This project maps how the gut microbiome transforms dietary polyphenols—compounds found in foods like berries, tea, and nuts—into bioactive metabolites that may influence health. Drawing on clinical studies, the review identifies specific microbial patterns associated with metabolite production (e.g., urolithins, equol) and highlights how individuals differ in their ability to generate these compounds. The findings support a shift toward precision nutrition, where dietary recommendations can be tailored to a person’s microbiome to optimize health outcomes.