[The first treatise on diet: the Kitāb Hawāss al-agdiyah de Yūhannā ibn Māsawayh].

The article presents the first treatise concerning dietetics, written in Arabic in the first half of the IX century by one of the most ancient doctors of Bagdād, Yūhannā ibn Māsawayh, known in the western world as Jean Mésué. Ibn Māsawayh, basing his work on Galen's Properties of Foods, describes the properties of 140 foodstuffs from the vegetable and animal kingdom, and their good or bad effects on the human body. The translation of this treatise has been made from the only manuscript surviving, in the National Library of Madrid.