The synthesis of protein takes place continuously in accordance with the dynamic state of the system. Proteins, Like other political compounds, are constant degradation and reconstruction. Some amino acids released during the decay of body proteins can be re -used for synthesis. While nitrogen products (usually very toxic to the body) from amino acid particles, which break down are excreted in the urine (np. urea, creatinine) And with sweat, feces or exfoliating epidermis, hair and nails.
The nutritional value of proteins is affected by digestibility and the type and quantitative proportions contained in them of the amino acids. It is primarily about exogenous amino acids, i.e. necessary, whose man or other mammals are unable to synthesize in their own system.
From a nutritional point of view, they are the most critical link in the protein economy in the body. Amino acids that do not belong to the group of necessary system can synthesize, which does not mean, that they are unnecessary in nutrition. They play a very important role as a source, e.g.. nitrogen used for synthesis of various political components. Proteins of the so -called. The amino acid composition close to the amino acid composition of the human system is full.
It is worth emphasizing, that the proteins of many plants meet this condition. It is true, that there are very few protein in most plants, and in cereal products it is defective (Mainly lysine deficiencies), but the proteins of legume seeds such as soy, beans, pea, Beaves are of great value. We also include the potato protein very valuable. Milk proteins, eggs belong to wholesome proteins. The degree of nutritional protein is determined by the ratio of the amount of nitrogen detained in the system to the amount of nitrogen absorbed in the digestive tract. This determination of protein's biological value is only possible by laboratory. For individual purposes, the so -called. chemical score (CS), where the protein of the entire chicken egg was adopted as a pattern (biological value = 100). The biological value of other proteins is determined on the basis of a comparison of their amino acid composition with this pattern. It was currently developed by FAO/WHO (World Organization DS of Food and Agriculture/World Health Organization) A new pattern for the protein amino acid composition. According to this new pattern, the value of plant proteins consumed by vegetarians looks much better. However, you have to remember, that all comparisons to patterns can only give orientation, and approximating the real needs of the body can be very high. Information on the specificity of metabolic changes of the proteins of individual human systems is also increasingly provided in literature. The deficit of a full -fledged protein for adults in Poland is hardly present. However, negative effects of excess animal protein are observed, Especially in the etiology of cancer.