Oxidative stress is thought to be a major cause of chronic diseases of the heart, joints, and brain. But in a surprising development, researchers have discovered that aging can blunt its effect on blood vessels.

Oxidation is a chemical reaction that causes iron to rust. In the body, it has long been linked to the chronic diseases of aging.

Researchers at the University of Missouri Medical School have discovered that the oxidative process may actually help the aging body to adapt, offering protection against biological stress.

They studied the inner lining, or endothelium, of small arteries in mice. These arteries are important to the cardiovascular system because they regulate blood flow and pressure.

The researchers stimulated the effect of oxidation on endothelial tissue in male mice at four months and 24 months of age, which correspond to humans in their early 20s and mid-60s.

They discovered that the death of the endothelial cells in younger mice was seven times greater than in older mice.

Although more research is needed to discover how the process works, the study shows that the body adapts to oxidative stress as it gets older, and that the arteries can still perform their job, the researchers said.