Randomized, double-blind, placebo-controlled trial of probiotics for primary prevention:: No clinical effects of Lactobacillus GG supplementation

BACKGROUND. The value of probiotics for primary prevention is controversial. Published trials vary considerably in study design and the applied probiotics, thereby limiting comparability of the results. OBJECTIVE. The purpose of this trial was to study the preventive effect of the probiotic Lactobacillus GG on the development of atopic dermatitis. METHODS. In a double-blind, placebo-controlled prospective trial, 105 pregnant women from families with >= 1 member ( mother, father, or child) with an atopic disease were randomly assigned to receive either the probiotic Lactobacillus GG ( American Type Culture Collection 53103; 5 x 109 colony-forming units of Lactobacillus GG twice daily) or placebo. Ninety-four families (89.5%) completed the trial. The supplementation period started 4 to 6 weeks before expected delivery, followed by a postnatal period of 6 months. The primary end point was the occurrence of atopic dermatitis at the age of 2 years. Secondary outcomes were severity of atopic dermatitis, recurrent episodes of wheezing bronchitis, and allergic sensitization at the age of 2 years. RESULTS. Atopic dermatitis was diagnosed in 14 (28%) of 50 in the Lactobacillus GG group and in 12 (27.3%) of 44 in the placebo group. The risk of atopic dermatitis in children on probiotics relative to placebo was 0.96 ( confidence interval 0.38-2.33). Severity of atopic dermatitis was comparable between the 2 groups. Notably, children with recurrent (>= 5) episodes of wheezing bronchitis were more frequent in the Lactobacillus GG group (26%; n = 13), as compared with the placebo group (9.1%; n = 4). No difference was observed between both groups in total immunoglobulin E concentrations or numbers of specific sensitization to inhalant allergens. CONCLUSIONS. Supplementation with Lactobacillus GG during pregnancy and early infancy neither reduced the incidence of atopic dermatitis nor altered the severity of atopic dermatitis in affected children but was associated with an increased rate of recurrent episodes of wheezing bronchitis. Therefore, Lactobacillus GG cannot be generally recommended for primary prevention.