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When cholesterol is measured, so are triglycerides, another type of blood fat that's an independent risk factor for heart disease. High triglycerides increase the likelihood of developing heart disease even when cholesterol levels are normal, especially in postmenopausal women. But triglycerides haven't gotten as much attention as LDL (bad) cholesterol and HDL (good) cholesterol, partly because their role in heart disease and stroke hasn't been well understood.

In recent years, scientists have learned more about how triglycerides are metabolized and how they contribute to atherosclerosis, the clogged arteries that raise the risk of heart attack, stroke, and other cardiovascular problems. High triglyceride levels are often correlated with low HDL and a type of LDL cholesterol that is particularly likely to produce harmful deposits in the arteries. High triglyceride levels are also a component of another heart disease risk factor — metabolic syndrome, a condition that occurs in most people with type 2 diabetes and includes high blood pressure and a large waist size. The American Heart Association (AHA) issued a scientific statement about triglycerides and cardiovascular disease that sets a new, lower optimal level of triglycerides and recommends intensive lifestyle measures for reducing elevated triglycerides. The AHA statement and a review of research were published online April 18, 2011, in the journal Circulation. Here are some of the highlights:

Research in women. In the United States, 27% of women have elevated triglyceride levels — that is, 150 milligrams per deciliter (mg/dL) of blood or more (see "Triglyceride levels"). On average, Mexican American women have the highest triglyceride levels and black women the lowest levels, with non-Hispanic white women in between. As women go through menopause, triglyceride levels increase; the relative influence of aging, hormonal changes, and lifestyle changes (lower levels of physical activity, for example) isn't clear. In the Study of Women's Health Across the Nation, triglyceride levels were at their highest during late perimenopause and early postmenopause. Estrogen taken orally — but not transdermally (by patch) — raises triglyceride levels; progestins can counter this effect. Tamoxifen (taken for prevention and treatment of breast cancer) can cause a marked increase in triglycerides.

Triglyceride levels*

Classification

Level (mg/dL)

Normal

Less than 150**

Borderline high

150–199

High

200–499

Very high

500 or higher

*Nonfasting

**Less than 100 mg/dL is optimal.

Measuring triglycerides. Your triglyceride levels vary considerably (throughout the day and over time) depending on various factors, including lifestyle, medications, and metabolic abnormalities. Levels can also be temporarily lowered when you sit down or lie down. So experts recommend that blood-sampling conditions be the same for each test — for example, having the patient sit for five minutes before the blood draw. Other circumstances can also affect test results: how long the tourniquet is applied and the kind of tube (serum or plasma) used to store the blood. The tourniquet should be left in place for no more than one minute (and released as soon as the blood begins to flow) and the same type of blood tube should be used consistently. Triglyceride levels spike after a meal, so tests are traditionally performed after an overnight fast. But now researchers think nonfasting levels can also be used as an initial screen.

The cutoff for normal triglycerides is still 150 mg/dL, but the authors propose a new optimal level of less than 100 mg/dL — the level often found in countries such as Greece, China, and Japan, where cardiovascular disease risk is low. For screening purposes, a nonfasting level of less than 200 mg/dL equals a fasting level of less than 150 mg/dL (normal) and requires no further testing, according to the authors.

Lifestyle measures. For the treatment of elevated triglycerides, the AHA statement recommends a focus on "intensive therapeutic lifestyle change," including weight loss, diet, and exercise. A weight loss of 5% to 10% can result in a 20% drop in triglycerides (as well as a 15% reduction in LDL and an 8% to 10% increase in HDL). You can further reduce triglyceride levels by as much as 20% to 30% if you engage in moderately intense exercise most days. Recommended dietary changes include limiting added sugars (especially from sugar-sweetened beverages) to less than 5% to 10% of calories consumed (about 100 calories per day for women), saturated fats to less than 7% of total calories, and fructose from both processed and whole foods (such as fruit) to less than 100 grams per day. (Fruits that are lower in fructose include cantaloupe, grapefruit, strawberries, bananas, and peaches.) People with high triglycerides should also focus on eating more vegetables, high-fiber whole grains, and healthier unsaturated fats, especially omega-3 fatty acids from fatty fish such as herring, salmon, sardines, and trout.

Last Annual Review Date: 2011-07-01T00:00:00-06:00 Copyright: Copyright Harvard Health Publications

Reference: Cholesterol section on Better Medicine


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An HDL level less than 40 mg/dL is low and is considered a major risk factor because it increases your risk for developing heart disease.