vitamin B4

vi·ta·min B4

1. formerly believed to be a factor necessary for nutrition of the chick, now identified simply as certain essential amino acids and/or adenine;

2. obsolete term for adenine.

vitamin B4

(1) A designation for factors/substances required for chick growth, which are now known to correspond to adenine and certain essential amino acids.
(2) An ill-defined factor of dubious validity, isolated from yeast or liver, described as alleviating myasthenia in experimental animals. Alleged vitamin B4 “deficiency” responds to various agents, including adenine, arginine, cystine, glycine and thiamine. It is not a vitamin.