How to get vitamin Drefers to both ergocalciferol (Vitamin D2) and cholecalciferol (vitamin D3). Due to exposure to sunlight, ergocalciferol is formed from ergosterol in yeasts and plants, while cholecalciferol is synthesized from 7-dehydrocholesterol (7-DHC) humans and animals. The metabolically active form in the body from vitamin D2 and vitamin D derives 1,25-dihydroxy vitamin D or calcitriol. For what has just been said, vitamin D is a micronutrient with very peculiar characteristics: in fact, the coverage of its metabolic needs can be independent of the diet.