Lowering Iron Levels Does Not Cut Risk of Heart Attack for Men
For immediate release: January 08, 2001
Boston, MA. -- Harvard School of Public Health researchers have determined that men in the US who donate blood do reduce iron stores in the body but do not reduce their risk of coronary heart disease (CHD) and heart attack. Iron levels in the body had once been thought to explain the difference in CHD rates among men and women. The study results, the most definitive to date on iron stores and CHD, appeared in the January 2, 2001 issue of Circulation (www.circulationaha.org).
Previous studies hypothesized that women have lower incidences of CHD than men because of a loss of iron in the blood through menstruation. Men can cut their iron level stores in half by donating one unit of blood per year and can further lower the level to that of premenopausal women by donating two or three units per year. The contrast between US men who donate blood, and those who do not, provided a test for the hypothesis.
Dr. Alberto Ascherio, associate professor of nutrition and epidemiology at the Harvard School of Public Health, led the HSPH researchers. Ascherio said, "The results of this study throw cold water on the twenty year old hypothesis that reduced iron levels decrease the risk of coronary heart disease." The study also suggests that reduced estrogen levels, rather than excess iron, increased the risk of heart disease for post-menopausal women.
The team examined the relationship between blood donation and the risk of CHD in 38,244 eligible men who participated in the Health Professionals Follow-up Study (www.hsph.harvard.edu/hpfs) between 1992 and 1996. Because past studies had suggested high body iron stores were of particular danger to men with high cholesterol levels, blood donors with this risk factor were examined.
The HSPH team documented 459 coronary incidents among study participants: 328 non-fatal heart attacks and 131 heart-related deaths. They found the differences in coronary risk factors between those who donated blood and those who never did were modest and found no relationship between the number of blood donations and risk of heart attack. Men with high blood cholesterol did not appear to benefit from donating blood and there was no relationship between coronary risk and donating blood among men who did not take antioxidant vitamins or aspirin on a regular basis. The study concludes that body iron stores do not contribute a major coronary risk factor for men in the US who have not had previous heart disease or diabetes.
The research was supported by grants from the National Institutes of Health.
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