This series covers positions that advise on, administer, supervise, or perform work in human nutrition requiring the application of professional knowledge of dietetics or nutrition directed toward the maintenance and improvement of human health. Dietetics is an essential component of the health sciences, usually with emphasis on providing patient care services in hospitals or other treatment facilities. The work of the dietitian includes food service management, assessing nutritional needs of individuals or community groups, developing therapeutic diet plans, teaching the effects of nutrition on health, conducting research regarding the use of diet in the treatment of disease, or consulting on or administering a dietetic program. Nutrition is the science of food and nutrients, their uses, processes, and balance in relation to health and disease. The work of nutritionists emphasizes the social, economic, cultural, and psychological implications of food usually associated with public health care services or with food assistance and research activities. The work includes directing, promoting, and evaluating nutritional components of programs and projects; developing standards, guides, educational and informational material for use in Federally funded or operated nutrition programs; participating in research activities involving applied or basic research; or providing training and consultation on nutrition.