The Strange Thing About Peanut Allergy Prevention

One theory about food allergies is that when you first introduce an allergenic food to an infant’s diet may affect the risk of whether your infant will develop the allergy. So, researchers conducted a systematic review and meta-analysis of studies of timing of the introduction of allergenic foods.

One of the most common modern food allergies is the allergy to peanuts. . . .

Based on two studies on peanuts that included 1,550 people, the researchers concluded with moderate certainty that introducing peanuts early at four to eleven months was associated with a significant reduction in the risk of the baby developing a peanut allergy. The risk was reduced by 71%. That means that in a population with a 2.5% incidence of peanut allergy, there would be eighteen less cases per 1000 people.

As for other common allergenic foods, early introduction of eggs at four to six months reduced the risk of egg allergy by 44%. There was only low, or even very low, certainty that early introduction of fish helped lower the risk of allergy to fish, and early introduction of gluten certainly did not reduce the risk of celiac disease.

Curiously, then, the theory that early introduction of a food influences the risk of developing an allergy to that food is true for some foods and false for others. It does seem to be true, counterintuitively, though, that feeding your child peanuts very early in life will reduce the risk that the child will develop a peanut allergy.

Though the meta-analysis included two studies, at least three studies have previously supported the idea that early introduction of peanuts prevents peanut allergy. The two studies showed that the beneficial effects of early introduction persisted in life (NEJM 2016;doi:10.1056/NEJMoa1514209) and that, though, as in this study, early introduction of other allergenic foods did not reduce the risk of developing allergies, early introduction of peanuts did (NEJM 2016;doi:10.1056/NEJMoa1514210).

So, it seems that, somewhat anomalously, feeding your child peanuts early in life is an effective way of preventing peanut allergies later in life.

JAMA 2016;316(11):1181-1192