Vitamin D vs Arthritis: Wrong Tool for the Job

In the medical profession, we have a variation on a theme that to the physician who only welds a hammer, everything looks like a nail.  That's why I have a fond distaste for miracle elixirs that promise to cure everything from cancer to dementia.  Or that fixing one hormone or taking just one supplement will solve all your maladies.

So you can imagine my lack of surprise when I stumbled upon a randomized, placebo-controlled, double-blind trial published yesterday in JAMA in which the authors noted that vitamin D supplementation for 2 years did not improve knee pain due to osteoarthritis, much less slow down loss of cartilage.  To arrive at these conclusions, the authors randomized 146 women & men, half of whom received placebo & the others 2,000-8,000 units of vitamin D daily.

For those of you D-believers who think that 2,000 units of vitamin D isn't enough, the participants' average 25OH vitamin D was 21.9-22.7ng/mL, just barely into the deficiency range w/insufficiency at less than 20ng/mL.  On average, those who received vitamin D were able to increase their 25OH vitamin D to 38.5ng/mL by 12 months.  

Others of you might consider that a 38.5ng/mL might not be high enough (some choose to aim for >50ng/mL) or that 21.9-22.7ng/mL wasn't low enough (must be below 15ng/mL).  Still others might consider 2 years inadequate for vitamin D to work its magic (epidemiologic studies last upwards of 8yrs).  

Don't get me wrong.  In one sense, D-believers have valid points to rebut this study.  Me, I'll stick to using vitamin D to improve bone strength.  The potential benefits of vitamin D garnered from observational studies are definitely intriguing but I won't be including reduction in OA pain in this latter group for now.

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