Iron deficiency may impede exercise

ITHACA, N.Y., March 22 (UPI) -- Relatively healthy women who begin exercising only to have disappointing results could be iron deficient, Cornell University researchers report in a study released Monday.

"A lot of people are out there training (and) if they didn't know they were iron deficient, they may be impaired in their ability to improve," said Cornell University's Dr. Jere Haas, one of the researchers involved in a study of iron supplement benefits in aerobic training. The study appears in the March 25 American Journal of Clinical Nutrition.

It is well-known that premenopausal women are prone to iron deficiency and in severe cases it can lead to anemia -- when where is not enough hemoglobin to carry oxygen to the body's cells. Impaired ability to carry oxygen around the body or use it in cells can limit exercise or even simple everyday activities, such as walking or climbing stairs.

But even healthy women, suffering from relatively modest iron deficiency -- mild enough that they fail to show signs of anemia -- still get less benefit from aerobic exercise than women with normal iron levels.

The study suggests iron supplementation can help. Women studied who took iron supplements saw twice as much improvement in maximal oxygen uptake by the body's tissues.

Women are roughly twice as likely as men to be anemic and many over-the-counter vitamin supplements for women are loaded with iron for that reason.

Haas cautioned, however, that, "We didn't do (the study) to promote iron supplementation. What we're suggesting is that women, in particular, should be concerned about their iron status even if they think they're normal."

Dr. Emily Haymes, a specialist in nutrition and exercise physiology at the University of Florida in Gainesville, agreed.

"I think we have to be really cautious in telling anybody who just feels run down or fatigued to go take an iron supplement and you'll feel better," she said.

Iron-deficiency in a training athlete might be something to attack with a short-term regimen of iron supplementation, but "if the person is truly sedentary, I'm not sure there would be any benefit in taking an iron supplement unless it's going to improve their ability to do their daily activities."

The research team, which included Haas and was led by Thomas Brownlie IV, took a group of 41 women and put 22 of them on a six-week regimen of iron supplements -- 50 milligrams twice a day. Two weeks into the study, they started doing a half-hour on an exercise bike five days a week. The other 19 women received placebos but the same exercise routine.

Both groups saw improvements, but the women taking supplements had stronger gains. The biggest gains of all among women who began the study with the most depleted levels of iron.

Physicians and nutritionists advise women who are planning to begin an exercise program to check with their doctor first. But after that, if women cannot meet realistic fitness goals despite diligence, experts say the next step might be blood tests to check hemoglobin levels. A low hemoglobin level points to anemia.

"If that's normal, I might then check serum ferritin," said Haas, indicating a way to check for iron deficiency without signs of anemia.

Douglas Kalman, a registered dietitian in Miami, said diet plays a factor. Women should try adapting what they eat before they turn to popping iron tablets and multivitamins. Red meat, green leafy vegetables like spinach, kale or broccoli, and vitamin-C enriched foods should all be on the menu, he said.

The research was sponsored by the National Institutes of Health and the Mead Johnson Research Fund.

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(Written by Jim Mathews in Washington.)