What if Americans ate less fat? A quantitative estimate of the effect on mortality.

Americans consume an average of 37% of their energy intake as fat. Many authorities recommend restricting fat intake to 30% of energy intake to reduce the rates of coronary heart disease and perhaps of cancers of the breast, colon, and prostate. Based on the assumptions that underlie those recommendations, we estimated the effect of this dietary change on mortality. If all Americans restricted their intake of dietary fat by reducing consumption of saturated fat and accompanying dietary cholesterol, the corresponding reductions in serum cholesterol levels could reduce coronary heart disease mortality rates by 5% to 20%, depending on age. If the relationship between dietary fat and cancer is as strong as has been observed in some studies, the proportional effects on mortality from fat-related cancers could be even greater, although the absolute effects--given the lower mortality rates--would be smaller. Overall, if the assumptions are correct, about 42,000 of the 2.3 million deaths that would have occurred in adults each year in the United States could be deferred. This 2% benefit, equivalent to an increase in average life expectancy of 3 to 4 months, would accrue chiefly to people over the age of 65 years. If recent concerns about the possibly harmful effects of cholesterol lowering on mortality from noncardiovascular causes--which mainly affect younger persons--are valid, these relatively modest benefits would be overestimates of the actual effect.