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Vitamin D & Multiple Sclerosis

Posted Jun 07 2011 8:30am
Dr. James L recently pointed out a case-control study published last month in Neurology demonstrating an association between low vitamin D & multiple sclerosis (MS) in African Americans.

We've known for quite some time that greater skin pigmentation as well as living in higher latitudes (farther from the equator) is associated with lower vitamin D levels.  So perhaps it wasn't too much of a surprise to find that African Americans w/MS had a lower vitamin D level (29.7nmol/L = 11.9ng/mL) than their controls (36.6nmol/L = 14.7ng/mL).

But what I found frightening is that 71% of controls were vitamin D deficient (<50nmol/L = <20ng/mL) and that 93% were insufficient (<75nmol/L = <30ng/mL).

Now, if this was the first study demonstrating a link between vitamin D & MS, I'd urge caution.  Remember, look for trends rather than flukes.  However, another case-control study published in the same journal this past February  offers physiologic plausibility by linking sun exposure & vitamin D levels to central nervous system demyelination.

Furthermore, a twin-twin study published almost 3 years ago offers evidence of a genetic basis for seasonal regulation of vitamin D in those affected by MS.  So, should we all start pumping up our vitamin D levels or at least enjoying the sunshine a bit more with the onset of summer?  Unfortunately, it's still a bit early to make conclusive recommendations based upon associative & observational data.  Remember that we still don't have cause & effect evidence, just the basis for developing a randomized controlled trial.  And don't forget that sun exposure has been linked to skin cancer.  

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