Ingredients & DescriptionVitamin D is called "the sunshine vitamin" because we can usually get it from the sun's ultraviolet rays. People who live far away from the equator may make enough vitamin D in their skin during long, gloomy winters. It is essential for bone development and is needed for calcium and vitamin C absorption and it supports the nervous system. Vitamin D plays a dual role as both a vitamin and a hormone. Natural factors uses Vitamin D3, which is the form found in fish oils and eggs, and is produced by sunlight on human skin. Vitamin D3 (cholecalciferol from animal source) is derived from sheep wool lanolin.