The gut:brain axis is emerging as an important information highway linking the foods we eat with neurophysiological development and functions. Some gut microorganisms have shown to alleviate anxiety and depression, improve cognitive performance and play a role in brain development in early life. However, most studies were conducted in laboratory animals and these findings await confirmation in carefully designed human interventions. Similarly, little attention has been given to how diet:microbe interactions within the gut can impact on neurotransmitter production or their subsequent biological effects within the nervous system. In this review, we discuss the possible influence of carbohydrates, polyphenols, lipids and proteins colonic fermentation on production, bioavailability and biological activity of metabolites linked to the gut-microbiota-brain axis. An increased understanding of how nervous system may be regulated by diet will greatly enhance our ability to design dietary strategies to improve healthy brain development and functions.
Keywords: Microbial fermentation; diet–microbe interactions; gut-brain axis; macronutrients metabolism; neuroactive compounds; tryptophan metabolism.