Iron promotes heart attacks, study says Women's lower risk explained by theory

September 08, 1992|By Lawrence K. Altman | Lawrence K. Altman,New York Times News Service

Surprising new findings from a large study in Finland show that high levels of iron are a strong risk factor for heart attacks.

The study, which is being reported today in Circulation, a scientific journal published by the American Heart Association, provides the first empirical evidence for a theory advanced 11 years ago that high amounts of iron promote heart attacks and low levels protect against them.

Proof that iron causes heart attacks and that drugs or other measures aimed at reducing the amount of iron in the body prevent them will still require much more research.

But such proof could eventually lead to a revival of bloodletting, once a common medical practice, to remove excess iron and prevent heart disease.

Iron lost from bloodletting would be replaced by iron drawn from stores in the bone marrow, liver and spleen, thus reducing the total amount of iron in the body.

But experts caution that it is too early to make any recommendation about lowering body iron, and that too great a reduction of iron can cause anemia, an energy-sapping blood disorder.

The new findings support the theory that iron helps form the plaque that hardens artery walls and blocks the flow of blood, leading to a heart attack.

Further research could also explain a wide range of phenomena, including these:

* Why heart attacks are rare among premenopausal women. The female hormone estrogen may not necessarily be the reason for the low rate of heart attacks in this group, as many scientists suspect; rather, the reason may be that menstruating women lose blood, and iron, each month.

* Why eating large amounts of red meat seems to be a heart attack risk. Red meat is rich in iron.

* Why aspirin and certain fish oils seem to protect against heart attack. They can cause small amounts of bleeding.

Over all, heart attacks are the leading killer in the United States and most other industrial countries. Heart attack death rates in eastern Finland, where the study was conducted, are the highest in the world.

The Finnish study involved more than 1,900 men from age 42 to 60 who had no clinical evidence of heart disease when the study began in 1984. The study, which ended in 1989, is being reported in Circulation by Dr. Jukka T. Salonen and his colleagues at the University of Kuopio in Finland.

In an accompanying editorial, Dr. Salonen's epidemiological study was called "a landmark paper" by Dr. Jerome L. Sullivan, director of clinical laboratories at the Veterans Affairs Medical Center in Charleston, S.C., who originally proposed the iron theory. Dr. Sullivan and other experts said further findings could challenge current recommendations for the amount of iron in the diet because the amounts now considered normal may turn out to be harmful.

The Finnish team found that for every 1 percent increase in serum ferritin, the form in which iron is stored in the body, there is a 4 percent increase in the risk of heart attack.

Typical levels for young women are 25 to 50 micrograms of iron per liter of blood while typical levels for men are 100 to 150 micrograms per liter, Dr. Sullivan said.

"Women lose their iron stores through menstruating for a large part of their adult lives, and they outlive men," Dr. Sullivan said.

Dr. Claude J. Lenfant, who heads the National Heart, Lung and Blood Institute, said in an interview that the Finnish study was "provocative and potentially very important" and that scientists at the federal agency in Bethesda, Md., were looking into ways to confirm the findings among Americans.

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