10/2/03 Probiotics and prevention of atopic diseaseSummaryPrevious studies from Scandinavia have suggested that ingestion of diets rich in benign probiotics such as lactobacillus GG by infants is associated with a subsequent incidence of atopic eczema by age 2 years. In this current study, Kalliomaki et al of the Univ. of Turku in Finland reported a follow-up at age 4 years in this placebo-controlled trial. They found evidence of atopic eczema of 26% (14 of 53) in those previously given lactobacillus vs 25 of 54 (46%) in age-matched children previously given placebo instead of the lactobacillus. There was no difference in the incidence of allergic skin test reactivity or respiratory allergies in the 2 groups. The authors concluded that the protective effect of lactobacillus ingestion in infancy extends out to at least 4 years of age. Reference Lancet 2003; 361:1869-71 Editor’s Comments These studies were initiated by earlier reports that children growing up in communities where probiotic diets were the custom had a lower incidence of atopic manifestations. It was postulated that such diets resulted in extensive colonization of the G-I tract with non-pathogenic bacteria during infancy. Such colonization was thought to stimulate Th1 immune responses with down modulation of Th2 responses (and therefore, less atopy). The present study confirms the earlier findings of a moderate decrease in atopic eczema. Incidence now still the case several years after ceasing addition of the probiotic agent lactobacillus GG to the diet. One might think that such decrease in atopic eczema incidence was due to decreased atopic reactivity, if the theory described above was valid. However, there was no reduction in IgE-mediated skin test reactivity or in the incidence of allergic respiratory diseases in the children formerly given lactobacillus GG. Thus, other mechanisms may be responsible for the decrease in atopic eczema incidence. A recent study showed that administration of lactobacillus (a major component in a probiotic diet) for 6 weeks moderately reduced the extent and severity of pre-existent atopic eczema (J Allergy Clin Immunol 2003; 111:389-95). It is of note that most impressive effect of the trials of prolonged breast feeding and then low-allergen diets in at-risk (strong atopic family history) infants is a reduction in atopic dermatitis (eczema) but much less if any effect on allergic respiratory diseases.
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