Ask you doctor about Vitamin D, and whether you need more of it. Most people think of Vitamin D as the "bone vitamin," but there's a lot more to it. Some medical experts believe Vitamin D is more like a hormone than a vitamin. Only the recently has the big news emerged: Vitamin D has role in helping prevent many serious diseases and illnesses. The discovery of vitamin D's benefits was a top-ten medical breakthrough in 2007. Sunlight is our primary source of Vitamin D; however, the risk of skin cancer from too much sun has given sunlight an overly bad rap. Over one billion people have inadequate amounts of Vitamin D, and 64 percent of North Americans are believed to be at risk for numerous diseases from having too little vitamin D.