. "Long-term vitamin D deficiency has been linked to immune disorders such as multiple sclerosis, rheumatoid arthritis, type I diabetes, and cancer.Vitamin D is a hormone not a vitamin and it is not just for kids anymore, writes Ruth A. Lawrence, MD, Editor-in-Chief of Breastfeeding Medicine, from the Department of Pediatrics, University of Rochester School of Medicine and Dentistry, in an accompan" . . .