Words that describe healthy gut microbes and their activity have specific meanings, although the terms themselves can be confused easily.

Probiotics: Live microorganisms that, when administered in adequate amounts, confer a health benefit to the host. The term developed as an antonym of “antibiotics.”

Prebiotics: Selectively fermented ingredients, generally nondigestible, that result in specific changes in the composition and/or activity of the gastrointestinal microbiota to confer benefit(s) upon host health. Thus, probiotic organisms consume (ferment) prebiotic ingredients.

Synbiotics: Mixtures of probiotics and prebiotics that benefit the consumer by improving the survival of live microbial dietary supplements in the gastrointestinal tract and by supporting the growth of health-
promoting bacteria. Do not confuse “synbiotic” with “symbiotic.”