Those Are the Breaks: Bone Supplements’ Aid Called Limited

Defying years of conventional medical wisdom, researchers reported today that calcium and vitamin D pills regularly consumed by millions of women provide limited protection from broken bones.

The supplements seemed to reduce the risk of hip fractures in women older than 60 who faithfully took them. But the pills did not reduce spine or wrist fractures, and increased the risk of kidney stones, researchers said.

The study, published in the New England Journal of Medicine, raised questions about the benefits of taking supplements to prevent osteoporosis, a condition marked by weakened bones and a heightened risk of fractures that commonly afflicts women after menopause.

Concerns about the disease have fueled sales of calcium supplements to the tune of almost $1 billion a year.

Despite the study’s weak support for calcium supplements, some researchers said they would endorse taking them if needed to meet federal guidelines for calcium and vitamin D.

“It’s like the old expression: It couldn’t hurt,” said Dr. Norman Lasser of the University of Medicine and Dentistry in New Jersey and one of the study’s authors. Federal guidelines recommend that women older than 50 consume 400 units of vitamin D and 1,200 milligrams of calcium daily, equivalent to four eight-ounce glasses of milk. Studies have found that as few as 5% of older women meet those requirements.

The $18-million study was part of the Women’s Health Initiative, a massive federal study that a few years ago showed hormone treatment after menopause conferred more risks than benefits. Last week, the study challenged the benefits of low-fat diets.

The calcium study tracked 36,000 women for seven years. Half of the women received 1,000 milligrams of calcium and 400 units of vitamin D daily. The rest received a placebo.

Researchers expected a positive result because calcium and vitamin D, which aids absorption of calcium, have long been assumed to increase bone strength.

They were surprised when the results showed no significant difference. Those taking supplements experienced hip fractures at a rate of 14 of every 10,000 women compared with a rate of 16 of 10,000 for those on placebos.

Only when researchers parsed the data to examine a subgroup of women -- those over 60 who diligently took their pills -- did they find evidence that the supplements could prevent hip fractures. Those taking supplements had hip fractures at a rate of 10 of 10,000 women compared with a rate of 14 of 10,000 for women in the placebo group.

Gauging the importance of the results was difficult. Researchers said one problem was that all the women already incorporated relatively high amounts of calcium in their diets. What’s more, women in the placebo group who took calcium pills before joining the study were allowed to continue, potentially improving their bone health.

Another problem, researchers said, was that a high percentage of women had trouble sticking to the supplement regimen, which required them to take pills twice each day. By the end of the study, 59% of the participants faithfully took their pills.

Dr. Joel S. Finkelstein, an endocrinologist at Massachusetts General Hospital in Boston, said in an editorial accompanying the study that the supplements also might have shown greater benefit if the women received higher dosages of vitamin D.

Given the difficulties, “it was a miracle we got the results we did,” Lasser said.

Dr. Elizabeth G. Nabel, director of the National Heart, Lung and Blood Institute, said the results strongly suggested that women older than 60 follow government recommendations for calcium and vitamin D to maintain healthy bones.

Women should take supplements only if they cannot get enough calcium through their diets and vitamin D through exposure to sunlight, Nabel said.

The advice for women in their 50s was less clear.

Marcia L. Stefanick, a researcher at the Stanford University School of Medicine and one of the study’s authors, said healthy women in their 50s with a good diet didn’t need the pills.

She said 800 milligrams of calcium daily appeared adequate for middle-aged women.

Finkelstein said the results should put older women on notice that supplements alone wouldn’t prevent bone fractures and that women with low bone density might also need osteoporosis drugs.

In a related study, researchers said calcium offered no protective effects from colon cancer.

It was possible that the seven-year study did not last long enough to see an effect because cancer can take many years to develop, researchers said.