Washington, Nov 17 Scientists have discovered a substance in the blood that may be useful in predicting a person's risk for heart disease.

The substance is cystine, an oxidized form of the amino acid cysteine and an indirect measure of oxidative stress, say researchers at Emory University School of Medicine.

In a study of more than 1,200 people undergoing cardiac imaging because of suspected heart disease, people with high levels of cystine in the blood were twice as likely to have a heart attack or die over the next few years.

Riyaz Patel, a postdoctoral researcher at Emory's Cardiovascular Research Group, says when considered independently of variables such as the presence of diabetes, high levels of cystine still predicted future trouble.

Patel was part of a team led by Arshed Quyyumi, MD, professor of medicine (cardiology) at Emory University School of Medicine.

In the current study, high levels means the quarter of the group of patients with the highest levels.

"Cystine could be a valuable marker of cardiovascular risk, but it also has a direct harmful effect on cells, so reducing it may be a valuable treatment strategy. What's exciting is there are already known ways to intervene and drive down cystine levels in patients," Patel said.

For example, a previous study has shown that supplementing the diet with zinc can lower cystine levels, he said.

Several studies have shown that levels of oxidized cysteine in the blood tend to rise as people age. Smoking and alcohol consumption are also linked with higher levels of oxidized cysteine.

Dean P. Jones, PhD, professor of medicine and director of the Clinical Biomarkers Laboratory at Emory University School of Medicine, and colleagues have shown that when white blood cells are exposed to high levels of cystine, they display signs of inflammation and become stickier. That makes them more likely to adhere to blood vessels in the heart, an event that contributes to the development of heart disease.

The study has been presented at the American Heart Association Scientific Sessions meeting in Orlando. (ANI)