HDL (high-density lipoprotein) cholesterol is called “good” because in this form it travels away from the arteries and back to the liver for elimination from the body. We’ve long believed that the higher your HDL, the lower your risk of heart disease. Indeed, studies have suggested that each increase of four milligrams per deciliter of blood (mg/dl) of HDL results in a 10 percent decrease in the risk of adverse coronary events. Both HDL and LDL (the “bad” form) cholesterol levels are influenced by heredity, diet, weight, exercise, age, gender, alcohol consumption, and stress.
The latest news about HDL comes from a study conducted in Denmark and published in August 2017, which found for the first time that very high HDL is associated with increased risk of death from all causes, not just cardiovascular disease. Researchers from the University of Copenhagen tracked 116,508 men and women for an average of six years. During that period, 10,678 of these individuals died. The investigators reported that men with extremely high HDL levels – ranging from 97 to 115 – had a 36 percent increased risk of death. That risk doubled among those whose HDL exceeded 116. Women with HDL levels above 135 had a 68 percent increased risk. Extremely high HDL was rare: only 2.3 percent of the men had levels exceeding 97, AND 0.3 percent of the women had HDL above 135.
Men in the study with the lowest death rates had HDL levels of 73 milligrams per deciliter. Among women, the lowest mortality was linked to an HDL of 93. As in previous studies, low HDL – levels under 39 – were also associated with a higher risk of death.
In addition to looking at the cholesterol levels of the men and women enrolled in the study, the researchers adjusted for risk factors such as age, body mass index, alcohol consumption, physical activity, diabetes and whether or not an individual was a current or former smoker.
Because this was an observational study, it doesn’t prove that extremely high HDL caused the deaths seen. And since the study included only white individuals of Danish descent, the findings might not apply to people elsewhere. Also, the results need to be confirmed by further studies.
High HDL is considered a predictor of good cardiovascular health and longevity. Unless your HDL is extremely high, you have nothing to worry about.
Andrew Weil, M.D.
Christian M. Madsen et al, “Extreme high high-density lipoprotein cholesterol is paradoxically associated with high morality in men and women: two prospective cohort studies.” European Heart Journal, August 21, 2017, doi.org/10.1093/eurheartj/ehx163