A white crystalline acid, C5H4NCOOH, that is a component of the vitamin B complex found in meat, wheat germ, dairy products, and yeast and is used to treat and prevent pellagra.

• 烟酸，尼克酸一种白色结晶酸，C5H4NCOOH，是在肉、麦胚、奶制品和酵母中发现的合成维他命B的一种成分