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Draft:Iron

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Fact Sheet

Summary

Studies show that those who eat varied meatless diets are no more at risk of iron deficiency than meat-eaters,[1] and may even have higher iron levels.[2] Furthermore, heme iron (found only in animal products) has been linked to chronic diseases such as heart disease[3] and lung cancer.[4]

Context

  • Iron is an essential mineral used to transport oxygen through the body.[5]
  • Research suggests that non-heme iron (found in both plants and animal products) is less well absorbed than heme iron (found only in animal products, mainly red meat).[6] As a result, many people believe that red meat is the only good source of iron. This has led to claims that vegans are at risk of iron deficiency, even though there are many excellent plant sources of iron.[7]

Evidence

  • Studies show that those who eat meatless diets are no more at risk of iron deficiency than meat-eaters,[1][8] and may even have higher iron levels.[2]
  • Research suggests that each milligram of heme iron consumed daily increases the risk of heart disease by 27 percent,[9] Type 2 diabetes by 16 percent,[10] and cancer by up to 12 percent.[11] Heme iron consumption has also been shown to increase stroke risk.[12]
  • The lower bioavailability of non-heme iron has long been considered a disadvantage. However, more recently it has been suggested that it may in fact be beneficial as it prevents too much iron from being absorbed. The body is able to regulate how much non-heme iron it absorbs from food, increasing or decreasing absorption as needed. Heme iron, on the other hand, passes straight into the bloodstream even if levels are already too high.[13][14] This iron overload contributes to the chronic diseases mentioned above, as iron is a pro-oxidant and can cause DNA damage and oxidative stress.[15][16]
  • One study even found that "In developed meat eating countries...iron excess may be more of a problem than iron deficiency."[14]
  • The European Food Safety Authority (EFSA) recommends that heme iron should not be added to food or used as a food supplement. This is because it could lead to overexposure to iron and potentially an increased risk of colon cancer.[17]
  • Even the meat industry acknowledges that heme iron is harmful. As a result, it is trying to create additives that "suppress the toxic effects of heme iron."[18]
  • Over 60 percent of the iron in red meat is non-heme iron, meaning that only 10-12 percent of the iron intake of the average meat-eater is from heme iron.[19] For this reason, medical doctor Ulka Agarwal argues that it is misguided to advise people to increase their red meat intake in order to get more iron. She suggests getting iron from leafy green vegetables, whole grains, and legumes instead, to avoid the health risks associated with red meat.[20]
  • Consuming vitamin C along with non-heme iron increases absorption of the iron.[21] Balanced plant-based diets containing plenty of fruits and vegetables are high in vitamin C,[22] which may partially explain why iron deficiency rates do not seem to be higher among those eating meatless diets.

Conflicting Claims

  • Some studies show that those eating meatless diets have lower iron stores than omnivores. However, the same studies also show that vegetarians and vegans are not more likely to develop iron deficiencies. According to one study, "adverse health effects from lower iron and zinc absorption have not been demonstrated with varied vegetarian diets in developed countries, and moderately lower iron stores have even been hypothesized to reduce the risk of chronic diseases."[19]
  • A few studies do show increased incidence of anemia in vegetarians, but these studies were carried out in developing countries such as India where many people do not have access to a varied diet.[23] One study states that "the iron and zinc deficiencies commonly associated with plant-based diets in impoverished nations are not associated with vegetarian diets in wealthier countries."[19]

Dietary Guidelines

  • In the USA, the recommended daily allowance (RDA) of iron is 8mg per day for adult men and 18mg for women of childbearing age. For postmenopausal women, the RDA is the same as that of adult men. For pregnant or lactating women, the RDAs are 27mg and 9mg respectively.[24]
  • Due to the risks associated with excessive iron consumption (described above), studies suggest that only those who have been diagnosed with iron deficiency anemia should take supplements. One study found that oxidative stress occurred even in the bodies of women with anemia after they took iron supplements.[25] As a result, nutrition expert Dr. Michael Greger recommends attempting to treat anemia with iron-rich plant foods before resorting to supplementation.[26]
  • Those who are concerned about their iron levels should avoid drinking tea and coffee with meals, as this can inhibit iron absorption.[27]

Sources of Iron

  • Nuts, vegetables, beans, and fortified grains are good plant-based sources of iron. Some of the best sources are white beans, dark chocolate, lentils, tofu, kidney beans, leafy green vegetables, and fortified breakfast cereals.[7]

See Also

Plain Text

Footnotes

  1. ↑ 1.0 1.1 Saunders, Angela V., Winston J. Craig, Surinder K. Baines, and Jennifer S. Posen. “Iron and Vegetarian Diets.” The Medical Journal of Australia 199, no. S4 (19 2013): S11-16.
  2. ↑ 2.0 2.1 Farmer, Bonnie, Brian T. Larson, Victor L. Fulgoni, Alice J. Rainville, and George U. Liepa. “A Vegetarian Dietary Pattern as a Nutrient-Dense Approach to Weight Management: An Analysis of the National Health and Nutrition Examination Survey 1999-2004.” Journal of the American Dietetic Association 111, no. 6 (June 2011): 819–27. Accessed February 7, 2020. https://doi.org/10.1016/j.jada.2011.03.012.
  3. ↑ Hunnicutt, Jacob, Ka He, and Pengcheng Xun. “Dietary Iron Intake and Body Iron Stores Are Associated with Risk of Coronary Heart Disease in a Meta-Analysis of Prospective Cohort Studies.” The Journal of Nutrition 144, no. 3 (March 1, 2014): 359–66. Accessed February 7, 2020. https://doi.org/10.3945/jn.113.185124.
  4. ↑ Lam, Tram Kim, Melissa Rotunno, Brid M. Ryan, Angela C. Pesatori, Pier Alberto Bertazzi, Margaret Spitz, Neil E. Caporaso, and Maria Teresa Landi. “Heme-Related Gene Expression Signatures of Meat Intakes in Lung Cancer Tissues.” Molecular Carcinogenesis 53, no. 7 (July 2014): 548–56. Accessed February 7, 2020. https://doi.org/10.1002/mc.22006.
  5. ↑ “Vitamins and Minerals - Iron,” October 23, 2017. Accessed February 11, 2020. https://www.nhs.uk/conditions/vitamins-and-minerals/iron/.
  6. ↑ Hurrell, Richard, and Ines Egli. “Iron Bioavailability and Dietary Reference Values.” The American Journal of Clinical Nutrition 91, no. 5 (May 1, 2010): 1461S-1467S. Accessed February 11, 2020. https://doi.org/10.3945/ajcn.2010.28674F.
  7. ↑ 7.0 7.1 “FoodData Central.” Accessed February 11, 2020. https://fdc.nal.usda.gov/.
  8. ↑ Craig, W J. “Iron Status of Vegetarians.” The American Journal of Clinical Nutrition 59, no. 5 (May 1, 1994): 1233S-1237S. Accessed February 11, 2020. https://doi.org/10.1093/ajcn/59.5.1233S.
  9. ↑ Yang, Wei, Bin Li, Xiao Dong, Xiao-Qiang Zhang, Yuan Zeng, Jian-Liang Zhou, Yan-Hua Tang, and Jian-Jun Xu. “Is Heme Iron Intake Associated with Risk of Coronary Heart Disease? A Meta-Analysis of Prospective Studies.” European Journal of Nutrition 53, no. 2 (March 2014): 395–400. Accessed February 7, 2020. https://doi.org/10.1007/s00394-013-0535-5.
  10. ↑ Bao, Wei, Ying Rong, Shuang Rong, and Liegang Liu. “Dietary Iron Intake, Body Iron Stores, and the Risk of Type 2 Diabetes: A Systematic Review and Meta-Analysis.” BMC Medicine 10, no. 1 (December 2012): 119. Accessed February 7, 2020. https://doi.org/10.1186/1741-7015-10-119.
  11. ↑ Fonseca-Nunes, A., P. Jakszyn, and A. Agudo. “Iron and Cancer Risk--A Systematic Review and Meta-Analysis of the Epidemiological Evidence.” Cancer Epidemiology Biomarkers & Prevention 23, no. 1 (January 1, 2014): 12–31. Accessed February 7, 2020. https://doi.org/10.1158/1055-9965.EPI-13-0733.
  12. ↑ Kaluza, Joanna, Alicja Wolk, and Susanna C. Larsson. “Heme Iron Intake and Risk of Stroke: A Prospective Study of Men.” Stroke 44, no. 2 (February 2013): 334–39. Accessed February 7, 2020. https://doi.org/10.1161/STROKEAHA.112.679662.
  13. ↑ Cook, J D. “Adaptation in Iron Metabolism.” The American Journal of Clinical Nutrition 51, no. 2 (February 1, 1990): 301–8. Accessed February 11, 2020.https://doi.org/10.1093/ajcn/51.2.301.
  14. ↑ 14.0 14.1 REZAZADEH, HASSAN, AMIR ALLAMEH, and MOHAMMAD ATHAR. “EFFECT OF IRON OVERLOAD ON 7, 12-DIMETHYL­BENZ (A) ANTHRACENE-INDUCED SKIN TUMORIGENESIS .” Medical Journal of The Islamic Republic of Iran 12, no. 2 (Summer 1998): 135–40.
  15. ↑ “Prooxidant Iron and Copper, with Ferroxidase and Xanthine Oxidase Activities in Human Atherosclerotic Material.” FEBS Letters 368, no. 3 (July 24, 1995): 513–15. Accessed February 9, 2020. https://doi.org/10.1016/0014-5793(95)00726-P.
  16. ↑ Giulivi, Cecilia, and Enrique Cadenas. “The Reaction of Ascorbic Acid with Different Heme Iron Redox States of Myoglobin: Antioxidant and Prooxidant Aspects.” FEBS Letters 332, no. 3 (October 18, 1993): 287–90. Accessed February 9, 2020. https://doi.org/10.1016/0014-5793(93)80651-A.
  17. ↑ “Scientific Opinion on the Safety of Heme Iron (Blood Peptonates) for the Proposed Uses as a Source of Iron Added for Nutritional Purposes to Foods for the General Population, Including Food Supplements.” EFSA Journal 8, no. 4 (2010): 1585. Accessed February 9, 2020. https://doi.org/10.2903/j.efsa.2010.1585.
  18. ↑ Corpet, Denis E. “Red Meat and Colon Cancer: Should We Become Vegetarians, or Can We Make Meat Safer?” Meat Science 89, no. 3 (November 2011): 310–16. Accessed February 11, 2020. https://doi.org/10.1016/j.meatsci.2011.04.009.
  19. ↑ 19.0 19.1 19.2 Hunt, Janet R. “Bioavailability of Iron, Zinc, and Other Trace Minerals from Vegetarian Diets.” The American Journal of Clinical Nutrition 78, no. 3 (September 1, 2003): 633S-639S. Accessed February 10, 2020. https://doi.org/10.1093/ajcn/78.3.633S.
  20. ↑ Agarwal, Ulka. “Rethinking Red Meat as a Prevention Strategy for Iron Deficiency.” ICAN: Infant, Child, & Adolescent Nutrition 5, no. 4 (August 1, 2013): 231–35. Accessed February 10, 2020. https://doi.org/10.1177/1941406413491285.
  21. ↑ Hallberg, L., M. Brune, and L. Rossander. “The Role of Vitamin C in Iron Absorption.” International Journal for Vitamin and Nutrition Research. Supplement = Internationale Zeitschrift Fur Vitamin- Und Ernahrungsforschung. Supplement 30 (1989): 103–8.
  22. ↑ Craig, W J. “Iron Status of Vegetarians.” The American Journal of Clinical Nutrition 59, no. 5 (May 1, 1994): 1233S-1237S. Accessed February 10, 2020. https://doi.org/10.1093/ajcn/59.5.1233S.
  23. ↑ Rammohan, Anu, Niyi Awofeso, and Marie-Claire Robitaille. “Addressing Female Iron-Deficiency Anaemia in India: Is Vegetarianism the Major Obstacle?” ISRN Public Health 2012 (2012): 1–8. Accessed February 11 2020. https://doi.org/10.5402/2012/765476.
  24. ↑ Institute of Medicine (U.S.), ed. DRI: Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc: A Report of the Panel on Micronutrients ... and the Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Food and Nutrition Board, Institute of Medicine. Washington, D.C: National Academy Press, 2001. 344-350.
  25. ↑ Mani Tiwari, Amit Kumar, Abbas Ali Mahdi, Sudarshna Chandyan, Fatima Zahra, Madan Mohan Godbole, Shyam Pyari Jaiswar, Vinod Kumar Srivastava, and Mahendra Pal Singh Negi. “Oral Iron Supplementation Leads to Oxidative Imbalance in Anemic Women: A Prospective Study.” Clinical Nutrition 30, no. 2 (April 2011): 188–93. Accessed February 9, 2020. https://doi.org/10.1016/j.clnu.2010.08.001.
  26. ↑ Risk Associated with Iron Supplements | NutritionFacts.Org. Accessed February 9, 2020. https://nutritionfacts.org/video/risk-associated-with-iron-supplements/.
  27. ↑ Zijp, Itske M., Onno Korver, and Lilian B. M. Tijburg. “Effect of Tea and Other Dietary Factors on Iron Absorption.” Critical Reviews in Food Science and Nutrition 40, no. 5 (September 2000): 371–98. Accessed February 10, 2020. https://doi.org/10.1080/10408690091189194.

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This fact sheet was originally authored by ??? with contributions by Greg Fuller. The contents may have been edited since that time by others.

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