Triglycerides are a type of fat found in the blood. They are the most common type of fat in the body. The human body burns some of the calories that we eat for short-term energy needs. It converts any extra calories into triglycerides to be used later. People who eat more calories than they burn tend to have high triglyceride levels. Normal amounts of triglycerides are vital to our health. When triglyceride levels rise too high, however, they may increase the risk of heart disease. Triglycerides can be measured using the same blood test that measures cholesterol.
"Triglycerides traditionally have been viewed as second-class citizens," said Dr. Michael Miller, director of preventive cardiology at the University of Maryland Medical Center and lead author of the study report, which appears in the Feb. 12 issue of the Journal of the American College of Cardiology. "LDL cholesterol has always taken center stage. We know that LDL is intimately involved in bringing cholesterol to scavenger cells, which deposit them to form plaques in the arteries. This study shows that triglycerides in and of themselves are also to blame."
When triglyceride levels rise too high, however, they may increase the risk of heart disease.
This study looked at 4,162 people, looking for any association between triglyceride levels and heart problems.
"The patients who had heart attacks came back after 30 days," said Miller. "We measured LDL levels and triglyceride levels and followed them over the next two years, evaluating for the occurrence of new events and death. If a patient had triglyceride levels below 150 [milligrams per deciliter], there was a 27 percent lower risk of having a new event over time. After multiple adjustments for such things as age, diabetes, high blood pressure and obesity, the risk reduction was 20 percent."
Unlike LDL cholesterol, for which there is a recommended blood level of 70 or below, there is no medical consensus on what constitutes "normal" blood triglyceride levels, Miller said, but 150 milligrams per deciliter or below is "considered as desirable."
The results obviously need verification, Miller said. "At the present time, we don't have a recommendation for triglyceride lowering, so the next logical step is a study to determine whether lowering triglycerides and LDL reduces risk more than lowering LDL alone," he said. Two such studies are in progress.
Dr. Leslie Cho, an interventional cardiologist and director of the Women's Cardiovascular Center of the Cleveland Clinic, noted that the new report "is not a huge surprise."
"The unique thing about this study is that even if you control bad LDL cholesterol to less than 70, you still need to look at triglycerides," Cho said.
There are several things we can do to lower triglyceride levels. One is to follow a so-called "Mediterranean diet", which generally means eating less meat and processed foods and more fish, fruits and vegetables. Omega-3 fatty acids, niacin and exercise are all known to lower triglyceride levels.
"If you can effectively get both LDL cholesterol and triglycerides down, you are going to do better," Miller said.