Research synthesisModerate evidenceMixed effect size6 studies · 5 beneficial · 1 neutral · 0 harmful
Across 6 studies, 5 reported beneficial effects of Bifidobacterium animalis subsp. lactis BB-12 on reducing upper respiratory infections, with effect sizes ranging from small to large. Statistically significant findings were observed in 4 studies, including a meta-analysis (moderate effect, RR=0.79) and RCTs in infants (small effect) and young children (moderate effect). The most studied population is healthy infants and young children, with a specific dose of 10 billion CFU/day reported in one high-quality study.
- Effective dose range: 10 billion CFU/day
- Studied populations: healthy infants, healthy young children (0-3 years)
Caveats: Available evidence is overwhelmingly positive — clinical literature in this area is subject to publication bias (null-result studies are less likely to be published or indexed). One neutral study (118 children in childcare settings) did not reach significance, suggesting effects may not generalize to all pediatric populations. Evidence base is small (only 6 studies) and one older review did not report effect significance or sample size, limiting interpretability.
Generated Jul 17, 2026