HDL CHOLESTEROL

Report #6639 11/10/95

Having low blood levels of the good HDL that prevents heart attacks is one of the strongest predictors of a person's susceptibility to suffer a heart attack, but only when a person is on a high-fat diet.

Studies on the effect of low blood levels of the good HDL cholesterol on susceptibility to heart attacks were done on middle- aged Americans eating a high-fat diet. There are no studies on how low blood levels of HDL predict heart attacks in people eating low-fat diets. HDL cholesterol is good because it helps prevent heart attacks by carrying cholesterol from your bloodstream to your liver where it can be converted to bile and removed from your body/ before it can form plaques in arteries. When you go on a low-fat diet, you unclog liver cells so they remove HDL from the bloodstream faster. Since low-fat diets cause your liver to remove HDL faster from your bloodstream and the rate of production of HDL remains the same, blood levels of the good HDL cholesterol go down in a good way. (1) Blood levels of HDL are like water in a bath tub. When water flows into a bathtub at the same rate that it flows out through the drain, the water level remains constant. However, when water flows through the drain at a faster rate, the water level drops. The same principle applies to HDL levels. As a general rule, when using HDL levels to predict a heart attack in people on very low-fat diets, you can add about 15 points to HDL levels.

By Gabe Mirkin, M.D., for CBS Radio News