Insufficient Sun Exposure Is Declared a Public Health EmergencyVitamin D is a steroid hormone produced in your body with the help of cholesterol molecules when you expose significant amounts of skin to the sun. It is an essential vitamin that interacts with a number of different systems in your body. One of the best ways to optimize your vitamin D blood levels is to get sensible sun exposure, taking great care never to get burned. Deficiency is very common in the U.S. but many Americans mistakenly believe they are not at risk simply because they eat foods fortified with vitamin D, such as milk. Before 2000, many physicians had not considered the possibility you could be deficient in vitamin D. A recent paper in Dermato-Endocrinology reviewed the current science for the risks and benefits of sun exposure and found insufficient exposure in the U.S. has become a major public health problem.