Iron is key to health—we need enough to manufacture red blood cells; anything beyond that is superfluous. Once our bodies absorb the mineral, though, the only way to get rid of it is by losing blood. Build up too much iron and it may interfere with circulation, which could explain why men in their 30s and 40s have a higher risk of cardiovascular disease than women: Menstruation may get rid of artery-damaging iron, at least until menopause, the time of life when a woman's risk nears that of a man's.
To see if bloodletting—phlebotomy, as it's officially known—could be protective, U.S. researchers conducted a multicenter six-year study of 1,277 men and women ages 43 to 87 who had diseased arteries in their legs. Every six months, about half the patients donated blood.
Sure enough, the procedure worked. In patients under 62, those who gave blood saw their risk of death, heart attack, and stroke fall by more than half. Patients 62 and over, however, didn't seem to benefit, suggesting that too much arterial damage may already have been done.
The study's authors are hesitant to recommend therapeutic phlebotomy just yet. But pathologist Jerome Sullivan, MD, PhD, associate professor at the University of Central Florida, who first suggested a link between iron and cardiovascular health, sees no reason why people shouldn't consider becoming volunteer blood donors. "It's an established, safe practice, and an effective way to reduce your iron level," he says. Now when you donate blood, you know that you could be doing your body a favor as well.