Predicting Heart Disease Risk

Reported November 30, 2009

(Ivanhoe Newswire) -- Consumers are well aware of the dangers of oxidative stress, if the number of juices and teas advertised as containing antioxidants is any indication. But what is the best way to measure oxidative stress – and to fight it?

Doctors at Emory University School of Medicine have identified a substance in the blood that may be useful in predicting an individual's risk for heart disease. The substance, cystine, is an oxidized form of the amino acid cysteine and provides an indirect measure of oxidative stress.

In a study of more than 1,200 people undergoing cardiac imaging at Emory for 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, MD, a postdoctoral researcher at Emory's Cardiovascular Research Group and part of a team led by Arshed Quyyumi, MD, professor of cardiology at Emory University School of Medicine, was quoted as saying that when considered independently of variables such as the presence of diabetes, high levels of cystine still predicted future trouble.

"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," said Patel. "What's exciting is there are already known ways to intervene and drive down cystine levels in patients."

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

Cysteine is itself a short-lived precursor to glutathione, one of the main antioxidants found inside cells, according to Dean P. Jones, PhD, professor of medicine and director of the Clinical Biomarkers Laboratory at Emory University School of Medicine. Jones was quoted as saying, "We need to have a continuous supply of cysteine, but it is too reactive for us to have very much at any one time. We are not sure why the oxidized form of cysteine accumulates with aging and disease. But our studies show that when it accumulates, it activates inflammation in cells."

Jones and colleagues have shown that white blood cells exposed to high levels of cystine display signs of inflammation and become stickier, making them more likely to adhere to blood vessels in the heart and contributing to the development of heart disease.

SOURCE: Presented at the American Heart Association Scientific Sessions meeting, Orlando, FL, November 16, 2009