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Peanut exposure prevents allergy: for many at-risk infants, early avoidance not a good strategy.

Infants getting small but regular doses of peanut butter are less likely to develop an allergy to peanuts than are similar babies who avoid peanuts altogether, a new study shows.

The finding--in infants at higher-than-usual risk of peanut allergy--calls into question the notion that peanut butter should be broadly avoided in infancy. In recent years, studies have hinted that early peanut consumption might be a better strategy to reduce susceptibility to this food allergy.

"This is the first real data to support that emerging theory," said Robert Wood, director of pediatric allergy and immunology at Johns Hopkins University. "The results of this study are dramatic. It's not a borderline effect."

Pediatric allergist Gideon Lack of King's College London and his team enrolled babies ages 4 to 11 months who were deemed at elevated risk of peanut allergy because they either had severe eczema or were allergic to eggs. Each baby underwent a skin-prick test with a trace of peanut, which revealed any excess immune reaction. Allergic or highly reactive children were kept out of the study. The remaining infants were randomly assigned to get small doses of peanut butter in their diet at least three times a week or to avoid it completely.

Among 530 babies who had no reaction to the skin test, the peanut allergy rate at age 5 was 13.7 percent in the avoidance group and 1.9 percent in the peanut butter group. Among 98 other babies who had a slight or modest reaction to the skin test, 35.3 percent of those assigned to avoidance were allergic by age 5. Only 10.6 percent of such 5-year-olds eating peanut butter as babies were allergic. Lack presented the results February 23. The findings also appear in the Feb. 26 New England Journal of Medicine.

In 2000, the American Academy of Pediatrics released guidelines calling on parents to avoid giving peanut butter to babies who show any risk of allergy. But in 2008, those guidelines were rescinded because no clear evidence supported the policy unless an infant was clearly allergic. Since then, the issue has been up in the air, with some studies suggesting that peanut consumption might often be a better approach, Wood said. "The time is really right for this to lead to changes in recommendations, which were evolving without data."

Despite years of peanut avoidance by many families, peanut allergy rates in Western countries have risen in the last 10 years, reaching up to 3 percent. The key may lie in infants' diets, said study coauthor George Du Toit, also at King's College. While exclusive breastfeeding is recommended for the first six months, "less than 10 percent of countries achieve that. Young children are taking on complementary foods, weaning early," he said. "We now need to embed peanuts within that."

Writing in the New England Journal of Medicine, Hugh Sampson of the Icahn School of Medicine at Mount Sinai in New York City and Rebecca Gruchalla of the University of Texas Southwestern Medical Center in Dallas call the trial a "landmark" and endorse a skin-prick test for infants ages 4 to 8 months who are at risk of peanut allergy. If the test is negative, they say, start the baby on peanut butter at least three times a week for three years. Mildly positive children, like many in the study, should be given peanut butter initially with a doctor's supervision.

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Title Annotation:BODY & BRAIN
Author:Seppa, Nathan
Publication:Science News
Date:Mar 21, 2015
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