New study supports calcium use

April 28, 2006|By JUDY PERES | JUDY PERES,CHICAGO TRIBUNE

Two months after a huge clinical trial concluded that calcium supplements don't do much to protect older women from bone fractures, a new study has found just the opposite. Or so it would appear.

The paper released this week in the Archives of Internal Medicine said older women who consistently took calcium for five years had significantly fewer broken bones than those who did not. But in February, the Women's Health Initiative - a large government-sponsored study - reported that calcium supplements had little effect.

What's a person to do?

Keep taking your calcium, doctors say, either as part of your diet or in supplement form.

The U.S. government recommends that women older than 50 get 1,200 mg of calcium a day, along with at least 400 IU (international units) of vitamin D. Perhaps surprisingly, the data compiled by the two most recent bits of research both support that recommendation.

In both studies, no clear benefit was found for women who were assigned to take calcium. But that is probably because many who were supposed to be taking the pills didn't actually do so.

When researchers looked only at those women who took their pills regularly, both studies showed a clear benefit on bone fractures. So, why were consumers jerked around by the confusing results?

Researchers who took part in the Women's Health Initiative, or WHI, said they had a duty to report the answer to the main question they had posed: Did calcium and vitamin D supplements protect older women from hip fractures?

"As an investigator and a scientist, you're obligated to report results the way the study was designed," said research nutritionist Linda Van Horn of Chicago's Northwestern Memorial Hospital, one of the WHI investigators. "Then people have the liberty to provide additional interpretation."

The WHI study involved signing up more than 36,000 women ages 50-79 and randomly assigning half of them to take a calcium supplement (1,000 mg plus 400 IU of vitamin D) and half to take an identical-looking dummy pill, or placebo. After an average of seven years, the group taking the real thing had fewer broken hips, but the difference was not statistically significant.

That finding led to the negative headlines and sound bites.

But buried deeper in the paper was another finding: Women who took the pills consistently had a 29 percent lower risk of breaking their hip than those taking a placebo, a statistically significant difference. In absolute terms there were 10 hip fractures per 10,000 women per year in the calcium group, compared with 14 in the placebo group.

The study also found that, in the calcium group, women older than 60 - who are more likely to suffer osteoporotic fractures in the first place - had a 21 percent reduced risk, whether or not they took the pills every day.

Other factors, too, may have affected the overall findings. A majority of women in the WHI were taking calcium supplements on the side, because researchers felt it would have been unethical to make participants give up something they believed was good for their health.

Judy Peres writes for the Chicago Tribune.

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