niacin      
noun [ U ]  chemistry, biology specialized uk/ˈnaɪə.sɪn/ us/ˈnaɪə.sɪn/
 烟酸(在小麦、牛肉、鸡肉和牛奶等食品中含有的一种复合维生素B,对体内能量转化和保持消化、神经系统健康有着重要作用)
one of the vitamin B complex found in foods such as wheat, beef, chicken, and milk, important for producing energy from food and for keeping the digestion and nervous system healthy