Delayed introduction of solids does not decrease the incidence of asthma or allergic rhinitis

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• Zutavern A, Brockow I, Schaaf B, von Berg A, Diez U, Borte M, et al., LISA Study Group. Timing of solid food introduction in relation to eczema, asthma, allergic rhinitis, and food and inhalant sensitization at the age of 6 years: results from the prospective birth cohort study LISA. Pediatrics 2008;121:e44-52
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Zutavern A, Brockow I, Schaaf B, von Berg A, Diez U, Borte M, et al., LISA Study Group. Timing of solid food introduction in relation to eczema, asthma, allergic rhinitis, and food and inhalant sensitization at the age of 6 years: results from the prospective birth cohort study LISA. Pediatrics 2008;121:e44-52 

Question Does a delayed introduction of solids (past 4 or 6 months) protect against the development of eczema, asthma, allergic rhinitis, and food or inhalant sensitization at the age of 6 years?

Design Prospective cohort study. Data from were analyzed at 6 years of age. Multivariate logistic regression analyses were performed for all children and for children without skin or allergic symptoms within the first 6 months of life to take into account reverse causality.

Setting Germany.

Participants A total of 2073 children in the ongoing LISA birth cohort study.

Intervention Questionnaires were completed by the parents at birth and when the children were 0.5, 1, 1.5, 2, 4, and 6 years of age. At age 2 and 6 years, children also underwent blood collection and physical examination.

Outcomes Physician diagnoses of eczema, asthma, and allergic rhinitis (collected through parent report and medical records).

Main Results A delayed introduction of solids (past 4 or 6 months) was not associated with decreased odds for asthma, allergic rhinitis, or sensitization against food or inhalant allergens at 6 years of age. On the contrary, food sensitization was more frequent in children who were introduced to solids later. The relationship between the timing of solid food introduction and eczema was not clear. There was no protective effect of a late introduction of solids or a less diverse diet within the first 4 months of life. However, in children without early skin or allergic symptoms, eczema was significantly more frequent in children who received a more diverse diet within the first 4 months.

Conclusions There is no evidence that delayed introduction of solids beyond 4 or 6 months prevents asthma, allergic rhinitis, and food or inhalant sensitization at the age of 6 years. For eczema, the results were conflicting, and a protective effect of a delayed introduction of solids cannot be excluded. A true protective effect of a delayed introduction of solids on food sensitization seems unlikely.

Commentary “When should I start feeding my baby solids?” This is a question pediatricians and family physicians confront regularly—especially given the rising incidence of allergy in children and the suspicion that infant dietary practices play a role. However, most evidence behind the recommendations for the timing of solid food introduction for infants has been conflicting and of limited quality. Against this backdrop, the analysis of the LISA birth cohort contributes high-quality evidence of the relationship between infant feeding and allergic disease in the largest birth cohort studied to date. In this study, the authors examined whether delayed introduction of solid foods (>4 or >6 months) prevents the development of allergic disease. Conducting research on infant feeding poses a number of challenges. First, there is the potential for parent recall bias and the use of imprecise definitions to classify disease. The authors overcame these issues by obtaining prospective feeding histories, collecting disease reports from parents and physicians, and conducting the analysis at 6 years of age—when asthma and allergic rhinitis are easier to diagnose. Second, there is the challenge of reverse causality that occurs when parents of infants with early allergy symptoms delay introduction of solids. This results in a false association between late feeding and allergic symptoms. To address this bias, the authors stratified their analyses by report of early allergy symptoms but still found no relationship between delayed introduction of solids and development of asthma, allergic rhinitis, and food or inhalant sensitization. However, the results for eczema were conflicting, a finding that will likely influence physicians' recommendations for infants with eczema or a positive family history. Overall, this is a well-conducted study that provides useful evidence on infant feeding practices for pediatric practitioners and parents.