Chhandogya Upanishad says "Aharashuddhau Sattvashuddhih Sattvashuddhau Dhruva Smratih, Smratilambhe Sarvagranthinam Vipramokshah"
Meaning: Purity of food helps in purifying the inner self. Purification of the inner self and hence of the mind and intellect, accelerates elimination of illusions and ignorance. This in turn, paves the way for salvation of the soul . The sages of the Vedic times, the rishis, had research ed and categorized the gross and subtle qualities and effects of food in three categories satvika, rajasika and tamasika. They had also enjoined that those desirous of having the purity, piety and sagacity of thoughts, feelings and emotions along with the vibrant health of the body, should avoid tamasika and rajasika food and take only satvika food.