Benefits of calcium, vitamin D questioned

BOSTON -- If you're an older woman who pops calcium and vitamin D supplements, you may boost your protection against hip fractures but you also raise the risk of kidney stones, according to a study released yesterday.

The study also showed no link between taking the supplements and the incidence of colon cancer.

Officially, the study of 36,282 women taking the supplements after menopause concluded that the treatment did not prevent broken bones of any kind.

That was based on assessments of all the women who participated, many of whom failed to follow the complete regimen of 1,000 milligrams of calcium carbonate along with 400 international units of vitamin D.

But those participants who consistently took the full dose for seven years seemed to cut the risk of a broken hip by 29 percent -- or four hip fractures per every 10,000 women, according to the report, to be published in today's New England Journal of Medicine.

Even that group did not reduce the likelihood of spine, wrist, or other types of fractures, and overall, the women increased their risk of developing kidney stones by 17 percent, according to the research.

Study leader Rebecca Jackson of Ohio State University said the findings show that for women over 60 -- when the risk of breaking a hip is greater -- ''there is some benefit in calcium and vitamin D" if they consistently take the supplements.

But the researchers had hoped for a greater benefit. Americans spend an estimated $993 million a year on calcium supplements to ward off osteoporosis, a disease in which bones become fragile and more likely to break.

''With the widespread marketing of calcium and vitamin D, many women believe that they are completely protected against the development of osteoporosis if they are taking these supplements," said Dr. Joel Finkelstein of Massachusetts General Hospital.

''This study should help correct this important misconception and allow more women to receive optimal therapy for bone health," such as prescription medication, he said in an editorial in the journal.

Finkelstein said it is possible ''that calcium with vitamin D supplementation would be more effective in a population of women with osteoporosis."