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.
- Vitamin D and Hypercalcemia (brassandivory.org)
- Vitamin D study suggests that pale people need supplements (cbsnews.com)
- Vitamin D and COPD (philadelphia.cbslocal.com)
- Bella Quiz: Do You Know Your ABCs. . .of Beauty Vitamins? (bellasugar.com)
- The Calcium Controversy (biosil.wordpress.com)
- Vitamin D – is it Really? (drkennethorbeck.com)
- Pale People at Risk for Vitamin D Deficiency (webmd.com)
- Pale Skin Is Pretty, But It Might Mean You Need More Vitamin D (blisstree.com)
- Vitamins – The adverse effects (intentious.com)
- Vitamin D: free teaching resource (brilliantbook.wordpress.com)