Challenging the conventional wisdom that simply having high levels of good cholesterol (HDL) and low levels of bad cholesterol (LDL) is necessary for good heath, researchers from the University of Chicago have shown that the good cholesterol has varying degrees of quality and that poor quality HDL is actually bad for you.

"For many years, HDL has been viewed as good cholesterol and has generated a false perception that the more HDL in the blood, the better. It is now apparent that subjects with high HDL are not necessarily protected from heart problems and should ask their doctor to find out whether their HDL is good or bad," said Angelo Scanu, M.D., a pioneer in blood lipid chemistry from University of Chicago and first author of the study.

The scientists reviewed published research on the subject before coming to the above conclusion.

In their review, they found that the HDL from people with chronic diseases such as rheumatoid arthritis, kidney disease, and diabetes is different from the HDL in healthy individuals, even when blood levels of HDL are comparable.

It was found that normal, ‘good’, HDL reduces inflammation, while the dysfunctional, ‘bad’, HDL does not.

"This is yet one more line of research that explains why some people can have perfect cholesterol levels, but still develop cardiovascular disease. Just as the discovery of good and bad cholesterol rewrote the book on cholesterol management, the realization that some of the ''good cholesterol'' is actually bad will do the same," said Gerald Weissmann, M.D., Editor-in-Chief of The FASEB Journal.