dietary fiber intake should be recommended in patients with NAFLD.
Added sugar and dietary fiber consumption are associated with creativity in preadolescent children.
Hassevoort Kelsey M,Lin Anna S,Khan Naiman A,Hillman Charles H,Cohen Neal J
Creativity requires the ability to combine existing mental representations in new ways and depends, in part, on the hippocampus. Hippocampal function is, in turn, affected by a number of health factors, including aerobic fitness, excess adiposity, and diet. Specifically, in rodent studies, diets high in saturated fatty acids and sugar - hallmarks of a western diet- have been shown to negatively impact hippocampal function and thereby impair performance on cognitive tasks that require the hippocampus. Yet relatively few studies have examined the relationship between diet and hippocampal-dependent cognition in children. The current study therefore sought to explore the relationship of several diet quality markers including dietary lipids (saturated fatty acids and omega-3 fatty acids), simple carbohydrates (added sugars), and dietary fiber with creativity in preadolescent children. Participants (N = 57; mean age = 9.1 years) completed the Verbal Form of the Torrance Test of Creative Thinking (TTCT), a standardized test of creativity known to require the hippocampus. Additionally, participants completed a 3-day food intake record with the assistance of a parent, underwent dual energy x-ray absorptiometry (DXA) to assess central adiposity, and VOmax testing to assess aerobic fitness. Added sugar intake was negatively associated, and dietary fiber was positively associated with overall TTCT performance. These relationships were sustained even after controlling for key covariates. These findings are among the first to report an association between added sugar consumption and hippocampal-dependent cognition during childhood and, given the key role of the hippocampus in learning and memory, as well as creative thinking, have potential educational and public health implications.
Considerations for best practices in studies of fiber or other dietary components and the intestinal microbiome.
Klurfeld David M,Davis Cindy D,Karp Robert W,Allen-Vercoe Emma,Chang Eugene B,Chassaing Benoit,Fahey George C,Hamaker Bruce R,Holscher Hannah D,Lampe Johanna W,Marette Andre,Martens Eric,O'Keefe Stephen J,Rose Devin J,Saarela Maria,Schneeman Barbara O,Slavin Joanne L,Sonnenburg Justin L,Swanson Kelly S,Wu Gary D,Lynch Christopher J
American journal of physiology. Endocrinology and metabolism
A 2-day workshop organized by the National Institutes of Health and U.S. Department of Agriculture included 16 presentations focused on the role of diet in alterations of the gastrointestinal microbiome, primarily that of the colon. Although thousands of research projects have been funded by U.S. federal agencies to study the intestinal microbiome of humans and a variety of animal models, only a minority addresses dietary effects, and a small subset is described in sufficient detail to allow reproduction of a study. Whereas there are standards being developed for many aspects of microbiome studies, such as sample collection, nucleic acid extraction, data handling, etc., none has been proposed for the dietary component; thus this workshop focused on the latter specific point. It is important to foster rigor in design and reproducibility of published studies to maintain high quality and enable designs that can be compared in systematic reviews. Speakers addressed the influence of the structure of the fermentable carbohydrate on the microbiota and the variables to consider in design of studies using animals, in vitro models, and human subjects. For all types of studies, strengths and weaknesses of various designs were highlighted, and for human studies, comparisons between controlled feeding and observational designs were discussed. Because of the lack of published, best-diet formulations for specific research questions, the main recommendation is to describe dietary ingredients and treatments in as much detail as possible to allow reproduction by other scientists.
Effects of Dietary Fiber Supplementation on Fatty Acid Metabolism and Intestinal Microbiota Diversity in C57BL/6J Mice Fed with a High-Fat Diet.
Zhai Xichuan,Lin Dehui,Zhao Yan,Li Wenwen,Yang Xingbin
Journal of agricultural and food chemistry
This work was to assess possible impacts of novel insoluble fiber 8% bacterial cellulose (BC), soluble fiber 8% konjac glucomannan (KGM), and their mixture (4% BC/4% KGM) on fatty acid metabolism and intestinal microbiota of C57BL/6J mice fed with a high-fat diet (HFD). HFD-fed mice receiving the dietary fibers (DFs) for 16 weeks exhibited an improvement in lipid-associated cytokines and a decrease in inflammation factors, which was associated with the improved hepatic and serum fatty acid composition. The DFs, notably the mixed BC/KGM, elevated the HFD-caused decrease in the contents of acetic acid (from 23.9 ± 0.85 to 32.2 ± 0.84 mM/g; p < 0.05), propionic acid (from 6.53 ± 0.28 to 12.8 ± 0.58 mM/g; p < 0.05), and butyric acid (from 7.73 ± 0.43 to 13.5 ± 0.47 mM/g; p < 0.05). Furthermore, the mixed BC/KGM significantly decreased the abundance of Firmicutes (from 90.4 to 67.6%) and Mucispirillum (from 4.77 to 1.58%) and dramatically increased the abundance of Bacteroidetes (from 7.83 to 25.0%) and Akkermansia (from 0.69 to 2.80%) in the gut of HFD-fed mice at the genus level. Moreover, correlation analysis revealed that the multiplicity of gut microbiota was useful in sustaining colonic integrity through producing short-chain fatty acids to some extent. This finding suggests that a mixture of insoluble BC and soluble KGM has positive effects on modulation of the intestinal microecosystem in mice.
Body Mass Index Mediates the Association between Dietary Fiber and Symptomatic Knee Osteoarthritis in the Osteoarthritis Initiative and the Framingham Osteoarthritis Study.
Dai Zhaoli,Jafarzadeh S Reza,Niu Jingbo,Felson David T,Jacques Paul F,Li Shanshan,Zhang Yuqing
The Journal of nutrition
Background:Dietary fiber reduces body weight and inflammation in clinical trials. It is unclear whether body mass index (BMI) and inflammation might explain the observed association between higher fiber intake and the lower risk of symptomatic knee osteoarthritis (SXKOA). Objectives:We quantified the extent to which BMI and inflammation influenced the relation between dietary fiber and SXKOA. Methods:We used longitudinal data from the Osteoarthritis Initiative (OAI) and the Framingham Offspring Osteoarthritis Study. At baseline of each study, men and women (mean age: 61 y) with or at risk of knee osteoarthritis were followed for 48 mo in the OAI. Adults (mean age: 53 y) were followed for 9.5 y in the Framingham study. Dietary fiber intake was estimated using a validated food-frequency questionnaire. Measured weight and height were used to calculate BMI. Serum high-sensitivity C-reactive protein (CRP) was measured in the Framingham study only. Incident SXKOA was defined as new onset of a combination of knee pain and radiographic osteoarthritis. We applied marginal structural models to quantify the mediation through BMI in the OAI and the sequential mediation through BMI and CRP in the Framingham study. Results:Incident SXKOA occurred in 861 knees among 2876 persons in the OAI and in 143 knees among 971 persons in the Framingham study. In persons whose fiber intake was ≥21 g/d compared with those with intakes <21 g/d, the OR (95% CI) was 0.70 (0.53, 0.91) for the overall association with SXKOA and was 0.93 (0.92, 0.95) for the mediation via BMI (per kg/m2) in the OAI. In the Framingham study, the overall association was 0.57 (0.30, 1.09), the mediation through BMI (via BMI and the influence of BMI on CRP) was 0.94 (0.85, 1.02), and the mediation through CRP (per milligram per liter) was 0.99 (0.84, 1.19). Conclusion:Our findings suggest that the inverse association of fiber intake and the risk of incident symptomatic knee osteoarthritis is partially mediated by BMI.
Comparison of Two Calorie-Reduced Diets of Different Carbohydrate and Fiber Contents and a Simple Dietary Advice Aimed to Modify Carbohydrate Intake on Glycemic Control and Inflammatory Markers in Type 2 Diabetes: A Randomized Trial.
Ghalandari Hamid,Kamalpour Mahdieh,Alimadadi Ashraf,Nasrollahzadeh Javad
International journal of endocrinology and metabolism
OBJECTIVES:The aim of this study was to compare the effect of a simple dietary advice with two energy-restricted diets with different carbohydrate and fiber contents on anthropometric, biochemical, and inflammatory markers over an 8-wk intervention period in individuals with diabetes. METHODS:Forty-seven patients with type 2 diabetes (31 women and 16 men; age: 52.9 ± 8.0 years, body mass index: 29.5 ± 4.9 kg.m) completed an 8-wk randomized intervention trial that compared a simple dietary advice aimed to modulate carbohydrate intake (n = 13) with the two calorie-restricted (CR) diets (25% caloric restriction from total energy requirements) differing with regard to carbohydrate and fiber content, one with higher fiber (CRHF) containing 55% energy from carbohydrate plus a tablespoon of psyllium powder (n = 18) and the other with lower carbohydrate (CRLC) containing 40% energy from carbohydrate plus placebo powder (n = 16). Weight, plasma concentrations of glucose, insulin, lipids, interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-α) were determined at baseline and after 8 weeks. RESULTS:The mean change of body weight and plasma lipids were not different between the groups. Fasting plasma insulin and the homeostasis model assessment of insulin resistance (HOMA-IR) were significantly lower in the CRHF group (changes from baseline values in simple advice, CRHF, and CRLC were 1.3 ± 1.9, -1.0 ± 1.2, and 0.3 ± 3.1 µIL/mL for insulin and 0.5 ± 0.7, -0.3 ± 0.6, and 0.2 ± 0.9 for HOMA-IR, respectively). The levels of IL-6 significantly decreased in the CRHF and CRLC groups (changes from baseline values in simple advice, CRHF, and CRLC were 7.5 ± 6.8, -1.2 ± 4.7, and -4.2 ± 5.6 pg/mL, respectively). TNF-α levels were significantly lower only in the CRHF compared to the advice group (P < 0.05). CONCLUSIONS:Our results suggest that in comparison with simple advice to modify carbohydrate intake, a calorie-restricted, moderate carbohydrate diet supplemented with psyllium has better effects on plasma insulin and pro-inflammatory cytokines in patients with type 2 diabetes.
Association Between Dietary Fiber Intake and Bone Loss in the Framingham Offspring Study.
Dai Zhaoli,Zhang Yuqing,Lu Na,Felson David T,Kiel Douglas P,Sahni Shivani
Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research
Dietary fiber may increase calcium absorption, but its role in bone mineralization is unclear. Furthermore, the health effect of dietary fiber may be different between sexes. We examined the association between dietary fiber (total fiber and fiber from cereal, fruits, vegetables, nuts, and legumes) and bone loss at the femoral neck, trochanter, and lumbar spine (L to L ) in older men and women. In the Framingham Offspring Study, at baseline (1996-2001), diet was assessed using the Willett food-frequency questionnaire, and bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry. Follow-up BMD was measured in 2001-2005 and 2005-2008 among 792 men (mean age 58.1 years; BMI 28.6 kg/m ) and 1065 women (mean age 57.3 years; BMI 27.2 kg/m ). We used sex-specific generalized estimating equations in multivariable regressions to estimate the difference (β) of annualized BMD change in percent (%ΔBMD) at each skeletal site per 5 g/d increase in dietary fiber. We further estimated the adjusted mean for bone loss (annualized %ΔBMD) among participants in each higher quartile (Q2, Q3, or Q4) compared with those in the lowest quartile (Q1) of fiber intake. Higher dietary total fiber (β = 0.06, p = 0.003) and fruit fiber (β = 0.10, p = 0.008) was protective against bone loss at the femoral neck in men but not in women. When examined in quartiles, men in Q2-Q4 of total fiber had significantly less bone loss at the femoral neck versus those in Q1 (all p < 0.04). For women, we did not observe associations with hip bone loss, although fiber from vegetables appeared to be protective against spine bone loss in women but not men. There were no associations with cereal fiber or nut and legume fiber and bone loss in men or women. Our findings suggest that higher dietary fiber may modestly reduce bone loss in men at the hip. © 2017 American Society for Bone and Mineral Research.
Dietary fiber intake and risk of metabolic syndrome: A meta-analysis of observational studies.
Wei Baozhu,Liu Yang,Lin Xuan,Fang Ying,Cui Jing,Wan Jing
Clinical nutrition (Edinburgh, Scotland)
BACKGROUND & AIMS:Epidemiological studies show inconsistent findings on the association of dietary fiber intake with risk of metabolic syndrome (MetS). Herein, we aim to conduct a meta-analysis of published studies to determine the role of dietary fiber in prevention of MetS. METHODS:A systematical search in PubMed and Embase databases through December 2016, together with reference scrutiny of relevant literature, was performed to identify studies for inclusion. We aggregated the odds ratios (ORs) with 95% confidence intervals (CIs) of MetS using a random effect model. Dose-response relationship between fiber intake and MetS was also evaluated. RESULTS:This meta-analysis included 8 cross-sectional and 3 cohort studies, totaling 28,241 participants and 9140 MetS cases. The highest versus lowest fiber intake was associated with a reduced risk of MetS (OR: 0.85, 95% CI: 0.79-0.92; P = 0.005), with moderate heterogeneity (I = 64%, P = 0.001) across studies. The benefit of fiber intake was significant among cross-sectional studies (OR: 0.85, 95% CI: 0.78-0.92; P < 0.001) but not among cohort studies (OR: 0.86, 95% CI: 0.70-1.06; P = 0.16). In dose-response analysis, we found a curvilinear relationship between fiber consumption and prevalence of MetS. Compared with non-fiber intake, the ORs (95% CIs) of MetS across fiber intake levels were 0.85 (0.79-0.91), 0.76 (0.67-0.85), 0.73 (0.65-0.83), and 0.73 (0.65-0.82) for 10, 20, 30, and 40 g/d, respectively. CONCLUSIONS:Dietary fiber intake is associated with less likelihood of having MetS. Additional large, prospective studies are warranted to enhance our findings.