Dietary stress may compromise bones

People who mentally wrestle about what and how much to eat produce elevated amounts of the hormone cortisol, a biomarker of stress, a new study finds.

Researchers at the University of British Columbia in Vancouver had observed that women who willfully regulate food intake sometimes develop subtle perturbations in their menstrual cycles. Since cortisol is known to affect menstrual cycles, the scientists monitored levels of the hormone in urine of 62 woman. Half of the women had scored high on tests of their propensity to restrain dietary intake; the other half scored low.

Self-restrained eaters excreted 18 percent higher concentrations in cortisol than their largely unrestrained counterparts, Susan I. Barr and her colleagues report in the January 2001 American Journal of Clinical Nutrition. The findings suggest that resisting gustatory temptation may be more than stressful. Studies by others, Barr notes, have shown that elevated cortisol in the body can suppress reproductive hormones, which is “generally associated with lower bone mass.”

The dieters also excreted roughly 30 percent less calcium in their urine. A comparison with their food intake suggests that these women were absorbing less calcium from their diets than they should be—a common side effect of elevated cortisol.

“Women who experience stress over dietary choices may, over the long term, face an elevated risk of bone loss and fractures,” Barr speculates.

Janet Raloff is the Editor, Digital of Science News Explores, a daily online magazine for middle school students. She started at Science News in 1977 as the environment and policy writer, specializing in toxicology. To her never-ending surprise, her daughter became a toxicologist.

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