Pre, Pro, and Postbiotics

*Excerpts from my book Reversing Time: My Journey to a Younger Self

The terminology of gut bacterial supplements can be confusing, and I wish they would change it for better clarity. I am explaining the terms here.

Prebiotics are non-digestible fibers found in onions, garlic, leeks, asparagus, bananas, and oats. They pass through the upper intestine undigested and feed beneficial microbes down in the colon.

Probiotics are live microorganisms that may offer health benefits when consumed in sufficient amounts, a concept dating back to Nobel Laureate Elie Metchnikoff, who in 1907 proposed that fermented milk could extend life. Specific probiotic strains, such as Lactobacillus rhamnosus and Bifidobacterium longum, can help reduce antibiotic-associated diarrhea and mild IBS symptoms. However, their effects are strain-specific, temporary, and highly individual; most disappear within days after stopping supplementation.

Postbiotics, a newer category, are byproducts or inactivated fragments of probiotic bacteria that form during fermentation or pasteurization. Even without live microbes, these metabolites can support immunity and gut health, though research is in its early stages.

Probiotics provide specific bacteria and can be useful for short-term needs, such as after antibiotic treatment. But prebiotics enrich the gut environment and provide a long-term foundation for gut health.