Nutrition
This is a part of the organism’s metabolism, the intake of food from the environment, its breakdown, processing, and consumption; one of the most important signs of life. Nutrition provides energy to sustain life, develop the body, grow, reproduce, and perform work.
All living organisms in nature are closely related by nutritional relationships and form the so-called food chain. It starts with producers (organism producers). These are green plants and chemosynthetic bacteria. Producers are the primary source of energy, which is used by consumers (consumer organisms) in subsequent chains, consuming organic matter. These are herbivorous animals and plant parasites (1st order consumers), carnivorous animals feeding on herbivores (2nd order consumers), and carnivorous animals feeding on other carnivores (3rd order). The food chain ends with decomposers that decompose dead organisms.
Human nutrition is of great importance for a child’s growth and development, an adult’s productivity, health, longevity, and active life span, as well as the body’s adaptation to the environment. Inadequate nutrition disrupts the functions of organs and their systems, leading to the deterioration of the organism. Overeating leads to obesity, promotes diabetes, atherosclerosis, ischemic heart disease. Rational nutrition is when a person receives the necessary amount of substances essential for normal body function. Its basis is the principle of balanced nutrition, i.e. the optimal ratio of consumed food components. Nutrition norms, regimen, and variety are also important. The body’s energy is generated by the oxidation of food substances; it is measured in kilocalories (kcal) or joules (J). The amount of food substances (nutrients) consumed per day constitutes a diet. It is regulated based on a person’s age, sex, and occupation. A person engaged in mental or light physical work needs about 2200 kcal per day on average.
Source | Glossary of Most Commonly Used Biomedical Terms and Concepts | Lithuanian University of Health Sciences | Academician Professor Antanas Praškevičius, Professor Laima Ivanovienė