Probiotics and prebiotic galacto-oligosaccharides in the prevention of allergic diseases: a randomized, double-blind, placebo-controlled trial.

Background: The increase in allergic diseases is attributed to a relative lack of microbial stimulation of the infantile gut immune system. Probiotics, live health-promoting microbes, might offer such stimulation.
Objective: We studied the effect of a mixture of 4 probiotic bacterial strains along with prebiotic galacto-oligosaccharides in preventing allergic diseases.
Methods: We randomized 1223 pregnant women carrying high-risk children to use a probiotic preparation or a placebo for 2 to 4 weeks before delivery. Their infants received the same probiotics plus galacto-oligosaccharides (n = 461) or a placebo (n = 464) for 6 months. At 2 years, we evaluated the cumulative incidence of allergic diseases (food allergy, eczema, asthma, and allergic rhinitis) and IgE sensitization (positive skin prick test response or serum antigen-specific IgE level >0.7 kU/L). Fecal bacteria were analyzed during treatment and at age 2 years.
Results: Probiotic treatment compared with placebo showed no effect on the cumulative incidence of allergic diseases but tended to reduce IgE-associated (atopic) diseases (odds ratio [OR], 0.71; 95% CI, 0.50-1.00; P = .052). Probiotic treatment reduced eczema (OR, 0.74; 95% CI, 0.55-0.98; P = .035) and atopic eczema (OR, 0.66; 95% CI, 0.46-0.95; P = .025). Lactobacilli and bifidobacteria more frequently (P < .001) colonized the guts of supplemented infants.
Conclusion: Probiotic treatment showed no effect on the incidence of all allergic diseases by age 2 years but significantly prevented eczema and especially atopic eczema. The results suggest an inverse association between atopic diseases and colonization of the gut by probiotics.
Clinical Implications: The prevention of atopic eczema in high-risk infants is possible by modulating the infant's gut microbiota with probiotics and prebiotics.