I'm not an expert by any means but I have been taking VitD because I do not get out very much working 2 jobs a day. My health specialist says that it is very hard to max out on VitD unless you are taking more than 50,000U a day. Also...she suggests that you find pills that are liquid gel instead of powder pills. She also said that 1000U is equivalent to 20min of sun....so if you think of it that way...
Anyway....I know I'm not really answering your question properly but just mentioning that VitD is very hard take incorrectly. 
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thanks for your answer,it was the kind of info.i was hoping to hear.
It definitely was of help