Proper nutrition determines the processes of human growth and development, the body?s resistance to the adverse effects of environmental factors, mental and physical performance, life expectancy and its quality. The actual nutritional status of the population reflects the result of the socioeconomic development of society and at the same time acts as a factor affecting this development. Nutrition affects both ontogenesis and the direction of human phylogenetic development.
Hygienic measures for the prevention of alimentary-dependent diseases are based on modern knowledge about the essence of metabolic processes and maintaining homeostasis.
Absorption (assimilation) of nutrients in the human digestive tract is carried out by the inclusion of the mechanisms of cavity (extracellular) and membrane digestion in the form of monomers without specificity - amino acids, monosaccharides, and fatty acids. In addition to nutrients, vitamins, minerals, hormones, and other physiologically active compounds, waste products of the intestinal microflora and foreign substances (xenobiotics) also take part in the assimilation process.
Maintaining a constant internal environment is the most important prerequisite for normal metabolism in the body. Even with a random choice of food products when the amount and ratio of nutrients vary significantly, the composition of the nutrients entering the internal environment varies slightly. In the small intestine along with the transport of substances from its cavity to the blood, an oppositely directed flow constantly exists from the blood to the cavity.
An increase in the content of any component in the diet affects the absorption of not only this but also other components. So, increasing the concentration of carbohydrates increases the absorption of all other substances. An increase in the content of fats and nitrogenous substances is accompanied by an increase in the absorption of only them and a slight decrease in the absorption of other components.