Parents should be feeding their babies potentially allergenic foods to ward off serious allergies, suggests a review of recent evidence.
The review, published Monday in the Canadian Medical Association Journal, states that most babies at four to six months of age can begin eating these foods, which include cow's milk, soy, peanuts, tree nuts, eggs, wheat, fish, shellfish and sesame.
And once those foods have been introduced, it's important the baby continue to eat them on a regular basis, or an allergy could develop.
"We're in the midst of a food allergy epidemic, so prevention is really important," said co-author Dr. Elissa Abrams of the University of Manitoba's department of pediatric allergy and clinical immunology.
In the past, parents of babies at high risk of developing allergies were advised to wait 12 to 36 months before introducing commonly allergenic foods.
"At the time, we thought that if you allowed the infants' immune system and gut to mature it would decrease the chance that they would become allergic," said Abrams, who co-authored the review with Dr. Allan Becker.
Instead of food allergy rates dropping, as was expected, there was an increase in some areas. "For example, in the U.K., when they started avoiding peanut there was as much as a tripling of peanut allergy," Abrams said.
Later studies "found that giving the foods late did not prevent allergies and in fact may actually increase the risk that these children would become allergic."
Groups including the Canadian Society of Allergy and Clinical Immunology now call for introducing peanuts to high-risk kids at between four and 11 months of age. The new review suggests it might be advisable for parents to visit an allergist if there is a history of allergies in the family. A recent survey of Canadian households found that 8 per cent, or one in 12 families, reported at least one food allergy.
Researchers have also learned more about what could be causing food allergies.
"We now think that you can actually become allergic through your skin: specifically broken skin, such as in children with eczema, if they're exposed to these foods in the environment and not already eating them," Abrams said.
"So that's why the guidelines have shifted so dramatically from the old guideline, which was wait, to the new guideline, which is there is no need to wait."
Current guidelines say mothers don't need to avoid foods that commonly cause allergies while pregnant or breastfeeding. Many mothers ask what's the harm in avoiding the foods as a preventative measure.
"There is a harm," said Abrams. "In some of the studies, when moms avoided foods when they were pregnant, they were at an increased risk of having small children and having children that were born early."
Dr. Susan Waserman, professor of medicine in the clinical immunology and allergy division at McMaster University, said in her clinic they haven't been telling parents to avoid allergenic foods for many years.
"But we never had good evidence even to make that recommendation until this study, which actually proves the point," she said. "You can't be 1,000 per cent sure in everybody, but eating peanut at that [young] age seems to be protective.
"Start slowly on the first feeding, watch your child, monitor … But for the most part, for most children, this will be a safe intervention."