Babies at high risk for becoming allergic to peanuts are much less likely to develop the allergy if they are regularly fed foods containing the legumes starting in their first year of life.

That's according to a big new study released Monday involving hundreds of British babies. The researchers found that those who consumed the equivalent of about 4 heaping teaspoons of peanut butter each week, starting when they were between 4 and 11 months old, were about 80 percent less likely to develop a peanut allergy by their fifth birthday.

"This is certainly good news," says Gideon Lack of King's College London, who led the study. He presented the research at the annual meeting of the American Academy of Allergy, Asthma and Immunology. It was also published in The New England Journal of Medicine.

As many as 2 million U.S. children are estimated to be allergic to peanuts — an allergy that has been increasing rapidly in the United States, Britain and other countries in recent years. While most children who are allergic to peanuts only experience relatively mild symptoms, such as hives, some have life-threatening reactions that can include trouble breathing and heart problems.

"Peanut allergy can be extremely serious," Lack says.

Lack's study was launched after he noticed that Israeli kids are much less likely to have peanut allergies than are Jewish kids in Britain and the United States.

"My Israeli colleagues and friends and young parents were telling me, 'Look, we give peanuts to these children very early. Not whole peanuts, but peanut snacks,' " Lack says.

Peanut snacks called Bamba, which are made of peanut butter and corn, are wildly popular in Israel, where parents give them to their kids when they're very young. That's very different from what parents do in Britain and the United States, where fears about food allergies have prompted many parents to keep their children away from peanuts, even though the American Academy of Pediatrics revised a recommendation to do so in 2008.

"That raised the question whether early exposure would prevent these allergies" by training babies' immune systems not to overreact to peanuts, Lack says. "It's really a very fundamental change in the way we're approaching these children."

To try to find out, Lack and his colleagues got funding from the U.S. National Institutes of Health to launch a study. They found 640 babies who were at high risk for developing peanut allergies because they already had eczema or egg allergy. They asked half of the infants' parents to start feeding them Bamba, peanut butter, peanut soup or peanut in some other form before their first birthday and followed them for about five years.

"What we found was a very great reduction in the rate of peanut allergy," Lack says. About 17 percent of the kids who avoided peanuts developed peanut allergies, compared with only 3.2 percent of the kids who ate peanuts, the researchers reported.

Based on the findings, Lack thinks most parents should start feeding their babies peanut products as early as possible — not whole peanuts or globs of peanut butter, but peanut mixed in some other food to avoid any possible choking hazard.

"We've moved, really, 180 degrees from complete avoidance to we should give peanuts to young children actively," Lack says.

Other allergy experts hailed the results as an important advance.

"This is a major study — really what we would call a landmark study," says Scott Sicherer, who advises the American Academy of Pediatrics on allergies. "There's been a huge question about why there's an increase in peanut allergy and what we can do to try to stem that increase. And this is a study that directly addresses that issue."

But Sicherer says we have to be careful, since some kids are really sensitive to peanuts.

"If you're a parent sitting at home with your child looking at them saying, 'Well, gee, they didn't eat peanut yet. Maybe I should run to the cupboard and get some peanut butter for them,' it could be a little bit dangerous because if you do that and the child has a bad allergic reaction, you would be at home and have a problem," Sicherer says.

So Sicherer says parents who have some reason to think their kids might be allergic to peanuts should get them tested first and then only try feeding them peanuts with a doctor in the room.

But other specialists say for most parents, the new findings should encourage them to start feeding their kids peanuts as early as possible.

"This is a question we get asked constantly in our clinic. When parents come in, they often have young children. They want to know what should they do. This really provides us with the answer," says Hugh Sampson, who heads the Jaffe Food Allergy Institute at Mount Sinai in New York. Sampson co-authored an editorial being published with the study.

"So now I think we're on firm ground, and we can go forward and look the parents in the eye and say, 'This is something that will be beneficial,' " Sampson says.

A key question is whether kids will have to keep eating peanuts to keep any allergy at bay. Lack is following the kids in his study to find out what happened to them after they stopped eating peanuts regularly.

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