Breast-feeding and cardiovascular risk factors and outcomes in later life: evidence from epidemiological studies

This paper considers the body of observational evidence examining the association of being breast-fed to cardiovascular risk factors and outcomes in later life, and whether any potentially advantageous findings are causal. Early cardiovascular consequences/correlates of breast-feeding, compared to being formula fed, include markedly higher levels of total blood cholesterol, lower levels of pre-prandial blood glucose and insulin and lower levels of adiposity. However, a key issue is whether these early differences at a period of rapid development programme/influence cardiovascular risk factors and outcomes in later life. Evidence of long-term effects of early feeding, largely from observational studies, has shown that those breast-fed have lower levels of blood total cholesterol, lower risk of type-2 diabetes and marginally lower levels of adiposity and blood pressure in adult life. There is no strong evidence to suggest effects of early feeding on adult levels of blood glucose, blood insulin and CHD outcomes, although further data are needed. However, the influence of confounding factors, such as maternal body size, maternal smoking and socio-demographic factors, and exclusivity of early feeding on these potentially beneficial associations needs to be considered before inferring any causal effects. Moreover, fewer studies have examined whether duration of exclusive breast-feeding has a graded influence on these risk factors and outcomes; such data would help further in deciding upon causal associations. While strong observational evidence suggests nutritional programming of adult cholesterol levels, associations with other markers of cardiometabolic risk and their consequences in later life need to be confirmed in well-conducted observational and experimental studies.