Background: Cardiovascular disease mortality in Norway during the last 50 years has been analysed and related to changes in dietary habits and serum cholesterol in the population.
Material and methods: Mortality and dietary data have been collected from official statistics. Changes in serum cholesterol have been estimated from changes in intake of fatty acids based on published regression equations. Data on changes in serum cholesterol and blood pressure are from the former National Health Screening Service.
Results: Mortality from ischemic heart disease (IHD) peaked in 1966-70 when it was 100% higher than in 1951-55 for men and 50% higher for women. For age group 40-69 years mortality has been reduced by more than one half during the last 30 years. For the period 1996-2000 and for all age groups, 30,903 fewer deaths occurred than expected, had the mortality remained the same as during 1971-75, that is 6180 per year. Mortality from sudden death has followed the same pattern as for IHD. Cerebrovascular disease mortality has shown a declining tendency during the entire period. Since 1960 the proportion of total fat in the diet has been reduced from 41 to 34% of energy and the proportion of unsaturated to saturated plus trans fatty acids has increased. Cholesterol in the diet has been reduced by almost one half. Based on changes in consumption in milk fat, fat from meat and margarine, and taken into consideration the change from boiled to filtered coffee the estimated reduction in serum cholesterol in the population is in the order of 0.8 mmol/l. This corresponds closely to the observed 0.5 to 1 mmol/l. Most of the reduction is due to changes in milk fat and margarine consumption and composition.
Interpretation: Based on the established relation between serum cholesterol and risk of IHD we conclude that reduction in serum cholesterol may explain most of the decline in mortality since 1970. Other factors that may have contributed are reduced smoking (in men), a small reduction in blood pressure, increased consumption of fruit, vegetables, cod liver - and fish oil and better means of treatment.