Trial of Infant Probiotic Supplementation to Prevent Asthma

BACKGROUND:

During infancy, environmental factors may affect immune system development and lead to the development of asthma. The hygiene hypothesis suggests that the absence of endotoxin exposure leads to an unfavorable Th1/Th2 balance. Thus, a controlled antigen exposure during infancy may establish a Th1/Th2 balance that blocks the onset of asthma or slows the progression of the disease.

Lactobacillus is a bacterium commonly found in many foods (e.g., yogurt) in the typical childhood diet. It is also used as a probiotic supplement to prevent the development of diarrhea. Due to its safety and availability, Lactobacillus is an ideal bacterium to use as an antigen exposure to test the hygiene hypothesis.

Consistent with the hygiene hypothesis, observational studies suggest that early Lactobacillus exposure leads to decreased risk of developing atopic dermatitis, which has been associated with asthma in later years. The investigators are aware of no study that has examined the effect of Lactobacillus on the development of early markers of asthma in children at risk for developing the disease. They hypothesize that Lactobacillus can be used as an antigen exposure to establish a Th1/Th2 balance that blocks the development of early markers of asthma.

DESIGN NARRATIVE: