SummaryIn recent years, epidemiological studies of the iron status of athletes involved in heavy training have suggested that these athletes may be prone to iron deficiency. Several investigators have observed a high prevalence of iron deficiency among athletes, particularly endurance runners, based on serum ferritin levels, which accurately reflect the size of the body’s iron stores. Furthermore, earlier reports on iron status in athletes frequently noted low haemoglobin values in those involved in heavy endurance training. In addition to iron deficiency anaemia, a condition known as ‘sports anaemia’ has also been described, in which the athlete experiences an increased destruction of erythrocytes and a drop in haemoglobin as a result of an acute stress response to exercise.Whether iron deficiency in athletes is due to an inadequate dietary intake of iron, an exercise effect on iron metabolism, or a combination of both, has yet to be determined. Certainly, it is questionable whether adequate iron is consumed in a typical Western diet, particularly by females, who already have an increased requirement related to menstruation. In addition, recent evidence strongly suggests that exercise may impose a significant iron ’cost’ on the athlete. This additional iron cost may be the result of the increased destruction of red blood cells, increased elimination of iron, or possibly an impaired iron absorption.Regardless of the cause, however, iron deficiency, with or without anaemia, is an undesirable condition for athletes. An essential constituent of haemoglobin, myoglobin and several iron-containing respiratory enzymes, iron plays a vital role in energy production. With only minor decrements in haemoglobin, anaemic subjects have been shown to have impaired physical performance. More recently, iron deficiency without anaemia has been examined and this condition has also been shown to reduce physical work capacity and lead to excess lactate production.Therefore, regular monitoring of the iron status of athletes is recommended to ensure optimal performance ability. This should include routine examination of serum ferritin and haemoglobin levels in addition to periodical dietary analyses of the athlete’s nutritional intake. If an iron-deficient condition is detected, prompt intervention involving nutritional counselling and/or iron supplementation is necessary.