Ayurveda relies on Tridosha theory for diagnosis and curing disease.Tridosha are the 3 dosha present in body. Increasing or decreasing these dosha causes ill in body. Dosha should be kept in harmony for proper functioning of the body.
The 3 dosha are:-
1)Vata, composed of air, governs all movement in the mind and body and must be kept in good balance. Too much vata leads to worries, insomnia, cramps and constipation. It controls blood flow, elimination of wastes, breathing and the movement of thoughts across the mind. It is also responsible for the activation of the nervous system, hearing and speech; and expresses as enthusiasm and creativity. Vata also controls the other two principles, Pitta and Kapha, and is usually the first cause of disease. Another word for Vata is Vayu - it is the more traditional Sanskrit word for air.
2) Pitta is said to be composed of fire and water; it governs all heat, metabolism and transformation in the mind and body. It controls how we digest food, how we metabolize our sensory perceptions, and how we discriminate between right and wrong. Pitta must be kept in balance, too. Too much it can lead to anger, criticism, ulcers, rashes and thinning hair. A balanced Pitta mind makes one a good leader with a warm personality.
3) Kapha is the watery humour. It cements the elements in the body, providing the material for physical structure and maintains the body resistance by lubricating the joints; providing moisture to the skin, helping to heal the wounds, filling the spaces in the body; giving the biological strength, vigor and stability, supporting memory retention and giving the energy to the heart and lungs. In all it maintains immunity.
Kapha is also responsible for emotions of attachment, greed and long-standing envy; it is also expressed in tendencies toward calmness, forgiveness and love. Too much Kapha leads to lethargy and weight gain, as well as congestion and allergies
Each being from his birth has one pre-dominant dosha, which represents his physique character and behavior. Ayurveda has the key to cure this imbalance in dosha to cure man and make him healthy.