Probiotics and prebiotics: immunological and clinical effects in allergic disease.

The intestinal microbiota plays an important role in immune development and may play a role in the development of allergic disorders. Manipulation of the intestinal microbiota may therefore offer an approach to the prevention or treatment of allergic diseases. Probiotics and prebiotics, used alone or together (synbiotics), can influence the intestinal microbiota and modulate immune responses in vitro and in vivo. Clinical studies suggest a potential role for selected probiotics (alone or in combination with prebiotics) in the prevention of atopic eczema. A prenatal component of treatment appears important for beneficial effects. Effects are dependent upon the specific bacteria and characteristics of the study population. One study reported beneficial effects for prebiotics in the prevention of eczema in high-risk infants, however, further studies are required to confirm this. The use of probiotics in the treatment of allergic disease is less promising. A Cochrane meta-analysis concluded that probiotics are not effective for the treatment of atopic dermatitis. Probiotic effects in the treatment of asthma and allergic rhinitis are conflicting. Probiotics, prebiotics and synbiotics offer potential treatments for the prevention of atopic eczema; however, there is currently insufficient evidence to recommend their use in clinical practice. Studies to clarify the optimal dose, bacterial species/strains, whether there is added benefit with synbiotics, the optimal timing for intervention, and the patient populations who would benefit most from such therapies are warranted.