'Good' cholesterol levels vary globally.

Researchers have known for more than 15 years that, on average, women have higher levels than men of high density lipoproteins (HDL), the so-called "good" cholesterol believed to protect against heart disease. Now, a University of North Carolina at Chapel Hill study has shown that such differences vary from country to country. Few differences in HDL cholesterol were found between the sexes in China, for example, while in Canada and the U.S., the disparities were significant, about 30%.

The findings are important and potentially good news, the researchers say, because they show environmental factors strongly affect HDL levels. As a result, it may be possible to change those factors, increase HDL cholesterol in men, and reduce heart disease, heart attacks, and strokes.

3. Ed Davis, professor of biostatics at the university's School of Public Health and director of the Collaborative Studies Coordinating Center, led the investigation with help from scientists in Russia, China, Poland, Israel, and Canada. "We found intermediate differences in populations in Russia, Poland, and among African-Americans...