Exercise can cause iron deficiency

USA Today (Society for the Advancement of Education), Feb, 1996

College-age women who engage in even moderate exercise may suffer from iron deficiency that results in anemia. In the first long-term study of the effects of exercise on the iron status of women, researchers from Purdue University, Pennsylvania State University, and the University of Florida studied previously sedentary women for six months and found that they lost enough iron to bring on feelings of fatigue, a symptom of anemia.

"We're seeing dramatic effects in iron loss in these women because their iron status isn't that good to begin with," indicates Connie Weaver, head of Purdue's Department of Foods and Nutrition and principal author of the study. "Women are typically more at risk for reduced iron levels because of blood loss due to menstruation and because women typically eat less red meat than men. Also, men have more hemoglobin in their blood, and therefore have a larger supply of iron to begin with."

Low iron levels in the blood, a condition known as anemia, usually brings on a lack of energy and loss of stamina. Those who suffer from anemia sometimes may be identified by the loss of healthy, normal coloration in the pals of their hands and beneath their fingernails. Anemia is of special concern to women who are pregnant. In some rare, extreme cases, it has resulted in heart failure.

The study randomly assigned 62 college-age women who previously were sedentary to four groups: one received an iron supplement, one a placebo, one a meat supplement to supply the proper amount of iron each day, and a control group was allowed to eat whatever it chose. Each group, except for the control one, was asked to exercise three times per week. The hemoglobin levels of the exercising group receiving the placebo were significantly lower than those receiving meat or iron supplements. The researchers suspect that the hemoglobin levels dropped because of exercise-induced hemolysis, or red blood cells breaking apart because of the physical force of the exercise.

While supplements were found to be effective at reversing the iron deficiency, the researchers say they are not as beneficial as a good diet. "The body more readily absorbs iron from foods than it does from pills," Weaver explains.

In addition to red meat, iron can be found in significant quantities in beans, grapes, raisins, tomato and apple juices, and other types of meat such as chicken. A rule of thumb is to detect the amount of iron in the meat by the color. Dark parts of chicken are better than white parts for providing iron, and beef and lamb are better still. The highest iron concentrations are found in organ meats, such as liver. Even what you drink with your meal makes a difference. Citrus juice helps the body absorb iron because of the vitamin C. Tea, on the other hand, will reduce the amount of iron absorbed because compounds called tannins in the tea inhibit iron absorption."

The U.S. Department of Agriculture's recommended daily allowance of iron is 15 milligrams for women and 10 milligrams for men. According to Weaver, a well-balanced balanced diet that includes four ounces of red meat several times each week would be sufficient for most people.