1. I. NTRODUUTION
1.1. Definition Human Nutrition
A deﬁnition of a nutrient is any chemical substance that can be used by an organism to sustain its metabolic activities. These metabolic activities in humans and other animals include the provision of energy, growth, renewal of tissues, reproduction and lactation. Human nutrition is a 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 (Burnett, 1989).
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 (Fieldhouse, 1986).
The selection, processing and manner of eating food will be strongly influenced by what is available and by the history, social stability and economy of the community. What and how a person eats is significantly affected by their family background and traditions, although travel is increasingly changing food choices. War, pestilence and famine can restrict food availability, and food may also be contaminated by pollutants from the environment. Being able to eat optimal amounts is dependent on agriculture and the political, educational and social organization in which the person lives. The chemical substances should be available in optimal amounts and in an attractive form for metabolism. Nutrition identifies measures and recommends optimal dietary intakes of the nutrient chemicals in health and disease (Fieldhouse, 1986).
All living creatures require a range of dietary chemicals for metabolism, growth and activity. These chemicals are obtained from a range of sources. The digestion, absorption and metabolism of ingested nutrients are determined in each individual by many factors, including inherited constitution, gender, age, activity, growth, fecundity and lactation.
A person needs an adequate energy intake as well as essential nutrients to provide for the needs and control of a genetically determined constitution (genome), which dictates protein and enzyme structure and hence metabolism. This brings nutrition to a central role in the story. The synthesis, maintenance, functioning and control of the protein complex and hence overall metabolism rely on ingested nutrients (WHO, 1998).
1.2. Research Problem