Timing of food introduction and development of food sensitization in a prospective birth cohort
The effect of timing of food introduction on the development of food allergy remains controversial. In 2000, infants at high risk for atopy were recommended to delay introduction of cow's milk products until 1 year; eggs until 2 years; and peanuts until 3 years of age.1 In 2006, a review of 52 studies reaffirmed concerns that early food introduction increased the risk of food allergy.2 In 2008, results from later studies3 suggested only weak evidence for delaying introduction of complementary foods beyond 4‐6 months of age.5 More recent birth cohort6 and cross‐sectional studies9 now suggest that early food introduction may protect against atopic diseases. In the Learning Early About Peanut allergy (LEAP) Study, infants randomized to regular peanut consumption had a greatly reduced risk of peanut allergy at 5 years.11 Most infant feeding guidelines currently indicate that parents should not delay introduction of “allergenic” foods beyond 4‐6 months, provided that children are developmentally ready.12
However, a recent trial has again cast doubt on the safety and efficacy of early feeding of allergenic foods, particularly egg. Infants not already sensitized to egg at 4‐6 months were randomized to receive either verum (egg white powder) or placebo.14 At age 1 year, egg sensitization in the verum group was doubled compared with the placebo group, although statistical significance was not reached.
The Canadian Healthy Infant Longitudinal Development (CHILD) Study, a population‐based prospective birth cohort,15 has extensive longitudinal data on breastfeeding, formula, and solid food consumption, and one of the few databases with skin test reactivity at age 1. We examined the relationship between timing of introduction of specific “allergenic” foods and sensitization to those foods at age 1 year.