Hamilton, ON, — Delaying the introduction of potentially allergenic foods until after a baby's first year may increase the likelihood of a food allergy later on, according to new findings from the Canadian Healthy Infant Longitudinal Development (CHILD) Study.

The research, published in Pediatric Allergy and Immunology, found that infants who avoided cow's milk products, egg, and peanut during the first year of life were more likely to be sensitized to these foods at age one.

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"Food sensitization early in life is associated with an increased risk of wheeze, asthma, eczema, and allergic rhinitis in later childhood," said Dr. Malcolm Sears, co-director of the CHILD Study and a professor of medicine at McMaster University.

"While not all food-sensitized infants become food allergic, sensitization is an important step on the pathway," he added. Sears is also a researcher at the Firestone Institute for Respiratory Health at St. Joseph's Healthcare Hamilton.

Using data from more than 2,100 Canadian children, the researchers found that infants who avoided cow's milk products in their first year were nearly four times as likely to be sensitized to cow's milk compared to infants who consumed cow's milk products before 12 months of age. Similarly, infants who avoided egg or peanut in their first year were nearly twice as likely to be sensitized to those foods compared to infants who consumed them before 12 months of age.

"Early introduction of eggs before one year of age seemed to be especially beneficial, as it significantly reduced the odds of developing sensitization to any of the three food allergens," says the study's first author, Maxwell Tran, a BHSc graduate from McMaster University and an AllerGen trainee.

"To our knowledge, this is the first observational study in a general population of infants to report on how the timing of introduction of multiple foods affects the risk of developing a food allergy."

The study also revealed that most Canadian parents delay the introduction of potentially allergenic foods, particularly egg and peanut: only three per cent of parents introduced egg before six months of age, while just one per cent of parents introduced peanut to their infants before six months of age and 63 percent of parents avoided feeding peanut entirely during the first year of life.

"Our findings support infant feeding guidelines that promote the introduction of foods such as cow's milk products, egg, and peanut between four to six months of age," says Tran. "This is an important shift in thinking away from avoidance of potentially allergenic foods, toward their early introduction to reduce the risk of food allergy later on."