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IRON in SUPPLEMENTS


Dr. Ann de Wees Allen
Chief of Biomedical Research
Glycemic Research Institute
Washington, D.C.

Data reviewed by Dr. M. Wessling-Resnick, Professor of Nutritional Biochemistry, Harvard School of Public Health, 03/27/2003

For the past twenty years, researchers have warned against the use of supplements that contain high doses of iron.
This warning is based on hundreds of studies showing that excess iron is a primary cause of human diseases including free radical induced degenerative disease. Iron accumulation and oxidative injury are presently under consideration (2003) as potential contributors to a number of neurodegenerative diseases, such as Alzheimer's and Parkinson's disease (Pinero et al, Cell Mol Biol. 2000;46 (4):761-776).

Dietary iron intake has been found to be related to risk of colorectal cancer. Increased red meat consumption (which is high in iron) raises the risk of developing colorectal cancer by elevating increased iron in the contents of the colon.
Beef contains 2.31 mg of iron per 3 ounces of cooked meat.

High iron levels are also linked to an increase in stroke damage (April 25, 2000 issue of Neurology, the American Academy of Neurology's scientific journal). Researchers found that stroke patients with elevated levels of iron are much more likely to experience severe neurological symptoms and increased brain damage.

Additionally, high blood iron levels are associated with increased cardiovascular disease. Neurologist and lead study author Antoni Davalos, M.D. states, "Blood ferritin (iron) levels should be tested as we test cholesterol or glucose levels in patients with cardiovascular diseases or cardiovascular risk factors."

Iron is a key element in the metabolism of almost all living organisms, and in humans is an essential component of hundreds of enzymes and proteins. Iron found in food is generally not a causal factor in iron overload, except in Hereditary Hemochromotosis (a genetic disorder). Ribonucleotide reductase is an iron-dependent enzyme required for DNA synthesis, thus iron is required for vital functions, including growth, healing, reproduction, and immune function. Iron is beneficial in humans, unless it reaches excess levels in the blood.

Iron deficiency in humans is related to the medical conditions: Storage Iron Depletion, Early Functional Iron Deficiency, and Iron Deficiency Anemia. A simple blood test can identify these forms of iron deficiencies. Typical symptoms include fatigue, rapid heart rate, palpitations, and rapid breathing on exertion.

Persons exhibiting mild iron deficiencies may elect to take supplemental vitamin C instead of iron supplements, as vitamin C strongly enhances the absorption of nonheme iron by reducing dietary ferric iron to ferrous iron and forming an absorbable iron-ascorbic acid complex. Soy protein inhibits iron absorption, and should be used selectively by persons with iron deficiencies.

Supplements that contain high doses of iron, or taking too many supplements that contain iron, are at issue, and not normal amounts of iron found in the food chain. Acute toxicity is potentially fatal and can occur with iron doses of 20-60 mg/kg of body weight. Medical experts conclude that "It would be prudent for those who are not at risk of iron deficiency to avoid excess iron intake."

The Tolerable Upper Intake Level (UL) for iron is:

INFANTS 0-12 months Not possible to establish/source of iron intake should be from food and formula only
CHILDREN 1-13 years 40 mg/day
ADOLESCENTS 14-18 years 45 mg/day
ADULTS 19 years + 45 mg/day

Food and Nutrition Board (FNB) of the Institute of Medicine

BOTTOM LINE
It has been shown that high iron stores are much more common than iron deficiencies (Fleming et al. Am J Clin Nutr. 2001;73(3):638-646). A supplemental dose of 18 mg of elemental iron per day, as contained in a multi-vitamin, would be the upper limit of acceptable iron ingested, particularly in men and postmenopausal women who are not at risk of iron deficiency. If iron deficiency is diagnosed, medical experts recommend determining the underlying cause, rather than treating it with iron supplements.

The bottom line is that multi-vitamin/mineral supplements that contain less than 18 mg of iron/day are safe and acceptable.

end report
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