human nutrition
process by which substances in food are transformed into body tissues and provide energy for the full range of physical and mental activities that make up human life.
The study of human nutrition is interdisciplinary in character, involving not only physiology, biochemistry, and molecular biology but also fields such as psychology and anthropology, which explore the influence of attitudes, beliefs, preferences, and cultural traditions on food choices. Human nutrition further touches on economics and political science as the world community recognizes and responds to the suffering and death caused by malnutrition. The ultimate goal of nutritional science is to promote optimal health and reduce the risk of chronic diseases such as cardiovascular disease and cancer as well as to prevent classic nutritional deficiency diseases such as kwashiorkor and pellagra.
This article covers the major issues of human nutrition, such as energy generation and balance, essential nutrients, and recommended dietary guidelines. For a full-length treatment of health problems created by failure in nutrition, see nutritional disease. The utilization of food materials by all living things is described in nutrition, and specific biochemical processes are described in metabolism.
Utilization of food by the body
Calories and kilocalories: energy supply
The human body can be thought of as an engine that releases the energy present in the foods that it digests. This energy is utilized partly for the mechanical work performed by the muscles and in the secretory processes and partly for the work necessary to maintain the body’s structure and functions. The performance of work is associated with the production of heat; heat loss is controlled so as to keep body temperature within a narrow range. Unlike other engines, however, the human body is continually breaking down (catabolizing) and building up (anabolizing) its component parts. Foods supply nutrients essential to the manufacture of the new material and provide energy needed for the chemical reactions involved.
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