Short-chain fatty acids (SCFA) are the main bacterial products of the catabolism of carbohydrates and proteins in the gut, and their role is essential in host–microbiota interactions. Acetic, ...propionic, and butyric acids are the major SCFA produced in the gut, and they have been extensively studied. In contrast, branched short-chain fatty acids (BCFA), mainly isovaleric and isobutyric acids, are produced in less amounts and their fecal levels in different human groups, intestinal microbial producing populations, and influence on health are insufficiently known. They have been proposed as markers of protein fermentation, which leads to the concomitant production of other fermentation products that can be harmful for the colon epithelium. In this context, the aim of this study was to shed light into the production of BCFA by the human intestinal microbiota, as related to age, body mass index (BMI), and diet. Fecal levels of the different SCFA were analyzed by gas chromatography in 232 healthy individuals with ages between 3 months and 95 years, and BMI in adults ranging from 19 to 54. Dietary assessments in adults were obtained through a food frequency questionnaire (FFQ). Molar proportions of BCFA in feces were strongly and positively related with aging. However, not a significant relationship was obtained between BCFA and BMI. A negative correlation was found between the consumption of dietary insoluble fiber and fecal levels of BCFA. More studies are needed for improving our understanding on the relationship of BCFA production profile with the intestinal microbiota composition and human health.
Epidemiological studies have linked increased incidence of inflammatory diseases and intestinal cancers in the developed parts of the world to the consumption of diets poor in dietary fibers and rich ...in refined carbohydrates. Gut bacteria residing in the intestinal lumen exclusively metabolize dietary fibers. Butyrate, propionate and acetate, which are collectively called short-chain fatty acids (SCFAs), are generated by fermentation of dietary fibers by gut microbiota. Evidences indicate that SCFAs are key players in regulating beneficial effect of dietary fibers and gut microbiota on our health. SCFAs interact with metabolite-sensing G protein-coupled receptors GPR41, GPR43 and GPR109A expressed in gut epithelium and immune cells. These interactions induce mechanisms that play a key role in maintaining homeostasis in gut and other organs. This review summarizes the protective roles of GPR41, GPR43 and GPR109A in dietary fibers-, gut microbiota- and SCFAs-mediated suppression of inflammation and carcinogenesis in gut and other organs.
Dietary fibers (DFs) regulate host health through various mechanisms related to their dietary sources, specific physicochemical structures, fermentability, and physiological properties in the gut. ...Considering the numerous types and sources of DFs and their different physicochemical and physiological properties, it is challenging yet important to establish the key mechanisms for the beneficial health effects of DFs. In this review, the types and structures of DFs from different fruits and vegetables were summarized and the effects of different processing methods on DF properties were discussed. Moreover, the impacts of DFs on gut microbial ecology, host physiology, and health were described. Understanding the complex interaction between different DFs and gut microbiota is vital for personalized nutrition. It is also important to comprehend factors influencing gut microbiota and strategies to regulate the microbiota, thereby augmenting beneficial health responses. The exploration of molecular mechanism linking DFs, gut microbiota, and host physiology may allow for the identification of effective targets to fight against major chronic diseases.
The merits of a fibre‐rich diet are well documented. Resistant starch (RS) is a form of starch that resists digestion in the small intestine and, as such, is classified as a type of dietary fibre. RS ...can be categorised as one of five types (RS1–5), some of which occur naturally in foods such as bananas, potatoes, grains and legumes and some of which are produced or modified commercially, and incorporated into food products. This review describes human evidence on the health effects of RS consumption, with the aim of identifying any benefits of RS‐rich foods and RS as a functional ingredient. The reduced glycaemic response consistently reported with RS consumption, when compared with digestible carbohydrate, has resulted in an approved European Union health claim. Thus, RS‐rich foods may be particularly useful for managing diabetes. There appears to be little impact of RS on other metabolic markers, such as blood pressure and plasma lipids, though data are comparatively limited. Promising results on markers of gut health suggest that further research may lead to the classification of RS as a prebiotic. Microbial fermentation of RS in the large intestine to produce short‐chain fatty acids likely underpins some of its biological effects, including increasing satiety. However, effects on appetite have not resulted in notable changes in bodyweight after long‐term consumption. Emerging research suggests potential for RS as an ingredient in oral rehydration solutions and in the treatment of chronic kidney disease. Overall, RS possesses positive properties as a healthy food component.
Restriction or ban on antibiotic administration in aquaculture encourages the development of environment‐friendly feed additives as immunostimulants. Short‐chain fatty acids (SCFAs) and their salts ...are ‘Generally Regarded as Safe’ and are often used as antimicrobials in the livestock feed industry. Formate, acetate, propionate, butyrate and their salts are among the most studied SCFAs in aquaculture. These SCFAs affect the host performance as well as physiological response upon three ways: either through effects of the feeds that are being administered, through effects on the gastrointestinal tract of the animal or through direct effects on metabolism. To date, most of the available data are focused on the effects of SCFAs on growth performance and feed utilization. Despite extensive research studies on the effects of the different type of SCFAs and their salts on growth performance and feed utilization, the effects of these feed additives on the health of aquatic organisms have only been receiving attention recently. The results of the studies demonstrated beneficial effects of SCFAs as promising feed additives in aquaculture. The present review article summarizes and discusses the topic of dietary administration of SCFAs and their salts in aquaculture with a closer look at the recent findings regarding the effects of SCFAs on growth performance and health status of fish and shellfish. Furthermore, this review identifies the gaps of existing knowledge regarding the roles of SCFAs in the growth and health status of aquatic animals and suggests research areas that merit further investigations.
The hypoglycemic effect of Phellinus linteus polysaccharide extract (PLPE) has been documented in several previous studies, but the functional interactions among PLPE, gut microbiota, and the ...hypoglycemic effect remain unclear. We examined the regulatory effect of PLPE on gut microbiota, and the molecular mechanism underlying improvement of insulin resistance, using a type 2 diabetic rat model. Here, 24 male Sprague‐Dawley rats were randomly divided into four groups that were subjected to intervention of saline (normal and model control group), metformin (120 mg/kg.bw), and PLPE (600 mg/kg.bw) by oral administration. After 8 weeks of treatment, PLPE increased levels of short‐chain fatty acids (SCFAs) by enhancing abundance of SCFA‐producing bacteria. SCFAs maintained intestinal barrier function and reduced lipopolysaccharides content in blood, thereby helping to reduce systemic inflammation and reverse insulin resistance. Our findings suggest that PLPE (in which polysaccharides are the major component) has potential application as a prebiotic for regulating gut microbiota composition in diabetic patients.
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•The relationship between intestinal flora and diseases was discussed.•Intestinal microbes involved in polysaccharide metabolism were introduced.•Polysaccharides can improve ...intestinal microecology to maintain human health.
As a complex ecosystem of the human body, the intestinal flora maintains a dynamic balance with the host and plays an irreplaceable role in life activities such as nutritional metabolism and host immunity. The intestinal flora interacts with polysaccharides, the intestinal flora digests non-digestible polysaccharides, and polysaccharides can be used as an important energy source for intestinal microorganisms. Disturbance of the gut microbiota (GM) leads to the occurrence of diseases, polysaccharides as prebiotics can improve the disease by regulating the composition of GM. In this paper, we reviewed the current knowledge about the relationship between polysaccharides, gut microbiota, and and human health, described the microbial composition of the human, the relationship between intestinal flora disorders and disease occurrence, and summarized the interactions between polysaccharides and intestinal microorganisms.
Summary
Commensal microbes and the host immune system have been co‐evolved for mutual regulation. Microbes regulate the host immune system, in part, by producing metabolites. A mounting body of ...evidence indicates that diverse microbial metabolites profoundly regulate the immune system via host receptors and other target molecules. Immune cells express metabolite‐specific receptors such as P2X7, GPR41, GPR43, GPR109A, aryl hydrocarbon receptor precursor (AhR), pregnane X receptor (PXR), farnesoid X receptor (FXR), TGR5 and other molecular targets. Microbial metabolites and their receptors form an extensive array of signals to respond to changes in nutrition, health and immunological status. As a consequence, microbial metabolite signals contribute to nutrient harvest from diet, and regulate host metabolism and the immune system. Importantly, microbial metabolites bidirectionally function to promote both tolerance and immunity to effectively fight infection without developing inflammatory diseases. In pathogenic conditions, adverse effects of microbial metabolites have been observed as well. Key immune‐regulatory functions of the metabolites, generated from carbohydrates, proteins and bile acids, are reviewed in this article.
The gut microbiota produce many metabolites. Production of metabolites is altered in many chronic inflammatory and malignant diseases. Microbial metabolites promote both immunity and immune tolerance.
Background
The intestinal microbiota and its metabolites have been reported to play an important role in stroke. Gut microbiota–originating short‐chain fatty acids (SCFAs) modulate brain functions ...directly or indirectly through immune, endocrine, vagal, and other humoral pathways. However, relatively few investigations have evaluated the gut microbiome and SCFAs spectrum or their potential associations with stroke outcomes in acute ischemic stroke (AIS) patients with different stroke severities.
Methods
We used 16S rRNA gene sequencing and gas chromatography to compare the fecal microbial composition and SCFA spectrum between AIS patients (n = 140) and healthy controls (n = 92). Their associations with 90‐day poor functional outcomes were evaluated by logistic regression models.
Results
We found that the intestinal microbiota distinguished AIS patients from healthy controls. A lack of SCFAs‐producing bacteria and a low fecal SCFAs level defined dysbiosis in AIS patients, especially those with increased stroke severity. The SCFAs levels were negatively correlated with stroke severity and prognosis. Reduced SCFAs levels, especially acetate, were associated with an increased risk of 90‐day poor functional outcomes even after adjustments.
Conclusions
Dysbiosis of SCFAs‐producing bacteria and SCFAs in AIS patients increased the subsequent risk for poor functional outcomes, indicating that SCFAs could be potential prognostic markers and therapeutic targets for stroke.
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