Although iron is an essential and important nutrient, excessive levels can cause significant harm. A new study has shown that excess iron can cause damage to the endothelium, the inner lining of blood vessels, boosting a person's chances of developing hardening of the arteries (atherosclerosis) and heart attack.

The mechanism of action of this effect seems to be that the high iron levels impede the action of nitric oxide, a chemical released by the endothelium, which aids in keeping blood vessels relaxed.

According to study lead investigator Dr. Hidehiro Matsuoka of Kurume Medical School, consuming high amounts of iron over the long term may increase iron levels in the body. He also said that people should get regularly tested for high iron levels if they are over 40 and have other risk factors for heart disease, such as high blood pressure or diabetes.

• Researchers injected 10 healthy volunteers with high doses of iron (0.7 milligrams per kilogram body weight) and used ultrasound imaging to observe arterial wall functioning.

• The excess iron raised levels of malondialdehyde, a chemical marker for oxidation, and inhibited normal endothelial function.

• As a separate part of the study, researchers also monitored the effects of lowering iron blood levels in 10 cigarette smokers and found that this caused endothelial function to return to normal.

The study also could help to explain why premenopausal women have less heart disease, since iron is removed from the body each month during menstruation.

Meeting of the American Heart Association's Council for High Blood Pressure Research October 2000

Dr. Mercola's Comments:

I have warned about the dangers of iron many times before in this newsletter. It is a potentially dangerous supplement and it needs to be used very cautiously, especially in those with an increased risk of heart disease. I almost always run a serum ferritin level on someone before I recommend going on iron. Ferritin is an iron carrying protein and when its levels drop below 20 that is a sign of iron deficiency. I have seen ferritin levels as low as 2. Occasionally ferritin will be greater than 20 and the person still may need iron. Those with inflammatory conditions such as rheumatoid arthritis, will have falsely elevated ferritin levels. Men are more prone to iron overload since women lose some iron every month through menstruation. Donating blood is an excellent way to lower iron levels if needed. The best form of iron, if it is required, is that obtained from red meat, as it is the most highly available form for absorption. Related Articles: Drug Treatment for Iron Overload Iron Overload Disorder Common and Increases Risk for Heart Attacks High Iron and Heart Attacks in Elderly