Holism (from Greek ὅλος holos "all, whole, entire") is the idea that various systems (e.g. physical, biological, social) should be viewed as wholes, not merely as a collection of parts. The term "holism" was coined by Jan Smuts in his 1926 book Holism and Evolution.
The exact meaning of "holism" depends on context. Smuts originally used "holism" to refer to the tendency in nature to produce wholes from the ordered grouping of unit structures. However, in common usage, "holism" usually refers to the idea that a whole is greater than the sum of its parts. In this sense, "holism" may also be spelled "wholism", and it may be contrasted with reductionism or atomism.
The term holistic when applied to diet or medical health refers to intuitive approach to food, eating, or lifestyle. One example is in the context of holistic medicine, "holism" refers to treating all aspects of a person's health, including psychological and societal factors, rather than only his/her physical conditions or symptoms. In this sense, holism may also be called "holiatry". Several approaches are used by medical doctors, dietitians, and religious institutions, usually recommended based on an individual basis. Adherents of religious institutions, that practice a holistic dietary and health approach, have been shown have longer lifespans than those of surrounding populations, including Ayurveda, Shinto, and the Seventh-Day Adventist Church.