Sunday, February 19, 2006
Big Study Confirms Calcium Pills Alone Will Not Prevent Osteoporosis
The recent news coverage of the results of the WHI study on calcium supplementation and bone health is highly misleading. This includes the 3/16/06 New York Times article entitled “Big Study Finds No Clear Benefit of Calcium Pills.”
The media’s sound-bite approach to nutrition is a shameful public disservice and perpetuates the simplistic view that foods and nutrients are either all good or all bad for all groups of people. In fact, since this story came out, many of my patients have asked if they should stop taking supplements altogether.
A more responsible summary of the study published in the 2/16/06 edition of the New England Journal of Medicine, is that it did find a significant hip fracture benefit for certain subgroups, namely – those who were not taking personal calcium supplements, those who adhered to the treatment (59% did not), and those over 60 years old.
But, the results were not as significant as they might have been since, as the editorial published with the study points out, “…several aspects…may have reduced the chances of detecting a benefit…”
- Many participants in both the treatment and control group were already taking calcium supplements, resulting in a mean calcium intake at baseline of 1150 mg, more than the intervention dose of 1000 mg.
- During the study, participants in both groups were allowed to continue to take these supplements and medications, which could seriously confound the study.
- 50% were on HRT, and some were also taking osteoporosis medications.
- 75% were overweight or obese, another factor thought to protect bones.
Thus, the total hip fracture rate among controls was about half of what was expected for a control group, making the difference in fracture rates between the two groups even less distinct.
Furthermore, on average, both groups were clinically deficient in vitamin D – at a level unlikely to be corrected by the amounts of vitamin D used in the study. Adequate magnesium was not addressed at all, and that is also vital for bone metabolism and calcium absorption. If all of that is not enough, the form of calcium used in the study was calcium carbonate, shown to be less well absorbed that some other forms of calcium. (These factors may help explain the increased risk of kidney stones found in the study. A well-designed calcium supplement that is better absorbed may actually reduce the risk of kidney stone.)
Perhaps the most important message to be gleaned from this study is that women need to do more than take calcium pills to prevent the development of osteoporosis. But, this is not news, so it was ignored by the media in favor of the more sensationalized message.
So what do you do with all of this information? See my next post, "How to Protect Your Bones -- Calcium is Not the Entire Solution."