VEGAN PRODUCT. Vitamin D is an essential nutrient that contributes to the normal function of the immune system and calcium levels in the blood, which in turn supports normal maintenance of bones and teeth. As fear of sun exposure has grown and lifestyles have become more sedentary, sun exposure has dropped dramatically and vitamin D deficiency and rickets incidence has skyrocketed. The skin cannot create vitamin D if it is covered by sunscreen or clothing, it is thought that a sunscreen with SPF15 will reduce the skin's ability to synthesize vitamin D by more than 95%. Vitamin D3 is the form of vitamin D that our bodies produce naturally, after a biotransformation of cholesterol due to exposure to ultra violet rays from the sun. Specifically, vitamin D3 is transformed by the liver into the circulating form – 25(OH)D3. The circulating form is then converted by the kidneys and other tissues to 1-25(OH)2D3, this is the active form, which is then capable of instigating the physiological effects associated with vitamin D. Conversion of D3 to 25( OH) D is slightly faster than D2. All Viridian Nutrition vitamin D supplements are vegan. Viridian Vitamin D3 2000IU are derived from lichens. How to use: As a dietary supplement, take one capsule a day with meals, or follow your doctor's recommendations.