Effects of dietary fiber and its components on metabolic health.

World Gastroenterology Organisation Global Guidelines: Diet and the Gut.

Wholegrain intake is linked to lower risk of lifestyle diseases, but little is known about its role in growth and metabolic health during the first years of life. We characterized wholegrain and dietary fibre intake in 439 Danish children at 9 and 36months of age and explored associations with height z-scores (HAZ), body mass index z-scores (BMIZ) and metabolic markers. We used pooled data from two infant cohorts and estimated intakes of total wholegrain, dietary fibre and wholegrain subtypes from 7-day dietary records. Associations with HAZ, BMIZ and non-fasting plasma low-density (LDLC) and high-density-lipoprotein cholesterol, triacylglycerol, insulin and glucose were analysed in mixed models, adjusted for potential confounders. Median (25th, 75th percentile) wholegrain intake was 7.5 (4.9, 10.5) and 6.5 (4.6, 9.0) g/MJ at 9 and 36months. Neither wholegrain nor dietary fibre intake were associated with HAZ (P ≥ 0.09). At 36months, wholegrain intake was inversely associated with LDLC (P = 0.05) and directly with glucose (P < 0.001). In secondary analyses, wholegrain rye was inversely associated with glucose at 9months and insulin at 36months (both P ≤ 0.03). Oat and wheat wholegrain were directly associated with glucose (both P ≤ 0.01) and wheat with BMIZ (P = 0.02) at 36months. Danish infants and toddlers have high intakes of wholegrain and dietary fibre, with no indication of compromised growth. In line with studies in adults, wholegrain intake was inversely associated with LDLC. The observed direct association between wholegrain intake and plasma glucose and associations with wholegrain subtypes should be investigated further.

Whole-Grain Intake, Reflected by Dietary Records and Biomarkers, Is Inversely Associated with Circulating Insulin and Other Cardiometabolic Markers in 8- to 11-Year-Old Children

ABSTRACTBackgroundHigher intakes of whole grains and dietary fiber have been associated with lower risk of insulin resistance, hyperinsulinemia, and inflammation, which are known predisposing factors for cancer.ObjectivesBecause the evidence of association with bladder cancer (BC) is limited, we aimed to assess associations with BC risk for intakes of whole grains, refined grains, and dietary fiber.MethodsWe pooled individual data from 574,726 participants in 13 cohort studies, 3214 of whom developed incident BC. HRs, with corresponding 95% CIs, were estimated using Cox regression models stratified on cohort. Dose–response relations were examined using fractional polynomial regression models.ResultsWe found that higher intake of total whole grain was associated with lower risk of BC (comparing highest with lowest intake tertile: HR: 0.87; 95% CI: 0.77, 0.98; HR per 1-SD increment: 0.95; 95% CI: 0.91, 0.99; P for trend: 0.023). No association was observed for intake of total refined grain. Intake of total dietary fiber was also inversely associated with BC risk (comparing highest with lowest intake tertile: HR: 0.86; 95% CI: 0.76, 0.98; HR per 1-SD increment: 0.91; 95% CI: 0.82, 0.98; P for trend: 0.021). In addition, dose–response analyses gave estimated HRs of 0.97 (95% CI: 0.95, 0.99) for intake of total whole grain and 0.96 (95% CI: 0.94, 0.98) for intake of total dietary fiber per 5-g daily increment. When considered jointly, highest intake of whole grains with the highest intake of dietary fiber showed 28% reduced risk (95% CI: 0.54, 0.93; P for trend: 0.031) of BC compared with the lowest intakes, suggesting potential synergism.ConclusionsHigher intakes of total whole grain and total dietary fiber are associated with reduced risk of BC individually and jointly. Further studies are needed to clarify the underlying mechanisms for these findings.

Resistant starch (RS) consumption can have beneficial effects on metabolic health, but the response, in terms of effects on the gut microbiota and host physiology, varies between individuals. Factors predicting the response to RS are not yet established and would be useful for developing precision nutrition approaches that maximize the benefits of dietary fiber intake. We sought to identify predictors of gut microbiota response to RS supplementation. We enrolled 76 healthy adults into a 7-week crossover study with 59 individuals completing the study. Participants consumed RS type 2 (RS2), RS type 4 (RS4), and digestible starch, for 10 d each with 5-d washout periods in between. We collected fecal and saliva samples and food records during each treatment period. We performed 16S rRNA gene sequencing and measured fecal short-chain fatty acids (SCFAs), salivary amylase (AMY1) gene copy number, and salivary amylase activity (SAA). Dietary fiber intake was predictive of the relative abundance of several amplicon sequence variants (ASVs) at the end of both RS treatments. AMY1-related metrics were not predictive of response to RS. SAA was only predictive of the relative abundance of one ASV after digestible starch supplementation. Interestingly, SCFA concentrations increased the most during digestible starch supplementation. Treatment order (the order of consumption of RS2 and RS4), alpha diversity, and a subset of ASVs were predictive of SCFA changes after RS supplementation. Based on our findings, dietary fiber intake and gut microbiome composition would be informative if assessed prior to recommending RS supplementation because these data can be used to predict changes in specific ASVs and fecal SCFA concentrations. These findings lay a foundation to support the premise that using a precision nutrition approach to optimize the benefits of dietary fibers such as RS could be an effective strategy to compensate for the low consumption of dietary fiber nationwide.

Dietary Fiber Intake Is Inversely Associated with Periodontal Disease among US Adults

Dietary Fiber Intake Is Inversely Associated with Periodontal Disease among US Adults

Background Higher 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). To our knowledge, no epidemiological study has yet examined the association between whole grain intake and HCC risk. Therefore, we hypothesized that long-term intake of whole grain and dietary fiber may be associated with lower risk of developing HCC. Methods We tested this hypothesis by utilizing data from two large U.S. prospective cohorts, the Nurses’ Health Study and Health Professionals Follow-up Study. Intake of whole grain and its subcomponents (bran and germ), and dietary fiber (cereal, fruit, and vegetable) were collected and updated almost every 4 years using validated food frequency questionnaires. Time-varying Cox proportional hazards regression model was utilized to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of of HCC by tertiles of energy-adjusted whole grain and fiber, after adjusting for sex, race, age, body mass index, alcohol drinking, smoking, physical activity, regular aspirin use, and type 2 diabetes. Results During up to 32 years of follow-up, we identified a total of 141 incident HCC cases. Higher whole grain intake was significantly associated with lower risk of HCC (the highest versus lowest tertile intake, HR=0.63, 95% CI: 0.41-0.96, Ptrend=0.04). A suggestive inverse HCC association was found for total bran (HR=0.70, 95% CI: 0.46-1.07, Ptrend=0.11), but not for germ. After mutual adjustment for bran and germ, the inverse association between total bran and HCC persisted (HR=0.66, 95% CI: 0.41-1.07, Ptrend=0.13). Increasing intake of cereal fiber (HR=0.68, 95% CI: 0.45-1.03, Ptrend=0.07), but not fruit or vegetable fiber, was also suggestively associated with reduced risk of HCC. In sensitivity analyses, the results did not materially change after excluding HCC cases with hepatitis B or C virus infections. In addition, we observed similar inverse associations for whole grain, bran and germ, or dietary fiber with risk of HCC subtypes by history of cirrhosis (i.e., cirrhotic versus non-cirrhotic HCC). Conclusions Intake of whole grains, cereal fiber, and bran could be associated with reduced risk of HCC among U.S. adults. Future studies that carefully consider hepatitis B and C virus infections are needed to replicate our findings, to examine these associations in other racial or high-risk populations, and to elucidate the underlying mechanisms. Citation Format: Wanshui Yang, Yanan Ma, Yue Liu, Smith-Warner Stephanie, Tracey G. Simon, Dawn Chong, Jeffrey A. Meyerhardt, Edward L. Giovannucci, Andrew T. Chan, Xuehong Zhang. Intake of whole grain and dietary fiber and risk of hepatocellular carcinoma among U.S. adults [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2680.

Inadequate dietary fibre (DF) intake is associated with suboptimal gut function and increased risk of several human diseases. Bread is commonly consumed and is ideal to incorporate cereal bran to increase DF content. No human studies have investigated the effects of defatted rice bran (DRB) in bread, which has triple the DF of white bread, purported hypo-allergenicity and a unique nutrient profile, as a dietary intervention in healthy adults. This study aims to assess the relative abundances of a composite of key faecal microbial genera and species involved in DF fermentation and metabolism following the habitual intake of DRB-fortified bread and its influence on other biological markers of host and microbial interactions, cardiovascular risk profile, patient-reported outcomes, total DF intake, and gut physiology in healthy adults with low baseline DF intake. Fifty-six healthy adults with low baseline DF intake (<18 g/day (females), <22 g/day (males)) completed a two-arm, placebo-controlled, double-blind, randomised, crossover study. Participants consumed three (females) or four (males) slices of DRB-fortified bread or control bread daily as part of their usual diet for four weeks, with the intervention periods separated by a two-week washout. Outcomes included faecal microbiota composite (primary outcome); relative abundances (taxa and gene); faecal moisture content and bile acid concentrations; plasma and faecal organic acid concentrations; cardiovascular risk profile; gut comfort, psychological wellbeing parameters; total DF intake; whole gut transit time, and were measured at baseline and following each intervention phase. Additionally, in a sub-study, 15 participants ingested gas-sensing capsules to assess whole and regional gut transit times, and total and regional colonic hydrogen and carbon dioxide concentrations at the same timepoints. DRB-fortified bread consumption significantly increased total DF intake from 20.7 g/day to 43.4 g/day (p < 0.001). No significant differences were observed in the primary outcome, microbial taxa composite within and between groups (False Discovery Rate (FDR) correction, p > 0.10). As compared to control, the DRB group had increased relative abundances of Faecalibacterium prausnitzii (unadjusted p = 0.04), Bifidobacterium longum (unadjusted p = 0.12), and Bacteroides ovatus (unadjusted p = 0.10); lower relative abundances in Coprococcus genus (unadjusted p = 0.09), Roseburia faecis (unadjusted p = 0.02) and Prevotella copri species (unadjusted p = 0.05). However, no significant differences were observed in the relative abundances of these taxa within and between groups (FDR correction p > 0.10) and for most of the other outcomes between groups (p > 0.05). Only mean serum high-density lipoprotein (HDL) concentrations significantly increased (p = 0.006), and mean total cholesterol (TC) to HDL concentration ratio significantly lowered (p = 0.02) in the DRB group compared to the control group. This is the first human study to show that a high-DF DRB-fortified bread improved DF intake, HDL cholesterol profiles, and may affect the gut microbiota composition in healthy adults with low DF intake. These findings support the substitution of white bread with DRB-fortified bread as an effective method to improve DF intake, which may have subsequent benefits on gut physiology and metabolic health.

Background: Dietary fibre consists of non-digestible forms of carbohydrate, usually as polysaccharides that originate from plant-based foods. Over recent decades, our diet within Westernised societies has changed radically from that of our hominid ancestors, with implications for our co-evolved gut microbiota. This includes increased ingestion of ultra-processed foods that are typically impoverished of dietary fibre, and associated reduction in the intake of fibre-replete plant-based foods. Over recent decades, there has been a transformation in our understanding of the health benefits of dietary fibre. Objective: To explore the current medical literature on the health benefits of dietary fibre, with a focus on overall metabolic health. Data Sources: We performed a narrative review, based on relevant articles written in English from a PubMed search, using the terms ‘dietary fibre and metabolic health’. Results: In the Western world, our diets are impoverished of fibre. Dietary fibre intake associates with overall metabolic health (through key pathways that include insulin sensitivity) and a variety of other pathologies that include cardiovascular disease, colonic health, gut motility and risk for colorectal carcinoma. Dietary fibre intake also correlates with mortality. The gut microflora functions as an important mediator of the beneficial effects of dietary fibre, including the regulation of appetite, metabolic processes and chronic inflammatory pathways. Conclusions: Multiple factors contribute to our fibre-impoverished modern diet. Given the plethora of scientific evidence that corroborate the multiple and varied health benefits of dietary fibre, and the risks associated with a diet that lacks fibre, the optimization of fibre within our diets represents an important public health strategy to improve both metabolic and overall health. If implemented successfully, this strategy would likely result in substantial future health benefits for the population.

Although many studies have explored the relationship between total dietary fiber intake and the risk of chronic non-communicable diseases, the results are mixed. There is also a lack of research on the association between dietary fiber intake from different food sources and disease. Using data from the China Nutrition and Health Database from 2004 to 2015, Cox proportional risk models were used to explore the associations between total dietary fiber and fiber intake from different food sources and the occurrence of type 2 diabetes, hypertension, obesity, cardiovascular disease, and all-cause mortality. After multi-factorial adjustment, the hazard ratios (95% confidence interval) of total dietary fiber intake (quartile 4 vs. quartile 1) in type 2 diabetes, hypertension, obesity, cardiovascular disease, and all-cause mortality cohorts were 1.20 (0.93, 1.55), 0.91 (0.75, 1.12), 0.93 (0.64, 1.35), 1.13 (0.60, 2.12), 1.13 (0.60, 2.12), and 1.13 (0.84, 1.52). Whole-grain fiber intake was positively associated with hypertension but not with the occurrence of other diseases. No association was observed between legume fibers, fruit fibers, and vegetable fibers in the cohorts of type 2 diabetes, hypertension, obesity, cardiovascular diseases and all-cause mortality. Our study did not find any association between total dietary fiber and dietary fiber intake from different food sources and type 2 diabetes, obesity, cardiovascular disease, and all-cause mortality in the Chinese population. The role of dietary fiber in the Chinese population may be overestimated. More extraordinary efforts are needed to further confirm the association between dietary fiber and these diseases in the Chinese population.

Intakes of dietary fibre in Australia are lower than recommended. An understanding of food choices associated with fibre intake can help to inform locally relevant dietary interventions that aim to increase its consumption. This study aimed to profile the relationship between dietary choices and fibre intake of Australians. Using Day 1 data from the 2011–2012 National Nutrition and Physical Activity Survey (n = 12,153, ≥2 years), dietary fibre intake was classified by quartiles for children (2–18 years) and adults (≥19 years). Intakes of the Australian Dietary Guidelines (ADG) food groups were calculated, as well as the major, sub-major, and minor food groups from the Australian Food Composition Database. Each of these food groups provide a progressively greater level of detail. Associations with ADG food groups and major food groups were determined, and the leading sub-major and minor food group sources of fibre for low (Quartile 1) and high (Quartile 4) fibre consumers were profiled. Energy-adjusted intakes of wholegrain and/or high fibre but not refined grain (cereal) foods, vegetables, and fruit were positively associated, and discretionary foods negatively associated, with quartile of fibre intake (p < 0.001). The top three sub-major food group sources of fibre were regular breads, cereal mixed dishes, and ready-to-eat breakfast cereals in high fibre consumers and regular breads, cereal mixed dishes, and potatoes in low fibre consumers. White breads was the leading minor food group contributor in low fibre consumers, and apples and lower sugar wheat based breakfast cereal were the leading fibre contributors in high fibre consumers in children and adults, respectively. Higher intakes of wholegrain, fruits, and vegetables, and a lower discretionary intake were associated with higher fibre intake. Encouraging these foods as part of any public health intervention is likely to be effective for increasing dietary fibre intakes.

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. To assess the associations of whole grain and dietary fiber intake with the risk of HCC. 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. 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. Multivariable hazard ratios (HRs) and 95% CIs were estimated using Cox proportional hazards regression model after adjusting for most known HCC risk factors. 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. 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.

Despite the established benefits of dietary fibre for cardiovascular health, it remains unclear whether and how dietary fibre intake, particularly from specific food sources, influences all-cause and cause-specific mortality in populations with established cardiovascular disease (CVD). This cohort study utilised data from the National Health and Nutrition Examination Survey 2003-2018. First, we compared dietary fibre intake between 3952 CVD individuals and 3952 age- and gender-matched non-CVD controls, generated by propensity score matching. Second, Cox proportional hazards regression models were employed to assess the associations of dietary fibre intake and source with all-cause, cardiovascular and cancer mortality in CVD populations. Third, to explore potential underlying mechanisms, we examined the associations of dietary fibre intake with validated biomarkers of metabolic health (triglyceride-glucose index, cardiometabolic index) and systemic inflammation (systemic inflammatory response index, systemic immune-inflammation index) in CVD populations. Adjustments were made for sociodemographic, dietary and health-related covariates. Compared to non-CVD individuals, CVD individuals had significantly lower average dietary fibre intake (15.7 g/day vs. 14.1 g/day, p < 0.001). Individuals with multiple coexisting CVDs exhibited the lowest dietary fibre intake (13.1 g/day). Only 9.3% of males and 11.7% of females met the recommended Adequate Intake standards (30 g/day for males, 21 g/day for females) in the CVD group. Over a median follow-up of 6.3 years, dietary fibre intake was inversely associated with all-cause, cardiovascular and cancer mortality in CVD populations. Compared to the first quartile, the all-cause mortality risk was reduced by 42% (hazard ratio [HR] 0.58, 95% confidence interval [CI] 0.45-0.75), cardiovascular mortality by 52% (HR 0.48, 95% CI 0.29-0.78) and cancer mortality by 50% (HR 0.50, 95% CI 0.24-1.02) in the fourth quartile of dietary fibre intake. In terms of dietary fibre sources, grain and legume/nut fibre had a stronger association with survival benefits than fruit and vegetable fibre. Mechanistic exploration analysis suggests that dietary fibre intake was associated with a decrease in triglyceride-glucose index and cardiometabolic index, but not with the systemic inflammation response index and systemic immune-inflammation index. Both CVD and non-CVD populations exhibited inadequate dietary fibre intake, with the deficiency being more pronounced in the CVD group. Among CVD populations, those with higher dietary fibre consumption had a lower risk of all-cause, cardiovascular and cancer mortality. Our findings highlight a significant and remediable nutritional gap in this high-risk population and underscore the importance of improving dietary fibre intake as a potential supplementary strategy to improve survival in adults with CVDs.

Inverse relation between dietary fiber intake and visceral adiposity in overweight Latino youth