Low and very high levels of high-density lipoprotein (HDL), known as ‘good cholesterol’ are associated with higher risk of dying from heart disease, cancer and other causes, said researchers from University of Toronto in Canada.
Low level of good cholesterol may not be a heart disease risk factor on its own and also raising HDL does not likely reduce a person’s risk of heart disease, they said.
To reduce risk of suffering a cardiac episode, many patients are treated to lower their low-density lipoprotein (LDL) or ‘bad cholesterol’, with statins – a medication used to block the enzyme needed in the body to produce cholesterol.
However, some people do not respond to this treatment, so researchers have been studying HDL and whether raising levels of ‘good cholesterol’ could have the same benefits as lowering ‘bad cholesterol’.
Researchers studied over 631,000 individuals without prior cardiovascular conditions through a research database that links together multiple individual-level population-based datasets on sociodemographics, cardiac risk factors and comorbidities, medications in Canada.
Patients were between 40 and 105 years old, with an average age of 57.2.
The study cohort was divided into groups based on their HDL to allow researchers to examine the relationship between HDL levels and mortality.
Researchers compared the HDL levels of people with healthier lifestyles to those with less healthy habits.
The lowest levels of HDL were seen in people who were socioeconomically disadvantaged and who had less healthy lifestyle behaviours, more cardiac risk factors and more medical comorbidities.
Even when adjusting for lifestyle factors, lower HDL levels were still associated with increased risk of both cardiovascular death and non-cardiovascular related death.
Individuals with very high HDL levels had an increased risk of non-cardiovascular related death.
“The link between good cholesterol and heart disease is complex,” said lead author Dennis Ko, associate professor from University of Toronto in Canada.
“However it seems certain that there is a connection between people with low good cholesterol levels and other well-known risk factors for heart disease such as poor diet and exercise habits and other medical conditions,” said Ko.
“Focusing on raising HDL is likely not going to help these patients, but these findings show that one of the best interventions in treating and preventing heart disease continues to be lifestyle changes,” he said.
The study appears in the Journal of the American College of Cardiology.