DOI 10.1007/s00535-008-2296-0 Review

Probiotics are defi ned as live microorganisms that, when administered in adequate amounts, confer a health benefi t on the host, including the gastrointestinal tract. While this benefi cial effect was originally thought to stem from improvements in the intestinal microbial balance, there is now substantial evidence that probiot-ics can also provide benefi ts by modulating immune functions. In animal models, probiotic supplementation is able to provide protection from spontaneous and chemically induced colitis by downregulating infl amma-tory cytokines or inducing regulatory mechanisms in a strain-specifi c manner. In animal models of allergen sensitization and murine models of asthma and aller-gic rhinitis, orally administered probiotics can strain-dependently decrease allergen-specifi c IgE production, in part by modulating systemic cytokine production. Certain probiotics have been shown to decrease air-way hyperresponsiveness and infl ammation by inducing regulatory mechanisms. Promising results have been obtained with probiotics in the treatment of human infl ammatory diseases of the intestine and in the pre-vention and treatment of atopic eczema in neonates and infants. However, the fi ndings are too variable to allow fi rm conclusions as to the effectiveness of specifi c pro-biotics in these conditions