Does iron cause cancer? On one hand, those who have read my book Dumping Iron as well as my articles on iron may not be surprised, but those new to this topic may wonder that there could be a link between iron, a required nutrient, and cancer, a deadly disease.
This article will take a look at just a small sample of the evidence that iron causes cancer.
A study done by Dr. Leo Zacharski (who wrote a preface for my book) and colleagues reduced iron via periodic phlebotomy in patients with peripheral arterial disease. The study was not designed to reduce cancer rates but to look for an effect on cardiovascular outcomes. But it did reduce cancer. See chart below, which shows the proportion of patients who got cancer in iron reduction group vs control.
Iron chelators work to both prevent and treat cancer in two different ways.
Curcumin is a natural compound derived from the spice turmeric, and both prevents and treats cancer. It’s thought to do this in a number of ways, but one of the most important is that it chelates iron. So potent an iron chelator is curcumin that mice that get large amounts of it in their food become iron deficient.
Regular blood donors may have a lower rate of cancer. One study found overall a 21% lower rate of cancer among all blood donors. The study used latency periods of from 0 to 15 years to account for a healthy donor effect; in other words, to select only those donors who were free of cancer at the time of the first donation.
Another study found a decreased risk of cancer only among those donors who lost the greatest amount of iron, and only in men. The fact that it was found only in men may indicate that most healthy women of child-bearing age do not have high enough iron to cause cancer, while lowering the iron levels of men, who typically have much higher iron, decreases their risk of cancer.
Coagulation is the process by which blood forms a clot, and is intricately regulated by dozens of blood proteins.
Hypercoagulation occurs when this process goes awry, and can lead to internal blood clots causing embolism, heart attack, or stroke.
Hypercoagulation also appears to be related to cancer. Persistent activation of coagulation is associated with much greater odds of a cancer diagnosis.
Dr. Zacharski, whom I cited above, writes:
We suggest that toxicity from elevated ambient body iron levels may explain the association between persistent coagulation activation and incipient cancer. The iron hypothesis is based on biochemical, animal and human data that have linked rising body iron stores, represented by the serum ferritin concentration, to the pathogenesis of several diseases of aging, including malignancy and vascular disease, through iron-mediated formation of oxygen free radicals capable of damaging lipids, proteins and DNA.
The mechanism of iron-catalyzed coagulation activation is, to simplify, that iron damages tissues through oxidative reactions, and this damaged tissue activates coagulation. In turn, this can lead to cancer.
Interestingly, aspirin, which has been associated with far lower cancer rates, enhances fibrinolysis, the process of dissolving a blood clot. A number of mechanisms have been proposed for the association of aspirin with less cancer, and this could be another way.
Most of what we’ve seen above are associations and do not prove causation between iron and cancer.
However, as Shinya Toyokuni, a noted cancer scientist, writes,
“The carcinogenicity of iron compounds has been unambiguously demonstrated in animal studies.”
Asbestos is a well-known carcinogen, but until recently it had always been something of a mystery why.
Tokokuni again: “Several lines of recent evidence suggest that the major pathology associated with asbestos-induced MM is local iron overload, associated with asbestos exposure.” (From “Iron overload as a major targetable pathogenesis of asbestos-induced mesothelial carcinogenesis“.
Cigarettes are also known to cause cancer, and iron is a large component of tobacco smoke. Inhalation of iron in other contexts, for example in miners or foundry workers, also causes cancer.
Cancer is the second leading cause of death in the U.S., and is strongly associated with older age.
As people get older, iron accumulates to excess levels, and this could be a prominent reason for higher cancer rates in older people.
As we’ve seen above, numerous lines of evidence point to iron causing cancer.
It doesn’t appear to be necessary to have very high levels to induce cancer either; dose relationships indicate that any level of iron above the minimum may have an effect.
Keeping iron (ferritin) levels within a safe, low-normal range may be one of the best things you can do for your health and to stay youthful.
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