Feb. 20, 2003 -- High levels of an amino acid called homocysteine found in the blood may be a strong indicator of stroke risk among people with heart disease. A new study shows that heart patients with the highest homocysteine levels are more than four times as likely to suffer the most common type of stroke compared with those with the lowest homocysteine levels -- even after accounting for other factors that affect stroke risk and homocysteine levels.
The study suggests that elevated homocysteine may be a new, independent risk factor for stroke. Researchers say that if further research confirms this finding it could have major public health implications because homocysteine can easily and inexpensively be controlled through dietary modifications and vitamin supplements.
Previous studies have shown that homocysteine levels can be effectively lowered by consuming more folic acid and vitamin B-12. Natural sources of these nutrients include citrus fruits, tomatoes, vegetables, and grain products.
In this study, published in the Feb. 21 issue of Stroke: Journal of the American Heart Association, researchers examined the medical records of 80 people with heart disease who had strokes over eight years of follow-up and compared them with 80 similarly matched people with heart disease who were stroke-free.
The study found that the stroke victims had higher homocysteine levels in general, and the likelihood of suffering a stroke increased as the homocysteine levels increased.
Although a direct, causal link between elevated homocysteine and heightened stroke or heart disease risk has not been found, researchers say these findings add to a growing body of evidence that suggests there's a strong link.
"Population studies show that too much homocysteine in the blood is related to a higher risk of cardiovascular disease and stroke, so high homocysteine may be a marker of increased risk," says David Tanne, MD, of Sheba Medical Center and Tel Aviv University in Israel, in a news release. "We add to this information by finding a strong graded association in patients already suffering from [heart] disease."
"It remains to be demonstrated whether reducing high homocysteine levels will reduce the risk for heart disease and stroke," says Tanne.
Although levels of homocysteine are known to rise after heart attack or stroke, researchers say it still isn't clear whether elevated homocysteine in these patients is a risk factor or a byproduct of tissue damage.