The plant form of vitamin D is called vitamin D 2 or ergosterol. There are also dietary sources of vitamin D, including egg yolk, fish oil and a number of plants.
Vitamin D is thus not a true vitamin, because individuals with adequate exposure to sunlight do not require dietary supplementation. Vitamin D 3, also known as cholecalciferol is generated in the skin of animals when light energy is absorbed by a precursor molecule 7-dehydrocholesterol.
The term vitamin D is, unfortunately, an imprecise term referring to one or more members of a group of steroid molecules. More recently, it has become clear that receptors for vitamin D are present in a wide variety of cells, and that this hormone has biologic effects which extend far beyond control of mineral metabolism. Endocrine System > Other Endocrine Tissues and Hormones Vitamin D (Calcitriol)īioactive vitamin D or calcitriol is a steroid hormone that has long been known for its important role in regulating body levels of calcium and phosphorus, and in mineralization of bone.
