New Montreal Study | Exposing Babies to Peanuts Reduces Allergy Risk

Giving babies peanuts can reduce the risk of allergies, a new Montreal study confirms. This strategy was proposed by a 2015 study, but this is the most comprehensive evidence to date that it works.

What does the new study say?

In 2017, Canadian recommendations advised exposing babies to peanuts before age 1, based on a study published in 2015.

Researchers from the MUHC Research Institute analyzed 429 cases of severe peanut allergies from the Montreal Children’s Hospital between 2011 and 2019.

Starting in 2017, in children under 2 years of age, the frequency of these cases began to decrease. The frequency of new cases of peanut allergies (for patients who had never had a previous diagnosis) fell from 40 to 20 cases per 100,000 visits.

“We didn’t know what the real-world impact of the new 2017 recommendations would be,” said Moshe Ben-Shoshan, lead author of the study published in the Journal of Allergy and Clinical Immunology: In Practice.

Data after 2019 were not used because the pandemic changed the profile of emergency department visits. Severe allergic reactions were typically anaphylaxis, a respiratory arrest.

Why does giving peanuts to babies reduce the risk of allergies?

Because babies’ immune systems are still developing. Exposure to a food teaches the immune system to tolerate it, explains Dr.^r Ben-Shoshan.

This phenomenon is sometimes called the “hygiene hypothesis”: the reduced exposure to bacteria and allergens in the modern world has made children’s immune systems more likely to overreact. Early studies in the 1980s and 1990s showed that asthma is less common in families with more children and also in East Germans, who are exposed to more pollution, compared with West Germans.

Have other similar studies been published?

In 2022, Australian researchers showed that the frequency of allergies increased more rapidly before recommendations to expose babies to peanuts than afterward. But according to Dr.^r Ben-Shoshan, the Montreal study is the first to test whether an emergency room visit for anaphylaxis was a first diagnosis for the little patient. Limiting the analysis to first diagnoses allows us to ignore babies with severe peanut allergies who go to the emergency room multiple times for this problem, inflating the number of total visits.

Will the frequency of peanut allergies continue to decline?

Probably, according to the MUHC researcher. “We don’t know what proportion of parents applied the 2017 recommendations,” he says. “But probably more of them are doing it now.” This new study could also convince worried parents to give peanuts to their babies.

Should Peanut Exposure Continue Throughout Childhood?

Probably not, according to the D.^r Ben-Shoshan: “When you do peanut exposure before the age of 1 year, you have to do it several times every month. But once tolerance has set in, it shouldn’t be necessary to continue.”

Where does the idea that early exposure to peanuts is beneficial come from?

The same researchers who did the definitive study on the subject in 2015 set the first milestone for this paradigm shift in 2008, according to Dr.^r Ben-Shoshan. Inspired by the hygiene hypothesis, they compared the frequency of peanut allergies in 10,000 Jewish children in England and Israel.

“In Israel, peanuts were part of babies’ diets, but not in England,” explains the Montreal researcher.

Peanut allergy rates were ten times higher in England. The study was limited to Jews to study two populations with similar genetics.

However, peanut allergy rates have increased among older Montreal children. Why?

“The increase is not significant,” qualifies the D^r Ben-Shoshan: But there are explanations related to the hygiene hypothesis.”

What are the next research questions on this topic?

It remains to be seen whether other provinces, with different genetic profiles, also see a decrease in peanut allergies in babies, says Dr.^r Ben-Shoshan.

“We’re also going to want to look at other allergens, to see if exposing babies to other foods can have the same effect.”

Could the same strategy be used for lactose intolerance?

“No, it’s completely different,” said D.^r Ben-Shoshan: It is related to the metabolism of milk. We are less interested in it because it is not dangerous for the life of the child.