BUFFALO, N.Y. -- The question of whether too much iron increases the risk of dying from heart disease has received another "no" answer through the results of a population-based, long-term, follow-up study conducted by researchers at the University at Buffalo.
The study, appearing in the October issue of Annals of Epidemiology, found no association between "high-normal" iron levels in the body and risk of death due to cardiovascular disease, coronary heart disease or heart attack, or between iron levels and risk of death from any cause.
Christopher Sempos, Ph.D., associate professor in the Department of Social and Preventive Medicine in the UB School of Medicine and Biomedical Sciences and lead author on the study, said of the findings: "Sound clinical guidance and public-health recommendations must be based on reasonably solid evidence that what is being recommended is both safe and effective.
"Currently available data do not support radical changes in dietary recommendations for iron intake or screening by physicians to detect high-normal levels of serum ferritin. Nor do they support the need for large-scale, randomized trials of dietary restriction or phlebotomy as a means of lowering iron stores."
There have been more than two dozen studies conducted in recent years on diseases of the heart and circulatory system and their association with levels of iron in the body, only a few of which showed positive findings, Sempos noted. Still, the subject remains controversial.
The current study was based on data collected from participants in the second National Health and Nutrition Examination Survey (NHANES II) between 1976 and 1980, and an analysis of death records through Dec. 31, 1992. The study sample consisted of 1,604 persons -- 128 black men and 100 black women; 658 white men and 718 white women -- between the ages of 45-74.
Iron status was based on concentrations of ferritin -- one of the chief forms in which iron is stored in the body -- in the serum of blood samples taken at the beginning of the study. Serum is the clear fluid that separates from blood when it clots.
Sempos and colleagues tested two hypotheses using this data: That any amount of excess iron increases heart-disease risk, and that only excess iron exceeding a high-normal level poses a risk.
• There was no statistically significant association between serum ferritin levels and death from any type of heart disease.
• There was no association between all-cause mortality and ferritin levels in white men or women of either race.
• Black men with low levels of excess iron in their serum were at three times the risk of death from any cause.
"Results from this study are consistent with others in showing that iron does not appear to play a direct role in the development of coronary heart disease," Sempos said. "More research needs to be done to study this issue in women and minorities."
Additional researchers on the study were Anne C. Looker, Ph.D., Richard F. Gillum, M.D., Cuong V. Vuong and Clifford L. Johnson, all of the National Center for Health Statistics, Centers for Disease Control and Prevention, and Daniel L. McGee, Ph.D., of Loyola University Stritch School of Medicine.
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