Fat/cholesterol: an update

American's increased awareness of fat and dietary cholesterol is explained in part by reports linking these nutrients to major chronic diseases, to recent dietary recommendations to consume less fat, especially saturated fat, and cholesterol, and to the development of foods and ingredients reduced or lacking in these nutrients. With respect to coronary heart disease, an elevated blood cholesterol level is one of several modifiable risk factors. Although there is increasing evidence for the importance of genetics, environmental factors also are implicated in the cause of coronary heart disease. Diet, in particular the quality and quantity of dietary fat and dietary cholesterol, influences blood cholesterol. Saturated fatty acids are known to increase blood cholesterol. Recent findings, however, demonstrate unique effects of specific fatty acids on blood cholesterol levels and risk of coronary heart disease. Not all saturated fatty acids are hypercholesterolemic. Stearic acid, for example, does not raise the blood cholesterol level as does palmitic acid. Monounsaturated fatty acids (e.g., oleic acid) likewise do not increase blood cholesterol levels. New findings also raise the possibility that omega-3 fatty acids, found mainly in cold-water marine fish and fish oils, protect against cardiovascular disease. Potential advantages of reducing total fat intake include a decrease in intake of saturated fatty acids and prevention of some forms of cancer and obesity, the latter being a major risk factor for coronary heart disease. Dietary cholesterol is another component that raises blood cholesterol. However, individuals vary in their blood cholesterol response to dietary cholesterol, and perhaps to saturated fatty acids as well. In addition to coronary heart disease, excess dietary fat has been associated with increased risk for certain types of cancer. However, more research is necessary to distinguish the effects of fat, energy, and obesity on different forms of cancer. An increasing number of health professional organizations and government agencies recommend a reduction in the intake of fat, particularly saturated fat, and cholesterol. These recommendations differ in their specificity and target audience (i.e., general healthy population vs. individuals "at risk"). There is general agreement, however, that all Americans over age 20 should have their blood cholesterol measured. Concern about overconsumption of fat and cholesterol has led to the development of food products reduced in these nutrients. In addition, several fat substitutes, although not yet approved for use, are under review by the U.S. Food and Drug Administration. Questions are being raised regarding the potential effect of fat substitutes on overall nutritional intake and health.