Overcleanliness in childhood may increase risk for peanut allergy

By Helen Albert, Senior medwireNews Reporter

An increased incidence of peanut allergy in children from more wealthy families supports the "hygiene hypothesis" that overcleanliness may promote the onset of childhood allergies, say US researchers.

The association with household income (HHI) and poverty income ratio (PIR) was only apparent in children aged 1 to 9 years, explained lead investigator Sandy Yip (US Air Force, San Antonio, Texas) who presented the data at the Annual Meeting of the American College of Allergy, Asthma and Immunology in Anaheim, California, USA.

"This may indicate that development of peanut sensitization at a young age is related to affluence, but those developed later in life are not," she suggested.

For the study, Yip and colleagues reviewed data collected from the 2005-2006 National Health and Nutrition Examination Survey (NHANES) on socioeconomic status, measured using HHI and PIR, and levels of peanut specific immunoglobulin (Ig)E antibodies.

Overall, peanut IgE measurements were available for 8306 people and were detectable in 776 (9.3%) of those tested. Adolescents aged 10-19 years had the highest prevalence of positive peanut IgE tests (boys 14.3%; girls 8.4%), but detectable levels of these antibodies were less common after middle age.

In the 1-9-year age group, the prevalence ratio for peanut IgE antibodies was significantly increased in children with a high PIR and HHI. Specifically, compared with children with the lowest HHI (US$ 19,999 [€ 15,700] or less) and PIR (less than 1.0), children with the highest PIR (4.0 or more) had a 3.71-fold increased risk for peanut allergy and children with the highest HHI (US$ 75,000 [€ 58,872] or more) had a 1.91-fold increased risk. Both these increases were statistically significant.

The researchers suggest that their finding lends support to the theory that oversanitization, which is linked with higher socioeconomic status, may increase the risk for childhood allergies.

The team emphasizes the importance of appropriate care and vigilance for peanut allergy patients throughout life, as only 20% of children are likely to outgrow such an allergy.

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