Designing and sticking to a healthy diet is a challenge for many Americans who are barraged with often conflicting advice about what to eat. Recommended fat intake, for one, can range from none to unlimited. New findings suggest that for middle-aged men, the most important variable is not how much fat they consume, but what type.

Previous research indicated that consumption of polyunsaturated fats had a beneficial effect on levels of LDL, the so-called bad cholesterol, whereas eating saturated fats served to increase it. As a result, many patients were advised to replace sources of saturated fats, such as animal fats and solid vegetable shortening, with unsaturated ones from natural vegetable oils in order to lower their risk of heart disease. But very little long-term data on individuals outside of hospital settings was available to test this hypothesis. David E. Laaksonen of the University of Kuopio in Finland and his colleagues followed 1,551 middle-aged men for 15 years, collecting information on their dietary habits and testing their cholesterol levels. The total amount of fat a man consumed was not associated with an increased risk of heart disease when other risk factors, such as smoking, age, weight and family history, were considered. The team determined, however, that the men whose diets contained relatively higher amounts of unsaturated fats compared with saturated ones were up to three times less likely to die of cardiovascular disease than men who ate the least amount of unsaturated fats. Participants in the former group ate nearly twice as much unsaturated fat than did those in the latter group.

"Dietary fat quality thus seems more important than fat quantity in the reduction of [cardiovascular disease] mortality in middle-aged men," the authors conclude. "Carrying out recommendations to replace saturated fat with polyunsaturated fat in the primary prevention of cardiovascular disease may substantially decrease [cardiovascular disease] and to a lesser degree overall mortality."