Food allergies now affect approximately one in 13 children in the US, representing an increase of 50% in the prevalence of food allergies between 1997 and 2011.
Experts attribute the rise to several factors, including a shift to more refined diets, vitamin D deficiencies due to a lack of sun exposure and the “hygiene hypothesis” — which posits that our cleaner contemporary environment exposes children to fewer microbes, causing their immune system to overreact to certain foods.
But a recent study published in the journal Pediatric Allergy and Immunology adds to a growing body of research that suggests one of the factors may be the delayed introduction of allergenic foods.
Researchers analyzed the data of 2,060 babies and found that introducing them to a diverse diet — categorized as consisting of 13 or 14 different foods — at 9 months of age was associated with a 45% decrease in the risk of food allergies by the time the infant reached 18 months.
However, the study suggests that the same protective effect does not seem to occur when implementing a diverse diet at an earlier age, such as six months.
This association held strong even after adjusting for factors like family history of allergies, breastfeeding duration, and the mother’s education levels — although the researchers noted that “children with a history of eczema may benefit the most from eating a diverse diet early in life for food allergy prevention.”
The results were obtained by asking parents to fill out a questionnaire that measured their infant’s diet diversity at six and nine months based on how often they consumed 14 foods, including six that are common allergies: wheat, egg, fish, dairy, nuts (especially peanuts) and soy.
At 18 months, 100 of the children in the study were diagnosed with a food allergy, the most common ones being cow’s milk (69 cases) and eggs (35 cases).
While food allergies are predominantly genetic, this study indicates that a baby’s diet at nine months could also have a significant impact on their likelihood of developing food allergies.
“Repeated exposure to foods in infancy is important both for tolerance development and maintenance,” the researchers wrote.
“One could assume that frequent consumption of plant-based foods including fruit, vegetables, and legumes which are rich in fiber and vitamins are especially important for reducing food allergy risk, in line with existing guidelines.”
These findings align with previous studies emphasizing the benefits of early introduction of allergenic foods.
For instance, a 2019 study found that introducing peanut-containing foods to babies between four to six months of age was associated with a reduced risk of peanut allergy.
Another study replicated those findings last year, finding that kids who ate peanuts as a paste or puree until age 5 were 71% less likely to develop a peanut allergy than those who didn’t have peanuts.
Other recent research “supports that the method and timing of food introduction can impact the likelihood of developing an allergy or sensitivity to the food.”
