Background: Coronary heart disease mortality has declined in Finland by 55% among men and 68% among women between 1972 and 1992. About three-quarters of this decline has been explained by changes in the main coronary risk factors, the decrease in serum cholesterol being the most important one. The aim of this study was to analyze to what extent dietary changes could explain the change in serum cholesterol.
Methods: Cardiovascular risk factor surveys have been carried out in Finland from 1972 to 1992 at 5-year intervals. Dietary surveys were carried out in connection with these surveys in 1982 and 1992. An earlier, representative dietary survey carried out in 1969-1972 was used as the baseline measure for diet.
Results: The total fat content of the Finnish diet changed from 38% of energy to 34%, saturated fat from 21 to 16%, and polyunsaturated fat from 3 to 5% and the intake of cholesterol decreased by 16%. Based on Keys equation these changes could have decreased serum cholesterol level by 0.6 mmol/liter (23 mg/dl) in both genders. A shift from boiled to filtered coffee could have further decreased serum cholesterol by 0.3 mmol/liter (11 mg/dl). Thus, these changes together could explain the total change in serum cholesterol, which has been on average 1.0 mmol/liter (38 mg/dl). Several other changes in the diet have also been favorable. Fruit and vegetable consumption has increased two- to three-fold during this time period. Supplementation of fertilizers with selenium since 1985 has tripled the intake of selenium.
Conclusions: Dietary changes seem to explain the decrease in serum cholesterol. Together with a decline in smoking among males as well as better blood pressure control they have contributed to the dramatic decline in coronary heart disease mortality in Finland.