Breast feeding has many important benefits in children and in mothers. These benefits are greatest in infants in developing countries in whom breast feeding, particularly when initiated early and practiced exclusively, protects against mortality and severe infectious morbidity. Studies from developed countries tend to show smaller health benefits than those observed in developing countries. Nevertheless, there is good quality evidence from the UK and other developed countries that breast feeding protects against diarrhoeal disease and respiratory infection in infancy, including hospitalisation for these infections. In addition, preterm infants who do not receive breast milk are at an increased risk of developing necrotising enterocolitis. A recent report, which was based on evidence from UK studies, estimated that a moderate increase in breastfeeding rates in the UK could save over £17 million annually as a result of the reduced costs of treating infants for diarrhoeal disease, respiratory infection, otitis media and necrotising enterocolitis.1

The evidence on the long-term effects of breast feeding is less clear and is the subject of much debate. A systematic review of the effect of breast feeding on five long-term outcomes (blood pressure; diabetes and related indicators; serum cholesterol; overweight and obesity; and intellectual performance) concluded that the evidence was either inconclusive or suggested no effect for most of these long-term outcomes. However, there was strong evidence of a causal effect of breast feeding on IQ although the magnitude of this effect seems to be modest.2 Most of the studies in the review were observational; hence, it is difficult to infer causality. As an example, in …