Ibn Sina is quoted as saying in “Avicenna’s Medicine” that “One who is seeking health preservation should endeavour not to have the essence of their food as medicinal foods such as green, leafy vegetables and fruits, and alike. 

"The attenuant food [that which thins or dilutes the fluids] chars blood (i.e. oxidizes), and heavy food causes phlegm and weightiness of the body.

"Food should be composed of meat, especially that of the young goat, young beef, and young lamb; wheat that has been cleaned and is free from contamination … sweets that are suitable to [the individual’s] temperament [mijaaz]; and good drinks made of fragrant herbs.

Other than that is used for treatment and preservation.”