Prebiotics in infants for prevention of allergic disease and food hypersensitivity

Background The composition of the intestinal microflora may be different in individuals with atopic eczema from those without this condition, and such differences may precede the development of eczema. Prebiotics are nondigestible food components that benefit the host by selectively stimulating the growth or activity of non-pathogenic bacteria in the colon. Prebiotics ( commonly oligosaccharides) added to infant feeds have the potential to prevent sensitisation of infants to dietary allergens. Objectives To determine the effect of prebiotics given to infants for the prevention of allergic disease or food hypersensitivity. Search strategy This included searches of the Cochrane Central Register of Controlled Trials ( Issue 1, 2007), MEDLINE ( 1966 - February 2007), EMBASE, PREMEDLINE, abstracts of conference proceedings and citations of published articles, and expert informants. Selection criteria Randomised and quasi-randomised controlled trials that compared the use of a prebiotic to no prebiotic; or the use a specific prebiotic compared to a different prebiotic. Data collection and analysis Assessment of trial quality, data extraction and synthesis of data were performed using standard methods of the Cochrane Neonatal Review Group. Main results Seven studies were eligible for inclusion. Only two studies reported an allergic disease outcome for 432 infants. Study quality was reasonable, although Moro 2006 reported 20% post-randomisation losses. Moro 2006 enrolled hydrolysed formula fed infants at high risk of allergy and reported a significant reduction in eczema in infants up to six months of age (RR 0.42, 95% CI 0.21, 0.84). Ziegler 2007 enrolled formula fed infants who were not selected on the basis of risk for allergy and reported no significant difference in eczema up to four months of age ( RR 1.62, 95% CI 0.62, 4.26). Meta- analysis of the two studies found no significant difference in eczema, but significant heterogeneity was detected. Differences were potentially attributable to differences in infant risk, prebiotic formulation or measurement of eczema. Analysis of five studies reporting measures of infant growth found no consistent adverse effects. Authors' conclusions There is insufficient evidence to determine the role of prebiotic supplementation of infant formula for prevention of allergic disease and food hypersensitivity. One small trial of prebiotic oligosaccharides with excess losses reported a reduction in eczema in high risk formula fed infants. Further trials are needed to determine whether this finding persists over a longer period of time, applies to other manifestations of allergic disease, is associated with reductions in allergen sensitisation, and is reproducible.