Vitamin D can work to prevent rickets (that's well known) but also 17 types of cancer including pancreatic, colon/rectal, stomach, prostate, lung, breast, bladder, uterine, espousal, kidney, ovarian, multiple myeloma, non-hodgkin's lymphoma, and leukemia, lower blood pressure, improve immune system function (prevents colds and flu), autoimmune function, inflammation, multiple sclerosis, autism, allergies, preeclampsia, both type 1 and type 2 diabetes, osteoporosis (also well known) depression, muscle and bone weakness and generalized pain.