Vitamin D is a vitamin that is commonly lacking for many people when they get their blood tested. The vitamin is essential in our diet, but it also can be synthesized from exposure to the sun, much like plants can photosynthesize chlorophyll. A new study looked at the mortality of humans who suffer from vitamin D deficiency. Low levels of the vitamin and high levels of parathyroid hormone have been found to increase mortality for African American and Caucasian older adults. However, there is a greater impact in African Americans due to a higher prevalence of insufficient vitamin D levels.