The best HDL cholesterol for the heart?

High-density lipoprotein (HDL) is a carrier molecule known as the "good cholesterol" for its role in removing fatty debris from artery walls. Researchers now report that some forms of HDL may provide better protection against heart disease than others.

A particular type of HDL, one that contains a particle dubbed apoA-I, seems to provide superior protection against the ravages of heart disease, says H. Bryan Brewer Jr. of the National Heart, Lung, and Blood Institute in Bethesda, Md. His research suggests that HDL with apoA-I collects cholesterol from the inner wall of the artery and transports it to the liver for excretion. Another type of HDL appears ineffective at such cholesterol scavenging.

More evidence on the merits of apoA-I comes from a mouse study. Edward Rubin of the University of California, Berkeley, has put the human gene coding for the apoA-I protein into a strain of mice. The resulting animals have high concentrations of HDL with the human apoA-I particle in their bloodstream.

When Rubin put these mice on a high-fat, high-cholesterol diet, he found that the apoA-I protected them from developing plaque. By contrast, unaltered mice (with normal concentrations of HDL in their bloodstream) did develop coronary artery disease when fed the fatty chow.

Of course, such animal studies do not prove apoA-I's benefits in humans, Rubin notes. But this evidence, as well as data from other studies, suggests that HDL with apoA-I may provide people with a more effective shield against heart disease, he says. Brewer agrees, noting that if further research confirms apoA-I's benefits, physicians may begin to order a more sophisticated cholesterol profile, one that includes a breakdown of HDL types.