Doctors should also keep an eye on the ratio of total cholesterol to HDL cholesterol in order to better determine heart disease risk, says lead researcher Dr. Sundar Natarajan of the New York University School of Medicine.

Data show that almost half of all patients with coronary heart disease have normal LDL levels but may have low levels of HDL, resulting in a high LDL/HDL ratio. In the study, those with similar ratios had similar risk for heart disease, regardless of any differences in LDL or total cholesterol levels.

The new findings may influence dietary recommendations for people with high cholesterol. For instance, certain low-fat diets that reduce both LDL and HDL levels may be less beneficial than diets that boost HDL cholesterol readings. Products that are high in LDL-lowering trans fats, such as margarine, may also cause an unwelcome drop in heart-protective HDL cholesterol.

The FDA will require food labels to list the amount of trans-fatty acids in food products beginning in 2006. The FDA is also considering putting a warning on foods that have trans fat.