Delayed Introduction of Solid Foods
The Introduction of Allergenic Foods and the Development of Reported Wheezing and Eczema in Childhood: The Generation R Study
Tromp II, Kiefte-de Jong JC, Lebon A, et al.
Arch Pediatr Adolesc Med. 2011;165: 933-938
Background. Parents give many reasons for delaying the introduction of complementary foods to a diet of breast milk or infant formula, including concerns about increased risk for early excessive weight gain, development of allergic sensitivity to the foods, and autoimmune diseases such as diabetes or celiac disease. Pediatric professional organizations generally recommend delaying the introduction of solid foods until the child is at least 4 months of age, with some recommending delaying these foods until the child is 6 months of age. Data about whether the early introduction of solid foods elevates the risk for allergies or other food sensitivities are conflicting.
Methods. This study evaluated the results of a generational cohort study from The Netherlands that followed more than 7000 infants and mothers who delivered their infants between 2002 and 2006. The goal was to determine whether the timing of introduction of allergenic foods such as cow’s milk, eggs, peanuts, tree nuts, soy, and gluten was associated with eczema and wheezing through the fourth year of life. The investigators also conducted subgroup analysis looking at children with and without a history of allergy to cow’s milk demonstrated during the first year of life and subgroup analysis comparing children with and without a parental history of atopic disease. The outcomes were assessed when the children were ages 2, 3, and 4 years, using questionnaires completed by their parents.
Approximately two thirds of the cohort parents responded at each of the survey points. Data on food introduction was obtained during visits when the child was between 6 and 12 months old, again collected by parental report on a questionnaire. Parents were asked about the age when they first introduced each of the allergenic foods. When children were between 6 and 12 months of age, parents again completed a short food frequency questionnaire.
The analyses controlled for appropriate covariates including gender, gestational age, maternal sociodemographic factors, and family history of allergic diseases. The investigators were also able to control for illnesses experienced by the child. Finally, breastfeeding was divided into 6 different categories ranging from children who were "never" breastfed to children who were "exclusively breastfed" through at least 4 months of age. Data were obtained on whether the child had ever been seen by a physician for cow’s milk allergy. The 2 main outcomes of interest were whether the child experienced eczema or wheezing, and the authors created prediction models for children experiencing either of those at age 2, 3, or 4 years.
Findings. The investigators stratified analyses by both cow’s milk allergy and parental history of allergic disease. There were 6905 children in the analysis cohort. At 2 years of age, 31% of the children had experienced wheezing and 38% had experienced eczema. At 3 years of age, 14% of the children reported wheezing and 20% reported eczema. At 4 years of age, 14% of the children had experienced wheezing and 18% had experienced eczema. Almost half (47%) of the children had a parent with a history of atopic disease. With respect to breastfeeding, 11% of the children had never been breastfed, whereas approximately 24% had been exclusively breastfed to at least 4 months. No respiratory illnesses at 12-24 months of life were reported by 48%. Three quarters of the children were in daycare during the second year of life.
When looking at the outcomes of wheezing and eczema, the introduction of allergenic foods at ≤ 6 months of age was not associated with the likelihood of wheezing or experiencing eczema at either 2, 3, or 4 years of life. Wheezing and eczema were both more likely in children who experienced cow’s milk allergy or who had a parental history of atopic disease, but introduction of allergenic foods before 6 months of life was not associated with either outcome in the stratified analyses. The investigators concluded that their data do not support delayed introduction of allergenic foods until after 6 months of age for the prevention of either wheezing or eczema.
The discussion section of this article reviews additional cohort studies that had very similar findings. It appears that the bulk of evidence suggests that delayed introduction of allergenic foods, even among those felt to be atopic prone, does not provide protection against the development of atopic illness. It will be interesting to see how long it takes for general practice to evolve, but the building data suggest that we should reconsider feeding recommendations, at least as they pertain to allergy.