Vitamin D3, or cholecalciferol, is a fat-soluble compound that is naturally produced in the skin with exposure to UVB light (sunlight). It is also commonly consumed in the diet through foods like fish, eggs, and cod liver oil, or through fortified foods such as milk or orange juice. The 2016 Reference Daily Intake for Vitamin D is 20mcg (800iu) for healthy adults and children over 4. As a dietary supplement, Vitamin D3 may help to support skeletal health, cardiovascular health, cognitive health, and a healthy immune system.^✝