Abstract Background The optimal timing for introducing complementary foods remains under debate. Although guidelines generally recommend introducing solids around 4–6 months of age, evidence linking timing to later food allergy remains inconsistent. We evaluated associations between age at food introduction, caregiver‐reported food‐related allergic symptoms, and allergen‐specific immunoglobulin E (IgE) levels up to 6 years of age. Methods Using data from the Japan Environment and Children's Study (JECS; 2011–2014), a nationwide birth cohort, we analyzed caregiver‐reported food‐related allergic symptoms in 63,693 children and allergen‐specific IgE levels in a subcohort of 2964 children. Logistic regression assessed associations between timing of food introduction and reported symptoms, and multiple regression evaluated associations with IgE titers. Results Introduction of certain foods at ≥13 months was associated with higher odds of caregiver‐reported food‐related allergic symptoms, particularly for egg and wheat (egg: aOR 5.69; wheat: aOR 26.69). Some associations were also observed for soy, fish and rice, although estimates were unstable in small subgroups. Children not introduced to egg or milk by 12–13 months had higher egg white– and cow's milk–specific IgE levels at 2, 4, and 6 years. No significant associations were observed for fruit, shellfish, buckwheat, or peanuts. Conclusions Delayed introduction of selected foods beyond 12–13 months was associated with higher odds of caregiver‐reported food‐related allergic symptoms and, for measured allergens, elevated IgE levels. Given the observational design and questionnaire‐based outcomes, findings should be interpreted cautiously. image
Nakatsu et al. (Fri,) studied this question.