The possibility that breast feeding might protect against allergy and asthma has generated interest for 70 years. In this week's BMJ, a cluster randomised trial by Kramer and colleagues assesses whether exclusive and prolonged breast feeding reduces the risk of asthma and allergy at 6 years of age.1 It found no significant difference in allergy and asthma symptoms reported by parents or the results of allergy skin prick tests.

Hospitals in Belarus were randomised to promotion of breast feeding or usual care, and mothers intending to breast feed were eligible. The intervention increased the total duration of breast feeding and exclusive breast feeding in the intervention group. Six years later, parents answered seven questions about wheezing, hay fever, itchy rash, and whether their child had ever had asthma or eczema. The children also had skin prick tests to determine hypersensitivity to five airborne allergens. Overall, 10% of parents reported that their child ever wheezed, …