Excessive milk consumption may adversely affect the circulation on account of the high calcium content of milk and because lactose promotes the intestinal absorption of calcium. Excessive calcium intake may cause calcification and rigidification of the large elastic arteries, which could be an important factor in causing myocardial ischaemia.The calcium hypothesis can throw light on some puzzling peculiarities of arterial disease, for instance the changing ratio of male and female mortality rates in various age groups, the apparently beneficial effect of a warm environment and the entirely different worldwide distribution of coronary heart disease and strokes.