Posted by: Chris Maloney | January 26, 2012

How Much Vitamin D is Too Much?


Image by DBduo Photography via Flickr

I was taught that that RDA of Vitamin D, 400 IU, was adequate and that more might cause hypercalcemia.  Hypercalcemia could cause heart arrhythmias.

Later on, I learned that, despite the risk, psoriasis patients were given 50,000 IU of vitamin D.  The only doses the pharmacies stocked were 400 IU and 50,000 IU.  It didn’t make a lot of sense.

In looking through the literature, I was unable to find more than a couple anecdotal reports of patients consuming hundreds of thousands of IU of vitamin D and giving themselves reversible arrhythmias.

But what is the safe amount?  Well, we have a nice study of a small group of MS patients taking 20,000 units a day for twelve weeks.  None of them had heart problems, and none of them developed hyper or hypo calcemia despite their blood levels of vitamin D reaching an average of 380 nmol/L.  Their starting was 50 nmol/L, which seems high for the U.S. population (I think our lower cutoff is 18nmol/L for deficiency).

So I’m not going to be prescribing 20k for my patients, but I’m going to be a little less cautious than the RDA guys who have now moved the RDA to 800 IU.

Here’s the MS study.

How good is vitamin D for you?  Here’s a two page discussion of its effects on lupus and autoimmune diseases.



  1. I take via supplement and food about 12 to 15,000 a day! I feel AMAZING! I will not quit this habit!

  2. I’m getting there, but I’m still leery of the idea of long term fat soluble vitamins building up in the blood. In other research, I found that vitamin D may, in very large quantities, act as an inflammatory agent in the skin. So I’m going to be holding at about 2,000 IU as a range. But I do see a need for higher levels in certain patients.

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