A stroke is the result of blood flow to a portion of the brain becoming disrupted. Because the brain is made of nervous tissue, it needs constant oxygen flow, so a stroke causes brain cells to die due to lack of oxygen. The levels of a form of cholesterol known as HDL are involved in calculating a person's risk of having a stroke.
Atherosclerosis and Stroke
One kind of stroke, known as an ischemic stroke, can be caused by atherosclerosis. Atherosclerosis is caused by cholesterol building up in the walls of arteries. When this happens, it causes the walls of the arteries to become more rigid and also narrows the amount of room through which blood can flow. If this happens in the arteries in the brain, it can result in decreased blood flow until the artery is ultimately closed off, resulting in an ischemic stroke.
Types of Cholesterol
Not all forms of cholesterol contribute to atherosclerosis. Cholesterol is found in the blood in complexes known as lipoproteins. One kind of lipoprotein, known as LDL or low-density lipoprotein, is thought to be involved in carrying cholesterol to other cells. Elevated levels of LDL are linked with an increased risk of atherosclerosis. High-density lipoprotein or HDL, on the other hand, works as a cholesterol scavenger and helps to remove cholesterol from the blood, the American Heart Association explains. High levels of HDL are associated with a decreased risk of atherosclerosis.
HDL Measurements
HDL cholesterol is usually measured as part of a lipid panel, which also measures the blood levels of LDL and another type of lipid known as triglycerides. Normal levels of HDL are between 40 and 50 mg per dL of blood in men and between 50 to 59 mg per dL of blood for women, LabTestsOnline explains. HDL levels above 60 mg per dL are considered optimal for the prevention of atherosclerosis and heart disease, whereas abnormally low levels are classified as a risk factor for cardiovascular problems.
HDL and Stroke
Although the effects of HDL cholesterol on a person's risk of heart disease are well established, there is not as much conclusive evidence on HDL levels as a risk factor for strokes. In elderly men, however, the effects pf HDL on stroke risk are much clearer. Elderly men with low HDL levels are 2.7 times more likely to have an ischemic stroke than men with high HDL levels, PreventDisease.com reports.
Raising HDL Levels
There are a number of ways to raise HDL levels. Exercising and losing weight can help most people increase the concentration of HDL in the blood, as can consuming a diet low in saturated and trans fats. Omega-3 fatty acids, the Mayo Clinic explains, can also increase HDL levels; omega3 fatty acids can be found in some kinds of fish, leafy green vegetables, soy and flax seed.
