Examining the hygiene hypothesis: the Trial of Infant Probiotic Supplementation.

The hygiene hypothesis suggests that the absence of infectious exposure at a critical point in immune system development leads to a greater risk for the later development of atopic disease. As a result, it may be possible to devise strategies that can block the onset of atopic diseases such as asthma. This paper outlines the rationale, background and design for the Trial of Infant Probiotic Supplementation study, which is designed to test the effectiveness of a daily infant probiotic supplement in the first 6 months of life in preventing the development of early markers of asthma.