Do you know the phrase “medicine and food source”? It is based on the Chinese idea of “medicine and food from the same source” such as medicinal dishes. The meaning is that [the essence of both curing illness and eating is to nourish life and maintain health] (from Kojien).
It is one of the basic concepts of Oriental medicine (traditional Chinese medicine), and indicates that the principle of the effect of "daily diet (food)" and "medicine" is the same.
The idea is that you can prevent or treat illness by paying attention to your daily diet.