April 26, 2000
Heres why. Each time you give blood, you remove some of the iron it contains. High blood iron levels, Sullivan believes, can increase the risk of heart disease. Iron has been shown to speed the oxidation of cholesterol, a process thought to increase the damage to arteries that ultimately leads to cardiovascular disease.
Sullivan has long suspected that blood iron levels help explain why a mans risk of heart disease begins earlier than a womans. Women lose blood and lower their iron levels each time they menstruate. Men, on the other hand, begin storing iron in body tissues starting in their twenties, which is just about the time their heart attack danger begins to climb.
According to Victor Herbert, M.D., a hematologist at the Mt. Sinai School of Medicine in New York City, there are normally about 1,000 milligrams of iron stored in the average adult mans body but only about 300 milligrams in a premenopausal womans. Once women stop menstruating, however, their iron levels and their heart disease risk begin to climb, eventually matching that of men.
Not everyones convinced by Sullivans notion. I do not believe there is proof of an association between iron level and the risk of heart disease in men with normal iron metabolism, says Peter Tomasulo, M.D., a director at the International Federation of Red Cross Societies. The data is preliminary at best. Most scientists, in fact, still think estrogen is probably the most important reason why women are protected from heart disease until they reach menopause.
But several recent findings lend support to the possibility that iron levels play a role. In research reported last year in the journal Circulation, Swedish scientists found that men with a genetic abnormality that causes slightly elevated blood iron levels had a 2.3fold increase in heart attack risk. A second study published in the same journal found that women with the abnormal gene were also at greater risk of cardiovascular disease. Together, Sullivan believes, those studies offer new support for his iron hypothesis.
Proof wont come until researchers conduct large and wellcontrolled studies that compare the heart disease risk of men who regularly give blood with that of men who dont. Already several small studies have been done, however, offering tantalizing evidence that donating blood might be a very good idea.
Take, for example, a study of 2,682 men in Finland reported in the September 1998 issue of the American Journal of Epidemiology. Men who donated blood at least once a year had an 88 percent lower risk of heart attacks than nondonors. Another study published in the August 1997 issue of Heart found that men who donated blood were less likely than nondonors to show signs of cardiovascular disease.
Critics are quick to point out that people who donate blood may simply be healthier to start with. Yet a 1995 study published in the Journal of Internal Medicine found that the use of bleeding to lower iron levels in a group of 14 patients did reduce cholesterol oxidation. Its another small piece of evidence in support of the benefits of donating blood. By now, Sullivan insists, there is abundant evidence that favors a public health recommendation to lower iron stores. Whats more, he says, there is no risk to a healthy person donating blood, and potentially significant benefit.
