Milk drinking, ischaemic heart disease and ischaemic stroke II. Evidence from cohort studies

Objective: Milk consumption is considered a risk factor for vascular disease on the basis of relevant biological mechanisms and data from ecological studies. The aim was to identify published prospective studies of milk drinking and vascular disease, and conduct an overview. Design: The literature was searched for cohort studies, in which an estimate of the consumption of milk, or the intake of calcium from dairy sources, has been related to incident vascular disease. Main outcome measures: Ischaemic heart disease and ischaemic stroke. Results: In total, 10 studies were identified. Their results show a high degree of consistency in the reported risk for heart disease and stroke, all but one study suggesting a relative risk of less than one in subjects with the highest intakes of milk. A pooled estimate of relative odds in these subjects, relative to the risk in subjects with the lowest consumption, is 0.87 (95% CI 0.74-1.03) for ischaemic heart disease and 0.83 (0.77-0.90) for ischaemic stroke. The odds ratio for any vascular event is 0.84 (0.78-0.90). Conclusions: Cohort studies provide no convincing evidence that milk is harmful. While there still could be residual confounding from unidentified factors, the studies, taken together, suggest that milk drinking may be associated with a small but worthwhile reduction in heart disease and stroke risk. Sponsorship: The University of Wales College of Medicine and Bristol University. Current support is from the Food Standards Agency.