The Force is Strong With This One
I'm pretty sure it take time to restore D levels, its not 1 month, rather 3 or more. Unless of course you have really low level then you would notice change. 10,000 i.u its not a lot, from what i understand it is average dose to restore. If you have low levels you need to take 10k every day for some time. (or i misunderstand how much you take)When i saw my vitamin D was low, i did take a 10,000 iu of vitamin D given by my doctor, i felt little/no difference, and, since then, i've tried it a few more times and had the same result.
We know what healthy person levels of D are, first time D was discovered was when people in UK had problems with bones etc and supplementation helped them so we know you can restore levels with supplementation and because of that we know what good levels are.My question: do we really know or not know the exact mechanism of how Vitamin D works? As they said - road to hell is paved with good intentions.
I don't see why you question this whole thread based on some book anecdote( I'm just trying to understand where you coming from, how much you know about vit D)