noun
1. : vitamin B complex
2. : any of numerous members of the vitamin B complex: as
a. or vitamin B 1 : thiamine
b. or vitamin B 2 : riboflavin
c. or vitamin B 6 : any or all of three closely related compounds pyridoxine, pyridoxal, and pyridoxamine that occur widely in combined form (as in liver, cereals, royal bee jelly, and yeast), that prevent rat acrodynia and are considered generally essential in the nutrition of vertebrates including man, and that are interconvertible in mammals and birds but vary in their activity as growth factors for microorganisms ; especially : pyridoxine
d. or vitamin B 12
(1) : a red crystalline complex cobalt-containing cyano antianemic compound C 63 H 90 CoN 14 0 14 P that is in part related chemically to porphin and is in part a nucleotide, that occurs in most animal products and especially liver, kidney, and various seafoods but is usually obtained commercially by bacterial fermentation, that is essential for normal blood formation, neural function, and growth and maintenance in man, various lower animals, and many microorganisms, and that is used chiefly in the treatment of pernicious anemia and other macrocytic anemias and of neuropathies and as a growth factor especially for hogs and poultry — called also antianemic factor, cyanocobalamin ; see animal protein factor , extrinsic factor
(2) : any or all of various compounds having similar biological activity to vitamin B 12 but differing chemically in containing hydroxyl or other group in place of the cyano group and readily interconvertible with vitamin B 12 : cobalamin ; broadly : any of various related compounds differing from vitamin B 12 in other respects (as in biological activity for higher animals and in the chemical composition of the nucleotide portion of the molecule) and formed in many cases by bacterial fermentation
e. or vitamin B c : folic acid 1
f. or vitamin B T : carnitine