What are probiotics?

An introduction to probiotics and why findings are strain-specific, plus how Probiotic Science organizes the evidence.

Probiotics are live microorganisms — most commonly particular strains of bacteria or yeasts — that are studied for their interactions with the human digestive system. Different products contain different strains and amounts, and research findings are typically specific to the exact strain studied rather than to probiotics in general. Probiotic Science is an independent project that organizes the scientific literature by strain and study, summarizing what researchers measured and reported and linking to the source papers. This material is for general information only and is not medical advice.