Biochemistry

3. Vitamins are not synthesized in the human body, with the exception of some of them. So, vitamins B 6 , B 12 , K, folic acid are formed in the body by the microflora of the colon, vitamin D - under the influence of ultraviolet rays, however, in insufficient quantities. 4. Vitamins are not stored “ in reserve ” . Therefore, these substances must present at every meal. 5. Natural vitamins are the most effective vitamins, not synthetic. This is due to the fact that the composition of the food includes several different vitamins that enhance the physiological effect of each other, as well as stimulants, or stabilizers of their action. Functions of vitamins. Vitamins provide the normal course of biochemical and physiological processes in the body. They participate in the catalysis of metabolic processes, since many of them are contained in the active groups of enzymes. For instance vitamin PP is a coenzyme of dehydrogenases that carry out the first stage of the oxidation of proteins, fats, carbohydrates; vitamin Bj is part of the active group of the enzyme that catalyzes the breakdown of one of the central intermediate metabolic products - pyruvic acid; Vitamin B )2 plays a role in protein synthesis. That is why a lack of vitamins in food or disorder of their assimi lation negatively affects many fundamental metabolic processes. Vitamins have a protective effect, neutralizing the influence of various negative factors. They increase resistance to cold, infectious diseases, physical overload, and give strength in healthy people. Vitamins contribute to the normalization of metabolism, improve the effect of therapeutic agents, neutralize the side effects of drugs, and reduce the effects of radiation in patients. Vitamin deficiency develops in the absence of one or more vitamins in food. There are two degrees of vitamin deficiency: avitaminosis and hypovitaminosis. Avitaminosis is a state of a deep deficiency of any vitamin in the body with a detailed clinical picture of insufficiency (scurvy, beriberi, pellagra, etc.). Hypovitaminosis - a state of the body with an insufficient content of one or more vitamins in food. Hypovitaminoses are more common in late winter and early spring, when the intake of vitamins from food is very limited, since they are destroyed during the storage of food. Hypovitaminosis is distinguishing as primary and secondary. Primary hypovitaminosis is associated with a low content of vitamins in foods, which can occur as a result of the following reasons: 1. Unilateral unbalanced nutrition of predominantly refined foods, inadequate consumption of plant foods. 2. Improper culinary processing of food, leading to the destruction of vitamins. 242