You may already know that high cholesterol is a risk factor for developing heart disease or having a stroke, but what about high triglycerides? Perhaps you can recite your LDL, HDL and total cholesterol levels by heart. But are you paying attention to that other number on your lipid panel? Research suggests that this other number--your triglyceride level--may deserve a closer look.
Triglyceride BasicsWhen total cholesterol levels are measured after an overnight fast, one number included in the report is the level of triglycerides, a form of fat that travels through the bloodstream. Triglyceride levels that are too high can increase the risk of developing cardiovascular problems. But how high is too high?
The triglyceride level guidelines set by The National Heart, Lung, and Blood Institute, part of the National Institutes of Health, are:
Normal: Less than 150 mg/dL
Borderline High: 150-199 mg/dL
High: 200-499 mg/dL
Very High: Greater than 500 mg/dL
High (and very high) triglyceride levels are linked to atherosclerosis, a condition in which cholesterol and other substances form plaques within the walls of an artery. If a plaque ruptures, the plaque fragments or blood clots can block the flow of blood in either an artery supplying the heart, which could cause a heart attack, or an artery supplying the brain, which could cause a stroke.
There are other important factors in the development of atherosclerosis -- above all, the levels of LDL, the so-called "bad cholesterol." Contributing factors to the development of atherosclerosis include obesity and insulin resistance. Insulin resistance is a pre-diabetic condition marked by an impaired response to insulin, the main hormone involved in the transfer of food energy to cells throughout the body.
While it is difficult to determine the specific cause of high triglyceride levels, elevated levels are associated with a number of factors, including:
- Obesity -- Excess weight generally increases the blood level of triglycerides
- Medical Conditions -- Diabetes, kidney disease, low thyroid function and liver disease are all associated with elevated triglyceride levels.
- Age -- Triglyceride numbers tend to creep up as you age.
- Poor Diet: -- Too much sugar or alcohol can increase the amount of triglycerides produced in the liver.
- Medications -- Oral contraceptives, steroids and diuretics are all associated with high triglyceride levels.
- Heredity -- High triglyceride levels may just run in the family.
A New Look at Triglycerides and StrokeAs a risk factor, triglyceride levels have traditionally been viewed as the sidekick to the other components of the standard lipid panel: total cholesterol, LDL and HDL (the "good cholesterol"). Elevated LDL levels have been deemed the prime suspect in the development of stroke. But research published in 2008 suggests that, when considered on their own, triglyceride levels have a strong link to stroke development.
Over a four-year period, researchers at the University of California, Los Angeles collected data on more than 1,000 patients who were admitted to a university medical center for transient ischemic attack (TIA), also referred to as a "ministroke." TIA is a condition in which an artery is temporarily blocked by a blood clot, but does not result in permanent symptoms or disability.
All of the study patients had fasting lipid panels drawn the day following admission to the hospital. By comparing these lipid panels, researchers found that the patients with the highest triglyceride levels were 2.7 times more likely to suffer a stroke than those with low triglyceride levels. LDL levels, however, showed no correlation to stroke risk.
A 2001 study reported similar results. Researchers in Israel analyzed more than 11,000 patients, all of whom had coronary heart disease (CHD) but had never suffered a stroke. During a follow-up period of up to eight years, 487 of the study patients had a TIA or full-blown stroke. In studying the overlap between this subgroup and the high triglycerides subgroup, researchers found that patients with triglyceride levels of 200 mg/dL or more had a 30% greater risk of having a stroke than patients with normal triglyceride levels.
Of course, LDL is not completely off the hook. While not closely linked to stroke in these studies, LDL does tend to be higher in stroke patients when compared to healthier subjects. Elevated LDL levels are also linked to an increased risk of developing CHD. That is why, while noting the role of triglycerides in CHD risk, the National Cholesterol Education Program of the National Heart, Lung, and Blood Institute maintains that LDL should remain the number one target in efforts to lower cholesterol.
Getting Triglycerides Under Control
Individuals with high triglyceride levels should know that there are things that can be done to help lower triglyceride levels:
Physical activity helps rid the body of excess fat, but even without weight loss, exercise can decrease the levels of fats in your blood.
- Choose Fish Instead of Steak
Meat, such as steak or pork, is high in saturated fat, but fish (especially deepwater, fatty fish such as albacore tuna and salmon) are high in omega-3 fatty acids, which helps to fight off high triglyceride levels.
- Be Cautious About Cocktails
Even moderate alcohol intake can considerable elevate triglyceride levels. On the other hand, moderate alcohol consumption also helps boost your HDL, the "good cholesterol," making this a complicated issue and one worth discussing with your doctor.
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American Heart Association Staff. "Transient Ischemic Attack (TIA)." Americanheart.org. American Heart Association. 4 Apr. 2008. <http://www.americanheart.org/presenter.jhtml?identifier=4781>.
American Heart Association Staff. "Triglycerides." Americanheart.org. American Heart Association. 4 Apr. 2008. <http://www.americanheart.org/presenter.jhtml?identifier=4778>.
Bang, O.Y., et. al.. "Association of Serum Lipid Indices With Large Artery Atherosclerotic Stroke." Neurology. 70. 11. 11 Mar. 2008. 841-847. <http://www.neurology.org/cgi/content/full/70/11/841> (subscription).
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National Cholesterol Education Program Staff. "Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) Final Report." Circulation. 106 (2002): 3143-3421.
Tanne, David, et. al.. "Blood Lipids and First-Ever Ischemic Stroke/Transient Ischemic Attack in the Bezafibrate Infarction Prevention (BIP) Registry: High Triglycerides Constitute an Independent Risk Factor." Circulation. 104. 24. 11 Dec. 2001. 2892 - 2897. <http://circ.ahajournals.org/cgi/content/full/104/24/2892> (subscription).