[The source of 'food depression' and its related theories].

'Food depression', as a term in traditional Chinese medicine, refers to a disease with main symptoms of dysthymia, dyspepsia, loose stool, insomnia and fatigue. It was first described by Zhu Danxi in <i>the Dan Xi Xin Fa</i> and the description was enriched and developed after that. Its definition, etiology, pathogenesis, treatment and prevention had been known specifically through the Ming and Qing Dynasties. This paper examines the early cognition, proposal and development of 'food depression'. It was found that 'food depression' is an important pathogenesis, leading to the occurrence and development of a variety of diseases. It is also an independent disease, often caused by emotional disorders or mixed with improper diet. These two findings are important to clarify the understanding of this disease clinically and theoretically today.