Extreme Levels of "Good Cholesterol" May Lead to Premature Death

High-density lipoprotein (HDL) has become known as “good cholesterol” because it helps reduce risk of stroke and heart attack. However, new research found that both high and low levels of HDL could increase a person’s risk of premature death. Conversely, moderate HDL cholesterol levels may help in prolonging life span.

“The findings surprised us,” said Ziyad Al-Aly, MD, an assistant professor of medicine at Washington University and the study’s senior author. “Previously, it was thought that raised levels of the good cholesterol were beneficial. The relationship between increased levels of HDL cholesterol and early death is unexpected and not fully clear yet. This will require further study.”

The new research from the Washington University School of Medicine in St. Louis and Veterans Affairs St. Louis Health Care System attempts to better understand the relationship between HDL cholesterol and all-cause mortality in patients with kidney disease. The researchers established this relationship by studying the eGFR levels (kidney function). The findings are published in the Clinical Journal of the American Society of Nephrology.

Study Design and Results

The study included more than 1.7 million male US veterans with at least one eGFR test between October 2003 and September 2004. The study period was up until September 2013 or death. It was found that patients with low HDL cholesterol and low eGFR were more vulnerable to co-morbid diseases. Conversely, patients with intermediate HDL cholesterol levels had a low risk of death across all levels of eGFR.

“The findings may explain why clinical trials aimed at increasing HDL cholesterol levels failed to show improved outcomes,” Al-Aly said. There is a strong connection between HDL cholesterol levels across all kidney functions and premature death, and the study attempts to establish that connection.

“Moderation” Is the Key

For years, it was believed that HDL is “good cholesterol” and hence, having elevated levels of HDL cannot be a bad thing. However, this study debunks the myth. Having elevated or low levels are both equally harmful. The risk of premature death increases at both ends of the spectrum. Maintaining steady intermediate HDL cholesterol levels would in fact, be hugely beneficial in prolonging life span.