This traditional knowledge and norms were learned by narrative forms as well as mythologies, though the time and changing society attributed some more and new dimensions of food philosophy as recited in Kavyas and folklores by some rites and rituals, but basic knowledge of identification of hot and cold food, rich and light food, rajasic, tamasic, and sattvic food has remained the same.
The principle behind the beginning of daytime meal with bitter things first as defined by Maharshi Charak, Maharshi Sushruta, Maharshi Dhanwantari, and Jeevaka in Ayurvedic Rasayanas, bengalees are following those ritually as "totka" (an empiric therapy) in every household. You can hear all the time "khete hoy ma or khete hoy baba" saying, "You should eat O my daughter/my son", which Ancient Indian Science of Ayurveda ascribed as a cooling agent that was socially acquired throughout the region of Anga, Banga, and Kalinga (now Bengal, Orissa, and Assam) to protect themselves from frequent changes in climatic conditions.
