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BMC Medicine Apr 2022Higher dietary fibre intakes are associated with a reduced risk of developing cardiovascular disease (CVD), and increasing intake has been shown to reduce blood pressure... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Higher dietary fibre intakes are associated with a reduced risk of developing cardiovascular disease (CVD), and increasing intake has been shown to reduce blood pressure and other cardiometabolic risk factors. The extent to which dietary fibre can further reduce risk for those with CVD and treated with cardioprotective drugs has not been clearly established. We have examined the evidence for dietary fibre as adjunct therapy in those with CVD or hypertension.
METHODS
Ovid MEDLINE, Embase, PubMed, and CENTRAL were searched to June 2021. Prospective observational studies reporting on fibre intakes and mortality in those with pre-existing CVD and controlled trials of increasing fibre intakes on cardiometabolic risk factors in those with CVD or hypertension were eligible. Outcomes were mortality (studies) and cardiometabolic risk factors (trials). Data synthesis was with random effects and dose response. Certainty of evidence was assessed using GRADE.
RESULTS
Three prospective studies including 7469 adults with CVD, and 12 trials of 878 adults with CVD or hypertension were identified. Moderate certainty evidence indicates reduced all-cause mortality (relative risk, RR0.75 (95% confidence interval, CI 0.58-0.97)) when comparing higher with lower fibre intakes. Low certainty evidence from trials of adults with cardiovascular disease indicates increasing fibre intakes reduced total (mean difference, MD - 0.42 mmol/L (95%CI - 0.78 to - 0.05) and low-density lipoprotein (LDL) cholesterol (MD - 0.47mmol/L (95%CI - 0.85 to - 0.10)). High certainty evidence from trials of adults with hypertension indicates increasing fibre intakes reduces systolic (MD 4.3 mmHg (95% CI 2.2 to 5.8)) and diastolic blood pressure (MD 3.1 mmHg (95% CI 1.7 to 4.4)). Moderate and low certainty evidence indicated improvements in fasting blood glucose (MD 0.48 mmol/L (- 0.91 to - 0.05)) and LDL cholesterol (MD 0.29 mmol/L (95% CI 0.17 to 0.40)). Benefits were observed irrespective of cardioprotective drug use.
CONCLUSIONS
These findings emphasise the likely benefits of promoting greater dietary fibre intakes for patients with CVD and hypertension. Further trials and cohort analyses in this area would increase confidence in these results.
Topics: Adult; Cardiovascular Diseases; Dietary Fiber; Humans; Hypertension; Observational Studies as Topic; Primary Prevention; Prospective Studies
PubMed: 35449060
DOI: 10.1186/s12916-022-02328-x -
The American Journal of Clinical... Jun 2018Dysfunction of the gut microbiota is frequently reported as a manifestation of chronic diseases, and therefore presents as a modifiable risk factor in their development.... (Meta-Analysis)
Meta-Analysis
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.
Topics: Adult; Bacteria; Dietary Fiber; Food Analysis; Gastrointestinal Microbiome; Humans
PubMed: 29757343
DOI: 10.1093/ajcn/nqy041 -
Archives of Disease in Childhood Nov 2022Fibre is an essential nutrient in the human diet that is crucial for human health. It provides a range of functional benefits, including stool bulking, and physiological... (Review)
Review
Fibre is an essential nutrient in the human diet that is crucial for human health. It provides a range of functional benefits, including stool bulking, and physiological benefits through fermentation of diverse fibre types by the gut microbiome including cholesterol lowering, glycaemic control and weight control. The by-products of the fermentation of fibre in the gut confer health benefits that extend beyond the gut to the immune system and organs such as the liver, kidneys and the brain. A lack of fibre in the diet has been associated with several disorders in children including constipation, irritable bowel syndrome, allergies and immune-related disorders. In paediatric practice, concerns exist over tolerance of dietary fibre which may lead to unnecessary restrictions, especially for children receiving nutritional support. One reason for this may be the terminology which has historically been used. Fibre is often described in terms of its physico-chemical properties (solubility, viscosity), rather than its physiological effects/functionality (fermentability, bulking effects). To describe fibre in these latter terms represents more clearly the important role it plays. Most international guidelines recommend a daily quantity of fibre, failing to mention the quality aspect of the fibre required for health. Here we consider the evidence base for the current recommendations for daily fibre intakes for healthy children, those requiring nutritional support and those with functional gastrointestinal disorders. We also consider the importance of the gut microbiome and the role of fibre in maintaining gut microbial health and its role in health beyond the gut.
Topics: Humans; Child; Dietary Fiber; Gastrointestinal Microbiome; Constipation; Irritable Bowel Syndrome; Diet
PubMed: 35277379
DOI: 10.1136/archdischild-2021-323571 -
Nutrients Oct 2018A major challenge in affluent societies is the increase in disorders related to gut and metabolic health. Chronic over nutrition by unhealthy foods high in energy, fat,... (Review)
Review
A major challenge in affluent societies is the increase in disorders related to gut and metabolic health. Chronic over nutrition by unhealthy foods high in energy, fat, and sugar, and low in dietary fibre is a key environmental factor responsible for this development, which may cause local and systemic inflammation. A low intake of dietary fibre is a limiting factor for maintaining a viable and diverse microbiota and production of short-chain fatty acids in the gut. A suppressed production of butyrate is crucial, as this short-chain fatty acid (SCFA) can play a key role not only in colonic health and function but also at the systemic level. At both sites, the mode of action is through mediation of signalling pathways involving nuclear NF-κB and inhibition of histone deacetylase. The intake and composition of dietary fibre modulate production of butyrate in the large intestine. While butyrate production is easily adjustable it is more variable how it influences gut barrier function and inflammatory markers in the gut and periphery. The effect of butyrate seems generally to be more consistent and positive on inflammatory markers related to the gut than on inflammatory markers in the peripheral tissue. This discrepancy may be explained by differences in butyrate concentrations in the gut compared with the much lower concentration at more remote sites.
Topics: Animals; Bacteria; Butyrates; Diet, Healthy; Dietary Fiber; Gastrointestinal Microbiome; Humans; Inflammation; Inflammation Mediators; Intestinal Absorption; Intestines; Nutritive Value; Permeability; Recommended Dietary Allowances; Signal Transduction
PubMed: 30322146
DOI: 10.3390/nu10101499 -
Advances in Nutrition (Bethesda, Md.) Dec 2021
Topics: Dietary Fiber; Humans
PubMed: 34687531
DOI: 10.1093/advances/nmab116 -
The American Journal of Gastroenterology Jun 2018
Topics: Anti-Bacterial Agents; Antidepressive Agents; Behavior Therapy; Constipation; Diarrhea; Diet; Dietary Fiber; Dietary Supplements; Exercise; Humans; Irritable Bowel Syndrome; Mentha piperita; Parasympatholytics; Plant Oils; Prebiotics; Probiotics; Randomized Controlled Trials as Topic; Synbiotics
PubMed: 29950604
DOI: 10.1038/s41395-018-0084-x -
Clinical Nutrition (Edinburgh, Scotland) Feb 2023Butyrate is a key energy source for colonocytes and is produced by the gut microbiota through fermentation of dietary fiber. Butyrate is a histone deacetylase inhibitor... (Review)
Review
Butyrate is a key energy source for colonocytes and is produced by the gut microbiota through fermentation of dietary fiber. Butyrate is a histone deacetylase inhibitor and also signals through three G-protein coupled receptors. It is clear that butyrate has an important role in gastrointestinal health and that butyrate levels can impact both host and microbial functions that are intimately coupled with each other. Maintaining optimal butyrate levels improves gastrointestinal health in animal models by supporting colonocyte function, decreasing inflammation, maintaining the gut barrier, and promoting a healthy microbiome. Butyrate has also shown protective actions in the context of intestinal diseases such as inflammatory bowel disease, graft-versus-host disease of the gastrointestinal tract, and colon cancer, whereas lower levels of butyrate and/or the microbes which are responsible for producing this metabolite are associated with disease and poorer health outcomes. However, clinical efforts to increase butyrate levels in humans and reverse these negative outcomes have generated mixed results. This article discusses our current understanding of the molecular mechanisms of butyrate action with a focus on the gastrointestinal system, the links between host and microbial factors, and the efforts that are currently underway to apply the knowledge gained from the bench to bedside.
Topics: Animals; Humans; Butyrates; Colonic Neoplasms; Dietary Fiber; Gastrointestinal Diseases; Receptors, G-Protein-Coupled; Gastrointestinal Microbiome
PubMed: 36502573
DOI: 10.1016/j.clnu.2022.10.024 -
Nutrients Jun 2022There is an increasing interest in investigating dietary strategies able to modulate the gut microbial ecosystem which, in turn, may play a key role in human health.... (Review)
Review
There is an increasing interest in investigating dietary strategies able to modulate the gut microbial ecosystem which, in turn, may play a key role in human health. Dietary fibers (DFs) are widely recognized as molecules with prebiotic effects. The main objective of this systematic review was to: (i) analyze the results available on the impact of DF intervention on short chain fatty acids (SCFAs) production; (ii) evaluate the interplay between the type of DF intervention, the gut microbiota composition and its metabolic activities, and any other health associated outcome evaluated in the host. To this aim, initially, a comprehensive database of literature on human intervention studies assessing the effect of confirmed and candidate prebiotics on the microbial ecosystem was developed. Subsequently, studies performed on DFs and analyzing at least the impact on SCFA levels were extracted from the database. A total of 44 studies from 42 manuscripts were selected for the analysis. Among the different types of fiber, inulin was the DF investigated the most ( = 11). Regarding the results obtained on the ability of fiber to modulate total SCFAs, seven studies reported a significant increase, while no significant changes were reported in five studies, depending on the analytical methodology used. A total of 26 studies did not show significant differences in individual SCFAs, while the others reported significant differences for one or more SCFAs. The effect of DF interventions on the SCFA profile seemed to be strictly dependent on the dose and the type and structure of DFs. Overall, these results underline that, although affecting microbiota composition and derived metabolites, DFs do not produce univocal significant increase in SCFA levels in apparently healthy adults. In this regard, several factors (i.e., related to the study protocols and analytical methods) have been identified that could have affected the results obtained in the studies evaluated. Future studies are needed to better elucidate the relationship between DFs and gut microbiota in terms of SCFA production and impact on health-related markers.
Topics: Adult; Dietary Fiber; Fatty Acids, Volatile; Gastrointestinal Microbiome; Humans; Microbiota; Prebiotics
PubMed: 35807739
DOI: 10.3390/nu14132559 -
Mucosal Immunology May 2022Barrier integrity is central to the maintenance of healthy immunological homeostasis. Impaired skin barrier function is linked with enhanced allergen sensitization and...
Barrier integrity is central to the maintenance of healthy immunological homeostasis. Impaired skin barrier function is linked with enhanced allergen sensitization and the development of diseases such as atopic dermatitis (AD), which can precede the development of other allergic disorders, for example, food allergies and asthma. Epidemiological evidence indicates that children suffering from allergies have lower levels of dietary fibre-derived short-chain fatty acids (SCFA). Using an experimental model of AD-like skin inflammation, we report that a fermentable fibre-rich diet alleviates systemic allergen sensitization and disease severity. The gut-skin axis underpins this phenomenon through SCFA production, particularly butyrate, which strengthens skin barrier function by altering mitochondrial metabolism of epidermal keratinocytes and the production of key structural components. Our results demonstrate that dietary fibre and SCFA improve epidermal barrier integrity, ultimately limiting early allergen sensitization and disease development.The Graphical Abstract was designed using Servier Medical Art images ( https://smart.servier.com ).
Topics: Allergens; Child; Dermatitis, Atopic; Dietary Fiber; Fatty Acids, Volatile; Food Hypersensitivity; Humans; Keratinocytes
PubMed: 35672452
DOI: 10.1038/s41385-022-00524-9 -
Food Chemistry May 2024Dietary fiber (DF) was established as a key dietary constituent some decades ago, as were some of its mechanisms of action and health effects. Although there is... (Review)
Review
Dietary fiber (DF) was established as a key dietary constituent some decades ago, as were some of its mechanisms of action and health effects. Although there is consolidated evidence on many features regarding DF, at the same time there are still many aspects to be explored in the field, e.g., deeper explorations of the contribution of phenolic compounds linked to cell walls to the biological activities of DF, or of the relevance of the gut-brain axis. At the same time, increasing DF intake should be seen as a major public health problem since worldwide intakes are quite far from recommendations. The awareness of this fact by public bodies should lead, among others, to the assessment of effective strategies for promoting DF intake among general population or specific groups; and to consider potential regulatory modifications in order to clarify several aspects potentially misleading for consumers.
Topics: Humans; Dietary Fiber; Diet; Phenols; Public Health
PubMed: 38039615
DOI: 10.1016/j.foodchem.2023.138076