ORLANDO, FL -- November 11, 1997 -- Further deepening a decade-old medical controversy, Finnish researchers have linked the amount of iron in the body in men to heart attacks. The new study, which uses more
precise techniques than earlier research, was reported today at the American Heart Association's 70th Scientific Sessions.
The amount of iron consumed in the diet also was associated with an increased risk of heart attacks. The researchers, led by professor Jukka Salonen, M.D., Ph.D., at the University of Kuopio, in Kuopio, Finland, found men with the highest amounts of iron stored in their bodies had almost three times the number of heart attacks than men with less iron in their blood and body.
Researchers say new studies looking at how lowering iron will affect heart disease is still needed to ultimately verify or refute the iron-coronary heart disease hypothesis.
"We believe the current evidence, although still inconsistent, is strong enough to justify screening for high iron stores at least in high-risk persons," Salonen said.
The American Heart Association states additional research is needed to prove
iron's role in heart disease before screening can be recommended. The
possibility increased iron stores heighten the risk of heart disease was first
posed in the mid-1980s in a theory by South Carolina scientist Jerome Sullivan,
In 1992 Salonen and his Kuopio colleagues reported the first study supporting Sullivan's theory. However, at least three groups of researchers in the United States failed to replicate the findings or explore other ways of testing Sullivan's theory. The U.S. scientists agreed their studies were inconclusive.
In the latest study, Salonen and his team looked at 99 men who had suffered a heart attack during the last three to almost nine years and 98 men who were healthy and who served as a control group for the study. The control group was among the 1,931 male participants in the on-going Kuopio Ischaemic Heart Disease Risk Factor Study who had no history of coronary heart disease, which causes heart attacks.
In their latest study, Salonen and his colleagues used a different technique
to measure iron stores in the body. "The technique is more specific, measuring
the concentration of receptors that regulate the intake of iron into the body
cells," Salonen explained. "Evidence concerning the role of body iron stores in
coronary heart disease is inconsistent, due to inappropriate or unreliable
measurements used in most previous studies."
The Finns measured the ratio of the transferrin receptors and ferritin, an iron-bearing protein that serves as the body's storehouse for iron. When body stores of iron increase, the receptors -- which act like a docking post for proteins -- down-regulate so that the cells are not overwhelmed with iron. Thus, it's also important to include measurements of the iron receptors. Salonen said hematologists agree this procedure is the best non-invasive way to measure just how much iron is in the body.
The men with the lowest ratio of transferrin receptors to ferritin had the
most iron in their body and the most risk of heart attack. The technique allowed
the researchers to eliminate other factors including inflammation in the risk
analysis. The only other factor to show an association was increased iron intake
from iron-rich food such as red meat.