Abstract
The gut microbiome plays an important role in human health and influences the development of chronic diseases ranging from metabolic disease to gastrointestinal disorders and colorectal cancer. Of increasing prevalence in Western societies, these conditions carry a high burden of care. Dietary patterns and environmental factors have a profound effect on shaping gut microbiota in real time. Diverse populations of intestinal bacteria mediate their beneficial effects through the fermentation of dietary fiber to produce short-chain fatty acids, endogenous signals with important roles in lipid homeostasis and reducing inflammation. Recent progress shows that an individual’s starting microbial profile is a key determinant in predicting their response to intervention with live probiotics. The gut microbiota is complex and challenging to characterize. Enterotypes have been proposed using metrics such as alpha species diversity, the ratio of Firmicutes to Bacteroidetes phyla, and the relative abundance of beneficial genera (e.g., Bifidobacterium, Akkermansia) versus facultative anaerobes (E. coli), pro-inflammatory Ruminococcus, or nonbacterial microbes. Microbiota composition and relative populations of bacterial species are linked to physiologic health along different axes. We review the role of diet quality, carbohydrate intake, fermentable FODMAPs, and prebiotic fiber in maintaining healthy gut flora. The implications are discussed for various conditions including obesity, diabetes, irritable bowel syndrome, inflammatory bowel disease, depression, and cardiovascular disease.
Highlights
The intestinal microbiome has recently been implicated in a host of chronic diseases ranging from inflammatory bowel disease (IBD), type 2 diabetes (T2D), and cardiovascular disease (CVD) to colorectal cancer [1,2,3]
Bacteroidetes phylum, bacterial strains from the genus Prevotella, whose enzymes degrade plant fiber, became displaced by dominant strains from the genus Bacteroides according to an individual’s time spent in the U.S The ratio of Bacteroides to Prevotella increased by factors of 10, correlating with the time in decades spent in the U.S Prior to this study, metagenomics had identified three clusters of variation in the human gut, referred to as enterotypes [13]
Despite plasma low-density lipoprotein (LDL) being used as the principal target in lipid-lowering therapy for the last three decades, recent evidence suggests that triglyceride, high-density lipoprotein (HDL), and apolipoprotein B blood levels may be more useful CVD predictors [230,231,232,233,234,235]
Summary
The intestinal microbiome has recently been implicated in a host of chronic diseases ranging from inflammatory bowel disease (IBD), type 2 diabetes (T2D), and cardiovascular disease (CVD) to colorectal cancer [1,2,3]. Nutrients 2019, 11, 1613 which refers to the community of microorganisms themselves, the relative abundance of individual species populations, and their function. Metagenomics and analysis of twins data has revealed that environmental factors such as diet and household cohabitation greatly outweigh heritable genetic contributions to the composition and function of gut microbiota [7]. Bacteroidetes phylum, bacterial strains from the genus Prevotella, whose enzymes degrade plant fiber, became displaced by dominant strains from the genus Bacteroides according to an individual’s time spent in the U.S The ratio of Bacteroides to Prevotella increased by factors of 10, correlating with the time in decades spent in the U.S Prior to this study, metagenomics had identified three clusters of variation in the human gut, referred to as enterotypes [13]. GI symptoms, mucosal inflammation, and microbial communities were compared for dietary and anti-TNF therapy and antibiotic use relative to healthy children. Since a defined formula was effective for restoring healthy microbiota, it is conceivable that a more general oral diet with the proper nutrition can restore the intraluminal environment [25,26,27]
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