Probiotics for prevention of atopic diseases in infants: systematic review and meta‐analysis

Systematic review and meta-analysis of 17 studies including 4755 children, with 2381 in probiotic groups and 2374 in control groups. Most participants were infants at high risk for atopy, and probiotic supplementation was started during pregnancy or in the first months of life.

Across included trials, the active intervention was oral probiotic supplementation given to mothers during pregnancy and/or to infants in early life, with regimens ranging from gestational week 24 to 36, 2 months before delivery, or after birth, and continuing from 6 months to 2 years depending on the study. Active products included single strains and multi-strain mixtures such as Lactobacillus rhamnosus HN001, HN019, Lactobacillus reuteri ATCC 55730, Lactobacillus rhamnosus GG, and combinations of Lactobacillus and Bifidobacterium strains.

Probiotics reduced infantile eczema overall, but they did not prevent asthma, wheezing, or rhinoconjunctivitis. For eczema, the pooled risk ratio was 0.78 (95% CI 0.69-0.89; P = 0.0003), and probiotic mixtures showed a stronger effect (RR 0.54, 95% CI 0.43-0.68; P < 0.00001) than single-strain Lactobacilli (RR 0.90, 95% CI 0.77-1.05; P = 0.18) or Bifidobacteria (RR 0.89, 95% CI 0.73-1.08; P = 0.23). The pooled estimates for asthma (RR 0.99, 95% CI 0.77-1.27), wheeze (RR 1.02, 95% CI 0.89-1.17), and rhinoconjunctivitis (RR 0.91, 95% CI 0.67-1.23) were not significant. Probiotics were generally safe in these perinatal and early-life studies.

The evidence was heterogeneous because trials used different probiotic strains, mixtures, start times, and treatment durations. Benefits were concentrated in eczema prevention, while other allergic outcomes were null, so the overall clinical effect is limited to a specific indication. Generalizability is also mainly to high-risk infants and perinatal/early-life use.