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By Richard Knox
Erin Brazil is frustrated. She'd hardly had time to digest the peanut allergy study that got heavy media coverage this week when, she says, she got "inundated by calls and emails and Facebook posts saying ‘There’s a cure, there’s a cure!’ ”
Brazil is a Boston food-allergy activist whose 4-year-old son Gabriel is severely allergic to peanuts and other foods. So she knows better than anyone that the new study, while a landmark in the field, represents no cure. "It doesn't do anything for Gabriel," she says.
What it does mean is that many future children will be able to avoid a life of worry about whether the merest trace of peanut protein — even an invisible smear from a candy bar left by another child on playground equipment — could send them to the emergency room gasping for breath.
I can finally look a mother in the eye and give her some advice that I feel confident in.Dr. Hugh Sampson
And the new study means that the recommendations parents have been given over the past 15 years — to withhold peanuts until the age of 3 in children deemed at risk — "were exactly wrong," says Dr. Wayne Shreffler, director of the Food Allergy Center at Massachusetts General Hospital.
"I strongly suspect they made things worse," Streffler adds, because at-risk children who were deprived of peanut exposure in food during infancy were more likely to suffer a lifelong allergy from later exposure to, say, house dust. It's almost impossible to avoid it.
In 2008, the American Academy of Pediatrics withdrew its recommendation to withhold peanuts until age 3, but until now there's been no solid evidence in favor of deliberately feeding peanuts to at-risk kids. That's what the new study strongly suggests parents should do — strictly under the supervision of their pediatricians. That flip-flop is widely expected to be enshrined in the next set of official guidelines.
It's a big change, but not only does it offer nothing to children like Gabriel who already have peanut allergy, it provides no answer to the really big question: Just why have food allergies soared lately, more than quadrupling among the current generation of American children?
Even though the study doesn't solve that mystery, allergy experts say it's certain to accelerate research already under way to unravel the causes and devise treatments, if not outright cures.
Six million U.S. children currently have food allergies, one out of every 13 kids, according to the largest recent study. Peanut allergy is the most common, and the most troublesome — not only because it's so hard to avoid exposure, but because peanut allergy is usually permanent, unlike those involving other foods. And peanut allergies are more likely to be fatal.
That explains why allergists are so enthusiastic about the new study.
The Bamba Effect
Lack and his colleagues discovered that peanut allergy was almost 11 times higher in Britain than in Tel Aviv. And they noticed that nearly all Israeli children consume a peanut snack called Bamba from infancy. Bucking the conventional wisdom of the day, they hypothesized that early exposure to peanuts might protect against allergy.
To test the idea, they studied 640 infants between 4 and 11 months old who were at high risk of developing peanut allergy because they had severe eczema, egg allergy or both. Infants who reacted strongly to peanut proteins with a skin-prick test were excluded, but those with mild reactions were allowed to stay in, under close supervision.
Researchers randomly assigned infants to get regular doses of peanut protein — the equivalent of four heaping teaspoons of peanut butter a week — or none at all. The results made this week's media splash. At the age of 5, 14 percent of those who had no peanut exposure were allergic compared to only 2 percent of those who had early exposure — an 86 percent reduction in risk.
Even the children who were mildly allergic to peanuts at the outset had a 70 percent lower risk of allergy at age 5 if they were fed peanut protein in infancy.
Shreffler, the MGH allergist, says he'll now begin routine testing of infants at risk and advise parents of those with negative or mildly positive skin tests to consider careful feeding of peanut protein in infancy.
"This is the high-risk population that accounts for a big proportion of the problem," he says.
Dr. Hugh Sampson, director of the Food Allergy Institute at the Icahn School of Medicine at Mount Sinai in New York, says the research is a landmark because "I can finally look a mother in the eye and give her some advice that I feel confident in. This is a definite cause-and-effect phenomenon."
The study "makes it clear that we can do something now to reverse the increasing prevalence of peanut allergy," Sampson and Dr. Rebecca Gruchalla of University of Texas Southwestern Medical Center wrote in a New England Journal of Medicine editorial.
Beyond that, Sampson thinks the new results may also lead to better understanding of why food allergies are rising so sharply.
The Hygiene Hypothesis
He thinks it's due to what's called the hygiene hypothesis — the notion that children in westernized cultures are raised in environments that are too clean, too protected from germs. It's a cumulative effect of immunizations, decline in infectious disease prevalence, preservatives in food, sanitary wipes, caesarean deliveries (that prevent exposure to bacteria in the birth canal), and other factors.
This has changed the makeup of bacterial populations in the gut. Those benign bacteria play a crucial role in processing food proteins and presenting them to the developing immune system in a way that promotes tolerance. Without this processing, the immune system can tip toward the inflammatory over-reaction that we call allergy.
"What this study suggests," Sampson says, "is that by withholding peanuts we were allowing children to become sensitized later by skin exposure to peanut protein in house dust, on their fingers, from siblings." Skin exposure may be more likely to lead to allergies than ingestion, he thinks.
This line of thinking is stimulating other studies that could help.
For instance, Australian researchers recently found that nearly 90 percent of a group of children who were allergic to peanuts overcame the problem after eating a daily dose of peanut protein along with a hefty amount of a probiotic — bacteria of a sort found in yoghurt. It's not clear yet whether their desensitization was lasting.
"It's a very plausible idea," says Shreffler, the Massachusetts General Hospital allergist, though he's not yet convinced. "If there is a benefit, it would probably be because those organisms are displacing more pathological ones and encourage a healthier immune system within the gut."
Within a few years, Shreffler hopes, "we'll have a much clearer idea about which probiotics may reduce the incidence of allergy."
But this isn't the only way researchers are tackling peanut allergies.
'Finally, We're Getting Somewhere'
Other groups, including Sampson's, are giving allergic children tiny doses of peanut protein over long period to "tolerize" them, with mixed results — an approach called oral immunotherapy. The Mount Sinai group and others are also trying skin patches containing small doses of peanut protein. Some think even a vaccine against peanut allergy might be feasible.
And this week, researchers at Johns Hopkins said they've found two genes linked to peanut allergy on an area of chromosome 6 that governs major immune responses. The newfound genes account for about 20 percent of peanut allergies in the 2,800 study participants.
The whole world is a potential danger for him: Playgrounds where another child may have left food residue on the monkey bars. Parks where squirrel-lovers have left behind peanut shells.
Clearly, whatever the causes of the peanut allergy epidemic, they're not simple — and the cures probably won't be either, nor soon in coming. But researchers are energized by the prospects.
"It's super-fun. And exciting," Shreffler says. "Finally we're getting somewhere."
None too soon for Erin Brazil. Gabriel's food allergies have taken over her life and fired a mission to help other parents cope — something she couldn't have imagined when she was in school, back in the 1970s and '80s, and didn't know any kid with a food allergy.
So when 7-month-old Gabriel started having rashes and swelling, "we were completely clueless."
Then, when he was 8 months old, his older sister gave him a noodle coated with peanut sauce from a dish of pad Thai. Within seconds he broke out with a rash, watery eyes, angry welts, swollen face. Subsequent skin tests showed he's strongly allergic to dairy foods and eggs as well as peanuts.
Since then Gabriel has been hospitalized nine times for severe allergic reactions called anaphylaxis, which causes internal swelling so intense that victims can suffocate. One episode occurred after he pushed an elevator button that had been contaminated with invisible traces of a food allergen left behind by a previous passenger.
Now the whole world is a potential danger for him: Playgrounds where another child may have left food residue on the monkey bars. Parks where squirrel-lovers have left behind peanut shells. "We never go out to restaurants," his mother says. "Birthday parties are awful." (Brazil always offers to bring a non-allergic cake.)
And she has to contend regularly with people who doubt Gabriel's problem is real.
"People think we're over-reacting, we're over-protective, this is attention-seeking behavior," she says. "But food allergies are not a matter of opinion. My child has had anaphylaxis. We're just doing the best we can to keep our children protected within this mysterious epidemic."
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