1. Epidemiological studies in Iwate, Northern Japan, have confirmed a higher incidence of cerebrovascular accidents and a lower incidence of ischaemic heart diseases in Japan than in North America and Western Europe.
2. The average daily diet in Iwate is relatively low in animal proteins and fat, but relatively high in sodium.
3. Serum cholesterol is relatively low in inhabitants of Iwate.
4. The higher incidence of cerebrovascular accidents may be related to the higher sodium intake, whereas the lower incidence of ischaemic heart disease may be related to the lower intake of animal protein and fat and probably consequent lower serum cholesterol.