Study Finds Normal Triglyceride Levels are Risky
For immediate release: May 01, 1998
Even "normal" levels of triglyceride, a type of blood fat, pose a significant risk of heart disease, according to a new study. In an 18 year follow up of 350 men and women, researchers found that people with triglyceride levels at or above 100 milligrams per deciliter (mg/dl) were 50 percent more likely than those with lower levels to suffer from future heart attacks, need bypass surgery or angioplasty, or die from heart disease. Today, levels below 200 mg/dl are thought to be desirable. The study is published in the May issue of the Journal of the American College of Cardiology.
"Previously, nobody thought triglyceride was a major risk factor at these lower levels," says Michael Miller, M.D., director of Preventive Cardiology at the University of Maryland Medical Center in Baltimore and an associate professor of medicine at the University of Maryland School of Medicine.
"This study is the first to look at such a low level of triglyceride. It turned out to be an important predictor of future heart disease," says Dr. Miller.
Dr. Miller adds the findings should prompt a review of national guidelines regarding triglyceride. Currently, the National Cholesterol Education Program designates a triglyceride level of 200 mg/dl as desirable.
In the study, Dr. Miller and his colleagues followed 278 men and 72 women age 30 to 80 who had been evaluated for coronary artery disease in 1977-1978. The researchers looked at how many had experienced a heart attack, had required a bypass or angioplasty procedure to open up blocked heart vessels, or had died from heart disease.
After adjusting for other risk factors such as smoking, hypertension, diabetes, lack of physical activity, low levels of HDL (the "good" cholesterol) and high levels of LDL (the "bad" cholesterol), the researchers found that triglyceride was an independent risk factor for heart disease, even at lower levels.
"To put it in perspective, it turns out from our study that people with triglyceride levels above 100 mg/dl had about the same risk for heart disease as those with low levels of HDL," says Dr. Miller.
"In fact, the level of 100 was a threshold, or dividing line, between those at higher risk and those who were not. Any level above 100 appeared to increase the risk. It is not like cholesterol, where the higher the level, the higher the risk," Dr. Miller says.
Triglyceride is a type of fat that is always circulating in the blood, especially after a meal high in saturated fat. These fat particles are normally broken down by enzymes. When that process is not working efficiently, the triglycerides that are only partially broken down can cause fatty deposits in blood vessels, leading to atherosclerosis, known as hardening of the arteries. Triglycerides have also been shown to increase the risk of blood clots, which combine with fatty deposits in the coronary vessels to cause heart attacks.
Dr. Miller says people can break down these fats by doing regular exercise, losing weight, eating a diet low in saturated fat, and eating foods that are high in omega 3 fatty acids. Those include fresh fish, such as salmon, herring, mackerel, and sardines and tuna that is either fresh or packed in water, not oil.
A combination of diet changes and exercise can reduce triglyceride levels by as much as 30 percent. Medications that can also lower triglyceride levels significantly include niacin, gemfibrozil and fenofibrate.
Dr. Miller's co authors were Alexander Seidler, Ph.D. and Azita Moalemi, M.D. from the University of Maryland School of Medicine in Baltimore and Thomas A. Pearson, M.D., Ph.D., from the University of Rochester School of Medicine in Rochester, N.Y.
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