Babies given peanuts, fish, eggs early less likely to become allergic, study affirms

Peanut butter for sale at the Northern store in Fort Smith, N.W.T., on Tuesday, July 22, 2025.

TORONTO — A new Canadian study says giving babies peanuts, eggs, fish and other common food allergens early and consistently decreases the risk they’ll be allergic to them.

Senior author Dr. Derek Chu says researchers analyzed more than 190 food allergy studies from around the world to identify the strongest risk factors in developing food allergies.

Their findings, published Monday in JAMA Pediatrics, found that delaying the introduction of peanut-containing foods until babies were over 12 months old doubled their likelihood of becoming allergic to the nut.

The study showed similar results for fish and eggs.

Babies who have other allergies, asthma, wheezing or eczema in their first year of life — or have an allergic parent or sibling — are also at higher risk of developing a food allergy.

Chu says it’s especially important to introduce potential allergens early to those higher-risk children to try to prevent food allergies.

“The longer we delay, the higher the risk of food allergy is,” said Chu, who is an allergist-immunologist and assistant professor at McMaster University in Hamilton, Ont.

“Early introduction is when baby’s ready. They’ve got the co-ordination to sit up and chew with their mouth, and they’re curious about food. For many, that’ll be around age four months, maybe five months, maybe six months.”

Food Allergy Canada cautions that peanuts are a choking hazard but a safe way to introduce them is by mixing peanut butter with hot water, cooling the mixture and adding it to soft foods the baby is already eating such as infant cereal or puréed fruits and vegetables.

The executive director of the non-profit organization dedicated to helping people living with food allergies, was a co-author of the study and endorsed the results.

“This publication confirms that food allergy development in children is influenced by multiple factors,” said Jennifer Gerdts in an emailed statement.

“Early introduction and continued inclusion of allergenic foods — central to our ‘Eat Early, Eat Often’ guidance — has shown promising results in reducing food allergy risk, but more needs to be learned about additional ways to prevent food allergy.”

Chu said it’s important to not only introduce allergenic food early, but to have babies continue to eat it consistently.

The guidance matches food allergy recommendations from the Canadian Paediatric Society, which suggests babies eat the newly introduced food a few times a week “to maintain tolerance.”

“The risk for a severe reaction at first exposure in infancy is extremely low. Pre-emptive in-office screening before introducing allergenic foods is not recommended,” the pediatric society posted on its website in Dec. 2021.

The study also found other potential correlations with developing a food allergy, including being first-born and being a male, but those were considered “minor” risk factors, Chu said.

The research also suggested that taking antibiotics in the first month of life could be a risk factor, but that requires additional study, he said.

One possible explanation for the correlation is that antibiotics could disrupt the body’s microbiome, which in turn could play a role in the development of food allergies — but that’s just a theory at this point, Chu said.

“Limiting the excessive use of antibiotics is important, but also maintaining it for critical life-saving situations (is) definitely still needed,” he said.

The finding could be useful by reinforcing the importance of introducing allergenic food to babies who had to take antibiotics to treat illness early in life, Chu said.

In addition to peanuts, eggs and fish, Chu said it’s important for parents to give babies other potentially allergenic food that is common in their household early, which could include tree nuts, dairy, wheat, soy, sesame and shellfish, he said.

This report by The Canadian Press was first published Feb. 9, 2026.

Canadian Press health coverage receives support through a partnership with the Canadian Medical Association. CP is solely responsible for this content.

Nicole Ireland, The Canadian Press