Studies in which anorexic women have been given oral contraceptives or estrogen to help restore bone mass have had mixed results, Dominguez and her team note, while the process by which bone thinning occurs in these patients is not fully understood. Further, they add in the July issue of the American Journal of Clinical Nutrition, "the role of nutrition in the recovery of bone has been underestimated."

To better understand bone loss and rebuilding in these patients, the researchers followed 28 women with anorexia nervosa who were undergoing treatment to help regain weight, comparing them to a control group of 11 healthy young women.

After just over two months on nutrition therapy, the anorexia nervosa patients showed significant increases in bone mineral density, the researchers found. Patients' levels of the protein osteocalcin, which is secreted by bone cells and is a key marker of bone formation, also rose. But levels of N-telopeptide, a marker for bone breakdown, remained abnormally high, except among eight women who began menstruating normally after recovering 90 percent of their ideal body weight.

The average bone mineral density among women who didn't begin menstruating after treatment was lower than the bone mineral density for the women who started menstruating and the healthy controls.

The findings suggest, Dominguez and her colleagues note, that women with anorexia have normal to increased rates of bone formation, but that bone breakdown outpaces bone building, resulting in loss of bone mineral density.

"Our data suggest that nutritional therapy is critical and necessary for optimal effect of other therapies," the researchers write. These drugs include antiresorptives -- drugs that block bone breakdown - and estrogen replacement therapy. In fact, they add, such treatment may not be effective until nutritional therapy has restored normal bone formation.

SOURCE: American Journal of Clinical Nutrition, July 2007.

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