NEW YORK (Reuters Health) - Hostility could increase people's risk of heart disease by depleting their levels of certain heart-healthy antioxidants, new research suggests.

Oxidative stress occurs when production of free radicals, which are normal byproducts of metabolism, outpaces the body's ability to neutralize them, resulting in tissue damage. It has been associated with heart disease, cancer and other illnesses. Antioxidant vitamins can help counteract oxidative stress, while cigarette smoking and pollution, among other factors, can increase it.

Hostility is associated with heart disease risk, Dr. Tetsuya Ohira of the University of Minneapolis and colleagues note. Given that hostile individuals are more likely to smoke and drink, while poor diet and smoking can deplete antioxidants, antioxidants could help explain the relationship, they suggest.

To investigate, they looked at 3,579 men and women 18 to 30 years old who were participating in the so-called Cardiovascular Risk Development In Young Adults study. The researchers measured levels of several different carotenoids, which are pigments with powerful antioxidant properties, as well as tocopherols (vitamin E).

People who had high levels of hostility at the study's outset were more likely to have lower levels of several types of carotenoids seven years later, the researchers found, but hostility didn't predict levels of tocopherols or lycopene.

If hostility does reduce levels of antioxidants, Ohira and colleagues say, lifestyle factors such as diet, smoking and drinking probably play a key role.

The increased risk they observed was "small, but significant," they add, so "it is not clear whether or not the differences are importantly related to the risk of coronary heart disease." Further research is needed to answer this question, they conclude.

SOURCE: American Journal of Epidemiology, January 1, 2008.