13 May 2010 --- Results of a nationwide telephone survey have shown that the rate of peanut allergies in children more than tripled from 1997 to 2008. The data are reported in the May 12 issue of the Journal of Allergy and Clinical Immunology.

Led by Scott H. Sicherer, MD, Professor of Pediatrics, Jaffe Food Allergy Institute at Mount Sinai School of Medicine, researchers surveyed a total of 5,300 households, representing 13,534 individuals in 2008, a response rate of 42 percent. The survey was previously conducted in 1997 and 2002, with a 52 percent and 67 percent response rate, respectively. In 2008, 1.4 percent of children in the survey were reported to have peanut allergies, as opposed to just 0.4 percent in 1997. The prevalence of combined peanut or tree nut allergies in children was 2.1 percent in 2008, compared to 0.6 percent in 1997.

"These results show that there is an alarming increase in peanut allergies, consistent with a general, although less dramatic, rise in food allergies among children in studies reported by the CDC," said Dr. Sicherer. "The data underscore the need for more study of these dangerous allergies."

The study is the first of its kind to incorporate all age groups within a national sample, and to use the same study methods over such an extended period of time. The study is also the first U.S. study to evaluate allergies to sesame seeds. Peanut and/or tree nut allergies remained steady among adults, with a rate of 1.3 percent. Tree nut allergies alone in children also increased from 0.2 percent in 1997 to 1.1 percent in 2008. Sesame allergy was reported in 0.1 percent of children and adults.

"Our research shows that more than three million Americans report peanut and/or tree nut allergies, representing a significant health burden," said Dr. Sicherer. "The data also emphasize the importance of developing better prevention and treatment strategies."

Several theories exist as to why there could be a spike in food allergies. The main theory to explain a rise in allergic disease, including food allergy, is the "hygiene hypothesis" that generally suggests that "clean living" with less farm living and the use of medications to prevent and quickly treat infections leaves our immune system in a state that is more prone to attack harmless proteins like those in foods, pollens, and animal dander. Other theories include the timing of introduction of the food and how the food is prepared.

The authors caution that the study has limitations inherent to telephone surveys, which may over-represent households of high socioeconomic status because homes without telephones are excluded. There are also limitations in the self-reported nature of the survey, and identifying "true" allergy. However, the rate of childhood peanut allergy estimated in the current study is similar to results from studies using different methods in Canada, Australia and the UK.