Excess Iron Promotes Diabetes and Cancer James Kenney

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The human body requires small amounts of iron and low levels of iron can lead to a microcytic anemia, fatigue, and impaired immune function. Iron deficiency anemia is still seen in some children and women of childbearing age. For many years the Food and Drug Administration (FDA) has required refined grains to be fortified with iron. In addition many food companies have added iron (and other nutrients) to many other foods. These measures have certainly helped reduce iron deficiency anemia. Serum ferritin levels in iron deficiency anemia are generally lower than 12mcg/L (or 12ng/mL). Ferritin levels above 150 to 200mcg/mL likely indicate excess iron stores.

Since the 1930s the addition of iron to many foods and supplements has become a double-edged sword. In children and younger women the extra iron has cut the risk of anemia but in men and post-menopausal women, anemia is fairly uncommon and rarely related to a simple dietary deficiency of iron. This is especially true for men who are homozygous for a gene linked to excess iron absorption. About 1 in 200 people of northern European descent are at high risk of iron overload disease (hemachromatosis). Men with hemochromatosis often develop serum ferritin levels of 1000mcg/L or more and are at much greater risk of developing cirrhosis of the liver and liver cancer and also type 2 diabetes.1 People with very high iron stores were once thought to be at increased risk of coronary artery disease but most research now suggests increased iron stores alone do not appear to be an independent predictor of coronary heart disease.2

Cancer Concern

There is little doubt that iron fortified foods, iron containing supplements along with the consumption of red meat all tend to increase iron stores in the liver over time, even in people who do not have hemochromatosis. A recent study attempted to determine if reducing even moderately elevated iron stores via phlebotomy in 1277 people with peripheral artery disease would reduce their disease risk. Half the men had their iron stores reduced to a mean of 58ng/mL via repeated blood draws. The results were reported at the American Society for Hematology meeting earlier this year in Atlanta. They found over the next 3 years 38 of the men who had their iron stores reduced by blood removal developed cancer compared to 60 of the men in the control group. According to Dr. Zacharski at Dartmouth University who conducted the study "These results merit further study, but we feel they strongly suggest potentially toxic iron stores may exist in asymptomatic individuals, with devas tating results."

Bottom Line:

It is certainly time to encourage men and older women who do not have iron deficiency to limit their intake of red meats, iron-fortified foods, and iron containing supplements. By reading the nutrition facts panel, you can easily see if a product is high in iron. Products with a Daily Value of 5% or more are low in a nutrient while products that contain more than should be limited.. Taking vitamin C supplements causes the body to absorb more iron. Persons with hemochromatosis or excess iron stores should not take vitamin C as a supplement. Eating foods that contain vitamin C is fine. There is no known health benefit to iron stores above 50 to 60 ng ferritin/mL and there is now reason to suspect extra stores of iron well above physiological need may promote several types of cancer. In addition there is growing research indicating that increased iron stores may contribute to the development of insulin resistance and diabetes mellitus.

Excess Iron Promotes Diabetes and Cancer Excess Iron Promotes Diabetes and Cancer James Kenney

By James J. Kenney, PhD, RD, FACN


1. N Engl J Med 2008;358:221-30

2. Clinical Chemistry 2002;48:601-3

Beware of Iron Excess:
Many processed foods contain a significant amount of added iron and some may even have more iron added than the label reports. Consider that:
? refined grains are enriched with iron
? many fortified foods contain added iron
? most one-a-day type supplements have a whole day's worth of iron
? Iron absorption is also enhanced by large amounts of vitamin C so those who take vitamin C and iron supplements are at even greater risk
Iron is almost the exact opposite of vitamin D. Too little D is contributing to cancer and insulin resistance (and other ills) and yet there is little vitamin D in most foods and the few foods are fortified with vitamin D and those that are have far too little because the RDA is too low. With iron it is found in many foods people eat a lot of so most Americans end up with extra iron stored in their livers an d other tissues. In excess, iron is a toxic heavy metal apparently promoting cancer, insulin resistance, and many other ills.

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