Health professionals maintain people health through the application of the principles and procedures of evidence-based medicine and caring. Health professionals study, diagnose, treat and prevent illness, injury and other physical and mental impairments in accordance with the needs of the populations they serve. They advise on or apply preventive and curative measures, and promote health with the ultimate goal of meeting the health needs and expectations of individuals and populations, and improving population health outcomes. They also conduct research and improve or develop concepts, theories and operational methods to advance evidence-based health care.
Cited from Transformative Education for Health professionals: http://whoeducationguidelines.org/content/1-definition-and-list-health-professionals