Iron for athletes

Iron is a vital micronutrient, especially for elite and recreational athletes, as most of it binds to haemoglobin and is essential for the transport and storage of oxygen.

Without enough oxygen uptake into the tissues, aerobic capacity and, in turn, performance are compromised.

Also, without enough oxygen delivered to the brain as a result of low iron levels, an athlete can feel tired, irritable and unmotivated to perform. Having enough iron is further essential for maintaining energy release from the mitochondrial electron-transport chain.

Athletes have greater physiological demands and requirements for iron. This is thought to be due to certain exercise-related mechanisms, including micro-ischaemia of the gut lining or the increased production of hepcidin levels after intense exercise, which has an inhibitory effect on iron absorption and disrupts the transfer of iron from macrophages to immature red blood cells. Endurance athletes are at more risk of iron depletion due to the greater physiological demands on them. This applies especially to female endurance athletes (due to the loss of iron through menstruation) and adolescent athletes (due to the demands of growth and development).

In the UK, the average man requires 8.7mg of iron per day while the average woman requires 14.8mg/day. In South Africa, these recommendations differ slightly: the average man requires 8mg/day and the average woman requires 18mg/day. Recommendations for athletes of different sports are lacking. However, dietary iron recommendations for athletes are 1.3 to 1.7 times higher than for non-athletes. The requirements for vegetarians are 1.8 times higher than for meat-eaters.

Athletes should pay special attention to their diet and ensure they are getting a variety of iron-rich foods, such as red meat, seafood, eggs, lentils, beans and spinach. Particular attention needs to be paid to haem (animal-based) and non-haem (plant-based) sources. Non-haem sources are poorly absorbed but can be enhanced by adding a haem source or a food rich in vitamin C. Athletes should also look at their coffee/tea consumption during meals as the tannic acid present in these drinks binds to iron, inhibiting its absorption in the gut. Methylation nutrients (folate and vitamins B6 and B12) are also vital for the production of haemoglobin. Deficiencies in these nutrients can cause vitamin deficiency anaemia, which athletes can help avoid by consuming the iron-rich foods mentioned above.

To correctly diagnose iron deficiency anaemia, it is important to assess an athlete’s dietary intake, their clinical symptoms and continually monitor their iron status by doing multiple blood tests rather than a one-off blood test. If a basal serum ferritin level of <30µg/l is presented, athletes may have to consider supplementation in order to restore levels to approximately <60µg/l. This can be achieved in a couple of months if 100mg of haem iron (equivalent to 3kg cooked beef) is ingested every day.

The first line of therapy is oral as this is a safe and effective approach. The most common oral iron supplements contain the ferrous form (ferrous fumurate, sulphate and gluconate), which is better absorbed than the ferric form due to its higher solubility. If oral therapy is not sufficient to restore iron balance, athletes may have to consider taking iron intravenously. There is evidence to show that the correct use of supplementation can restore iron balance and may benefit an athlete’s performance. However, iron supplementation should not be encouraged in athletes who do not present iron deficiency anaemia as this may be detrimental to their health and counterproductive for performance.

If this topic interests you, you can read more about it in the article I wrote for Functional Sports Nutrition magazine. Click here.