Your cholesterol level is the sum of your “good cholesterol” — high-density lipoprotein or HDL-C; your low density lipoproteins or LDL-C, the “bad cholesterol;” and your triglyceride levels.

HDL levels have been thought to be somewhat protective, so if your overall cholesterol level was high due to high HDL values as opposed to LDL, you were believed to be at less risk for developing heart disease. As a result, scientists have been looking into whether raising levels of good cholesterol — HDL-C — could offer the same benefit as lowering LDL levels.

Unfortunately, a new Canadian study suggests that raising levels of HDL-C is unlikely to reduce a person’s risk of heart disease.

“This study shows HDL-C levels are not a direct cardiovascular marker, which goes against conventional wisdom about HDL-C,” Dennis Ko, lead author of the study, told TheDoctor. The benefits of a healthy lifestyle are likely to be as important as a person's actual HDL-C number.

Even though it is called “good” cholesterol, there is probably little benefit to aiming for a really high HDL-C level.

The study looked at the relationship between good cholesterol levels and death among people living in the same geographic area and participating in the same healthcare system. The investigators evaluated data from more than 631,000 men and women between 40 and 105 years old. The people were divided into groups based on their HDL-C levels.

Those with lower HDL-C levels were more likely to have lower incomes, unhealthier lifestyles, higher triglyceride levels, other cardiovascular risk factors and medical problems, compared to those with HDL-C levels in the normal range. Those with the lower HDL-C levels were also more likely to die of cardiovascular disease and other diseases such as cancer, compared to persons with normal HDL-C levels. Those with higher HDL-C levels (>70 mg/dL in men, >90 mg/dL in women) had an increased risk of death from non-cardiovascular related causes such as cancer.

This study suggests that even though it is called “good” cholesterol, there is probably little benefit to aiming for a really high HDL-C level, said Ko, an associate professor at the Institute for Evaluative Sciences in Toronto, Canada. Once HDL-C reaches a certain level, the researchers saw no significant changes in benefits or risks from a higher level of HDL-C. “I think people should really focus on healthy living: not smoking, eating healthy, and exercising,” said Ko.

The study is published online recently in the Journal of the American College of Cardiology.