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.