Treatment reduces kids' peanut allergy risk up to 86%

For years, parents were told that the best way to prevent kids from becoming allergic to peanuts was to withhold peanuts from their children's diet.

That advice couldn't have been more wrong, a new study shows.

For the first time, researchers have shown that children who are regularly fed small amounts of peanuts from their infancy are actually less likely than others to develop peanut allergies.

Babies regularly given peanuts for at least four years cut their risk of peanut allergy by an average of 81%, compared with children who avoided peanuts, according to a study published Monday in The New England Journal of Medicine. Authors note that this regimen should be attempted only under a doctor's supervision, because allergic reactions to peanuts can be life-threatening.

The results are "without precedent," said Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, which helped fund the study of 640 children. "The results have the potential to transform how we approach food allergy prevention."

The prevalence of peanut allergies has doubled in the past decade, increasing to 3% of children in developed countries, according to the study, presented Monday at a meeting of the American Academy of Allergy, Asthma and Immunology in Houston.

And although peanut allergies are still relatively rare, they have had an outsize influence at schools and day care centers, many of which have banned nuts from classrooms and cafeterias in order to prevent potentially deadly reactions.

In 2000, the American Academy of Pediatrics recommended that parents withhold peanuts from children at risk of allergies until age 3. The academy withdrew that recommendation in 2008, after the number of cases of peanut allergy continued to rise.

British researchers decided to carefully test whether avoiding peanuts was making allergies more common. They focused on babies at high risk for peanut allergies because of an egg allergy or eczema, an inflammatory skin disorder that can make skin red and itchy.

They began by testing babies ages 4 months to 11 months old for peanut allergies with standard skin-prick tests. Babies who had strong reactions to peanuts were excluded from the experiment for their own safety, according to the study.

Researchers randomly assigned the others to either avoid peanuts or to consume the equivalent of 24 peanuts a week, divided into three meals. Most babies consumed the peanuts in the form of a snack called Bamba, made from puffed corn and peanut butter. Babies who didn't like the puffed snacks got peanut butter.

Researchers then retested children for peanut allergies at age 5.

Eating peanuts helped all children, including those with mild reactions to peanuts during early tests. In this group, 35% of kids who avoided peanuts developed full-blown allergies, compared with 11% of those who ate peanuts — a 70% reduction in risk.

Among kids with no sensitivity to peanuts at the beginning of the study, 14% who avoided peanuts became allergic, compared with 2% of those who were fed peanuts — an 86% reduction in risk, the study says.

Doctors don't know whether children will continue to be protected from peanut allergies if they stop eating peanuts regularly, says Gideon Lack, the study's lead author and a professor at King's College London. Researchers hope to answer this question by continuing to follow the children.

The treatment appears safe. The rate of hospitalizations and serious complications was the same among children who ate peanuts and in those who avoided them.

The new study is "good news, in that we know now that we can do something to reverse the increasing prevalence of peanut allergy," says Todd Mahr, chairman of the American Academy of Pediatrics' section on allergy and immunology, who wasn't involved in the new study.

But parents shouldn't try this diet on their own, says Rebecca Gruchalla, chair of allergy and immunology at the University of Texas Southwestern Medical Center in Dallas. Parents of high-risk babies should see a doctor, who can perform appropriate tests to show whether the peanut regimen used in the study is safe for their child.

Because the study included only babies at high risk, doctors don't know whether the regimen is safe for babies who are strongly allergic to peanuts, says Gideon Lack, the study's lead author and a professor at King's College London.

Doctors also don't know whether the regimen will benefit babies at low risk for peanut allergies, says Scott Sicherer, a professor of pediatrics and researcher at the Jaffe Food Allergy Institute at Mount Sinai in New York who wasn't involved in the new study.

"We can presume that eating peanut earlier is still a good idea (for average-risk kids), but this study does not really address that," Sicherer says. "We just do not know if eating it so soon might backfire."

Doctors can't say for sure what led peanut allergies to become more common, although the new study suggests that telling parents to withhold peanuts may have made the problem worse, Mahr says. He notes that many allergic conditions have been increasing.

Lack says the rise in peanut allergies may be tied to the increase in eczema and the immune system's complex reaction to peanuts.

In children with eczema, skin can become so irritated that it cracks and bleeds. That can allow babies to be exposed to peanut dust through the skin, Lack says. Peanut protein is commonly found in household dust.

Children exposed to peanuts through the skin may react very differently than those whose first experience of a peanut comes through the digestive tract.

According to this hypothesis, the body's immune system reacts to peanut protein entering through breaks in the skin much as it would to germs or parasites that enter the body through cuts in the skin: It attacks. The immune system continues to overreact whenever it encounters peanut protein, Lack says.

The immune system doesn't overreact, however, if it first encounters peanuts in the digestive tract, Lack says. The body encounters lots of different kinds of proteins that way, after all.

Eleanor Garrow-Holding, whose son is allergic to peanuts and other food, says the study results are exciting. She is the president and CEO of a patient group called the Food Allergy & Anaphylaxis Connection Team.

"While we still don't have all the answers," she says, "I think any parent who worries their child may develop a peanut or other food allergy has much to be hopeful about due to these results."

The study was funded by a variety of sources, including the Atlanta-based National Peanut Board. Peanut manufacturers weren't involved in designing the study, analyzing data or writing the report.