Holistic living is a term used to describe lifestyle changes and therapies that attempt to treat the patient as a whole person. That is, instead of treating an illness, as in orthodox allopathy, holistic treatment looks at an individual's overall physical, mental, spiritual, and emotional well-being. A holistic approach treats the symptoms of illness as well as looking for the underlying cause of the illness. Holistic medicine also attempts to prevent illness by placing a greater emphasis on optimizing health. The body's systems are seen as interdependent parts of the person's whole being. Its natural state is one of health, and an illness or disease is an imbalance in the body's systems. Holistic therapies tend to emphasize proper nutrition and avoidance of substances—such as chemicals—that pollute the body. The techniques are non-invasive.