My doctor also put me on a Vit D. therapy. I don't play in the sun but I also don't stay indoors a lot so I asked him how come so many people are deficient nowadays and he told me that they've upped the minimun daily requirement; they found people need more of it. So now I take a multi vitamin for seniors (yes, I'm going to be graduating soon), calcium and Vit D. I do feel pretty good. thanks for posting this.