Iron
What is it? Overview Usage Side Effects and Warnings
Answers
askAsk

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.

Requirements/Sources

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.

Menorrhagia

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.

References

  1. Shils ME, Olson JA, Shike M, eds. Modern Nutrition in Health and Disease. 9th ed. Baltimore, MD: Williams & Wilkins; 1999: 1772.
  2. Shils ME, Olson JA, Shike M, eds. Modern Nutrition in Health and Disease. 9th ed. Baltimore, MD: Williams & Wilkins; 1999: 210,860,1422,1424.
  3. Hamilton SF, Campbell NR, Kara M, Watson J, Connors M. The effect of ingestion of ferrous sulfate on the absorption of oral methotrexate in patients with rheumatoid arthritis. J Rheumatol. 30(9):1948-50.
  4. Kara M, Hasinoff BB, McKay DW, Campbell NR. Clinical and chemical interactions between iron preparations and ciprofloxacin. Br J Clin Pharmacol. 31(3):257-61.
  5. Polk RE, Healy DP, Sahai J, Drwal L, Racht E. Effect of ferrous sulfate and multivitamins with zinc on absorption of ciprofloxacin in normal volunteers. Antimicrob Agents Chemother. 33(11):1841-4.
  6. Campbell NR, Kara M, Hasinoff BB, Haddara WM, McKay DW. Norfloxacin interaction with antacids and minerals. Br J Clin Pharmacol. 33(1):115-6.
  7. Lehto P, Kivistö KT. Different effects of products containing metal ions on the absorption of lomefloxacin. Clin Pharmacol Ther. 56(5):477-82.
  8. Neuvonen PJ. Interactions with the absorption of tetracyclines. Drugs. 11(1):45-54.
  9. Campbell NR, Hasinoff BB. Iron supplements: a common cause of drug interactions. Br J Clin Pharmacol. 31(3):251-5.
  10. Campbell NR, Hasinoff BB. Iron supplements: a common cause of drug interactions. Br J Clin Pharmacol. 31(3):251-5.
  11. Campbell N, Paddock V, Sundaram R. Alteration of methyldopa absorption, metabolism, and blood pressure control caused by ferrous sulfate and ferrous gluconate. Clin Pharmacol Ther. 43(4):381-6.
  12. Campbell NR, Hasinoff BB. Iron supplements: a common cause of drug interactions. Br J Clin Pharmacol. 31(3):251-5.
  13. Osman MA, Patel RB, Schuna A, Sundstrom WR, Welling PG. Reduction in oral penicillamine absorption by food, antacid, and ferrous sulfate. Clin Pharmacol Ther. 33(4):465-70.
  14. Campbell NR, Hasinoff BB, Stalts H, Rao B, Wong NC. Ferrous sulfate reduces thyroxine efficacy in patients with hypothyroidism. Ann Intern Med. 117(12):1010-3.
  15. Campbell NR, Hasinoff BB. Iron supplements: a common cause of drug interactions. Br J Clin Pharmacol. 31(3):251-5.
  16. Hallberg L. Does calcium interfere with iron absorption? Am J Clin Nutr. 68(1):3-4.
  17. Cook JD, Dassenko SA, Whittaker P. Calcium supplementation: effect on iron absorption. Am J Clin Nutr. 53(1):106-11.
  18. Dawson-Hughes B, Seligson FH, Hughes VA. Effects of calcium carbonate and hydroxyapatite on zinc and iron retention in postmenopausal women. Am J Clin Nutr. 44(1):83-8.
  19. Hallberg L, Rossander L, Skånberg AB. Phytates and the inhibitory effect of bran on iron absorption in man. Am J Clin Nutr. 45(5):988-96.
  20. Sandström B, Davidsson L, Cederblad A, Lönnerdal B. Oral iron, dietary ligands and zinc absorption. J Nutr. 115(3):411-4.
  21. Haschke F, Ziegler EE, Edwards BB, Fomon SJ. Effect of iron fortification of infant formula on trace mineral absorption. J Pediatr Gastroenterol Nutr. 5(5):768-73.
  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.
  25. Hinton PS, Giordano C, Brownlie T, Haas JD. Iron supplementation improves endurance after training in iron-depleted, nonanemic women. J Appl Physiol. 88(3):1103-11.
  26. Friedmann B, Weller E, Mairbaurl H, Bärtsch P. Effects of iron repletion on blood volume and performance capacity in young athletes. Med Sci Sports Exerc. 33(5):741-6.
  27. Brutsaert TD, Hernandez-Cordero S, Rivera J, Viola T, Hughes G, Haas JD. Iron supplementation improves progressive fatigue resistance during dynamic knee extensor exercise in iron-depleted, nonanemic women. Am J Clin Nutr. 77(2):441-8.
  28. Celsing F, Blomstrand E, Werner B, Pihlstedt P, Ekblom B. Effects of iron deficiency on endurance and muscle enzyme activity in man. Med Sci Sports Exerc. 18(2):156-61.
  29. Klingshirn LA, Pate RR, Bourque SP, Davis JM, Sargent RG. Effect of iron supplementation on endurance capacity in iron-depleted female runners. Med Sci Sports Exerc. 24(7):819-24.
  30. TAYMOR ML, STURGIS SH, YAHIA C. THE ETIOLOGICAL ROLE OF CHRONIC IRON DEFICIENCY IN PRODUCTION OF MENORRHAGIA. JAMA. 187():323-7.
 
Share

0 Comments

No one has made any comments yet. Be the first!

Your Comment