Health science is the branch of science focused on health. There are two main approaches to health science: the study and research of the body and health-related issues to understand how humans (and animals) function, and the application of that knowledge to improve health and to prevent and cure diseases and other physical and mental impairments. The science builds on many sub-fields, including biology, biochemistry, physics, epidemiology, pharmacology, medical sociology. Applied health sciences endeavor to better understand and improve human health through applications in areas such as health education, biomedical engineering, biotechnology and public health.
In 1989 and 2003, the Vatican issued two documents: Aspects of Christian meditation and "A Christian reflection on the New Age," that were mostly critical of eastern and New Age practices. The 2003 document was published as a 90-page handbook detailing the Vatican's position. The Vatican warned that concentration on the physical aspects of meditation "can degenerate into a cult of the body" and that equating bodily states with mysticism "could also lead to psychic disturbance and, at times, to moral deviations." Such has been compared to the early days of Christianity, when the church opposed the gnostics' belief that salvation came not through faith but through a mystical inner knowledge. The letter also says, "one can see if and how [prayer] might be enriched by meditation methods developed in other religions and cultures" but maintains the idea that "there must be some fit between the nature of [other approaches to] prayer and Christian beliefs about ultimate reality." Some[which?] fundamentalist Christian organizations consider yoga to be incompatible with their religious background, considering it a part of the New Age movement inconsistent with Christianity.
Health, as defined by the World Health Organization (WHO), is "a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity." This definition has been subject to controversy, as it may have limited value for implementation. Health may be defined as the ability to adapt and manage physical, mental and social challenges throughout life.