Retinol (vitamin A) is found in foods of animal origin.

Retinol (vitamin A) is found in foods of animal origin. Rich in this vitamin is butter, egg yolk, cow's milk, liver, fish oil, especially a lot of retinol in the liver of some fish ( halibut, cod, sea bass ) and marine animals ( whale, walrus, seal ). In the plant world, vitamin A is not found, its pro-vitamins are widely distributed - carotene pigments found in many plants - carrots, spinach, lettuce, parsley, green onions, sorrel sour, red pepper, black currant, dogrose, blueberry, gooseberry, tomatoes, peaches , Apricots, etc. Vitamin A is formed from carotene in the body.

Group retinolov - complex unstable organic compounds, consisting of 20 carbon atoms, it is fat-soluble vitamins. Retinol and carotene are destroyed by exposure to atmospheric oxygen, sunlight and elevated temperature accelerate this process. The daily requirement of the adult body in retinol is 1.5-2.5 mg, or 4.5 mg of carotene per day. Half of the daily requirement for vitamin A is covered by animal products, and the rest is recovered from vegetable products containing provitamin A - carotene.

The biological activity of carotenes depends on their origin and processing before consumption. Retinol is of great importance for nutrition and the preservation of human and animal health. It has a beneficial effect on the metabolism, growth and development of the body, the function of lacrimal, sweat and sebaceous glands, participates in the formation of visual pigment, ensures normal activity of the organ of vision, increases resistance to infections, poisons and toxins, supports the functions of the epithelium of the skin and mucous membranes. Vitamin A is also called an antioxidant-ophthalmic, anti-infective vitamin that protects the epithelium.

Retinol is formed from carotenes in the intestinal wall, but is converted and stored in the liver, which contains 80-90% of the total amount of this vitamin in the body, the rest of the vitamin A is distributed to other organs. Retinol takes part in the synthesis of hormones of the adrenal cortex and gonads, positively influences the regeneration of skin epithelium and the reproduction processes.

Deficiency of retinol in the body is accompanied by dryness and pallor of the skin, fragility of the hair and nails, degenerative changes in the mucous membranes, damage to the eye, increased fatigue, exhaustion, growth retardation in children, impaired functions of the nervous system and glands (lacrimal, sebaceous, sweat) Etc. The lack of vitamin A in the food causes keratinization of the skin, dryness of the mucous membranes, tear ducts are clogged, dry eyes (xerophthalmia) occur with subsequent damage to the cornea and complete loss of vision. Retinol is a part of the photosensitive substance in the retina of the eyes, with a deficiency of the vitamin, a slow restoration occurs to the norm of rhodopsin (visual purpura), which is decomposed under the influence of light, is related to retinol. As a result, there is gemeralopia (night blindness) - loss of visual acuity, especially at dusk, when a person who sees well in the day, sharply deteriorates vision with the onset of darkness.

There is a loss of orientation, fuzzy visibility of objects, reminiscent of a photograph on a low-sensitivity film with a short exposure. Hypervitaminosis A leads to a disorder in the hormonal function of the adrenal glands, because the mineralocorticoids they produce negatively affect water-salt metabolism, disrupting the normal ratio of potassium-sodium in erythrocytes and blood plasma. The lack of vitamin A in the body is accompanied by intensive formation of stones in the kidneys and bladder.

As a remedy, retinol and its drugs are used for A-avitaminosis, hypovitaminosis, atherosclerosis, hypertension, hyperthyroidism (goitre), eye diseases (pigment retinitis, hemorrhagia, keratomalacia, xerophthalmia), skin diseases (frostbite, burns, wounds, keratosis, ichthyosis, Psoriasis, tuberculosis, some forms of eczema), digestive organs (chronic gastritis, liver cirrhosis, inflammatory and erosive ulcerous intestinal lesions). Retinol accelerates recovery for colds, tracheitis, bronchitis, chronic respiratory diseases, pneumonia and certain infections (tuberculosis, measles, whooping cough, dysentery), helps with malignant tumors; It needs people whose work is connected with a constant voltage of vision: the drivers of transport (tram, trolley, taxi), pilots, machinists, typesetters, proofreaders working in the evening and at night.

Retinol dissolves only in fats and fat solvents, with the usual cooking of products is preserved, and when drying is lost in a significant amount, like carotene. Vitamin A is used to prevent the formation of concrements in the biliary and urinary tracts, it is prescribed inside (single dose for adults - 35-50 000, for children - 5000 IU), intramuscularly and externally (solutions in oil).

Taking large doses of retinol can cause an exacerbation of cholelithiasis and chronic pancreatitis. A-avitaminosis is a systemic disease that affects the entire body, mainly all epithelial integuments. The daily dose of retinol (2-3 mg) is contained in 6 g of fish oil, 7 g of beef liver, 170 g of butter, half of the chicken egg. The drugs used are retinol - retinol acetate, retinol palmitate, vitamin A concentrate, fish oil (normal and vitaminized), Aevit.