Large Chinese study shows raising "good" cholesterol may not protect heart

WASHINGTON, Nov. 15 (Xinhua) -- Raising so-called "good" cholesterol by blocking a key protein involved in its metabolism may not protect against heart disease or stroke, a large genetic study of 150,000 Chinese adults suggested Wednesday.

There are two types of cholesterol in the blood: one considered "good" and one considered "bad." Lowering "bad" cholesterol has been demonstrated to reduce the risk of heart diseases and stroke, but the causal role of "good" cholesterol in cardiovascular diseases is less clear even though observational studies have shown an inverse association.

Blocking a protein called CETP, or cholesterol ester transfer protein, can raise levels of "good" cholesterol and thus is considered a potentially important approach for prevention and treatment of cardiovascular diseases.

In the new study published in the U.S. journal JAMA Cardiology, researchers assessed the potential benefits of raising "good" cholesterol by looking at genetic variants that alter the activity of CETP to mimic the effects of CETP-inhibitor drugs.

Researchers at the University of Oxford, Peking University and Chinese Academy of Medical Sciences examined data from 150,000 Chinese adults enrolled into a large prospective study called the China Kadoorie Biobank.

After ten years of follow-up, over 5,000 study participants had coronary heart disease and 19,000 had a stroke.

The researchers found that CETP genetic variants raised levels of "good" cholesterol substantially, but did not lower "bad" cholesterol and did not lower the risk of cardiovascular diseases such as heart disease and stroke.

There was also no effect on atherosclerotic plaques and thickness of the arteries, or on other conditions such as diabetes and kidney disease.

However, the study found increased risk of eye diseases as a possible adverse effect of CETP inhibition, a finding which is supported by other genetic studies in East Asian and Western populations.

The results, according to the researchers, complement findings from the recent REVEAL clinical trial of the CETP inhibitor anacetrapib, which found that beneficial effects of CETP inhibition for heart disease were more likely to be due to lowering "bad" cholesterol than raising "good" cholesterol.

"Our research has helped clarify the role of different types of cholesterol, and suggests that raising levels of ('good' cholesterol) by blocking CETP activity, without also lowering ('bad' cholesterol), does not confer any major benefits for cardiovascular disease," study author Iona Millwood from the University of Oxford said in a statement.