Homocysteine

Definition

Homocysteine is a chemical found in blood. There is considerable evidence that homocysteine may prove to be a useful marker for risk of heart attacks, since elevated levels have been detected in people with coronary artery disease.

Description

Homocysteine forms when the body breaks down protein. Normally, several enzymes act on it and either turn homocysteine back into methionine (an amino acid), which the body uses to build its own proteins, or break it down for excretion in the urine.

Folic acid, vitamin B6 and vitamin B12 are necessary for metabolism of methionine. A number of genes influence utilization of folate, vitamins B6 and B12, and can predispose to deficiency, leading to high levels of homocysteine.

Causes and Risk Factors

Exactly how homocysteine causes damage is not clear. It is possible that it damages the delicate cells that line arteries, eventually causing clogged arteries, or it may make blood clot more easily. Both of these can lead to heart attack, stroke, and peripheral vascular disease.

Diagnosis

Relatively few laboratories currently provide highly reliable blood tests for homocysteine.

Treatment

One means of preventing heart disease, stroke, and peripheral vascular disease may be a diet high in folic acid, vitamin B6 and vitamin B12. Folate is found in a variety of fresh fruits and vegetables such as orange juice and romaine lettuce.

For those at risk, some physicians recommend at least 1 mg of folate per day. Since deficiency of vitamins B6 and B12 may also be associated with high homocysteine levels, increasing the amount of these vitamins in the diet is prudent. Daily vitamin supplementation is another, less palatable option.

Questions to Ask Your Doctor

What is the homocysteine level?

Is this abnormal?

Could there be a risk for heart disease or stroke?

Do you recommend any dietary changes?

Would daily vitamin supplementation help?