Big effect
A meta-analysis linked Bifidobacterium animalis to a 21% lower risk of respiratory infections — but the finding rests on just three trials with 751 participants total.
This is one of the first systematic looks at this specific probiotic for respiratory infections, so while the effect is promising and statistically significant, the small number of trials means the real-world benefit could be smaller — or even absent — once larger studies are done.
Researchers pooled data from 107 randomized trials to rank which supplements best prevent respiratory infections. Bifidobacterium animalis stood out with a moderate-sized reduction in infection risk, but the evidence came from only three studies. The analysis also found that multi-strain probiotics shortened symptom duration and that high-dose vitamin D specifically cut COVID-19 or influenza risk — so the benefit of this single strain is narrower than it first appears.
Where this fits in the evidence
This is among the first studies we've indexed on Bifidobacterium animalis for Reduced Upper Respiratory Infections — treat it as an early signal until more research accumulates.
The study
- Meta-Analysis
- n = 751
- 2025-10
- EClinicalMedicine
This is a plain-language summary of a research finding, not medical advice. Pillser surfaces research signals to help you decide what's worth investigating — always consult a qualified professional before changing what you take.