Anemia: Iron Deficiency Anemia
In studies of adolescent women athletes the prevalence of iron deficiency anemia ranges up to 20 percent and is particularly high in cross-country runners. Another 20–60 percent of women athletes are iron deficient but not yet anemic (low ferritin, normal hemoglobin). In studies development of iron deficiency during training was found to occur in 20 percent of women runners in the United States and was found to be preventable by iron supplementation. Adolescent girls may be especially susceptible because they need more iron to meet the demands of growth and to counter the loss of blood caused by the onset of menses as well as erratic dietary practices.
Although athletes may lose iron through urine, sweat, gastrointestinal sources, or hemolysis (destruction of red blood cells), these losses are usually negligible and not significant enough to cause appreciable iron deficiency. Excessive use of nonsteroidal antiinflammatory medication (aspirin, ibuprofen) may increase gastrointestinal losses because of gastrointestinal bleeding.The most common cause of iron deficiency in women athletes and nonathletes alike is inadequate dietary intake of iron to compensate for menstrual losses. In the United States the recommended daily allowance (RDA) for iron to meet basic daily needs for women is 15 milligrams a day. The average diet in the United States contains 5–7 milligrams of iron per 1,000 calories. Therefore, women need about 3,000 calories per day to get at least the RDA of 15 milligrams of iron. However, many women athletes consume less than 2,000 calories a day, particularly women athletes who participate in sports (such as gymnastics) that emphasize lean body physique. In addition, in an attempt to eat healthfully and reduce fat intake, many women athletes eat little red meat, which is the primary food source of iron.Vegetarian diets pose an increased risk of anemia because of the lower quantities of iron in nonmeat foods and lower bioavailability (the degree and rate at which a substance is absorbed into a living system).