Fortunately, microbial modulation is no longer theoretical. Increasing dietary fiber promotes the growth of beneficial microbes that produce short-chain fatty acids (SCFAs) – key molecules that help strengthen the intestinal barrier, support immune balance, and contribute to gut resilience. Other approaches, such as probiotic and prebiotic supplementation have also been shown to influence microbial activity.

As research has advanced, it has become increasingly clear that microbial composition tells only part of the story. What ultimately matters is not just which microbes are present, but what they do – their metabolic output. In other words, microbial function an effect on overall health.

This shift in focus has brought microbial metabolites – small, bioactive compounds produced by the gut microbiota – into the spotlight. These metabolites serve as messengers, interacting with receptors in the body and influence key physiological processes such as immune signaling, gut barrier integrity, energy balance, and even brain function. Among the most physiologically influential of these are metabolites derived from tryptophan, an essential amino acid whose fate within the gut is strongly shaped by the health and composition of the gut microbiota.  

Quick summary 

• Diet, especially fiber and polyphenols, can improve microbiota composition and restore microbial balance – promoting the production of beneficial metabolites that support health.  
• Poor lifestyle habits and dietary choices conversely trigger microbial imbalance and increase the production of metabolites associated with stress and imbalance.