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What is it? Overview Usage Side Effects and Warnings

Iron Overview

Written by FoundHealth.

The element iron is essential to human life. As part of hemoglobin, the oxygen-carrying protein found in red blood cells, iron plays an integral role in nourishing every cell in the body with oxygen. It also functions as a part of myoglobin, which helps muscle cells store oxygen. Without iron, your body could not make ATP (adenosine triphosphate, the body's primary energy source), produce DNA, or carry out many other critical processes.

Iron deficiency can lead to anemia, learning disabilities, impaired immune function, fatigue, and depression. However, you shouldn't take iron supplements unless lab tests show that you are genuinely deficient.


The official US recommendations for daily intake of iron are as follows:

  • Infants
  • 0-6 months: 0.27 mg
  • 7-12 months: 11 mg
  • Children
  • 1-3 years: 7 mg
  • 4-8 years: 10 mg
  • Males
  • 9-13 years: 8 mg
  • 14-18 years: 11 mg
  • 19 years and older: 8 mg
  • Females
  • 9-13 years: 8 mg
  • 14-18 years: 15 mg
  • 19-50 years: 18 mg
  • 50 years and older: 8 mg
  • Pregnant Women:27 mg
  • Nursing Women: 9 mg (10 mg if 18 years old or younger)

Iron deficiency is the most common nutrient deficiency in the world; worldwide, at least 700 million individuals have iron-deficiency anemia. 1 While iron deficiency is widespread in the developing world, it is also prevalent in developed countries. Groups at high risk are children, teenage girls, menstruating women (especially those with excessively heavy menstruation, known as menorrhagia), pregnant women, and the elderly. 2 There are two major forms of iron: hemeiron and nonhemeiron. Heme iron is bound to the proteins hemoglobin or myoglobin, whereas nonheme iron is an inorganic compound. (In chemistry, "organic" has a very precise meaning that has nothing to do with farming. An organic compound contains carbon atoms. Thus "inorganic iron" is an iron compound containing no carbon.) Heme iron, obtained from red meats and fish, is easily absorbed by the body. Nonheme iron, usually derived from plants, is less easily absorbed.

Rich sources of heme iron include oysters, meat, poultry, and fish. The main sources of nonheme iron are dried fruits, molasses, whole grains, legumes, leafy green vegetables, nuts, seeds, and kelp . Contrary to popular belief, there is no meaningful evidence that cooking in an iron skillet or pot provides a meaningful amount of iron supplementation. 3 Iron absorption may be affected by the following substances: antibiotics in the quinolone (Floxin, Cipro) 4 5 6 7 or tetracycline 8 9 families, levodopa , 10 methyldopa , 11 carbidopa , 12 penicillamine , 13 thyroid hormone , 14 captopril (and possibly other ACE inhibitors ), 15 calcium , 16 17 18 soy , 19 zinc , 20 copper , 21 or manganese , 22 or multivitamin/multimineral tablets. 23 Conversely, iron may inhibit their absorption, too.

In addition, drugs in the H 2 blocker or proton pump inhibitor families may impair iron absorption. 24

Therapeutic Dosages

The typical short-term therapeutic dosage to correct iron deficiency is 100 to 200 mg daily. Once your body's iron stores reach normal levels, however, this dose should be reduced to the lowest level that can maintain iron balance.

What Is the Scientific Evidence for Iron?

Sports Performance

A double-blind, placebo-controlled trial of 42 non-anemic women with evidence of slightly low iron reserves found that iron supplements significantly enhanced sports performance . 25 Participants were put on a daily aerobic training program for the latter 4 weeks of this 6-week trial. At the end of the trial, those receiving iron showed significantly greater gains in speed and endurance as compared to those given placebo.

In addition, a double-blind, placebo-controlled study of 40 non-anemic elite athletes with mildly low iron stores found that 12 weeks of iron supplementation enhanced aerobic performance. 26 Benefits with iron supplementation were observed in other double-blind trials as well also involving mild low iron stores. 27 However, other studies failed to find significant improvements, 28 29 suggesting that the benefits of iron supplements for non-anemic, iron-deficient athletes is small at most.


One small double-blind study found good results using iron supplements to treat heavy menstruation. This study, which was performed in 1964, saw an improvement in 75% of the women who took iron (compared to 32.5% of those who took placebo). Women who began with higher iron levels did not respond to treatment. 30 This suggests once more that supplementing with iron is only a good idea if you are deficient in it.


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  22. Freeland-Graves JH. Manganese: an essential nutrient for humans. Nutr Today. 1988;23:13-19.
  23. Moriarty-Craige SE, Ramakrishnan U, Neufeld L et al. Multivitamin-mineral supplementation is not as efficacious as is iron supplementation in improving hemoglobin concentrations in nonpregnant anemic women living in Mexico. Am J Clin Nutr. 2004;80:1308-1311.
  24. Champagne ET. Low gastric hydrochloric acid secretion and mineral bioavailability. Adv Exp Med Biol. 249():173-84.
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