WHAT'S KNOWN ON THIS SUBJECT:The intestinal microbiome may play a role in immune system maturation, and it has been postulated that early-life probiotic administration may reduce the risk of allergies and asthma in childhood. To date, however, results from clinical trials have been inconsistent. WHAT THIS STUDY ADDS:In this meta-analysis, administration of probiotics in early life may reduce total immunoglobulin E level and protect against atopic sensitization but do not seem to protect against asthma/wheezing. Future trials should carefully select probiotic strains and include longer follow-up. abstract BACKGROUND AND OBJECTIVE: Probiotics may reduce the risk of atopy and asthma in children. However, results from clinical trials have been conflicting, and several of them may have been underpowered. We performed a meta-analysis of randomized, placebo-controlled trials to assess the effects of probiotic supplementation on atopic sensitization and asthma/wheeze prevention in children. METHODS:Random-effects models were used to calculate pooled risk estimates. Meta-regression was conducted to examine the effect of potential factors on probiotics efficacy.RESULTS: Probiotics were effective in reducing total immunoglobulin E (IgE) (mean reduction: -7.59 U/mL [95% confidence interval (CI): -14.96 to -0.22]; P = .044). Meta-regression showed that the reduction in IgE was more pronounced with longer follow-up. Probiotics significantly reduced the risk of atopic sensitization when administered prenatally (relative risk: 0.88 [95% CI: 0.78 to 0.99]; P = .035 for positive result on the skin prick test and/or elevated specific IgE to common allergens) and postnatally (relative risk: 0.86 [95% CI: 0.75 to 0.98]; P = .027 for positive result on skin prick test). Administration of Lactobacillus acidophilus, compared with other strains, was associated with an increased risk of atopic sensitization (P = .002). Probiotics did not significantly reduce asthma/wheeze (relative risk: 0.96 [95% CI: 0.85 to 1.07]).CONCLUSIONS: Prenatal and/or early-life probiotic administration reduces the risk of atopic sensitization and decreases the total IgE level in children but may not reduce the risk of asthma/wheeze. Follow-up duration and strain significantly modified these effects. Future trials for asthma prevention should carefully select probiotic strain and consider longer follow-up. Pediatrics 2013;132:e666-e676 AUTHORS:

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