Vitamin D deficiency can cause rickets in children, and osteoporosis in adults. An increased risk of other ills, such as cancer of the colon, breast, or prostate, as well as multiple sclerosis and type 1 diabetes might be linked to vitamin D deficiency. More research is needed before all of these associations can be considered certain but in the meantime it seems reasonable for everyone to take prudent measures to maintain an adequate blood level of vitamin D.