Ingredient guide
What are probiotics?
Learn what probiotics are, why evidence is strain-specific, how products differ, and how Probiotic Science reviews published studies, findings, and limitations.
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.
Explore the probiotic guide by question
The structured guide connects this foundational page to the product comparison and focused research summaries.
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What Are Probiotics?
The baseline definition: live microorganisms, strain specificity, and why generic probiotic claims are weak.
Open guide →Probiotic Strains
Why the strain matters more than generic species-level marketing.
Open guide →CFU Count Guide
How to interpret colony-forming units without treating bigger numbers as automatically better.
Open guide →Probiotics for IBS
What IBS-focused probiotic research suggests and why effects are product- and strain-specific.
Open guide →Probiotics with Antibiotics
Research context for antibiotic-associated diarrhea and timing questions.
Open guide →Probiotics for Women
Women-specific probiotic questions and where the evidence is more or less direct.
Open guide →Product comparison
An evidence-informed comparison of leading probiotic supplements, evaluated on strain characterization, labeled CFU, transparency, and testing.