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Iron's Irony: It Can Make You Strong or Kill You
Any adult who grew up watching Popeye squeeze open a can of spinach will tell you that iron makes you strong. So indoctrinated is this idea that doctors find it difficult to teach the public that too much iron actually fuels heart disease, cancer, diabetes and other potentially fatal diseases.
Who would have thought that a foul-mouthed, pipe-smoking, pugnacious sailor could be a poor role model for health?
The latest bit of bad news for iron-loving carnivores comes from researchers at the University of Kentucky Medical Center, who have found that excess "heme iron," the kind that is in meat, causes gallstones. They published this massive 16-year study of nearly 45,000 males in February issue of the American Journal of Clinical Nutrition.
I am Iron Man
Low blood iron is indeed a major health concern for billions of people, mostly in developing nations. Low levels of iron in the bloodstream leave the body fatigued and vulnerable to disease. This is a crushing blow to worker productivity, too, and contributes to the cycle of poverty in which less-productive workers earn lower wages and cannot feed themselves and their families well.
Low blood iron is also a concern for women of child-bearing age because they lose blood, and thus iron, during their monthly periods. Women roughly age 15 to 50 require twice as much iron as men.
Most men in the United States don't need extra iron, but they can't escape it. Just two servings of red meat per week would be enough to supply the adult male body (and post-menopausal female body) with enough iron. Yet many men eat meat every day, often with every meal. All wheat is fortified with iron. And some men get even more iron, unknowing, when taking a multivitamin.
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The problem is that men and post-menopausal women have no natural way of shedding iron. The body does a decent job of only absorbing iron from food when it needs it, but a diet too rich in iron taxes this regulatory system. Iron starts accumulating in the organs.
The free radical maker
Heme iron from shellfish, liver and red meat is more readily absorbed by the body than non-heme iron from vegetables.
In fact, spinach isn't a particularly good source of iron because oxalic acid in the spinach impedes iron absorption.
Iron's effect at the molecular level in the body is well known. Iron creates free radicals, which are reactive molecules that attack cell walls and DNA, causing disease. More iron means more damage and more disease. Iron also suppresses the immune system, promotes cancer cell growth, and triggers the creation of blood-clotting platelets, for example, increasing the risk for heart disease and stroke.
A simple blood test can determine whether you have too much iron, a measure of serum ferritin.
Medieval medicine to the rescue
Doctors say that most men and post-menopausal women do not need extra iron, so those interested in taking a daily multivitamin should find one that is iron-free. However, you don't necessarily need to give up red meat and shellfish, the most generous sources of heme iron, to lower your body's iron store.
Bloodletting, known today as blood donation, is an excellent way to shed iron. Dr. Leo Zacharski, head of the Iron Surveillance Program at the federally funded Norris Cotton Cancer Center at Dartmouth University, says that healthy individuals can donate blood two or three times yearly for their own health and the health of the receiver.
The National Institutes of Health Office of Dietary Supplements provides a nice overview of the complicated iron issue here.
Christopher Wanjek is the author of the books “Bad Medicine” and “Food At Work.” Got a question about Bad Medicine? Email Wanjek. If it’s really bad, he just might answer it in a future column. Bad Medicine appears each Tuesday on LIveScience.
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Christopher Wanjek is a Live Science contributor and a health and science writer. He is the author of three science books: Spacefarers (2020), Food at Work (2005) and Bad Medicine (2003). His "Food at Work" book and project, concerning workers' health, safety and productivity, was commissioned by the U.N.'s International Labor Organization. For Live Science, Christopher covers public health, nutrition and biology, and he has written extensively for The Washington Post and Sky & Telescope among others, as well as for the NASA Goddard Space Flight Center, where he was a senior writer. Christopher holds a Master of Health degree from Harvard School of Public Health and a degree in journalism from Temple University.