While it is well known that severe vitamin D deficiency causes rickets, osteoporosis, and osteomalacia, it is not generally known that even a mild deficiency may cause such problems as muscle weakness, fibromyalgia, impaired balance, and depression. [link to www.townsendletter.com] Vitamin D deficiency as a cause of fibromyalgia - Literature Review & CommentaryTownsend Letter for Doctors and Patie