A Bone to Pick?

Increasingly, research studies published in major medical journals conclude the same way: with a plea for more studies. The writers say they have found evidence leading them to believe that drug X “may be helpful” or drug Y "did not produce a measurable difference in outcomes" and urge additional testing to confirm (or presumably refute) their results. So, it was interesting to note that a recent study of vitamin D and bone health concludes not only that the authors found no evidence that vitamin D is beneficial in preventing or treating falls, fractures, or osteoporosis, but that also that no further study is warranted. The writers confidently assert that this latest study, a meta-analysis that examines all the well-done studies to date, including 45 recent studies that were not included in previous meta-analyses, should be the last word on the subject. Unless you have rickets or osteomalacia, two relatively rare conditions, the authors conclude that you should not bother to take vitamin D supplements.

In the past, the response to negative studies of vitamin D has been a chorus of “but, but, but.” But what about the effect of the dose of vitamin D—maybe 400 International Units is not enough to do anything but 800 is. The current examination looked at this question and failed to detect any difference in outcomes between people taking high dose or lower dose vitamin D. But what about the importance of age—can vitamin D make a difference in the oldest old, people at the highest risk of fracture? The current examination didn’t find any evidence it does. But what about the thickness of the bones at the time that vitamin D is initiated—maybe it’s too late to matter if there has already been a great deal of bone loss, but can be helpful at an earlier stage. The authors of the new report don’t think so.

Two years ago, I addressed the issue of vitamin D in my blog post, “Make No Bones About It.” I concluded that the evidence supporting vitamin D supplements was weak, but because falls and fractures are so devastating for older people and the cost of vitamin D is so low, with almost non-existent side effects, it wouldn’t hurt to take it—and maybe, just maybe, it might help. What do I advocate today? What will I personally do? Well, I still have a large bottle of vitamin D (1000 IU capsules) in my medicine cabinet. I’ll finish the bottle. Then what? Unless someone comes up with a compelling reason to continue, I’ll probably stop. But I will make sure to drink lots of milk, eat cheese, and get plenty of sunshine to ensure that my non-medicinal intake of vitamin D is sufficient.

Hip Hip Hooray

             You might think it wouldn’t be difficult to figure out whether vitamin D and calcium supplements help prevent hip fracture in older people. You would be wrong. For the last twenty or thirty years, researchers have asked this question and have reached differing conclusions. The last time I blogged about the question, a study had come out showing that vitamin D matters, at least when taken in sufficient quantities (800 units a day). Since then, I’ve been dutifully taking the suggested amount of vitamin D. I still take TUMS, too, to get some extra calcium, but I haven’t been as conscientious about this because the data is weaker. Now, JAMA  has published an article that looked specifically at community-dwelling older people (that is, it excludes nursing home residents)—and concluded that neither calcium not vitamin D nor the combination of them has any discernible effect in preventing hip fractures.

            Granted, this study is a “meta-analysis,” a study of studies, rather than the gold standard, a randomized controlled trial. Granted, this study looks primarily at hip fractures, arguing that they have the greatest effect on quality of life (and health care costs), though plenty of older people manage to break a wrist or suffer from back pain due to compression fractures without breaking a hip. Maybe the real reason that the individual studies that form the basis of the current analysis have not consistently any benefit from vitamin D or calcium is that few people actually take the drugs that they say they’re taking. Whatever the explanation for the findings, the hard, cold reality is that the current research is another blow, a particularly powerful blow, against the view that diet can prevent fractures in older people.

            Here it is, New Year’s Day. Should I resolve to stop taking vitamin D and calcium? It would be an exceptionally easy resolution to stick to. It’s tempting. I might make the irrational decision to keep taking vitamin D until the bottle that I currently have is empty. Or I might wait until I see my primary care physician for my next routine appointment and do whatever she advises. But here’s what I think I will do: I will continue taking vitamin D, knowing that it probably isn’t effective, but recognizing that it might be in light of the studies to date that have arrived at differing conclusions. I will continue taking TUMS for calcium in the same somewhat haphazard way I've been doing. As long as there is almost no down side of taking these, I’ll take them. Right now, it’s fairly inexpensive, I have no trouble swallowing the pills, I’m not taking other medications, and I have had no side effects of the vitamin or calcium. This is the key point: there are almost no adverse effects of vitamin D; ditto for calcium when taken in moderation. How often can we say that about a medical intervention?