Calcium is still key to having strong bones

The Women’s Health Initiative has been wreaking havoc with our preconceived notions here in the medical biz. Now the WHI has taken on calcium and its value in preventing fractures, particularly hip fractures.

Hip fractures fell 300,000 Americans annually, and 25 percent of those affected will die in the year following their fracture. One in five will end up in a nursing home, which, for many in one study, was considered a fate worse than death.

This was a huge study, involving more than 36,000 post-menopausal women. It was a prospective, randomized, double-blind, placebo controlled study, the best kind. Half the women received 1,000 milligrams of calcium and 400 units of vitamin D a day, and half received placebo. Neither the women nor the researchers knew which the women were getting. The women were followed for an average of seven years.

The average age of the study participants was well into the post-menopausal years—62 years old. And only about 5,000 women in each group were already taking calcium supplements. At the end of the trial, only 59 percent of the women were taking 80 percent or more of their study medication, while 76 percent were taking some of it. Which shows you how hard it is to take your medicine regularly, even if researchers are bugging you on a regular basis!

Some of the women had their bone density measured. Women on the calcium with vitamin D supplements had greater preservation of their hip bone density than did their non supplement sisters. But how did this transfer to the end point we are really concerned about — hip fractures? Looking at the group as a whole, women on the calcium with vitamin D supplements had a lower hip fracture rate, but it was not statistically significant.

But women who remembered to take their pills more than 80 percent of the time had a 29 percent reduction in hip fractures. And, not surprisingly, women who did not fall had significantly fewer fractures. Another interesting finding, given all the bad press that hormones have received lately, is that women who were in the hormone therapy arm of the WHI and taking the calcium with vitamin D supplements had 40 percent fewer hip fractures. Finally, women over 60 benefited the most from the calcium with vitamin D therapy.

On the down side of calcium replacement, there was a slight increase in the number of women who developed kidney stones.

So what does all this mean? Should we throw away our calcium supplements? I don’t think so.

First of all, as the study’s authors point out, the vitamin D dose might have been too low. Studies that were published after this study had begun showed that the calcium with the vitamin D dose used here, 400 units, had no effect on fracture rate, while vitamin D doses greater than 600 units combined with calcium did show a benefit.

This study, although well designed, had some problems. The researchers saw fewer than half the hip fractures they predicted, and that made the study less powerful. Since they had fewer hip fractures than they predicted, they needed more women to see if the calcium supplements worked.

And the study was designed to find at least an 18 percent reduction in risk. To find a lower but still significant decrease in hip fractures, the study again needed more participants.

Here’s the bottom line: Our bones get weaker as we get older. And our balance gets weaker as we get older.

We still need adequate calcium and vitamin D intake, but we probably need more than that to keep us from a hip fracture. We need to keep an eye on our bone density and take medications to increase our bone strength if necessary.

We need to exercise.

And we need to work on our balance and take measures to reduce the risk of falls, so we don’t find ourselves lying on the floor, writhing in pain, and cursing ourselves because we didn’t turn the light on when we went to the bathroom.