Washington: A sub-class of high-density lipoprotein (HDl) cholesterol, known as "good" cholesterol, may not protect against coronary heart disease (CHD) and in fact may be harmful, says a study.
This is the first study to reveal that a small protein, apolipoprotein C-III (apoC-III), that sometimes resides on the surface of HDl cholesterol may elevate heart disease risk and that HDl cholesterol without this protein may be especially heart protective.
"This finding, if confirmed in ongoing studies, could lead to better evaluation of risk of heart disease in individuals and to more precise targeting of treatments to raise the protective HDl or lower the unfavourable HDl with apoC-III," said Frank Sacks, professor of cardiovascular disease prevention at Harvard School of Public Health and senior study author.
A high level of HDl (good) cholesterol is linked with low incidence of CHD. But trials of drugs that increase HDl cholesterol have not consistently shown decreases in CHD, leading to the hypothesis that HDl cholesterol may contain both protective and non-protective components, the Journal of the American Heart Association reported.
Blood samples collected in 1989 and 1990 from 32,826 women in the Brigham and Women`s Hospital-based Nurses` Health Study were examined, along with blood samples collected from 1993 to 1995 from 18,225 men in the Health Professionals Follow-up Stud, according to a university statement.
During 10 to 14 years of follow-up, 634 cases of coronary heart disease were documented and matched with controls for age, smoking, and date of blood drawing. The researchers compared plasma concentrations of total HDl, HDl that has apoC-III, and HDl without apoC-III as predictors of the risk of CHD.