Systematic Review on Effects of Diet on Gut Microbiota in Relation to Metabolic Syndromes

The microbiota is a complex ecosystem of microbes, the bulk of which reside mainly in the colon, and has been shown to be significantly influenced by the diet. The biological functions of the microbiota have been strongly linked to health and disease, including the development of metabolic syndrome (MetS). The aim of this paper was to review current literature on the effects of the diet on gut microbiota in relation to the development of MetS through the following objectives: (i) to determine how the diet influences the composition and functions of the microbiota; (ii) evaluate evidence of how this is linked with development obesity and biomarkers of MetS; (iii) investigate the significance of diet-microbiota interactions in relation to obesity and MetS. Multiple databases were used to find and collate relevant literatures. The main findings highlight that a plant-based diet, rich in indigestible carbohydrate was strongly associated with a richer, more diverse microbiota profile compared to a high-energy, high-fat Western diet. Studies in mice have indicated that weight gain can be induced via inoculation of an obese-type microbiota without changes in dietary intake. Additionally, polyphenols appear to interact with the microbiota, producing metabolites which have shown to possess more health potential than their precursors. Unabsorbed polyphenols also seem to beneficially modulate the microbiota, resulting in positive health outcomes. More in vivo human studies are necessary to conclude the significance of the microbiota and mechanisms of action in the development of MetS. With this knowledge, there may be potential to manipulate the gut microbiota toward the generation of desired health outcomes as an alternative to pharmaceuticals.