Impact of Nutrition on the Gut Microbiota

Nutrition influences the composition and function of the human gut microbiota, with possible ramifications for health and disease. The effects of complex carbohydrates on the gut microbiota are well studied: microbiota-accessible carbohydrates are fermented in the colon by bacteria, yielding potentially health-promoting end products (short-chain fatty acids). Protein fermentation by microbes may also occur in the colon, producing some metabolites known to be harmful to intestinal health. Little research exists addressing the impact of fats on the human intestinal microbiota, but animal studies suggest that both the quantity and quality of dietary fats may modulate microbial composition. Dietary patterns exert long-term selective pressure on the gut microbiota. In contrast with the dietary patterns of traditional societies, the “Western” diet pattern is associated with adverse health outcomes and deleterious changes to gut microbiota structure (i.e., decreased species diversity) and function. Vegetarian diets and the Mediterranean diet also appear to impact the gut microbiota and are associated with beneficial health effects. Various polyphenols (including flavonoids) may particularly affect the gut microbiota; emulsifiers and noncaloric sweeteners are linked with potentially detrimental effects on the intestinal environment and health. Finally, it must be noted that evidence is increasing for gut microbial involvement in individualized responses to diet.