HDL cholesterol is also known as ‘good cholesterol’. However, Danish researchers discovered that high levels of HDL increase the risk of death.
HDL and (V)LDL cholesterol
We have all heard of “good” and “bad” cholesterol. The well-known explanation in short: Cholesterol is produced by the body (especially in the liver), but it is also found in animal foods. Moreover, fats in food can cause the liver to produce more cholesterol.
There are different types of cholesterol. LDL and VLDL cholesterol (low density lipoproteins and very low density lipoproteins) transport the cholesterol packaged in a little ball made of fat and protein to the cells. Handy because cholesterol is necessary for the production of certain hormones, vitamin D, and substances that help with metabolism.
HDL (high density lipoproteins) cholesterol removes excess cholesterol to the liver where it is broken down. Therefore, higher HDL levels are needed to prevent, for example, clogging of the veins due to the accumulation of triglycerides (the fats in the ‘ball’) with high (V)LDL levels.
Doctors therefore look at both the balance between the two as well as the individual values. A high HDL is generally considered good because it provides protection against high (V)LDL.
“Too much good cholesterol is not good”
However, Danish researchers wanted to know more about the effects when the levels of this ‘good cholesterol’ are high. They examined the data of more than 116,000 men and women with an average age of 57. On average, they were followed for six years.
During those six years, 10,678 men and women from the group had died. After adjusting for other risk factors, an HDL of 73 milligrams per deciliter in men and 93 in women was found to be associated with the fewest deaths (from all causes). Men with an HDL of 97 mg/dl had a 36 percent higher risk of death and a twice as high risk with an HDL above 116 mg/dl. In women, the risk of death increased by 68% with an HDL of 135 mg/dl.
As seen in previous studies, low HDL was also associated with a higher risk of death.
Extremely High HDL
Now it is useful to put this into perspective. The study looked at the effects of extremely high HDL levels.
Only 2.3 percent of men had an HDL above 97 mg/dl and only 0.3 percent of women had an HDL higher than 135. A 68% higher risk of death is less impressive when you have only a 0.3 percent chance of falling into that risk group. The study provides insight only into the effects at extreme values. Thus, it becomes clear that even in the case of HDL cholesterol, the old wisdom holds true that too much is never good.
Dr. Borge G. Nordestgaard, a professor at the University of Copenhagen, told the NY Times that until now he congratulated patients with very high HDL levels. “The higher the better!”
But now we know that’s not so. These people should protect themselves — exercise, stop smoking, eat a healthy diet and so on
References
- Christian M. Madsen, Anette Varbo, Børge G. Nordestgaard; Extreme high high-density lipoprotein cholesterol is paradoxically associated with high mortality in men and women: two prospective cohort studies, European Heart Journal, Volume 38, Issue 32, 21 August 2017, Pages 2478–2486,
- Cox RA, García-Palmieri MR. Cholesterol, Triglycerides, and Associated Lipoproteins. In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Boston: Butterworths; 1990. Chapter 31. Available from: https://www.ncbi.nlm.nih.gov/books/NBK351/
