Science Questions

Can you overdose on vitamin D?

Sun, 22nd Jan 2012

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Nathaniel Bolt, Facebook; James Townley, Twitter asked:

Can you overdose on vitamin D since you were talking about perhaps taking it? Could too much vitamin D be toxic like too much vitamin A?


John -   If you take very large volumes or quantities of vitamin D, you'll get hypercalcaemia and that can have adverse effects and indeed can cause kidney failure if you really overdo it. 

But as George was saying, in fact, itís very hard to get anywhere near those levels.  You have to really work quite hard at it and for the general population, the sort of supplements that we will get from our diet and from adding a tablet of vitamin D to our routine is not going to take you anywhere near that level.

George:: I agree.  The safety here has been demonstrated in volunteers.  So, the institute of medicineís recommendation was up to 4,000 units a day for adults.

The safety factor is huge so that volunteers have been given over 100,000 units a day when itís been gradually increased over time, which is you know, letís say 25 times the Institute of  medicine maximum recommendation and no ill-effects were seen. 

So if you increase the amount of water you took a day by 25-fold, then it would be fatal, but you can increase the amount of vitamin D slowly and in fact, no side effects have been found.  I'm not recommending people to take that, but there's a big safety factor.


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On the other hand, while water isn't used as a rat poison, vitamin D is.

It's difficult to poison yourself with vitamin D, but why take the risk?
Bored chemist, Tue, 24th Jan 2012

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