Iron requirements for vegan athletes
Iron is very important component in sports nutrition and performance. It plays an essential role in both transporting oxygen to muscles cells and energy metabolism. Iron status has the potential to influence performance by affecting both maximal and sub maximal exercise capacity.
It is thought as much as 65% of body iron is incorporated into haemoglobin (protein molecule that transports oxygen around the body), when haemoglobin levels decline, maximal oxygen consumption diminishes, which can ultimately affect endurance performance (1).
It is recommended that men (aged 19-50) need 8 mg/day of iron and women (aged 19-50) need 18 mg/day of iron. The Institute of Medicine (IOM) recommended that vegan and vegetarians consume 1.8 times that of omnivores, suggesting intakes of 14 mg/day and 33 mg/day (2).
This recommendation is based on the assumption that the bioavailability of iron in a vegetarian diet is less than that from an omnivores diet (discussed in further detail below) (3). There is debate as to whether these recommendations have been exaggerated because of the limited data and methods used in the studies they are based on (10).
The reference nutrient intake for athletes is considered the same as sedentary individuals. Although, some studies suggest requirements for endurance athletes (particularly endurance runners) could actually increased by approximately 70% (4). Those most at risk of iron deficiency are female athletes (especially if they have been pregnant in the last year) and athletes consuming less than 2000 kcal a day.
Iron intake on a plant based diet
Plant based diets generally contain as much or more total iron than omnivore diets. Vegans tend to consume more total iron than vegetarians because dairy contains relatively little iron. Therefore, the concern over iron status in vegetarian and vegan athletes is due to the bioavailability (amount that the body can absorb) of iron in plants rather than the total amount of iron in the diet (5).
The main source of iron in the vegan diet is found in the non-haem form, whereby its bioavailability is considered to be about 10% compared to 18% of haem iron found in animal products (3).
Plant based diets also tend to contain higher amounts of phytates which are found in whole grains and legumes. Phytates alongside tannin (found in tea, coffee and cocoa) are dietary inhibitors and can reduce the amount of iron absorbed by the body (5).
Therefore, the effective timing of hot drinks and use of soaked, sprouting or activated foods may help to increase absorption. There is evidence to suggest that low iron status can lead to intestinal adaptation that increases absorption and reduces secretion of iron (6).
A recent review also reported variation in non-haem iron absorption rates between 1%-23% depending on iron status and dietary enhancers and inhibitors (9). Overall, studies have not shown adverse health effects related to reduced iron absorption in vegan and vegetarians (7).
On the plus side, it has been shown that iron absorption can also be increased by the consumption of vitamin C. For that reason, meals containing both vitamin C and iron rich food sources can be beneficial (5).
Although those following a plant-based diet might have to consume more iron, it does have its advantages. There is evidence to suggest that consuming higher amounts of haem iron is associated with increased risk of several cancers, including colorectal, pancreatic cancer and lung cancer (8).
It is worth noting that your body cannot eliminate excess iron from the body. Due to the lower absorption rates of non-haem iron it is extremely difficult to reach toxic levels, which is a plus over haem iron.
The consumption of whole plant-based foods provides you with a range of nutrients from antioxidants to phytochemicals to help support your overall health and wellbeing, not only your iron status. A whole foods approach is the healthiest way to ensure you are getting your recommended intake of iron alongside the other nutrients you require.
Recommendations for vegan athletes
Be aware of your energy requirements and don’t follow a calorie-restricted diet.
Choose many wholefood iron sources within your meals (try combining these with foods containing vitamin C).
Reduce tea and coffee intake when consuming iron rich foods. Drink between meals or wait at least ½-1 hour after eating.
Incorporate soaked, sprouted, activated and/or fermented foods in diet where possible.
If you have concerns over your iron status it is best to contact a registered health professional. If you suffer with symptoms like fatigue, dizziness and for female athletes abnormal menstrual cycles you should inform your doctor. Iron supplements should only be taken under medical supervision and can reduce the absorption of other essential nutrients including zinc and calcium.
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(1) Deldicque, L. and Francaux, M. (2015). Recommendations for Healthy Nutrition Female Endurance Runners: An Update. Frontiers in Nutrition 2:17.
(2) Institute of Medicine (US) Panel on Micronutrients. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington (DC): National Academies Press (US); 2001
(3) Food and Nutrition Board, Institute of Medicine. Iron. (2001). In: Dietary References Intake for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium and Zinc.
Washington, DC: The National Academies Press: 290-393
(4) Whiting, S. J., Barabash, W. A. (2006). Dietary reference intakes for the micronutrients: considerations for physical activity. Applied Physiology Nutrition Metabolism, 31: 80-5
(5) Venderley, A, M., Campbell, W., W (2006). Vegetarian Diets, Nutritional Considerations for Athletes. 36 (4): 293-305
(6) Phillips F. (2005) Vegetarian Nutrition. Nutr Bull. 30(2):132–67.
(7) Dagnelie P. C, van Staveren W. A, Vergote F. J, Dingjan P. G, van D. B, Hautvast J. G. (1989). Increased risk of vitamin B- 12 and iron deficiency in infants on macrobiotic diets. Am J Clin Nutr. 50(4):818.
(8) Kelly C. (2002). Can excess iron increase the risk for coronary heart disease and cancer? Nutr Bull. 27(3):165–79.
(9) Collings R, Harvey LJ, Hooper L, et al. (2013). The absorption of iron from whole diets: A systematic review. Am J Clin Nutr.98 (1):65-81.
(10) Melina, V., Craig, W., & Levin, S. (2016). Position of the academy of nutrition and dietetics: Vegetarian diets Elsevier.