Probiotics

What the evidence says

'Probiotic' is not one treatment. Benefits demonstrated for a named strain or multi-strain preparation at a tested dose cannot automatically be transferred to another organism, yogurt, gummy, spore product, or generic colony-forming-unit count.^[4][3]

The best-supported broad use is prevention of antibiotic-associated diarrhea. A 2021 meta-analysis of 42 adult trials and 11,305 participants found lower risk overall, while effects varied by baseline risk, dose, and species. A network meta-analysis likewise found meaningful differences between preparations rather than one uniform class effect.^[1][2]

AGA guidance recommends only specific strains or combinations for selected antibiotic recipients and certain other narrow settings; for most digestive diseases it finds insufficient evidence or recommends use only in clinical trials. This does not support routine probiotics for vague goals such as detoxification, immunity, mood, or a universally 'balanced microbiome.'^[3][4]

Gas, bloating, and temporary bowel changes are common. Bloodstream infection or fungemia is rare but reported, particularly in people who are critically ill, immunocompromised, have central venous catheters, or have a severely disrupted intestinal barrier. Product contamination and label accuracy are additional concerns because many products are supplements rather than drugs.^[5][4]