OBJECTIVE: To evaluate the impact of exclusive breastfeeding and introduction of cow's milk in the first year of life on the diagnosis of asthma, wheezing, and atopy in children aged 3 to 4 years. METHODS: This is a cohort study nested in a randomized field trial investigating the effectiveness of dietary guidelines during the first year of life of children in the city of São Leopoldo, southern Brazil. Children who had their diet monitored during the first year of life, in a primary study, were revisited three years later, when their parents answered a questionnaire related to respiratory problems, applied during home visits by trained interviewers. Children were also skin-prick tested to assess responses to common environmental allergens. RESULTS: Of the 397 children followed during the first year of life, 354 were reassessed between 3 and 4 years of age. Prevalence of wheezing, evaluated for the 12 months prior to questionnaires, was 21.3%, while prevalence of asthma and atopy was 5.5 and 28.7%, respectively. Children fed cow's milk previous to being four months of life were significantly more likely to have asthma between three and four years of age (OR 3.22; 95%CI 1.05-9.80). In the same line, exclusive breastfeeding for a period shorter than six months was marginally associated with atopy. CONCLUSIONS: The early introduction of cow's milk was an important risk factor for triggering asthma/wheeze symptoms at the age of 4 years. Exclusive breastfeeding for longer than six months was also potentially associated with protection against the development of atopy. The results of this study suggest that dietary interventions during the first year of life have the potential to reduce the impact of asthma, and possibly, atopy.
Breastfeeding; cow's milk; asthma; diet; child
