Nutrition: Calorie Intake May Affect Bone Health of Young Women

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Source: New York Times June 12th, 2007
Author: Eric Nagourney

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When a young woman stops menstruating, doctors often take it as a red flag that she may not be eating enough, which, among other problems, can inhibit bone formation.

But a new study has found that some young women who have regular periods may still be eating so little that they endanger the health of their bones.

There are a number of reasons a teenager may not be consuming enough nutrients. Anorexia is a common one, but young women who work out intensively for a sport like gymnastics without increasing their energy intake are also at risk.

The study, by Anne Loucks and Aiden Shearer of Ohio University, looked at the role of nutrient intake and bone formation in women ages 18 to 32. It was presented last week at a meeting of the Endocrine Society.

For five days, the researchers restricted the women’s caloric intake and had them exercise for more than an hour and a half each day. The women were separated into two groups, one younger and one older.

When the researchers drew volunteers’ blood at the end of the five days, they found decreased levels of two markers for bone formation.

While earlier research found that calorie restriction did not disrupt the reproductive system in the older group of young women, the new study suggests that taking in too few calories still impairs their bone formation.

The implications may be greatest for women who exercise a lot and do not consume enough food.

“Regular menstrual cycles do not reliably indicate that they are eating enough for what they’re expending,” Dr. Loucks said.