during the last decades , there have been great advancements in the field of preventive medicine .
research has demonstrated that nutrition plays a crucial role in the prevention of chronic diseases .
it proposes to consider food not only vital to survive , but also a mean for mental and physical well - being , contributing to the prevention and reduction of risk factors for diseases .
however , there is evidence that the concept was believed by ancient physicians as well .
rhazes said ;  as long as a disease could be treated with food , medicine should be avoided 
we carried out a review of avicenna s canon of medicine and rhazes books for the definition of food and drug and similar concepts of functional food .
rhazes has a book called  manafe al - aghziyeh , in which he writes about the medicinal benefits of different nutrition .
five concepts ( food , drug , medicinal food , nutritional medicine and antidote or poison ) were noted in these books .
there are many recommendations on food for the prevention and treatment of diseases in tpm books , which can be the basis for novel research studies .
 background : during the last decades , there have been great advancements in the field of preventive medicine . 
 research has demonstrated that nutrition plays a crucial role in the prevention of chronic diseases . 
 the concept of functional food was first introduced in japan during the 1980s . 
 it proposes to consider food not only vital to survive , but also a mean for mental and physical well - being , contributing to the prevention and reduction of risk factors for diseases . however , there is evidence that the concept was believed by ancient physicians as well . 
 one of the traditional systems of medicines is traditional persian medicine ( tpm ) . 
 rhazes said ;  as long as a disease could be treated with food , medicine should be avoidedmethods : we carried out a review of avicenna s canon of medicine and rhazes books for the definition of food and drug and similar concepts of functional food . 
 we listed the identified concepts along with their examples.results:the classification of food and their therapeutic use were explained in canon of medicine . 
 rhazes has a book called  
 manafe al - aghziyeh , in which he writes about the medicinal benefits of different nutrition . 
 five concepts ( food , drug , medicinal food , nutritional medicine and antidote or poison ) were noted in these books.conclusion:there are many recommendations on food for the prevention and treatment of diseases in tpm books , which can be the basis for novel research studies . 
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