New evidence indicates that practices that prevent exposure to potentially disease-causing microbes early in life may do more harm than good by increasing a person's risk of developing allergies and asthma. The findings provide support for the hygiene hypothesis, which suggests that a lack of childhood exposure to microorganisms increases susceptibility to certain diseases by failing to promote the natural development of the immune system.
Emerging research is providing new information and insights into the well-documented link between increased hygiene and sanitation and higher rates of asthma, allergies, and autoimmune disorders. For example, a recent analysis notes that a greater focus on cleanliness for girls compared with boys may help explain why women have higher rates of these conditions (Clough S. Soc Sci Med. 2011;72:486-493).
Hampton T. Research Provides New Insights on How Hygiene Affects Asthma and Allergies. JAMA. 2011;305(14):1400-1401. doi:10.1001/jama.2011.434