Early exposure to peanuts may prevent allergy

NEW YORK (Reuters Health) - Contrary to widespread recommendations, the consumption of peanuts in infancy is associated with a low prevalence of peanut allergy, the results of a new study suggest.

"Our study findings raise the question of whether early introduction rather than avoidance of peanut in infancy is the better strategy for the prevention of peanut allergy," write researchers in the Journal of Allergy and Clinical Immunology.

In the UK, Australia and, until recently, the United States, guidelines have recommended that women avoid peanuts during pregnancy and breastfeeding, and should not introduce peanuts into their children's diets during infancy, note Dr. George Du Toit of King's College London and colleagues.

The researchers analyzed the prevalence of peanut allergy and diet histories for 5,171 Jewish children from the UK and 5,615 Jewish children from Israel.

They found that children from the UK had a prevalence of peanut allergy that was 10-fold higher than that of children from Israel -- 1.85 percent versus 0.17 percent.

"This difference is not accounted for by differences in atopy," the investigators write. Atopy is the inherited tendency to develop common allergic diseases such as eczema, hay fever or asthma.

They also found no differences between the two groups in environmental exposure to common causes of allergy, such as house dust mite and grass pollen, social class or genetic background.

"The most obvious difference in the diet of infants in both populations occurs in the introduction of peanut," they note. Approximately 69 percent of infants in Israel consume peanuts by 9 months of age, compared with just 10 percent of those in the UK.

Likewise, when compared with the UK mothers, the Israeli mothers consumed significantly more peanuts during pregnancy, Du Toit and colleagues point out.

The researchers suggest that recommendations to avoid peanut in early infancy could be behind the increase in peanut allergy in the UK, Australia and the US.

In a written statement, Dr. Jacqueline A. Pongracic, who is vice chair of the American Academy of Allergy, Asthma & Immunology (AAAAI) committee on Adverse Reactions to Foods, cautions that while this study's findings "provide optimism for prevention of peanut allergy in the future, randomized, controlled trials are needed to verify that early introduction of peanut is indeed effective."

The Learning Early about Peanut Allergy (LEAP) study, a large randomized study in the UK, is currently testing the effects of early peanut exposure.

Journal of Allergy and Clinical Immunology, November 2008.