That assumes your body is absorbing all of it. I suspect a lot of people's aren't, hence the high doses. I have found for example that 1000iu in the form of dro

That assumes your body is absorbing all of it. I suspect a lot of people's aren't, hence the high doses. I have found for example that 1000iu in the form of drops under the tongue has dramatically more effect than 1000iu in the form of a chewable tablet.