Can you overdose on vitamin D?

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, it's 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 medicine's 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 it's been gradually increased over time, which is you know, let's 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.