Dosha (, IAST: doṣa) is a central term in Ayurveda originating from Sanskrit, which can be translated as "that which can cause problems" (literally meaning "fault" or "defect"), and which refers to three categories or types of substances that are believed to be present in a person's body and mind. Beginning with twentieth-century Ayurvedic literature, the "three-dosha theory" (, ) has described how the quantities and qualities of three fundamental types of substances called wind, bile, and phlegm (, , ; , , ) fluctuate in the body according to the seasons, time of day, process of digestion, and several other factors and thereby determine changing conditions of growth, aging, health, and disease. Doshas are considered to shape the physical body according to a natural constitution established at birth, determined by the constitutions of the parents as well as the time of conception and other factors. This natural constitution represents the healthy norm for a balanced state for a particular individual. The particular ratio of the doshas in a person's natural constitution is associated with determining their mind-body type including various physiological and psychological characteristics such as physical appearance, physique, and personality. The Ayurvedic three-dosha theory is often compared to European humorism although it is a distinct system with a separate history. The three-dosha theory has also been compared to astrology and physiognomy in similarly deriving its tenets from ancient philosophy and superstitions. Using them to diagnose or treat disease is considered pseudoscientific. Role in disease, Roga Doshas are purely imaginary; their existence is not supported by any evidence. The Ayurvedic notion of doshas describes how bad habits, wrong diet, overwork, etc. may cause relative deficiencies or excesses which cause them to become imbalanced in relation to the natural constitution () resulting in a current condition () which may potentially lead to disease. For example, an excess of is blamed for mental, nervous, and digestive disorders, including low energy and weakening of all body tissues. Similarly, excess is blamed for blood toxicity, inflammation, and infection. Excess of is blamed for increase in mucus, weight, oedema, and lung disease, etc. The key to managing all doshas is taking care of , that is taught to regulate the other two. Principles The doshas derive their qualities from the five elements (; ) of classical Indian philosophy. Vāta or vata is characterized by the properties of dry, cold, light, minute, and movement. All