Calcium Study Finds Modest Benefit in Female Bone Health

By TOM VOGT, Columbian staff writer

Calcium supplements help reduce the risk of hip fractures among women over 60, but they don’t prevent other types of broken bones or provide overall protection against fractures, according to the results of a nationwide study released today.

The seven-year study of 36,282 older women — including 76 from Clark County — found a “modest benefit in preserving bone mass” in certain groups who took daily supplements of calcium and vitamin D.

It was the final segment of the Women’s Health Initiative, a three-part investigation that studied the effects of hormone therapy, diet and nutritional supplements in preventing a range of health problems in postmenopausal women.

The hormone studies were halted early because of increased health risks, and results of the low-fat diet study released last week didn’t show any protection against cancer or heart disease. So, today’s findings were the first from the project to offer women some, anyway an option for reducing health risks.

“I think this definitely gives people something they can do,” said Dr. Evelyn Whitlock, a researcher with the Kaiser Permanente Center for Health Research in Portland. “For women over the age of 60, the message is that calcium and vitamin D show an improvement in bone density and a decrease in hip fractures.”

Many people have been hoping for “news you can use” findings from the study, but researchers haven’t been able to offer much so far.

“People want a clear answer of what to do in a positive way, and sometimes the answers we get are part of a large jigsaw puzzle,” Whitlock said.

The women were from 50 to 79 years old when the calcium study began. Half took daily supplements of 1,000 milligrams of calcium and 400 international units of vitamin D, which helps the body absorb calcium; the other half took “dummy” placebo pills.

The overall findings, reported today in the New England Journal of Medicine, indicate that women who took the supplements improved the density of their hip bones by 1 percent. Women taking the supplements suffered 175 hip fractures, while women who took placebos had 199 fractures.

There were more pronounced differences among some subgroups. Women older than 60 taking the supplements had a 21 percent reduction in hip fractures.

Consistent dosage was another factor. At the end of the study, only 59 percent of the women in the supplement group were taking their full dose of pills; the women who maintained their pill schedule showed a 29-percent decrease in risk of hip fracture.

Because of so many variables, “We look at those subgroups with some caution,” said Whitlock, one of the authors of the report.

Investigators will continue to look at the study findings for the next five years. “There are a host of interesting opportunities,” Whitlock said.

An estimated 10 million Americans have osteoporosis a skeletal disorder characterized by weakened bones and 34 million have low bone mass. Researchers were looking to see if observational evidence, which suggests that calcium with vitamin D makes bones stronger, could be supported by a major clinical trial.

The Women’s Health Institute study assumed an 18 percent reduction in hip fractures, according to the report. But that wasn’t the only expectation that didn’t pan out: Researchers tallied about half the hip fractures they’d expected.

The women in the study group were reasonably heavy, Whitlock said, and heavier people have stronger bones. (About three-fourths of the women were overweight or obese according to the “body mass index” scale.)

“They were allowed to take their own supplements,” she added, so at the start of the study, “They had a high baseline level of calcium.”

In a secondary study, investigators found the supplements had no effect in preventing other types of bone fractures or in lowering the risk of colorectal cancer.

In another finding, the group taking the calcium and vitamin D supplements had a 17 percent increase in kidney stones.

“There were five more cases of kidney stones per 10,000 people. But six hip fractures were prevented (per 10,000) in women over 60, and hip fracture is associated with disability and death,” Whitlock said.

There was another key element in the project that Whitlock didn’t want to forget.

“Our thanks to the women in the study,” she said. “A lot has gotten lost about how much these women have contributed. They keep participating, and they’re all aging thank heavens, considering the alternative. But it is not as easy as you get older, and we so appreciated the effort.”

The Women’s Health Initiative is sponsored by the National Heart, Lung and Blood Institute of the National Institutes of Health.

Tom Vogt writes about health issues for The Columbian. Contact him at 360-759-8008 or at tom.vogt@columbian.com.

Update

Previously: Women’s Health Initiative findings were announced on studies of hormone therapy and the effect of low-fat diet on several diseases.

What’s new: Findings from the third portion of the study show that supplements of calcium and vitamin D offer some protection against hip fractures for some groups of women.

What’s next: Researchers will continue to follow participants in the study and will take a closer look at blood samples and other material gathered over the past decade.