Ask an Expert: Homocysteine, vitamins and stroke prevention

Q: A friend of mine is taking folic acid and vitamin B12 supplements to lower her homocysteine levels and help prevent a stroke. What exactly is homocysteine? Should I be taking vitamin supplements if I’m worried about having a stroke?

Answer from Dr. Ted Lowenkopf, medical director of Providence Stroke Center:

Homocysteine is a natural body chemical that helps the cells in your body to work normally. It enters your body through the foods you eat. When combined with folic acid and other B vitamins, homocysteine turns into protein and maintains the normal functions of your body’s tissues.

Homocysteine can accumulate in the blood if you do not have enough folic acid and vitamin B12 in your system to help convert it into protein. Some people have a genetic defect that causes too much homocysteine to accumulate in the blood. Research studies have found that people who have high blood levels of homocysteine are at increased risk of stroke or heart attack from the formation of fatty plaques in blood vessels (atherosclerosis) and from blood clots. We do not yet know whether excess homocysteine actually causes vascular damage or is simply a side product of some other activity in the body that makes a person prone to a stroke or heart attack.

Although high homocysteine levels put a person at risk for heart disease and stroke, we cannot yet say that taking vitamin supplements to lower homocysteine can prevent strokes or heart attacks. The Oregon Stroke Center is participating in a national study on this subject, and the results should help address this question.

In the meantime, there is little harm in taking vitamin supplements in moderation along with a balanced diet. Any concern about reducing your stroke risk should start with identifying your risk factors and implementing a prevention plan designed by you and your doctor. Such a plan could focus on controlling established stroke risk factors such as weight, high blood pressure, diabetes, high cholesterol and smoking.