Sep. 1, 1997 Story by Rosemary Hope
KANSAS CITY, Kan. - Men who donate blood may reduce their risk of heart disease by up to 30 percent, according to a study led by David Meyers, M.D., professor of internal medicine and preventive medicine at the University of Kansas Medical Center.
The study, "Possible association of a reduction in vascular events with blood donation," is published in the August issue of the journal Heart.
The study supports the "iron hypothesis" which suggests that women are protected from atherosclerosis, or hardening of the arteries, because they have lower body stores of iron than men. Through menstrual blood loss, women have one-half the iron stores and suffer about one-half the heart attacks and deaths from heart disease as men of similar age.
"What this means for men is - if you donate blood, in a sense you can become a virtual woman and protect yourself from heart disease," said Meyers. "We have identified another reason for blood donation, beyond altruism, for men."
Subjects for the study were men and women, aged 40 or older, with no history of heart disease. They were drawn from the Nebraska Diet Heart Study, a 1985-1987 population-density-based and demographically representative study. The subjects were recontacted from 1992 to 1993 and surveyed about 39 items that included demographics, occurrences of heart disease or procedures, diet, cholesterol levels, smoking and blood donation.
Of the 3,855 in the study, 655 reported donating at least one unit of whole blood in the preceding 10 years. Of the donor group, 9.77 percent reported "vascular events," defined as heart attack, stroke, angioplasty, bypass surgery and nitroglycerin use, compared to 17.72 percent of the non-donors.
When the study group was divided into males and females, the benefit of blood donation was apparent only in the men. The benefit was negated in men by cigarette smoking. There was a much smaller benefit in reduced heart disease risk for women who donated blood.
The observed reduction in vascular events can be explained in two ways, said Meyers. "Either iron depletion through blood donation truly affects atherosclerosis, or on the other hand, mainly healthy people who are at low risk of heart disease are blood donors."
Meyers plans to conduct a randomized clinical trial of 4,000 men in the Kansas City area to determine which answer is correct. The results of the study may not prove that blood donation prevents heart disease, said Meyers. But the study does support the iron hypothesis, which suggests that stored iron in the body stimulates the process in which cholesterol is oxidized, an event that is thought to be involved in atherosclerosis. A smaller study published in March in the British Medical Journal supports the hypothesis also. This study reported that blood donation reduced the risk of heart attack by 86 percent among 2,682 Finnish men. "It could be a win-win situation," said Meyers. "Even if the iron hypothesis is proved incorrect, donating blood is still the right thing to do."
Meyers' co-authors for the study are Daniel Strickland, M.S.P.H., Ph.D., Pierre Maloley, Pharm.D., and Jeanette Seburg, M.T.., all of the University of Nebraska Medical Center, Omaha; and Janet Wilson, M.T., and Bruce McManus, M.D., Ph.D., of the University of British Columbia, Vancouver, Canada. - KUMC -
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