Allergy prevention: Maybe you’re doing it wrong

By Jordan Todd

Food allergies are a growing issue in Canada and around the western world. There is no cure. According to Anaphylaxis Canada, about 2.5 million Canadians self report having a food allergy and about two per cent of Canadian children are allergic to peanuts. And, it turns out, we may have been going about preventing allergies all wrong. A recent study, called the Learning Early About Peanut Allergy (LEAP) trial, has found that exposing infants to peanuts from a very early age significantly decreases the likelihood of them developing a peanut allergy.

The study took over 600 infants, aged four to 11 months, and gave them a skin-prick test to determine their sensitivity to peanuts. They then divided them into two categories: no sensitivity to peanuts and mild sensitivity to peanuts. The infants from each category were then randomly assigned into either the peanut-exposure group, where they were fed peanut products regularly, or the peanut-avoidance group, where they were not. At five years old, they were retested for peanut allergy.

The results were impressive. In the no-sensitivity category, 14 per cent of the infants who had avoided peanuts had a peanut allergy, compared to just two per cent who were exposed. For infants with mild sensitivity, 35 per cent of the avoidance group were allergic, while only 11 per cent of the exposure group were.

Dr. Sandy Kapur, president of the Canadian Society of Allergy and Clinical Immunology, says this study could be groundbreaking.

“If we start introducing it early on a widespread basis, I think what we’re going to see is a reduction in peanut allergy, which is very exciting,” he says. “I think, as we move ahead, we’re going to see less kids diagnosed with peanut allergy over time.”

Kapur says it is important to inform doctors and parents that early exposure can help reduce peanut allergy, but cautions that parents should get their child checked for peanut allergy before exposing them to peanut products.

The study came together when researchers noticed a strange thing. Jewish children in London who had not been exposed to peanut-based products in their first year were 10 times more likely to be allergic than Jewish children in Israel who had been exposed to peanut products in their first year. This observation made them curious, and the LEAP study was born.

For those living with peanut allergy, exposure to peanut products of any kind can be potentially deadly. © Baden Russell-Petigrow

Living with a peanut allergy can be quite a burden. Meredith Logan, mother of two children with peanut allergy, says it can be very stressful.

“You certainly have to be vigilant when you have children with allergies. You are always the mom with an epipen in her purse and constantly asking if there are nuts or eggs in anything served at a party. I sometimes feel like people don’t take the allergies seriously and that is concerning,” says Logan.

She adds that she was given no advice on preventing allergies from developing in her children.

This study may represent a major shift in allergy prevention approaches, says Kapur. In the 1990s, the accepted advice to prevent allergies was to avoid allergenic foods such as peanuts and eggs early in life. But by the early 2000s, says Kapur, most allergists had a sense that this was not working. The increase in peanut allergy was not going away.

“(The increase in peanut allergy) was happening before those suggestions were made, and continued happening after,” he says. “Many were questioning: does this make any logical sense?”

By the mid-2000s, new guidelines were published stating that avoiding allergenic foods early in life was not beneficial. It’s only recently, says Kapur, that studies have been coming out showing a link between early exposure to allergenic foods and declines in allergies.

“For peanut, this new study, I think, quite clearly says that early introduction is a benefit,” says Kapur. “It’s a very well-done study, randomized in two well-studied groups, suggesting a very large difference by early introduction in preventing peanut allergy.”

While he says this study seems quite definitive, Kapur cautions against assuming we will see the same results with other allergenic foods.

“We just don’t have similar data for milk or for eggs or for other things,” he says. “Most of us would think that it’s probably going to be the same, but we don’t have that data.”

There are plenty of theories as to what causes allergies. The hygiene hypothesis postulates that because early in life we are not being exposed to enough germs, our immune system is looking for something to do, so it starts to fight allergens, explains Kapur. Others think that it is our gut bacteria that causes it, or that vitamin D plays a large role.

“The bottom line is I think this increase we’re seeing in allergic disease, we’ve been seeing in western societies. We don’t see it in the developing world. So there’s something about western society, the way we’re living, that’s related to this. What exactly it is is hard to tease out,” says Kapur.

Dr. Rebecca Gruchalla, an allergy specialist at the University of Texas Southwestern Medical Center in Dallas, wrote in a commentary she penned about the study that while questions remain, especially about how this study corresponds to other food allergies, “the LEAP study makes it clear that we can do something now to reverse the increasing prevalence of peanut allergy.”