By sports nutritionist Nilo Ghajar-Williams
Iron deficiency is one of the most common deficiencies in North America (1). Iron is a mineral important for aerobic exercise performance and energy production due to its role in oxygen transport and utilization (2).
Athletes at risk for iron deficiency include females with heavy menses, distance runners, and strict vegetarians (i.e. vegans) (3;4). Signs and symptoms of iron deficiency are fatigue, poor performance, weakness, impaired concentration, cold intolerance, pale skin, shortness of breath, and dizziness (5).
The current Recommended Daily Allowance (RDA) is 8 mg for men and post-menopausal women and 18 mg for females (aged 19 – 50) (6). The recommended intake for strict vegetarians is 32 mg for women and 14mg for men due to the lower bioavailability of non-heme iron from plant-based sources (7; 8).
The two forms of iron found in food are heme from animal sources and non-heme iron from plant-based sources.
|Heme iron food sources||Non-heme iron food sources (consume with vitamin C rich foods!)|
|Seafood: Shellfish (clams, oysters, mussels), canned sardines, shrimp, scallops, crab, halibut, salmon, tuna, mackerel, trout, bass||Legumes: lentils, soybeans (tofu, tempeh), red kidney beans, white beans, chickpeas, navy beans, lima beans, pinto beans, peas|
|Organ meats: beef, lamb, chicken liver||Dried fruits: dates, prunes, raisons, figs, apricots|
|Beef, Lamb, Poultry (dark meat): turkey, chicken||Nuts: almonds, peanuts, cashews, hazelnut, macadamia, pistachio|
|Egg yolk||Seeds: sunflower, squash, pumpkin, sesame|
|Vegetables: cooked spinach, swiss chard, canned beets, beet greens, parsley, asparagus, kale, potato with skin, tomato|
|Grains: enriched/fortified grains and cereals, oatmeal, teff, amaranth, buckwheat, quinoa|
|Miscellaneous: blackstrap molasses, dark chocolate (cocoa)|
Heme iron is more bioavailable than non-heme iron with an absorption efficiency of 20 – 45% vs. 1 – 10%, respectively (9).
|Inhibitors of non-heme iron absorption||Enhancers of non-heme iron absorption|
|Phytic acid found in grains, legumes, nuts, and seeds||Vitamin C (ascorbic acid) à found in oranges, peppers, kiwi, grapefruit, tomato, strawberries, broccoli, brussel sprouts (note: try to eat raw or lightly cook/steam to not lose nutritional quality)|
|Polyphenols/phenolic acids in coffee, tea (black & herbal), red wine, and dark chocolate (cocoa)||Carotenoids & other organic acids found in fruits & vegetables à grapes, tomato, citrus fruits, pineapple, peppers, dark leafy greens|
|Calcium found in dairy products, as well as supplements||Soaking & sprouting|
|Oxalic acid found in spinach, beet greens, and rhubarb (note: oxalic acid is also a major inhibitor of calcium absorption)||Consuming meat, poultry, and fish rich in heme iron|
|Low iron stores or low iron content in your meal can increase absorption|
- Fink, H.H. & Mikesky, A.E. (2013). Practical applications of sports nutrition. Sudbury, MA: Jones & Bartlett Learning.
- Barr S.I. & Rideout C.A. (2004). Nutritional considerations for vegetarian athletes. Nutrition, 20, 696-703.
- Malczewska J., Raczynski G., & Stupnicki R. (2000). Iron status in female endurance athletes and in non-athletes. Int J Sport Nutr Exerc Metab, 10 (3), 260-76.
- Whiting S.J. & Barabash WA. (2006). Dietary reference intakes for the micronutrients: considerations for physical activity. Appl Physiol Nutr Metab., 31, 80-85.
- Hark L. & Morrison G. (2009). Medical nutrition & disease: a case-based approach. West Sussex, UK: Wiley-Blackwell.
- Fuhrman J. & Ferreri D.M. (2010). Fueling the Vegetarian (Vegan) Athlete. American College of Sports Medicine, 9(4), 233-241.
- Institute of Medicine, Food and Nutrition Board. (2005). Dietary Reference intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, DC: National Academies Press.
- Otten J.J., Hellwig J.P., & Meyers L.D., editors. (2006). The dietary reference intakes: the essential guide to nutrient requirements. Washington, DC: Institute of Medicine, National Academies Press.
- Santiago P. (2011). Ferrous versus ferric oral iron formulations for the treatment of iron deficiency: a clinical overview. The Scientific World Journal, 1-5.