Note, before you assume this means high doses are always safe: Synthesis of vitamin D will stop once your body thinks you have enough. It isn't capable of ceas

Note, before you assume this means high doses are always safe: Synthesis of vitamin D will stop once your body thinks you have enough. It isn't capable of ceasing absorption through the digestive system in the same way. That said, constant supplementation of a medium dose -- say, 8000-1000 IUs daily -- should be mostly safe, and probably a good idea.