Bacteria in the gut produce metabolites, which can interact with the human organism, at local and systemic level. Gut microbiota metabolites can derive from 1) fermentation of dietary components, 2) fermentation of human metabolites, such as bile acids, or 3) de novo synthesis, such as branched chain amino acids or bacteria-derived vitamins. Gut microbiota metabolites are suggested to regulate physiologic processes by serving as signalling molecules to various cells and to serve as cell substrates. Gut microbiota metabolites represent a potential mechanistic link for the interaction between the microbiota and the human organisms (Yang & Cong, 2021).
In a healthy state, gut microbiota metabolites are associated with beneficial effects. Short-chain fatty acids are the most frequent studied metabolites that provide benefits. Although the gut microbiota and its metabolites have been investigated extensively since the 1990s, many metabolites and their effects remain unidentified today (Kim, 2018).