In Samkhya philosophy there are three guṇas(Qualities):tamas guṇa, sattva guṇa, and rajas guṇa. These categories have become a common means of categorizing behavior and natural phenomena in Hindu philosophy, and also in Ayurvedic medicine, as a system to assess conditions and diets. Guṇa is the tendency of the mind and not the state. For instance, sattva guṇa is that force which tends to bring the mind to purity but is not purity itself. Similarly rajas guṇa is that force which tends to bring the mind to perform some action but is not action itself.
Charaka says that a substance conducive to an individual is called as satmya and the use of such substance results in the well-being of that individual. A person should consume food of his choice. The quantity and quality of food depends on the individual himself.
This means that if a person likes to eat food in less quantity and likes sweet and dry items then that is his individual taste. If a person consumes food which he does not like then the nutrient value of the particular food is not completely utilised by the body even if the food given to him is highly healthy. Digestion and the effect on the body depend upon the state of mind. A wholesome diet may be incompatible if the state of mind is not proper. Food does not come to us merely by our mouths. It comes through all our senses and through our minds.
So, diet and mind are inter-related. Diet is essential for a healthy mind. In other words, a healthy mind is responsible for proper digestion and utilisation of its nutrients in the body.
The link between food and mind has been proved by modern science. Our brains produce chemicals, called neurotransmitters that regulate our moods, emotions and even how we experience pain. Nutrients in the foods we eat trigger certain amino acids that, in turn, produce or decrease production of emotional neurotransmitters such as dopamine, epinephrine and serotonin. In modern science, the way food affects moods is completely new but this concept has been there since ages in Ayurveda.
Sattva (being, existence, entity") has been translated to mean balance, order, or purity. This typically implies that a person with more of Sattva has a positive or balanced state of mind. Such a person is psychologically kind, calm, alert and thoughtful. Compare also the bodhisattvas in Buddhism. Indologist Georg Feuerstein translates sattva as "lucidity".
- "guiding light" (insight)
- "Lights hope"
- Working for God, towards the benifit of all living things.
Rajas (atmosphere, air, firmament) leads one to activity, explained by the term Yogakshem, composed of two words: Yoga and Kshem. Yoga in the present context is acquiring something that one does not have. Kshem means losing something that one already has. Rajas is the force that creates desires for acquiring new things and fears for losing something that one has. These desires and fears lead one to activity. (Rajas is etymologically unrelated to the word raja.) Feuerstein translates rajas as "dynamism".
- "vitalizes the air" (morale boost)
- "excites the atmosphere"
- Working for others, towards the benifit of family, community, & country.
Tamas (originally "darkness", "obscurity") has been translated to mean "too inactive", negative, lethargic, dull, or slow. This typically implies that a person with more of Tamas has a negative, imbalanced, or self-destructive state of mind. A person with Tamas may mean something while saying something completely different. Attributes associated with it are Darkness, Death, Destruction, Ignorance, Sloth. Tamas is also known to be the heaviest, slowest, and most dull. Feuerstein translates tamas as "inertia".
- "may lead to darkness" (gives in to urges)
- "obscures the soul"
- Working for self, towards the satisfatction of marerial desires and/or bodily desires.