Vitamins occur in a variety of related forms known as<unk> s. A<unk>  () of a particular vitamin is one of several related compounds that exhibit biological activity against a specific vitamin deficiency. Early research identified vitamins by their ability to cure vitamin-specific deficiency diseases. For example, vitamin B1 was first identified as a substance that prevented and treated beriberi . Subsequent nutrition research has revealed all<unk> s exhibit biological activity against their specific vitamin deficiency, although different<unk> s exhibit different potencies against those diseases. A set of<unk> s with related biological activity are grouped together by a general name, or generic descriptor, that refers to similar compounds with the same vitamin function. For example, vitamin A is the generic descriptor for the class of vitamin A<unk> s which include retinol, retinal, retinoic acid, and provitamin carotenoids such as beta-carotene among others.
Vitamer
Hermaphrodite 
QuantiFERON
Gadobenic acid
Denatured alcohol
Medrogestone
Retinoid
Co-codaprin