The role of dietary proteins and carbohydrates in gut microbiome composition and activity: A review

The intestinal microbiota is a preponderant mediator of dietary effects on host health, through the metabolism of undigested dietary macronutrients. Gut microbial metabolism results in numerous metabolic end products, acting both locally and systemically. The current review of recent studies, reveals that the composition and activity of gut microbiota are profoundly dependent on the dietary intake of carbohydrates and proteins. Generally, proteolytic fermentation generates toxic metabolites, which are implicated in the development of diseases. However, high dietary fiber intake can modulate microbial metabolism and composition, generating the production of short-chain fatty acids (SCFAs), and suppressing proteolytic activity. The amount and digestibility of dietary proteins are also major factors impacting the extent of colonic proteolytic fermentation. Complementing previous reviews, this review describes the metabolic interaction between dietary proteins and carbohydrates. This includes the modulation of fermentative pathways and microbial composition, production of metabolites, and their impact on human health. The role of some milk- and Maillard-based glycoproteins in gut microbiota composition and activity is also discussed. Understanding how dietary patterns influence host-microbiome interaction is crucial for the future development of targeted interventions. Such approaches aim to improve the health of the human host and to achieve specific health-beneficial outcomes.