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Gut Feb 2023Dietary fibres are essential for maintaining microbial diversity and the gut microbiota can modulate host physiology by metabolising the fibres. Here, we investigated...
OBJECTIVE
Dietary fibres are essential for maintaining microbial diversity and the gut microbiota can modulate host physiology by metabolising the fibres. Here, we investigated whether the soluble dietary fibre oligofructose improves host metabolism by modulating bacterial transformation of secondary bile acids in mice fed western-style diet.
DESIGN
To assess the impact of dietary fibre supplementation on bile acid transformation by gut bacteria, we fed conventional wild-type and TGR5 knockout mice western-style diet enriched or not with cellulose or oligofructose. In addition, we used germ-free mice and in vitro cultures to evaluate the activity of bacteria to transform bile acids in the caecal content of mice fed with western-style diet enriched with oligofructose. Finally, we treated wild-type and TGR5 knockout mice orally with hyodeoxycholic acid to assess its antidiabetic effects.
RESULTS
We show that oligofructose sustains the production of 6α-hydroxylated bile acids from primary bile acids by gut bacteria when fed western-style diet. Mechanistically, we demonstrated that the effects of oligofructose on 6α-hydroxylated bile acids were microbiota dependent and specifically required functional TGR5 signalling to reduce body weight gain and improve glucose metabolism. Furthermore, we show that the 6α-hydroxylated bile acid hyodeoxycholic acid stimulates TGR5 signalling, in vitro and in vivo, and increases GLP-1R activity to improve host glucose metabolism.
CONCLUSION
Modulation of the gut microbiota with oligofructose enriches bacteria involved in 6α-hydroxylated bile acid production and leads to TGR5-GLP1R axis activation to improve body weight and metabolism under western-style diet feeding in mice.
Topics: Animals; Mice; Bile Acids and Salts; Body Weight; Dietary Supplements; Glucose; Mice, Inbred C57BL; Mice, Knockout; Receptors, G-Protein-Coupled; Dietary Fiber; Gastrointestinal Microbiome; Diet, Western
PubMed: 35697422
DOI: 10.1136/gutjnl-2021-326541 -
The American Journal of Clinical... Jun 2019Inulin-type fructans (ITFs) are a type of fermentable dietary fiber that can confer beneficial health effects through changes in the gut microbiota. However, their... (Clinical Trial)
Clinical Trial
BACKGROUND
Inulin-type fructans (ITFs) are a type of fermentable dietary fiber that can confer beneficial health effects through changes in the gut microbiota. However, their effect on gut sensitivity and nutritional behavior is a matter of debate.
OBJECTIVE
We evaluated the impact of consuming ITF-rich vegetables daily on gut microbiota, gastro-intestinal symptoms, and food-related behavior in healthy individuals.
METHODS
A single group-design trial was conducted in 26 healthy individuals. During 2 wk, the participants were instructed to adhere to a controlled diet based on ITF-rich vegetables (providing a mean intake of 15 g ITF/d). Three test days were organized: before and after the nutritional intervention and 3 wk after returning to their usual diet. We assessed nutrient intake, food-related behavior, fecal microbiota composition, microbial fermentation, and gastrointestinal symptoms.
RESULTS
The major microbial modifications during the intervention were an increased proportion of the Bifidobacterium genus, a decreased level of unclassified Clostridiales, and a tendency to decrease Oxalobacteraceae. These changes were reversed 3 wk after the intervention. The volunteers showed greater satiety, a reduced desire to eat sweet, salty, and fatty food, and a trend to increase hedonic attitudes towards some inulin-rich vegetables. Only flatulence episodes were reported during the dietary intervention, whereas intestinal discomfort, inversely associated with Clostridium cluster IV and Ruminococcus callidus, was improved at the end of the intervention.
CONCLUSIONS
A higher consumption of ITF-rich vegetables allows a substantial increase in well-tolerated dietary fiber, which may in turn improve food-related behavior. Moreover, it leads to beneficial modifications of the gut microbiota composition and function. This trial is registered at clinicaltrial.gov as NCT03540550.
Topics: Adolescent; Adult; Aged; Bacteria; Diet; Dietary Fiber; Feces; Feeding Behavior; Female; Gastrointestinal Microbiome; Healthy Volunteers; Humans; Inulin; Male; Middle Aged; Prebiotics; Vegetables; Young Adult
PubMed: 31108510
DOI: 10.1093/ajcn/nqz001 -
BMJ Open Gastroenterology Aug 2020A diet low in fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) is an effective way to reduce gut symptoms in people with irritable bowel... (Randomized Controlled Trial)
Randomized Controlled Trial
Does Fibre-fix provided to people with irritable bowel syndrome who are consuming a low FODMAP diet improve their gut health, gut microbiome, sleep and mental health? A double-blinded, randomised controlled trial.
INTRODUCTION
A diet low in fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) is an effective way to reduce gut symptoms in people with irritable bowel syndrome (IBS). This diet reduces the intake of fermentable fibres, leading to changes of the gut microbiota and insufficient fermentation in the large bowel, resulting in reduced production of short-chain fatty acids (SCFAs), such as butyrate, which has unfavourable implications for gut health, sleep and mental health. This study will examine the effect of Fibre-fix, a supplement containing a mix of dietary fibres, on the human gut microbiome composition, fermentative capacity, sleep, quality of life (QOL) and mental health of people with IBS who consume a low FODMAP diet (LFD).
METHODS AND ANALYSIS
A randomised, double-blind, placebo-controlled, study design is proposed to examine whether Fibre-fix added to an existing LFD may help modulate gastrointestinal function, improve markers of sleep, mental health and promote QOL in patients with IBS. Participants will provide stool and blood samples, daily bowel symptoms diaries and 3-day diet records. Additionally, they will complete validated questionnaires relating to FODMAP intake, sleep, mental health and QOL before and after a 3-week intervention. Gut health will be assessed via faecal microbiome composition, faecal pH and SCFA levels. Alteration of sleep will be recorded using an actigraphy device worn by all participants over the whole study. Multivariate analysis will be used to examine the gut microbiome and repeated measures Analysis of variance (ANOVA) will be used for dependent variables from questionnaires related to bowel symptoms, stool type, sleep, mental health and QOL to assess the differences between intervention and control groups after adjustment for confounding variables.
ETHICS AND DISSEMINATION
Ethics approval was obtained from the Human Research Ethics Committee of Edith Cowan University (2019-00619-YAN). Results will be disseminated in peer-review journal publications, and conference presentations. Participants will be provided with a summary of findings once the study is completed. If Fibre-fix is shown to result in favourable changes in gut microbial composition, SCFA production, sleep and mental well-being without exacerbating symptoms, this will provide additional dietary management options for those with IBS following an LFD.
TRIAL REGISTRATION NUMBER
ACTRN12620000032954.
Topics: Adult; Aged; Case-Control Studies; Dietary Fiber; Disaccharides; Double-Blind Method; Fatty Acids, Volatile; Feces; Female; Fermentation; Gastrointestinal Diseases; Gastrointestinal Microbiome; Humans; Irritable Bowel Syndrome; Male; Mental Health; Middle Aged; Monosaccharides; Oligosaccharides; Outcome Assessment, Health Care; Polymers; Quality of Life; Sleep; Surveys and Questionnaires
PubMed: 32816830
DOI: 10.1136/bmjgast-2020-000448 -
Nutrients Oct 2023Grains are widely consumed all over the world, providing calories, macronutrients, micronutrients, dietary fiber, minerals, and plenty of phytochemicals [...].
Grains are widely consumed all over the world, providing calories, macronutrients, micronutrients, dietary fiber, minerals, and plenty of phytochemicals [...].
Topics: Humans; Edible Grain; Nutritional Status; Energy Intake; Dietary Fiber; Cardiovascular Diseases; Diet
PubMed: 37960258
DOI: 10.3390/nu15214605 -
Nutrients May 2023Dietary fibers include non-digestible plant carbohydrates, lignin and resistant starch. Dietary fibers provide immune, cardiovascular, metabolic and intestinal... (Review)
Review
Dietary fibers include non-digestible plant carbohydrates, lignin and resistant starch. Dietary fibers provide immune, cardiovascular, metabolic and intestinal beneficial effects in humans. Fibers naturally present in foods (fruits, vegetables, legumes, cereals) or used as supplements have different physical, chemical and functional profiles. This narrative review provides an update to the knowledge on the effects of dietary fibers in healthy subjects and in children with gastrointestinal disorders. Soluble fibers are digested by gut bacteria, producing short-chain fatty acids and energy for colonocytes, and may exert prebiotic effects that promote the growth of bifidobacteria and lactobacilli. Non-soluble fibers are bulking agents and may improve intestinal transit. The exact amount and characteristics of the fiber requirement in infants and children need to be further established. There are limited data evaluating fibers in children with gastrointestinal disorders. The low intake of fibers has been associated with constipation, but the intake of excessive fibers is not recommended as it may cause flatulence and abdominal discomfort. Certain fibers (particularly psyllium in irritable bowel syndrome) have shown beneficial effects in children with gastrointestinal disorders, but the limited and heterogenous data do not currently allow a specific recommendation.
Topics: Infant; Humans; Child; Dietary Fiber; Gastrointestinal Diseases; Constipation; Resistant Starch; Flatulence; Vegetables
PubMed: 37432354
DOI: 10.3390/nu15092208 -
Advances in Nutrition (Bethesda, Md.) Dec 2022Nondigestible carbohydrates (NDCs) are food components, including nonstarch polysaccharides and resistant starches. Many NDCs are classified as dietary fibers by the US... (Review)
Review
Nondigestible carbohydrates (NDCs) are food components, including nonstarch polysaccharides and resistant starches. Many NDCs are classified as dietary fibers by the US FDA. Because of their beneficial effects on human health and product development, NDCs are widely used in the food supply. Although there are dietary intake recommendations for total dietary fiber, there are no such recommendations for individual NDCs. NDCs are heterogeneous in their chemical composition and physicochemical properties-characteristics that contribute to their tolerable intake levels. Guidance on tolerable intake levels of different NDCs is needed because overconsumption can lead to undesirable gastrointestinal side effects, further widening the gap between actual and suggested fiber intake levels. In this review, we synthesize the literature on gastrointestinal effects of NDCs that the FDA accepts as dietary fibers (β-glucan, pectin, arabinoxylan, guar gum, alginate, psyllium husk, inulin, fructooligosaccharides and oligofructose, galactooligosaccharides, polydextrose, cellulose, soy fiber, resistant maltodextrin/dextrin) and present tolerable intake dose recommendations for their consumption. We summarized the findings from 103 clinical trials in adults without gastrointestinal disease who reported gastrointestinal effects, including tolerance (e.g., bloating, flatulence, borborygmi/rumbling) and function (e.g., transit time, stool frequency, stool consistency). These studies provided doses ranging from 0.75-160 g/d and lasted for durations ranging from a single-meal tolerance test to 28 wk. Tolerance was NDC specific; thus, recommendations ranged from 3.75 g/d for alginate to 25 g/d for soy fiber. Future studies should address gaps in the literature by testing a wider range of NDC doses and consumption forms (solid compared with liquid). Furthermore, future investigations should also adopt a standard protocol to examine tolerance and functional outcomes across studies consistently.
Topics: Adult; Humans; Gastrointestinal Tract; Carbohydrates; Dietary Fiber; Feces; Alginates
PubMed: 36041173
DOI: 10.1093/advances/nmac094 -
Annals of Medicine Dec 2023Dietary fibre and cognitive function are associated with the risk of mortality, respectively. Inadequate dietary fibre intake and cognitive impairment frequently...
BACKGROUND
Dietary fibre and cognitive function are associated with the risk of mortality, respectively. Inadequate dietary fibre intake and cognitive impairment frequently co-occur in older adults, but the combined effect of dietary fibre and cognitive function on mortality remains unknown. The study was to investigate the combined effect of dietary fibre and cognitive function on mortality over a 13-year follow-up in a representative of older adults from the U.S.
METHODS
We analyzed data from two cycles of the National Health and Nutrition Examination Survey (NHANES) 1999-2000 and 2001-2002 with mortality follow-up data through 13 December 2015 obtained from Public-use Linked Mortality Files. Low dietary fibre intake was defined as the lowest quartile of dietary fibre intake. Cognitive impairment was defined as below the median of Digit Symbol Substitution Test. The separate and combined effects of low dietary fibre intake and cognitive impairment on all-cause and cause-specific mortality were assessed in older adults using weighted Cox proportional hazard models adjusting for potential confounders.
RESULTS
A total of 2012 participants (weighted sample was 32,765,094) aged 60 years and older were enrolled in the study. After a median follow-up of 13.4 years, 1017 participants (50.4%) were identified as all-cause deaths, including 183 (9.1%) participants dying from cancer, 199 (9.9%) participants dying from cardiovascular disease, and 635 (31.5%) participants dying from non-cancer/non-cardiovascular disease. Participants with low dietary fibre intake and cognitive impairment had nearly twice the risk of all-cause (HR, 2.030; 95% CI, 1.406-2.931) and non-cancer/non-cardiovascular (HR, 2.057; 95% CI, 1.297-3.262) mortality, and over triple cancer (HR, 3.334; 95% CI, 1.685-6.599) mortality, compared to those without both.
CONCLUSIONS
The combination of low dietary fibre intake and cognitive impairment was associated with an increased risk of all-cause, cancer and non-cancer/non- cardiovascular mortality in older adults.
Topics: Humans; Middle Aged; Aged; Nutrition Surveys; Cause of Death; Diet; Cardiovascular Diseases; Cognition; Neoplasms; Dietary Fiber
PubMed: 37287268
DOI: 10.1080/07853890.2023.2221036 -
Journal of Nutritional Science and... 2019Rice (Oryza sativa) is one of the most important food crops in the world, and the effect of its consumption on human health is of great concern. Evidence has accumulated... (Review)
Review
Rice (Oryza sativa) is one of the most important food crops in the world, and the effect of its consumption on human health is of great concern. Evidence has accumulated that rice contains several components, such as γ-oryzanol and rice bran fibers, which modulate the immune system. In addition, rice has other immunologically beneficial characteristics. It has a low allergenic potential and is gluten-free, reducing the risk of development of food allergies and diseases related to gluten sensitivity such as coeliac disease. This review presents the recent advances in our understanding of the immunomodulatory function of rice components.
Topics: Dietary Fiber; Humans; Immunologic Factors; Oryza
PubMed: 31619655
DOI: 10.3177/jnsv.65.S9 -
Cell Reports Sep 2022Dietary fibers are potent modulators of immune responses that can restrain inflammation in multiple disease contexts. However, dietary fibers encompass a biochemically...
Dietary fibers are potent modulators of immune responses that can restrain inflammation in multiple disease contexts. However, dietary fibers encompass a biochemically diverse family of carbohydrates, and it remains unknown how individual fiber sources influence immunity. In a direct comparison of four different high-fiber diets, we demonstrate a potent ability of guar gum to delay disease and neuroinflammation in experimental autoimmune encephalomyelitis, a T cell-mediated mouse model of multiple sclerosis. Guar gum-specific alterations to the microbiota are limited, and disease protection appears to be independent of fiber-induced increases in short-chain fatty acid levels or regulatory CD4 T cells. Instead, CD4 T cells of guar gum-supplemented mice are less encephalitogenic due to reduced activation, proliferation, Th1 differentiation, and altered migratory potential. These findings reveal specificity in the host response to fiber sources and define a pathway of fiber-induced immunomodulation that protects against pathologic neuroinflammation.
Topics: Animals; Cyamopsis; Diet; Dietary Fiber; Encephalomyelitis, Autoimmune, Experimental; Galactans; Mannans; Mice; Plant Gums
PubMed: 36103823
DOI: 10.1016/j.celrep.2022.111328 -
Nutrients Jun 2023Dietary fiber is a functional substance with strong antioxidant activity that plays an important role in human health. Dietary fiber has been shown to reduce the risks...
BACKGROUND
Dietary fiber is a functional substance with strong antioxidant activity that plays an important role in human health. Dietary fiber has been shown to reduce the risks of many types of cancers, but whether it can reduce the risk of death in cancer survivors remains undetermined.
METHODS
This study included the dietary data of cancer survivors who participated in the National Health and Nutrition Examination Surveys from 2001 to 2018. Firstly, the relationship between fiber intake and composite dietary antioxidant index (CDAI) was explored by weighted multiple regression and smooth curve. Subsequently, multivariable Cox proportional hazards regression models were used to explore the effects of dietary fiber intake and CDAI level on the risks of all-cause, tumor, and cardiovascular death among cancer survivors.
RESULTS
A total of 2077 participants were included in the study, representing approximately 11,854,509 cancer survivors in the United States. The dietary fiber intake of tumor survivors had a nonlinear positive relationship with CDAI levels (β = 0.24, 95% CI: 0.08-0.40, = 0.004). Multivariable Cox proportional hazards regression models showed that high dietary fiber intake and CDAI levels were associated with reduced risks of all-cause and tumor death in tumor survivors, but were not associated with the risk of cardiovascular death.
CONCLUSION
An increased dietary fiber intake can enhance the body's antioxidant capacity. A higher dietary fiber intake and CDAI level may reduce the risk of all-cause and tumor death in tumor survivors.
Topics: Dietary Fiber; Antioxidants; Cancer Survivors; Nutrition Surveys; United States; Humans; Mortality; Male; Female; Middle Aged; Aged
PubMed: 37447293
DOI: 10.3390/nu15132968