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Cholesterol Does Not Predict Stroke Risk in Women

Cholesterol and other lipids (fats), attached to proteins, form globules that circulate in our blood stream. As a graduate student, I studied the proteins in these fat globules to elucidate their role in disease. One of these globules, LDL (low density lipoprotein) and total cholesterol are routinely measured to predict stroke risk.

But a new study suggests that neither high levels of total cholesterol or LDL are predictive of stroke risk in postmenopausal women, whereas triglycerides, a relatively ignored measurement, are highly predictive.

What are triglycerides?

Triglycerides are the main fats stored in our bodies. If you are overweight, your belly or hips are loaded with triglycerides. When we eat food, the large fat molecules are broken down in our gut into triglycerides. Any excess food, such as carbohydrates, is also chemically converted by our bodies to triglycerides. Chemically, triglycerides are made up of three molecular chains of fatty acids, attached to a “head”, a glycerol molecule.

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Triglycerides clump together and travel to the liver, where they are packaged into lipoprotein globules. The lipoprotein globule, called VLDL (very low density lipoprotein) contains about 90 percent triglycerides, while LDL, the bad cholesterol, only contains about 10 percent triglycerides. After eating dietary fat, the gut produces fat globules, called chylomicrons, that are almost 100 percent triglycerides.

Stroke risk

About 800,000 people in the United States suffer a stroke annually, according to the Centers for Disease Control and Prevention (CDC). Although stroke risk increases with age, about 25 percent of strokes occur in people under 65 years of age. Most strokes (about 87 percent) are caused by a blood clot, according to the CDC. The blood clot clogs an artery in the brain, causing a “brain attack”. The stroke risk for women increases dramatically after menopause.

Study: triglycerides vs. cholesterol

Researchers looked at 972 women, who experienced a stroke during the 15-year long Women Health Initiative (WHI) study. They compared the data from the blood tests of these women to those of another 972 women in the WHI study, who never had a stroke. The study found no linkage between high levels of total cholesterol and LDL, the bad cholesterol, and stroke, but instead found that high triglyceride levels at the beginning of the study were predictive of stroke risk in postmenopausal women.

The belief that high LDL (the bad cholesterol) is predictive of stroke risk may be due to the fact that people with high triglyceride levels, also often have high LDL levels. It is not known yet if triglycerides also are a risk factor for premenopausal women or men.

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Why do statins reduce stroke?

Statins reduce death and the incidence of heart disease and stroke. Statins inhibit an enzyme in the body that makes cholesterol, but statins also have anti-inflammatory effects. The Jupiter trial, run by researchers from Brigham and Women’s Hospital in Boston, MA, showed that statins also reduced C-reactive protein, a marker of inflammation. With statins now widely used, more side effects emerge. Women may be especially susceptible to muscle weakness caused by statins.

How to reduce triglycerides

A major way to reduce triglycerides and stroke risk is to change your lifestyle. Reducing your weight, moderate exercise or physical activity and a diet rich in fruits, vegetables, whole grains and reduced amounts of saturated and trans fats go a long way toward reducing triglycerides in your body. Omega-3s in food or supplements and niacin and fibrate medication may also help to lower triglycerides.