Probiotics
Probiotics are live microorganisms, mostly bacteria and yeasts, taken in fermented foods or supplements.
Can they prevent diarrhea during antibiotics?
A review of 42 adult trials with 11,305 participants found a 37% relative reduction in antibiotic-associated diarrhea. Evidence was rated moderate, and trials with low baseline risk did not show a benefit. This does not mean 37 fewer cases per 100 people. 1
What about constipation?
A 2022 review found responses in 57% of probiotic recipients versus 44% of controls. Stool frequency improved overall, but consistency did not; Bifidobacterium lactis showed a subgroup benefit while several other preparations did not. Study differences and bias limit certainty. 2
Some preparations may help adults with chronic constipation; this is not a class-wide effect. 2
Is there a dependable choice for IBS?
NCCIH describes possible improvements in overall IBS symptoms and pain, but insufficient clarity about the helpful species, strains or combinations. A broad promise of better gut health is less informative than evidence for a defined symptom. 3
Does everyone need a daily supplement?
There are no formal recommendations for or against probiotics in healthy people. Evidence-based guidance instead addresses particular preparations for particular conditions. 4
Effects by health goal
Open an effect to see the studies behind its rating. Bars show the size of the effect; the letter grades the evidence.
Gut Health4 effects
Immune Support3 effects
No study is linked to this rating.
Cognition1 effect
No study is linked to this rating.
Other effects2 effects
All studies
23 publications are linked to Probiotics, newest first.
Sources
- Probiotics: Fact Sheet for Health Professionals NIH Office of Dietary Supplements