Human Nutrition in Health and Disease

A disease is any condition which results in the disorder of a structure or function in a living organism that is not due to any external injury. The study of disease is called pathology, which includes the study of cause. Disease is often construed as a medical condition associated with specific symptoms and signs. It may be caused by external factors such as pathogens or by internal dysfunctions, particularly of the immune system, such as an immunodeficiency, or by a hypersensitivity, including allergies and autoimmunity.

Health is the ability of a biological system to acquire, convert, allocate, distribute, and utilize energy with maximum efficiency. The World Health Organization (WHO) defined human health in a broader sense in its 1948 constitution as "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, in particular as lacking operational value, the ambiguity in developing cohesive health strategies and because of the problem created by use of the word "complete", which makes it practically impossible to achieve. Other definitions have been proposed, among which a recent definition that correlates health and personal satisfaction.

Humans (taxonomically Homo sapiens) are the only extant members of the subtribe Hominina. The Hominina are sister of the Chimpanzees with which they form the Hominini belonging to the family of great apes. They are characterized by erect posture and bipedal locomotion; high manual dexterity and heavy tool use compared to other animals; open-ended and complex language use compared to other animal communications; and a general trend toward larger, more complex brains and societies.

Human nutrition deals with the provision of essential nutrients in food that are necessary to support human life and health. Poor nutrition is a chronic problem often linked to poverty, food security or a poor understanding of nutrition and dietary practices. Malnutrition and its consequences are large contributors to deaths and disabilities worldwide. Good nutrition helps children grow physically, promotes human biological development and helps in the eradication of poverty.

Nutrition is the science that interprets the interaction of nutrients and other substances in food in relation to maintenance, growth, reproduction, health and disease of an organism. It includes food intake, absorption, assimilation, biosynthesis, catabolism, and excretion.