I was having pains in my legs to the point I couldn't sleep at night. I couldn't walk thru a mall without getting a kink in my knees. My doctor put me on 50,000 units of vitamin D a week. The pain is gone. The pain returns if I am late by a few days of taking the vitamin D. I have a prescription for 50,000 iu's levels of Vitamin D have been linked with several types of cancer.Many in the helath field consider VITAMIN D is more of a hormone rather than a vitamin. It is very difficult to get enough sun for vitamin D. In fact, in the winter it is almost impossible to get enough sun for vitamin D if you live north of Atlanta, georgia.