Scientists have believed that higher levels of high-density lipoprotein cholesterol helped lower the risk of heart attacks. But new research shows that while HDL has for years been described as being the “good” cholesterol, high HDL is not always beneficial.
Cholesterol is a waxy, fat-like substance that exists in all the cells in your body. It is necessary for good health because it helps the body produce hormones along with vitamin D, and helps digest food.
The human body naturally produces all the cholesterol it needs. We also take in cholesterol through the foods we eat.
There are two basic types of cholesterol:
• LDL – low-density lipoproteins transport cholesterol that is considered to be “bad” cholesterol
• HDL – high-density lipoproteins carry cholesterol that is called “good” cholesterol
High cholesterol can be hazardous to your health. Cholesterol travels through the bloodstream. Excess cholesterol cling to the walls of blood vessels and forms plaque between the layers of the artery.
This can clog the artery and prevent blood from moving freely, which can result in a heart attack or stroke.
Until recently, scientists believed that too much LDL or too little HDL increased the risks of heart disease and stroke.
But new research published in the Clinical Journal of the American Society of Nephrology may discredit that traditional belief.
The large study included data from 1.7 million male U.S. veterans collected over approximately 10 years. As expected, the study showed that too-low levels of HDL cholesterol increased the risk of death.
But researchers were surprised to see that high levels of HDL cholesterol also produced an increased risk of death. Moderate or intermediate levels of HDL cholesterol were the only levels that appeared to lower the risk of heart disease and premature death.
The study itself had inherent strengths and weaknesses.
On the plus side, the study had a large number of participants who were all followed for a long period of time. On the negative side, the study subjects were primarily older white men, which did not allow for a diverse population study.
Dr. Ziyad Al-Aly is an assistant professor of medicine at the Washington University School of Medicine, co-director of the VA St. Louis Health Care System’s Clinical Epidemiology Center, and a researcher in the study.
Aly explained that this new data is timely because recent clinical trials have also failed to achieve the expected results.
When testing drugs intended to increase the levels of HDL cholesterol, clinical study researchers were surprised when the drugs failed to decrease the risks of heart disease. Even when the medications succeeded in raising HDL levels, patient heart health did not improve.
“I think our analytic approach explains some of that,” said Aly. “Maybe too much of a good thing is actually a bad thing.”
If you are currently taking a prescription drug to increase HDL levels, talk to your doctor before making any changes to your medication.
If you have questions about your cholesterol levels or heart health, talk to your health care provider.
Reviewed September 12, 2016
by Michele Blacksberg RN
Edited by Jody Smith