PURPOSE OF THE STUDY.
Some studies suggest that early probiotic administration reduces the risk of allergies and asthma in childhood. This study evaluates the effects of probiotic supplementation on asthma and atopic sensitization.
The study included 4031 subjects in 20 cohorts primarily in Europe, Asia, and Australia. Probiotics were administered prenatally to pregnant mothers (2 studies), prenatally and postnatally (10 studies), or only postnatally directly to the child (9 studies).
This meta-analysis included 25 double-blind, randomized, placebo-controlled trials published between 2001 and 2012. Meta-regression was performed to evaluate the effect of potential factors on probiotic efficacy. The pooled risk estimates were calculated by using random effect models. Atopic sensitization was measured by a positive skin prick test or elevated serum-specific IgE level to any food or inhalant allergen. Asthma was diagnosed directly by a physician or indirectly by parental report of a physician diagnosis.
Total IgE and atopic sensitization was significantly reduced in subjects who received probiotics. This reduction was more pronounced with longer follow-up for total IgE levels (correlation coefficient: –1.95 [95% confidence interval: –3.69 to –0.21]; P = .028). The effect on atopic sensitization was only significant when probiotics were administered both prenatally and postnatally (relative risk: 0.08 [95% confidence interval: 0.78 to 0.99]; P = .035) but not when only administered postnatally (P = .825). However, probiotics did not significantly reduce the prevalence of asthma or wheeze. Lactobacillus was found to be associated with increased atopic sensitization.
Early probiotic administration reduces the risk of atopic sensitization, but it does not reduce the risk of developing asthma. There was no significant association in subgroup analysis according to age group or treatment length.
Results on atopy and asthma in association with probiotic administration have been conflicting. This study showed that probiotic administration was significant in reducing atopic sensitization but not disease. Similar to the hygiene hypothesis, in which a relative lack of microbial exposure during infancy and early childhood could result in an imbalance with a shift of Th1/Th2 cytokine balance toward a more allergic Th2 response, probiotics may promote a healthy gut microbiome, shifting this balance to a nonallergic Th1 response. Future trials are still needed to achieve more consistency among studies.
- Copyright © 2014 by the American Academy of Pediatrics