Homocysteine is an amino acid found in blood. There is now 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.

Also, a study reported in the February 2002 New England Journal of Medicine gives evidence for an association between high homocysteine levels and the risk of developing dementia. The study showed the risk of Alzheimer's disease was nearly twice as high among those with the highest homocysteine levels.


Homocysteine forms when the body breaks down protein. Normally, several enzymes either turn homocysteine back into methionine (another amino acid), which the body uses to build its own proteins, or they 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 how the body uses folate, vitamins B6 and B12, and can predispose to a person to folate deficiency, leading to high levels of homocysteine.


Exactly how homocysteine causes damage to body tissues 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.


Because homocystine has only recently been identified as a meaningful risk factor for heart disease and other diseases, accurate test for it are sometimes available only through larger clinical reference laboratories. Consult your physician about the availability and cost of this test in your area.


One means of preventing heart disease, stroke, peripheral vascular disease and Alzheimer's 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.