An active female athlete involved in a rigorous training program has an increased risk for iron deficiency anemia. Iron deficiency is common with or without anemia, decreases performance for the athlete, and often is not detected on a standard blood test. The capacity to transport oxygen to the cells of the muscle via myoglobin is impaired (energy production is limited), which is vital for competition.
Male endurance athletes and vegetarian athletes may also be at an increased risk for iron deficiency. To ensure optimum iron stores, athletes should eat meals or snacks that contain adequate quantities of iron-rich foods.
-USDA Dietary Reference Intakes for Vitamins and Elements.