Introduction of complementary foods and the relationship to food allergy.

Abstract

The study analyzed the significance of complementary feeding and breastfeeding in association with allergy development.This study was a nested case-control trial of 41 infants with food allergy diagnosed by age 2 years and 82 matched controls within a cohort study involving 1140 infants. The infants’ food allergies were confirmed by using double-blind, placebo-controlled food challenges, the gold standard for diagnosing food allergies.Infants with food allergies were recruited from the PIFA (Prevalence of Infant Food Allergy) study in the United Kingdom. Parents kept prospective daily food diaries and were also asked to complete a telephone questionnaire when their infant was 12 and 24 months old. The questionnaire was designed to identify infants with potential food allergies. Infants with potential food allergies based on food diary and telephone questionnaire data underwent skin prick tests and serum-specific IgE tests to common food allergens. Infants provisionally diagnosed as food allergic based on results of their skin prick test or serum-specific IgE tests then underwent double-blind, placebo-controlled food challenges.Most (95%) mothers initiated breastfeeding. Exclusive breastfeeding occurred for a median of 8 weeks, total breastfeeding occurred for a median of 20 weeks (0–64 weeks), and there was no significant difference between infants who developed food allergy compared with control subjects. However, infants who developed food allergy had a shorter duration of concurrent breastfeeding when cow’s milk was introduced compared with control subjects (5.5 vs 9 weeks; P = .47). The mean age of introduction of solids was ∼20 weeks. Significantly more food-allergic infants were introduced to complementary foods (not necessarily common allergens) at <17 weeks of age than control subjects (35% vs 14%; P = .011). Infants with food allergy were introduced to cow’s milk and peanut significantly earlier compared with the control infants.The infants who were diagnosed with food allergy by age 2 years were less frequently breastfed when cow’s milk protein was first introduced into their diet and were also introduced to solids earlier than the control infants.The authors conclude that early introduction of solids was associated with the development of food allergy, which supports the current recommendations by the American Academy of Pediatrics to breastfeed exclusively and to delay introduction of solids until 4 to 6 months of age. Data are accumulating to suggest that breastfeeding seems protective against food allergies and that there is a critical window in which solid foods, including highly allergenic foods such as cow’s milk, eggs, and peanut, should be introduced in infancy. Breastfeeding should also continue concurrently for 2 to 3 months while cow’s milk and solids are introduced into the diet because it is thought to play a role in the development of oral tolerance.