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Iron is involved in sports performance through its role in oxygen transport in the blood (haemoglobin) and muscles (myoglobin), as well as its action as a cofactor for many of the enzymes involved in fuel oxidation. A low iron status can reduce performance, although it is still uncertain how to distinguish true iron deficiency from some of the alterations in iron status measures that are caused by exercise. For example, endurance training causes a drop in haemoglobin levels due to an increase in blood volume. This haemodilution, often termed ‘sports anemia’, does not impair exercise performance, but has probably caused an overdiagnosis of the true prevalence of iron deficiency in athletes. Nevertheless, some athletes are at true risk of becoming iron deficient when increased iron needs (e.g. due to growth, or small but consistent iron losses from the gastrointestinal bleeding or ‘footstrike’ damage to red blood cells are compounded by a poor intake of bioavailable iron.

Low iron consumers include ‘restricted’ eaters, vegetarians and other athletes eating high CHO, low meat diets. The haeme form of iron found in red meat, liver products and shellfish is much better absorbed than non-haeme iron found in plant foods such as wholegrain cereal foods, legumes and green leafy vegetables. Low iron status, such as that indicated by serum ferritin levels lower than 20 ng/ml, should be considered for treatment. Present evidence does not support that iron deficiency without anemia reduces exercise performance. However many athletes with such low iron status, or a sudden drop in iron status, frequently complain of fatigue and inability to recover after heavy training. Many of these athletes respond following an improved iron status. At the very least, treatment may prevent the situation from progressing to clinical anemia. Evaluation and management of iron status is best done on an individual basis by a sports medicine expert. Prevention and treatment of iron deficiency may include iron supplementation.

However this should be considered as a part of the management plan along with dietary counseling to increase the intake of bioavailable iron, and appropriate strategies to reduce iron loss. Mass supplementation of athletes with iron, or self-diagnosis of low iron deficiency, are to be avoided since they exclude the opportunity for a more holistic plan. Dietary guidelines for increasing iron intake should be integrated with the other nutritional goals of the athlete, so that goals of high CHO intakes or reduced energy intake to reduce body fat can be met simultaneously. This is where the expertise of a sports dietitian is most useful.