Vitamins, minerals and trace elements have multiple and synergistic functions across many body systems. When deficiencies occur for whatever reason, more than one vitamin and/or mineral is usually responsible. Physical activity increases the metabolic requirements for vitamins and minerals associated with energy metabolism (particularly B vitamins, magnesium, chromium and iron). Prolonged aerobic exercise increases red blood cell mass and the requirements for nutrients involved in red blood cell production and haemoglobin synthesis (e.g. iron, vitamin B12 and possibly folate). Current evidence supports a higher antioxidant requirement in athletes than non-athletes to help reduce oxidative damage induced by short-duration exercise.
Population nutrient references (i.e. EAR/AI) are unlikely to match these higher requirements. Because of the multiple functional interactions between micronutrients, it is not possible to quantify micronutrient requirements of athletes, except for iron, which has been extensively studied. Recommended iron requirements for athletes are 1.3–1.7 times higher than population nutrient references. Measures on micronutrient status and supplementation trials are needed to evaluate whether normal dietary intakes of other micronutrients in athletes are sufficient to cover their increased requirements.
Micronutrient deficiencies are rarely reported in athletes. Athletes at risk of deficiency are those who restrict energy intakes or avoid one or more food groups or in exceptional circumstances or extreme endurance events. Marginal micronutrient depletion is more common.