脚气病是一种由缺乏维生素B₁引起的疾病，病症包括体重下降，精神萎靡，感官功能衰退，体虚，间歇性心律失常。

西方诸语言中的脚气病多为Beriberi一词，它是由僧伽罗语引用过来，在僧伽罗语中是“不能不能”的意思，指为病重得不能做任何事。1901年荷兰医学家伊科曼和格里金斯发现其致病原因是缺乏某种存在于谷皮中的营养素。

在以精制或白米为主食的区域中，脚气病一度很常见。此种米食因为去除米糠，所以可以增加保存期限与口感，但也因此去除掉硫胺（thiamine）。T.在19世纪末之后才发现精制米类与脚气病的关系。1925年发现这种营养素是维生素B1。

Beriberi refers to a cluster of symptoms caused primarily by a nutritional deficit in vitamin B1 (thiamine). Beriberi has conventionally been divided into three separate entities, relating to the body system mainly involved (peripheral nervous system or cardiovascular) or age of person (eg. infantile). Beriberi is one of several thiamine-deficiency related conditions which may occur concurrently, including Wernicke's encephalopathy (mainly affecting the central nervous system), Korsakoff's syndrome (amnesia with additional psychiatric manifestations), and Wernicke-Korsakoff syndrome (with both neurologic and psychiatric symptoms).