True vitamin a. Consequences of hypovitaminosis A

Good day, dear visitors of the project “Good IS!” ", section " "!

In today's article I will tell you about such a useful and essential vitamin for a person like Vitamin A, as well as its significance in our Everyday life. So…

Vitamin A , aka "Retinol" - a fat-soluble antioxidant necessary for good vision, bones, healthy skin, hair, and the functioning of the immune system.

Vitamin A got its name because it was the first to be discovered. vitamin group, in 1913 by two independent groups of scientists (McCollut - Davis and Osborne).

Vitamin A participates in redox processes, regulation of protein synthesis, promotes normal metabolism substances, functions of cellular and subcellular membranes, plays important role in the formation of bones and teeth, as well as fat deposits. Necessary for the growth of new cells, slows down the aging process. Vitamin A is pale yellow in color and is produced from the red plant pigment beta-carotene.

Retinol does not dissolve in water, because... It is fat soluble, so it requires fats to be absorbed by the digestive tract, as well as minerals. Vitamin A stores remain in the body long enough that you don't need to replenish your reserves every day.

There are two forms of this vitamin:

— ready-made vitamin A (retinol);
- provitamin A (carotene), which in the human body is converted into vitamin A, so it can be considered plant form vitamin A.

Vitamin A is involved in redox processes, regulation of protein synthesis, promotes normal metabolism, the function of cellular and subcellular membranes, plays an important role in the formation of bones and teeth, as well as fat deposits; necessary for the growth of new cells, slows down the aging process.

Vitamin A supports night vision by producing a pigment called rhodopsin, which can detect minimal light, which is very important for night vision. It also helps to moisturize the eyes, especially the corners, protecting them from drying out and subsequent injury to the cornea.

Vitamin A is essential for the normal functioning of the immune system and is an integral part of the process of fighting infection. The use of retinol increases the barrier function of mucous membranes, increases the phagocytic activity of leukocytes and other factors not specific immunity. Vitamin A protects against and infections respiratory tract, digestive tract, urinary tract. The presence of vitamin A in the blood is one of the main factors responsible for the fact that children in more developed countries suffer infectious diseases such as much more easily, while in countries with low level life is much higher mortality from these “harmless” viral infections. Providing vitamin A prolongs the life of even AIDS patients.

Retinol is necessary for the maintenance and restoration of epithelial tissues that make up the skin and mucous membranes. It’s not for nothing that in almost all modern cosmetics it contains retinoids - its synthetic analogues. Indeed, vitamin A is used in the treatment of almost all skin diseases (acne, etc.). In case of skin damage (wounds, sunburn), vitamin A accelerates the healing process and also stimulates collagen synthesis, improves the quality of newly formed tissue and reduces the risk of infections.

Due to its close relationship with mucous membranes and epithelial cells, vitamin A has beneficial effects on lung function and is also a worthwhile addition in the treatment of certain diseases gastrointestinal tract(ulcers,).

Retinol is necessary for normal embryonic development, nutrition of the fetus and reducing the risk of pregnancy complications such as low birth weight of the newborn.

Vitamin A takes part in the synthesis of steroid hormones (including progesterone), spermatogenesis, and is an antagonist of thyroxine hormone thyroid gland.

Both vitamin A and β-carotene (beta-carotene), being powerful antioxidants, are means of prevention and treatment, in particular, preventing the reappearance of tumors after surgery.

Both vitamin A and β-carotene protect brain cell membranes from destructive action free radicals, while β-carotene neutralizes the most dangerous species free radicals: radicals polyunsaturated acids and oxygen radicals.

The antioxidant effect of β-carotene plays an important role in the prevention of heart and artery diseases, it has protective effect in patients, and also increases the level of “good” cholesterol (HDL) in the blood.

Lutein and zeaxentin are the main carotenoids that protect our eyes: they help prevent and also reduce the risk of degeneration macular spot (the most important body vision), which in every third case is the cause of blindness.

Another carotenoid - lycopene (found mainly in tomatoes) protects against oxidation and accumulation of low-density cholesterol on the walls of arteries. In addition, it is the most powerful carotenoid in terms of protection against cancer, especially breast, endometrial and prostate cancer.

- for adults 800-1000 mcg;
- for pregnant women 1000-1200 mcg;
— for nursing mothers 1200-1400 mcg;
- for children, depending on age and gender, 400-1000 mcg.

For diseases associated with retinol deficiency, the dosage can be increased to the upper permissible consumption threshold - 3000 mcg.

It should be noted that hard work, illness or disease require a sharp increase in vitamin A in the diet - however, the same can be said about many vitamins and. Climatic conditions also matter: in a temperate or even cold climate, there is no need to increase vitamin A standards, but in a hot, sunny climate, much more is needed, so those who like to holiday in warm countries should pay closer attention to their diet.

It is known that vitamin A accumulates in the liver, but its reserves there are sharply reduced after a procedure such as an x-ray examination.

Symptoms of Vitamin A Deficiency

- dry skin, appearance of wrinkles;
- increased sensitivity of tooth enamel;
- decreased immunity;
— ;
- weakened erection;
— ;
— exhaustion;
- respiratory infections;
- blurred vision;
- poor night vision (night blindness);
- dry conjunctiva of the eye;
- growth disorders in children.

Symptoms of vitamin A overdose

- bleeding gums;
— ;
— ;
- dry skin;
— ;
— ;
— Spontaneous abortions and fetal malformations are possible in pregnant women.

Vegetable: Green and yellow vegetables (carrots, pumpkin, Bell pepper, spinach, broccoli, green onions, parsley), legumes (soybeans, peas), peaches, apricots, apples, grapes, watermelon, melon, sea buckthorn, cherries; herbs (alfalfa, borage leaves, burdock root, cayenne pepper, fennel, hops, horsetail, kelp, lemongrass, mullein, oats, parsley, raspberry leaves, clover, bearberry, violet leaves, sorrel).

Animals: Fish oil, liver (especially beef), caviar, milk, butter, margarine, sour cream, cottage cheese, cheese, egg yolk.

Synthesis in the body: Formed as a result of the oxidative breakdown of β-carotene.

The best sources of vitamin A are fish oil and liver, followed by butter, egg yolk, cream and whole milk. Cereal products and skim milk, even with vitamin supplements, are unsatisfactory sources, as is beef, which contains negligible amounts of vitamin A.

Active ingredient: retinol acetate (vitamin A-acetate);
1 ml of the drug contains retinol acetate (vitamin A-acetate), in terms of 100% retinol acetate - 34.4 mg (100,000 ME);
Excipient: refined deodorized sunflower oil, grade “P”, frozen.

Description

clear oily liquid from light yellow until dark yellow, without rancid odor.

pharmachologic effect

Pharmacodynamite. Vitamin A (retinol) belongs to the group fat-soluble vitamins. The drug Retinol acetate is an analogue natural vitamin And it is necessary to restore normal concentrations of retinol in the body. Vitamin A plays an important role in the synthesis of proteins, lipids, mucopolysaccharides, and regulates the balance of minerals.
The most specific function of vitamin A is to support vision processes (photoreception). Retinol is involved in the synthesis of visual purple - rhodopsin, located in the retinal rods.
Vitamin A modulates differentiation processes epithelial cells, participates in the development of secretory glands, keratinization processes, regeneration of mucous membranes and skin.
Vitamin A is essential for normal functioning endocrine glands and growth of the body, because it is a synergist of somatomedins.
Vitamin A influences the division of immunocompetent cells, the synthesis of specific (immunoglobulin) and nonspecific (interferon, lysozyme) factors that protect the body from infectious and other diseases, and stimulates myelopoiesis.
Retinol increases the level of glycogen in the liver, stimulates the production of trypsin and lipase in the digestive system; inhibits photochemical free radical reactions and cysteine ​​oxidation; activates the inclusion of sulfates in components connective tissue, cartilage, bones; satisfies the need for sulfocerebrosides and myelin, ensuring the conduction and transmission of nerve impulses.
With a lack of vitamin A, twilight vision impairment (night blindness) and atrophy of the epithelium of the conjunctiva, cornea, and lacrimal glands develop. Degenerative-dystrophic processes are observed in the respiratory tract (mucous membranes of the nasopharynx, paranasal sinuses, trachea, bronchi), in the genitourinary system (epithelium of the renal pelvis, ureters, Bladder, urethra, vagina, ovaries, fallopian tubes and endometrium, seminal vesicles and cords, prostate gland), in the digestive system (mucosa of the digestive tract, salivary glands, pancreas). Vitamin A deficiency leads to impaired skin trophism (hyperkeratosis), deterioration in the growth and quality of hair and nails, as well as the function of sebaceous and sweat glands. In addition, there is a decrease in body weight and slower bone growth, a decrease in the synthesis of glucocorticoids and steroid hormones, and a violation of the body's resistance to infectious and other diseases. There is a tendency to cholelithiasis and nephrolithiasis.
A deficiency or excess of vitamin A in a woman’s body can lead to abnormalities in the intrauterine development of the fetus.
Retinol has an antitumor effect that does not apply to non-epithelial tumors.

Pharmacokinetics

Retinol acetate taken orally is well absorbed into upper sections small intestine. Then, as part of chylomicrons, it is transported from the intestinal wall to lymphatic system and enters the bloodstream through the thoracic duct. Transport of retinol esters in the blood is carried out by p-lipoproteins. The maximum level of vitamin A esters in the blood serum is observed 3 hours after administration. The place of deposition of vitamin A is the liver parenchyma, where it accumulates in stable ether forms. In addition, a high content of vitamin A is determined in the retinal pigment epithelium. This depot is necessary for the regular supply of vitamin A to the outer segments of rods and cones.
The biotransformation of retinol takes place in the liver, and then it is excreted by the kidneys in the form of inactive metabolites. Retinol may be partially excreted in the bile and participate in the enterohepatic circulation. Elimination of retinol occurs slowly - 34% of the drug dose is eliminated from the body in 3 weeks.

Indications for use

Hypo-, vitamin deficiency A.
In complex therapy of diseases accompanied by increased need in vitamin A:
- infectious and inflammatory diseases, including acute respiratory diseases;
- lesions and skin diseases (frostbite and first degree burns, ichthyosis, hyperkeratosis, seborrheic dermatitis, neurodermatitis, some forms of eczema);
- eye diseases (retinitis pigmentosa, hemeralopia, xerophthalmia, keratomalacia), eczematous lesions of the eyelids;
- gastrointestinal diseases accompanied by impaired absorption of vitamin A (gastrectomy, diarrhea, steatorrhea, celiac disease, Crohn's disease, malabsorption syndrome).

Contraindications

Hypersensitivity to the components of the drug, acute and chronic nephritis, heart failure in the stage of decompensation, cholelithiasis, chronic pancreatitis, hypervitaminosis A, retinoid overdose, hyperlipidemia, obesity, sarcoidosis (including a history), chronic alcoholism. Acute inflammatory diseases skin, pregnancy, childhood up to 7 years. With caution: liver cirrhosis, viral hepatitis, jade, renal failure, elderly age.

Directions for use and doses

Retinol acetate is prescribed orally 10-15 minutes after meals and externally. 1 drop from an eye dropper contains about 3,000 IU of vitamin A. 1 ml of the drug contains 100,000 IU of vitamin A. When determining doses of the drug, it is assumed that a single dose of vitamin A is no more than 50,000 IU for adults, for children over 7 years of age - 5 LLC ME. Higher daily dose for adults it is 100,000 ME, for children - 20,000 ME.
Therapeutic doses of vitamin A for mild and moderate avitaminosis are for adults - up to 33,000 IU per day. For skin diseases, the daily dose of vitamin A for adults is 50,000-100,000 IU, for children - 5,000-10,000-20,000 IU. For retinitis pigmentosa, xerophthalmia, hemeralopia, the daily dose for adults is 50,000-100,000 IU (riboflavin is prescribed at the same time in a daily dose of 20 mg). For lesions skin
(ulcers, burns, frostbite, etc.) the affected areas after hygienic cleaning are lubricated with a solution of Retinol acetate and covered with a gauze bandage (5-6 times a day, with the number of applications decreasing to one as epithelialization occurs). At the same time, the drug is prescribed orally. IN pediatric practice, for children over 7 years of age with complex therapy of rickets, acute respiratory diseases occurring against the background of exudative diathesis, acute and chronic bronchopulmonary diseases, malnutrition and collagenosis, the drug is prescribed after meals, 1 drop per day.
For children under 7 years of age, the drug is prescribed in a different dosage form.

Side effect

Long-term intake of large doses of vitamin A can cause the development of hypervitaminosis A.
From the outside nervous system and sensory organs: fatigue, drowsiness, lethargy, irritability, headache, loss of sleep, convulsions, discomfort, intraocular hypertension, visual impairment.
From the digestive system: loss of appetite, weight loss, nausea, very rarely - vomiting.
Possible exacerbation of liver diseases, increased activity of transaminases and alkaline phosphatase.
From the urinary system: pollakiuria, nocturia, polyuria.
From the outside hematopoietic system: hemolytic anemia.
From the outside musculoskeletal system: changes in bone radiographs, gait disorder, pain in the bones of the lower extremities.
Allergic reactions: cracks in the skin of the lips, yellow-orange spots on the soles, palms, in the area of ​​the nasolabial triangle, subcutaneous swelling, in some cases, an itchy maculopapular rash may occur on the first day of use, which requires discontinuation of the drug, itching, erythema and rash, dry skin, dry mouth, fever, facial flushing followed by peeling.
Others: hair loss, menstrual irregularities, abdominal pain, aphthae, photosensitivity, hypercalcemia.
With a dose reduction or temporary discontinuation of the drug side effects pass on their own.
For skin diseases, the use of high doses of the drug after 7-10 days of treatment may be accompanied by an exacerbation of local inflammatory reaction, which does not require additional treatment and subsequently weakens. This effect is associated with the myelo- and immunostimulating effects of the drug.
If any adverse reactions Consult your doctor regarding further use of the drug!

Overdose

Symptoms of overdose: dizziness; confusion, diarrhea, severe dehydration, irritability; generalized rash followed by large-layer peeling starting from the face; bleeding gums, dryness and ulceration of the oral mucosa, peeling lips, sharply painful palpation of long tubular bones due to subperiosteal hemorrhages.
Acute and chronic hypervitaminosis A is accompanied by severe headache, fever, drowsiness, vomiting, blurred vision (double vision), dry skin, pain in the joints and muscles, the appearance age spots, an increase in the size of the liver and spleen, jaundice, changes in the blood picture, loss of strength and appetite. In severe cases develop seizures, cardiac weakness and hydrocephalus. Treatment. Treatment is symptomatic, thyroxine is prescribed as an antagonist, the use of ascorbic acid, vitamin E.

Interaction with other drugs

If you are taking any other medications, be sure to tell your doctor!
Estrogens increase the risk of developing hypervitaminosis A.
Retinol acetate reduces the anti-inflammatory effect of glucocorticoids.
Retinol acetate should not be taken simultaneously with nitrates and cholestyramide, as they interfere with the absorption of the drug.
Retinol acetate should not be used with other vitamin A derivatives due to the risk of overdose and the development of hypervitaminosis A.
The combination with vitamin E promotes the preservation of retinol acetate in its active form, absorption from the intestines and anabolic effects.
The simultaneous use of Vaseline oil may interfere with the absorption of the vitamin in the intestines.
The simultaneous use of vitamin A and anticoagulants increases the tendency to bleeding. Isotretinoin increases the risk of toxic effects when taken concomitantly.

Features of application

Before starting treatment, consult your doctor!
When using the drug, you must adhere to the doses recommended by your doctor!
The drug is taken under the supervision of a doctor. At long-term use Retinol acetate must be monitored for biochemical parameters and blood clotting time.
When treating twilight vision impairment (night blindness), Retinol acetate should be used with riboflavin and nicotinic acid.
Use with caution in case of severe damage to the hepatobiliary system, diseases accompanied by blood clotting disorders.
It is not recommended to use the drug during long-term therapy tetracyclines.
Retinol should be taken 1 hour before or 4-6 hours after taking cholestyramine. The drug tends to accumulate and remain in the body for a long time. Women who took high doses retinol, you can plan a pregnancy no earlier than 6-12 months later. This is due to the fact that during this time there is a risk of abnormal development of the fetus under the influence of high levels of vitamin A in the body.
For normal absorption of vitamin A a necessary condition is the presence of fats in food. Abuse of alcohol and tobacco interferes with the absorption of the drug from the digestive tract.
The drug contains butylated hydroxytoluene.
Use during pregnancy or breastfeeding. Due to the high dose of vitamin A, this drug is contraindicated for oral administration during pregnancy and lactation.
The ability to influence the reaction rate when driving a vehicle or working with other mechanisms. There is no data on the effect of the drug on the ability to drive a car or operate complex machinery.
Children. The drug is prescribed to children aged 7 years and older.

Release form

10 ml of 3.44% solution in glass bottles; 1 bottle in a cardboard pack.

Storage conditions

Store in original packaging in the refrigerator (at temperatures from + 2 °C to + 8 °C).

Should not be used medicine after the expiration date indicated on the packaging.Keep out of the reach of children.

Best before date

Shelf life - 2 years.

Conditions for dispensing from pharmacies

Without a doctor's prescription.

Retinol Acetate (vitamin a) analogues, synonyms and group drugs

Self-medication can be harmful to your health.
You should consult your doctor and read the instructions before use.

Vitamin A (Retinol) is a representative of the class of fat-soluble vitamins that can accumulate in the body. Essential for vision and bone growth, healthy skin and hair, normal operation immune system, etc. In its pure form it is unstable and is found in both plant products and animal sources.

Vit. A was discovered in 1913. Then two groups of scientists, independently of each other, found that the yolk of a chicken egg and butter contain a certain substance that stimulates the growth of animals.

After this, during the First World War, numerous cases of xerophthalmia and keratophthalmia, dryness and pathological keratinization of the sclera and cornea of ​​the eyes were described. At the same time, the relationship of these diseases with a deficiency of butter in the diet was noted.

The substance isolated from butter was initially designated as fat-soluble factor A. Later, in 1916, it was renamed vit. A. In 1921, signs of vitamin A deficiency were described, in 1931 the structure of the vitamin was described, and in 1937, vit. A was obtained in crystalline form.

Varieties

In addition to Retinol Vit. A includes a group of vitamers, substances similar in chemical composition and by the effect it produces. These substances are called retinoids. In addition to Retinol (vit. A 1), this includes its derivatives:

• Retinal is the aldehyde form of vit. A 1
• 3-dehydroretinol (Vit. A 2) – trans-isomer of Retinol
• 3-dehydroretinal is the aldehyde form of vit. A 2
• Retinoic acid is the acidic form of vit. A 2
• Retinyl acetate, retinyl palmitate are ether derivatives of Retinol.

These are just the basic forms. Along with them, there are many other retinoids that occur naturally or are formed in the body of humans and mammals during metabolic reactions. The functions of many of them remain poorly understood. Based on the name of the main component, A 1, this vitamin is usually called Retinol.

Physical properties

The chemical name of Retinol is trans-9,13-Dimethyl-7-(1,1,5-trimethylcyclohexen-5-yl-6)-nonatetraen-7,9,11,13-ol (as palmitate or acetate). Formula – C 20 H 30 O. Given chemical compound It is a yellowish prismatic crystal with a specific odor and a melting point of 64 0 C.

It dissolves well in fatty substances and other organic solvents - ethyl and methyl alcohols, dicyclohexanes, dichloroethanes. Practically insoluble in water. Unstable during external environment– is destroyed by atmospheric oxygen and solar ultraviolet radiation. Other substances from the retinoid group have similar properties.

Physiological action

• Metabolism

With its participation, many redox reactions are carried out in the body. It regulates all types of metabolism. It stimulates protein biosynthesis and activates many enzyme systems.

• Immunity

Retinol is an excellent immunomodulator. It enhances the phagocytic activity of leukocytes, stimulates the production of antibodies, and participates in the synthesis of interferon and lysozyme. Thus, it strengthens the immune system and increases the body’s resistance to many types of bacterial and viral infections. It is also an excellent antioxidant that prevents free radical damage to tissues. Antioxidant and immunostimulating effects lead to the fact that atypically changed cells are recognized in time, destroyed, and cancerous tumors do not develop.

• Skin and mucous membranes internal organs

Vitamin A normalizes the growth and division of epithelial cells and prevents excessive keratinization. Also stimulates collagen synthesis. As a result, the barrier resistance of the mucous membranes of the respiratory system, gastrointestinal tract and genitourinary system to the action of pathological agents. Under its action, the skin becomes elastic, without wrinkles, swelling, age spots and other signs of aging.

• The cardiovascular system

Reduces the formation of low-density cholesterol, which is responsible for the formation of atherosclerotic plaques. Being an antioxidant, it prevents sclerotic and dystrophic changes in the myocardium.

• Musculoskeletal system

Increases the strength of ligaments, bones, cartilage. Promotes bone growth in length.

• Endocrine system

Retinol is involved in the synthesis of adrenal and sex hormones. It also reduces the level of thyroxine when it is overproduced by the thyroid gland.

• Reproductive system

In men it stimulates spermatogenesis, in women it ensures the normal course of the menstrual cycle. During pregnancy, this vitamin, along with other factors, shapes growth and proper development fetus

• Visual system

It has a tremendous impact on the state of the visual analyzer. Retinal is part of Rhodopsin. This visual pigment provides light sensitivity to the rod receptors of the fundus. Retinol's precursors, carotenoids, moisturize the cornea and sclera, preventing their pathological keratinization (hyperkeratosis) and the development of cataracts. This vitamin also maintains the function of the macula, the place of greatest visual perception of the retina.

Daily requirement

Categories	Norm, mcg	Norm, IU
Infants up to 6 months.	400	1333
Infants from 6 months. up to 1 year	500	1667
Children 1-3 years old	300	1000
Children 4-8 years old	400	1333
Children 9-13 years old	600	2000
Teenagers over 14 years of age and adult men	1000	3300
Teenage girls over 14 years old and adult women	800	2667
Pregnant women	200-800	667-2667
Breastfeeding women	400-1200	1333-4000
Elderly and old people	800	2667

In this table, IU are international units that reflect the activity of the drug. As for Vit. And, here 1 IU corresponds to 0.3 mcg.

Signs of Deficiency

A typical manifestation of vitamin A deficiency is the so-called night blindness or hemeralopia, deterioration of twilight vision. Also on the part of the eyes, keratomalacia and xerophthalmia will be noted, manifested by softening, dryness of the cornea, redness of the sclera with pathological lacrimation. In this case, visual acuity will be reduced, and cataracts will often form.

The skin is dry, flaky, with an unhealthy color, pustular rash and reduced elasticity. Such skin creates favorable conditions for various dermatitis, psoriasis, and eczema.

The barrier function of the mucous membranes of internal organs decreases. In combination with low immunity, this will be accompanied frequent bronchitis, pneumonia, erosive-inflammatory processes in the gastrointestinal tract, inflammation of the genitourinary system with urinary incontinence.

Suffering reproductive system– the menstrual cycle in women is disrupted, men complain of erectile dysfunction and early ejaculation. Male and female infertility often occurs.

Appears general weakness, increased fatigue, drowsiness during the day and insomnia at night. On the mental side, unmotivated irritability, anxiety and depression are noted. Danger increases malignant tumors, especially breast cancer, and in smokers and those who often suffer from colds - lung cancer.

Predisposes to deficiency:

• lack of intake of Retinol and carotenoids from food
• diseases of the gastrointestinal tract in which its absorption is impaired
• shortage of others nutrients, in particular, zinc, Vit E (Tocopherol), Vit B 4 (Choline).

Vitamin deficiency, as a rule, develops with a combination of these unfavorable factors.

In addition, some conditions increase the need. This:

• physical exercise
• psycho-emotional stress
• period of growth and puberty
• X-ray studies
• taking cholesterol-lowering medications
• diabetes
• staying in an area with a hot climate
• increased load on visual analyzer (long sitting at the computer, at the TV)
• alcohol abuse
• pregnancy and breastfeeding.

Vitamin A rich foods

Retinol enters the body with food. Contents vit. And in 100 g of food products:

Product	Amount, mcg/100 g
Fish fat	25000
Cod liver	30000
Turkey liver	8000
Beef liver	6500
Chicken liver	3300
Sweet bell red pepper	2100
Green pepper	18
Carrot	830
Broccoli	800
Butter	680
Milk	30
Chicken eggs	140
Green salad	550
Cheese	265
Tomatoes	40
Green pea	38

It's easy to see that greatest number vit. And it is found in animal products, while there is not so much of it in greens and vegetables. Although you should not rely entirely on the data from the table. The fact is that in most well-known products, vitamin A is not represented by Retinol, but by its predecessors, provitamins, carotenoids.

These substances include alpha, beta and gamma carotene. The most active of them is beta-carotene. This is a natural pigment of bright red color, which is transformed during metabolic processes.

There is especially a lot of beta-carotene and other carotenoids in vegetables and fruits that have an orange-red color. Red carrots are not rich in vitamin A, as many believe, but in its provitamin, beta-carotene. In general, carotenoids are found mainly in plant foods, while animal foods are rich in Retinol - milk, cheese, cod liver and mammalian liver, egg yolk. In addition, beta-carotene is many times weaker in its activity than Retinol - 12 mcg of this provitamin is equivalent to 1 mcg of Retinol.

Synthetic analogues

The most commonly used in clinical practice are Retinol acetate and Retinol palmitate. These medications are available in the following dosage forms:

• dragee 3300 IU
• capsules with oil solution for oral administration 3300 IU
• capsules with oil solution for oral administration 5000 IU
• capsules with oil solution for oral administration 33000 IU
• film-coated tablets 33000 IU
• solution for external use 3.44%, 100,000 IU/ml
• injection solution 0.86%, 25,000 IU/ml
• injection solution 1.72%, 50,000 IU/ml
• injection solution 3.44%, 33,000 IU/ml.

Injections of oil solutions are done only intramuscularly, into a vein under no circumstances! External solution is used in the treatment of skin diseases, and preparations for internal reception– for the prevention of vitamin A deficiency and treatment of related conditions.

To prevent the development of hypervitaminosis A, you must carefully follow the dosages determined by the doctor. Typically, drugs containing 3300 IU are used for preventive purposes, while more “heavy” ones dosage forms- in medicinal.

Along with Retinol acetate and palmitate, vitamin A is present in many vitamin-mineral complexes, including:

• Supradin,
• Duovit,
• Complivit,
• Vitrum,
• Aevit, and many others.

In addition to pharmaceuticals Vit. It is included in many dietary supplements and cosmetics for skin and hair care. Unlike natural Retinol, which quickly breaks down, synthetic retinoids are more stable and retain their properties for quite a long time.

Indications for use

Along with the prevention and treatment of vitamin A deficiency, synthetic retinoids are used as part of complex treatment for the following conditions:

• eye diseases with damage to the eyelids, sclera, cornea, retina - hemeralopia, retinitis pigmentosa, keratomalacia, xerophthalmia and keratophthalmia
• diseases of the stomach and intestines, consequences of operations on the gastrointestinal tract with impaired absorption of vit. A
• skin diseases and injuries - eczema, psoriasis, seborrheic dermatitis, neurodermatitis, mild degree burns and frostbite
• spicy and chronic infections, incl. influenza, pneumonia, bronchitis, childhood infectious diseases (measles, scarlet fever, chicken pox, etc.).
• rickets in children
• malignant skin tumors, leukemia.

Metabolism

Absorption of Retinol, which is part of foods and drugs, occurs in the upper parts of the small intestine. Food contains esterified Retinol (in the form of esters) or carotenoids. In the intestinal lumen, under the action of pancreatic and small intestinal enzymes, Retinol esters are destroyed (hydrolyzed, emulsified) to form free Retinol.

Next, in the mucous membrane of the small intestine, with the participation of specific enzymes, esters of Retinol fatty acids are synthesized again. In this form, it enters the lymph and is delivered to the liver. Here it is deposited in the form of the ester compound Retinyl Palmitate. In addition to the liver, vitamin A is deposited in the lungs, kidneys, retina, adrenal glands, mammary glands, and adipose tissues.

But still, the main depot is the liver - up to 80% of vit is stored here “in reserve”. And in the form of Retinyl palmitate. In case of insufficient receipts or increased consumption, these reserves may last for 2-3 years. If necessary, Retinol is released from the liver with the participation of zinc and binds to the protein transthyretin. Next, it is delivered to the cells of organs and tissues, where it combines with retinol binding protein (RBP), which is also synthesized by the liver.

Being an alcohol in chemical structure, Retinol destroys cell membranes. Therefore, before entering the cell, Retinol is transformed into Retinal and Retinoic acid. Compared to Retinol, these compounds are softer and do not have a destructive effect on cells. Carotenoids are absorbed in the intestines 6-12-24 times worse (depending on the type). Their transformation into Retinal occurs in the cells of the small intestine with the participation of a specific enzyme containing iron.

The activity of this enzyme depends on the condition of the thyroid gland. If its function is insufficient (hypothyroidism), this process will be disrupted, and unutilized carotenoids will accumulate in the body. In this case, pseudojaundice will be noted - coloring of the skin and mucous membranes in a rich yellow color.

Vit. And it is better absorbed in combination with fats and proteins. Therefore, fasting, restrictive diets, hobby plant foods– all this complicates the absorption of vit. And it contributes to its deficiency. The absorption of Retinol is also difficult in diseases of the liver, gallbladder and pancreas, when its emulsification and hydrolysis are impaired. The unabsorbed part of vit. And in the form various metabolites eliminated through the kidneys and intestines.

Interaction with other substances

• Zinc

Promotes the release of vitamin A from the depot. Therefore, against the background of a deficiency of this mineral, activation will be slow.

• Dietary fats and proteins

Facilitate the absorption of vitamin A in the small intestine.

• Vegetable oils, laxatives

Being fat soluble, vit. And it easily dissolves in these substances and is removed from the intestines. Therefore, regular intake of vegetable oils will lead to malabsorption.

• Enterosorbents

They also interfere with the absorption of Retinol.

• Vit. E (Tocopherol)

Prevents destruction. Therefore, vitamin deficiency. E is often accompanied by a deficiency of vit. A. For this reason, it is advisable to take both vitamins together.

Signs of hypervitaminosis

Due to the ability to accumulate, the daily dose of Retinol for children should not exceed 900 mcg, and for adults – 3000 mcg. Eating only food rich in vit. And, it is unlikely to cause hypervitaminosis A.

Although in medical practice One remarkable case was described when a group of polar explorers decided to feast on liver polar bear. In harsh climate conditions, the body of this animal has adapted to accumulate vit. And in huge quantities. And since the main depot of the vitamin is the liver, the polar explorers received real Retinol poisoning, and most of the unfortunate people died. But such cases are unique and are not the rule.

Basically, hypervitaminosis A develops with an overdose of synthetic retinoids or when they are combined with foods rich in vitamins. A. The main signs of hypervitaminosis A:

• abdominal pain, diarrhea
• nausea, vomiting
• general weakness
• hepatomegaly and splenomegaly - enlargement of the liver and spleen in size
• redness and itching of the skin, sweating at night
• pseudojaundice
• hair loss, dandruff
• drowsiness, insomnia
• bleeding gums, ulcerations in the mouth
• tenderness and swelling of soft tissues
• muscle cramps
• confusion.

Pregnant women have an overdose of vit. And can provoke teratogenic effect– disruption of embryonic development and the appearance of deformities in the fetus.

The trouble is that due to some similarity in manifestations, hypervitaminosis A can be mistaken for its deficiency. And then, instead of stopping taking the vitamin and changing the nature of the diet, on the contrary, they increase its dosage and take food rich in Retinol and carotenoids. To prevent this from happening, if you experience any alarming symptoms, you should consult a doctor and undergo the necessary laboratory tests.

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Vitamin A was discovered in 1913 by scientists who studied the effect of yolk on the body chicken eggs and butter. Two groups, McCollut and Osborne and their colleagues, independently concluded that these products contain a fat-soluble substance that is necessary for the growth of animals. It was called “A factor”, which was renamed vitamin A by Drummond in 1916. In 1921, Steenbock described vitamin A deficiency with signs of growth retardation, a tendency to infectious diseases and eye damage.

Vitamins of group A

Vitamin A1 is called retinol or axerophthol; in its pure form it is unstable, so retinol palmitate or retinol acetate is used for use.

Vitamin A2 differs from retinol by an additional double bond in the molecule and is called dehydroretinol. Contained in the liver of freshwater fish.

The role in the body for the two forms of vitamin A is the same. For ease of understanding they are combined common name– retinol or vitamin A.

General characteristics of vitamin A

Due to the fact that retinol is highly soluble in fats, it easily penetrates into adipose tissue and accumulates in the body. Therefore, when used in a dose of more than 200 mcg (micrograms) per day, it can cause symptoms of hypervitaminosis. Long-term continuous use of the drug has the same effect. Both deficiency and excess of vitamin A are harmful to health.

Therefore, the best option is to use natural retinol or carotene. Retinol from animal products is absorbed immediately and almost completely. Carotene from plants is first oxidized to retinol, then used by the body.

Poor absorption of vitamin A from plant products, and disruption of its absorption when there is an abundance dietary fiber and lack of fat, lead to the conclusion that it is necessary to prescribe it to vegetarians, and especially to vegans who do not use animal products for nutrition.

In the blood, vitamin A combines with transport proteins that deliver it to the liver. If a person does not get the vitamin from food, then its reserves in the liver can last for a year.

Retinol from the liver constantly enters the blood in small quantities and is transferred to the organs that consume it. A vitamin from food or a synthetic drug first goes to the liver to replenish reserves, and the remaining amount circulates in the blood.

In cells, retinol is converted into active forms– retinoic acid and retinal. Only in this form can they be used for integration into enzymes and biological compounds.

Biological role of vitamin A

Active forms of retinol, when entering cells, trigger a chain of biological reactions described below.

1. Activates chondroitin hyaluronic acid, contained in cartilage, bone tissue and intercellular fluid.
2. Enhances the effect of heparin - thins the blood, reduces coagulation and the formation of blood clots.
3. Taurine involved in the synthesis growth hormone and in transmission nerve impulse under the influence of retinol it is activated.
4. Participates in the formation of liver enzymes that neutralize toxic substances.
5. Forms the pigment rhodopsin, which is responsible for night vision.
6. Somatomedins accelerate protein synthesis in muscle tissue, as well as collagen formation. They can only work in the presence of retinol.
7. Takes part in the production of female and male sexual hormones, immune factors: lysozyme, interferon and immunoglobulin A.
8. Prevents desquamation of the epithelium due to the formation of special enzymes in it.
9. Activates cell receptors for vitamin D.
10. Inhibits the growth of atypical tumor cells.

Beneficial properties of vitamin A

Biological functions retinols are diverse and are associated with the growth and development of cells of all organs and systems. Vitamin A in the body is necessary for the following processes:

• Growth and formation of bones.
• Functioning of mucous membranes and skin epithelium (prevents dryness, desquamation and cell degeneration).
• It is part of rhodopsin in the retina and is found in cells that provide vision in low light.
• Supports normal structure hair, teeth and nails.
• Participates in the process of embryo formation, development of fetal organs and tissues.
• Stimulates the deposition of glycogen in the liver and muscle tissue.
• Participates in the synthesis of testosterone, estrogen and progesterone.

In addition, vitamin A prevents the development of malignant tumors, stimulates cellular immunity, enhancing phagocytosis and the formation of T-killer and T-helper cells, as well as antibodies for the humoral part of the immune response.

Vitamin A is an antagonist of the thyroid hormone - triroxine, so its use in thyrotoxicosis reduces heartbeat and improves metabolic processes and the well-being of patients.

The antioxidant activity of vitamin A allows it to protect organs from damage by free radicals, which prevents aging and the development of atherosclerosis, diabetes and tumor processes. In addition to retinol, beta-carotene is also an antioxidant. It protects artery walls from cholesterol deposits and prevents angina pectoris.

Toxic properties of retinol

The difference between medicine and poison is the dose. Vitamins are no exception. When consuming foods rich in vitamin A (shark, halibut or polar bear liver), poisoning of the body may develop with the following symptoms:

• Sudden drowsiness, weakness.
• Irritability.
• Dizziness.
• Temperature increase.
• Cramps.

Nausea and vomiting, food intolerance and diarrhea may occur.

An overdose of vitamin A is dangerous for infants in this way: after 10 hours, symptoms of high blood pressure appear cerebrospinal fluid, vomiting, redness and rash on the skin.

If you take more than 10 thousand IU of retinol daily (1 IU of vitamin A: biological equivalent of 0.3 mcg retinol, or 0.6 mcg β-carotene), you will develop chronic poisoning vitamin A. It manifests itself as a general malaise, elevated temperature, pain in the stomach, bones, muscles of the neck, back, legs, headache.

Retinol activity units

Vitamin A activity is measured in international units - IU. In this case, 1 mcg of retinol corresponds to 3.33 IU.

To establish the biological equivalence of retinol and beta carotene preparations, a standard has been adopted - 1 ER (retinol equivalent).

It corresponds to 1 mcg of retinol and 6 mcg of beta-carotene, 12 mcg of other carotenoids.

In terms of IU, the equivalent of retinol is 3.33 IU and 10 IU for beta-carotene.

Sources of Vitamin A

Plant sources described below.

Vegetables and fruits contain provitamin A, which gives them a yellow color - carrots, sweet peppers, tomatoes, pumpkin, peaches, apricots, sea buckthorn, cherries.

There is a lot of carotene in spinach, green onions, parsley and broccoli. It is also found in peas and soybeans, apples, grapes, melon and watermelon.

In addition, there are herbs with beta-carotene:

• Alfalfa.
• Burdock root.
• Borage leaves.
• Fennel.
• Horsetail
• Kelp.

To compensate for vitamin A deficiency, herbal remedies made from hops, lemongrass, nettle, oats, mint, sage and plantain, and raspberry leaves are used.

Animal sources are listed below.

The most best sources retinol is fish oil, caviar and beef liver, then egg yolk and butter, cream, sour cream, cheese and cottage cheese, unskimmed milk. Meat and skim milk are low in vitamin A.

The effect of retinol

Vitamin A is necessary for normal vision, it increases the synthesis of visual pigments and improves the recognition of visual objects. The carotenoids lutein and zeaxanthin protect the lens of the eye from clouding and prevent cataracts and blindness.

Retinol increases the barrier function of mucous membranes and enhances the immune response, protects against influenza and viral respiratory tract infections, and prolongs the life of seriously ill patients, including AIDS.

By protecting the mucous membranes of the digestive tract, it helps prevent exacerbation of gastritis and peptic ulcer, accelerates the epithelization of the ulcer.

A sufficient intake of vitamin A during gallstone disease reduces the risk of large stones, as it prevents the destruction and desquamation of the mucous membrane of the gallbladder.

With a normal supply of retinol, the urinary tract is protected from infection, which improves the course of cystitis and pyelonephritis.

The effect of vitamin A on the skin is manifested in the following actions:

• Acceleration of healing of wounds and burns, frostbite, postoperative sutures.
• Protection of the skin epithelium from keratinization and desquamation during dry skin and acne, psoriasis.
• Stimulating collagen synthesis in the treatment of aging skin, used for the prevention and treatment of wrinkles.

Retinol and its provitamin forms are used to treat infertility, as they participate in the formation of progesterone and spermatogenesis, necessary for the formation of embryonic tissues of the fetus, and prevent malformations of the child.

Protecting organs from oxidative damage gives vitamin A the ability to prevent aging and inflammation inner wall blood vessels, atherosclerosis and cancer.

Daily requirement for retinol

To provide daily requirement in vitamin A, it should be consumed in the dose indicated in the table. To convert to IU, you need to multiply the dose in mcg by 3.33. For medicinal purposes, higher doses are recommended (as prescribed by a doctor).

Age	Dose
Children under 6 months
Children from 7 months to one year
Children from 1 year to 3
Children from 4 to 8 years old
Children from 9 to 13 years old
Male teenagers
Female teenagers
Men
Women
Aged people
Pregnant
During lactation

Vitamin A dosage

For adults, 3300 IU of retinol per day is sufficient. To do this, it is enough to eat 50 g per day. beef liver and 100 g of stewed carrots. Other foods contain much less vitamin A. So, for example, to get the recommended dose, you need to eat a kilogram of fatty cottage cheese or drink 3 liters of milk.

For a normal ratio of retinol and carotene, it is recommended to replenish 1/3 of the requirement from animal products, and 2/3 to receive carotene from plant foods.

Vitamin A and its precursor (carotene) are absorbed only from foods containing fat, since for it to penetrate into the blood it must be combined with bile. With a lack of fat, the flow of bile decreases and 90% of the vitamin is not absorbed, but is excreted through the intestines.

Certain conditions increase the need for vitamin A (described below).

• Hard physical work.
• Nervous overstrain.
• Visual strain, especially in poor lighting.
• Prolonged exposure to the sun.
• X-ray irradiation.
• Diseases of the intestines, liver, biliary tract.

Interestingly, women taking oral contraceptives have a lower requirement for vitamin A.

Signs of vitamin A deficiency

A deficiency of vitamin A can be suspected if the following symptoms occur:

1. Increased dryness of the skin, peeling and thickening of the skin on the elbows and knees, increased acne, and the appearance of pustules.
2. The number of wrinkles on the skin increases and it ages earlier.
3. Hair becomes dull, dry and lifeless, and dandruff occurs.
4. Nails peel and break.
5. Vision decreases, especially at dusk and at night. Eyes water in the cold. Mucus accumulates in the corners, creating a feeling of “sand” in the eyes.
6. Increased susceptibility to infectious diseases.
7. In men, erection weakens and sperm quality deteriorates.

Causes of hypovitaminosis A

We can talk about hypovitaminosis of retinol if its level in the blood is below 0.35 µmol/l; the liver begins to lose its reserves at a level of 0.7 µmol/l.

Reasons reduced content vitamin A can be:

• Lack of food, especially in spring and winter.
• Monotonous food.
• In children with early transfer to formula feeding.
• Vegetarian or vegan diet.
• Deficiency of complete proteins.
• Reducing fat in the diet.
• Diseases of the liver or intestines, resection of the small intestine.
• Diseases of the biliary tract and pancreas.
• Disruption of the thyroid gland and adrenal glands.
• Taking antibiotics.
• Helminthic infestations.
• Stress.
• Living in very cold or hot climates.

Hypovitaminosis can occur during any long-term illness, radiation or chemotherapy of a tumor.

Symptoms of hypovitaminosis A

With vitamin A hypovitaminosis, the symptoms of the following skin diseases intensify:

• Xerophthalmia – dryness of the mucous membrane of the eyes.
• Xanthelasma of the eyelids is the deposition of cholesterol in the form of plaques on the eyelids.
• Seborrheic dermatitis.
• Acne.
• Benign and malignant diseases skin.
• Withering skin, wrinkles.
• Itching and dandruff, dry hair.

Lesions of the digestive system manifest themselves in the form of atrophic gastritis, colitis, cholelithiasis, diarrhea, cysts in the liver, and pancreatic tumors.

Impaired immune defense causes frequent colds, sinusitis, pneumonia and bronchitis, bronchiectasis and lung cancer develop.

Pathology of the genitourinary system with hypovitaminosis leads to the following conditions:

• Bladder sphincter weakness and urinary incontinence.
• Erectile dysfunction.
• Weakening of sexual desire.
• Mastopathy.
• Cervical erosions.
• Polyps.
• Adenomatosis.
• Leukoplakia.
• Breast cancer.

Retinol deficiency leads to increased soreness of tooth enamel, impaired pain and temperature sensitivity, developmental disorders, slow growth, anemia, insomnia and exhaustion.

Consequences of hypovitaminosis A

A constant lack of vitamin A in children leads to stunted growth, physical and mental development. In adults, it causes disturbances in visual perception in the form of decreased vision when moving from lighted to dark places. Early signs This pathology may cause “flickering of flies” before the eyes.

Diseases of the digestive system develop due to decreased secretion gastric juice and losses protective properties mucous membranes of the stomach and intestines.

Diseases of the respiratory and genitourinary systems also develop. Retinol deficiency causes early aging and increases the risk of cancer processes.

Most typical for hypovitaminosis A is the development of skin diseases with increased keratinization and dryness of the skin, mucous membranes of the eyes, brittle hair and transverse striations of the nail plates.

Signs of vitamin A overdose

Acute hypervitaminosis A can occur when a large dose is taken at once. Such cases have been described when eating the liver of polar bears. It is manifested by pain in the abdomen, bones and joints, weakness, headache and vomiting, diarrhea, enlarged liver and severe itching of the skin of the body.

Chronic hypervitaminosis is more common when consuming doses that slightly exceed the maximum permissible. Main symptoms:

• Peeling of the skin of the palms and soles.
• Itching and redness or yellowing of the skin.
• Hair loss.
• Pain along the bones of the thigh, leg, shoulder, ribs, collarbone.
• Tendon calcification.
• Headache, agitation, irritability.
• Sleep disorders.
• Nausea, vomiting and diarrhea.
• Increased intracranial pressure.
• Ulcers in the mouth.

During pregnancy, taking vitamin A in a dose above 5000 IU slows down fetal growth, and a dose above 13,000 calls for birth defects development.

Vitamin A and its importance for health

Vitamin A, like carotene, has valuable property– destroy free radicals, which are formed under the influence of radiation, toxic substances, metabolic disorders.

Free radicals are destructive molecules that destroy organs and tissues, contribute to heart disease, vascular disease, cataracts, aging and cancer.

Retinol is a powerful antioxidant that neutralizes the most dangerous types of polyunsaturated acid and oxygen radicals.

The thymus gland, the central organ of the immune system, is under special protection of carotene and retinol. With age, it decreases, reducing its functions. Vitamin A rejuvenates thymus gland, strengthening immune defense against infections and tumors.

Retinol is involved in the formation of protein in the body, cleans cell membranes from damage, strengthens bone tissue, which is used in the treatment of osteoporosis, especially in older people.

Vitamin A supports vision in conditions of minimal illumination, moisturizes the mucous membrane of the eyes, protecting it from injury.

The presence of retinol in the blood allows children in more developed countries to more easily tolerate childhood infectious diseases– measles, scarlet fever, chicken pox. In countries with a low standard of living due to poor nutrition, the mortality rate from such diseases is much higher.

Retinol and its derivatives are used in skin care products, as it treats most skin diseases - dryness, wrinkles, acne, eczema, psoriasis. Ointments with retinol relieve inflammation and accelerate the healing of skin damage, accelerate the synthesis of collagen fibers.

For diseases of the lungs and bronchi, the use of vitamin A protects the mucous membranes from destruction and facilitates expectoration.

The use of retinol preparations accelerates the healing of stomach ulcers or duodenum, and also restores the intestinal mucous membranes in case of erosive or ulcerative colitis.

Compatibility of retinol with other substances

Zinc and vitamin A mutually enhance each other's effects. A lack of zinc prevents carotene from turning into retinol.

Vitamin E protects vitamin A from breakdown and oxidation; their effect increases when used together. When taking large doses of vitamin E, it can inhibit the absorption of retinol.

Vitamin A at joint use with iron helps it penetrate into the blood and allows the use of iron reserves in the liver.

Alcohol inhibits the absorption of vitamin A and its processing in the liver.

Taking cholesterol-lowering medications interferes with the absorption of retinol in the intestine, so simultaneous administration Not recommended.

Laxatives reduce the supply of fat-soluble vitamins, including retinol.

Vitamin A does not combine with retinoids and antibiotics from the tetracycline group.

Estrogen drugs and oral contraceptives increase the concentration of vitamin A in the blood.

Vitamin D and glucocorticosteroids reduce the risk of side effects and overdose of retinol.

Everyone needs vitamin A

Unique properties Vitamin A makes it necessary for all age categories:

1. For children for growth, formation of bones and teeth.
2. For teenagers to improve vision and skin condition.
3. For women to maintain beautiful hair, nails, and youthful skin.
4. For men to enhance potency.
5. For older people to prevent heart disease and slow down aging.

Use of various dosage forms

The release forms of vitamin A are described below.

For oral administration, capsules of 3300, 5000, 33000 IU, tablets of 33000 IU, dragees of 3300 IU of retinol acetate are used. An oil solution in 1 ml containing 100 thousand IU is also used. The dosage is prescribed individually according to the indications.

For intramuscular injections - ampoules of 25 thousand IU, 50 thousand IU and 100 thousand IU in 1 ml of retinol acetate.

Retinoic ointment in tubes of 20 g 0.05% and 0.1%. For external use for acne.

For good absorption Vitamin A from food must be combined with vegetable or animal fat. Therefore, the greatest benefit will be carrot juice with a teaspoon of olive, sunflower oil or sour cream.

Taking vitamin A supplements orally with therapeutic purpose should not exceed the maximum permissible dose - 100 thousand IU. Since it tends to accumulate in the liver. The course of treatment must be agreed with the doctor.

Indications for use of retinol

For medicinal use vitamin A is included in complex therapy such diseases:

Eye diseases:

• retinitis, xerophthalmia, eczema and xanthelasma of the eyelid skin;
• keratitis, conjunctivitis, eyelid dermatitis;
• corneal ulcer, retinal dystrophy, work with high visual load.

Skin diseases:

• ichthyosis, pyoderma, follicular dyskeratosis;
• skin tuberculosis and subcutaneous tissue, frostbite, burns and wounds;
• psoriasis, dry eczema, atopic dermatitis, keratosis.

Childhood diseases: rickets, exudative diathesis, malnutrition, growth retardation.

Respiratory diseases: Chronical bronchitis, tracheitis, laryngitis, respiratory diseases, pneumonia, emphysema.

Digestive diseases: gastritis, gastric ulcer, ulcerative colitis, enteritis, liver cirrhosis, diarrhea of ​​microbial or food origin.

Autoimmune diseases: rheumatoid arthritis, systemic lupus erythematosus and other collagenoses.

Infectious diseases: measles, influenza, acute respiratory viral infections.

Contraindications for prescribing retinol

Taking vitamin A preparations is contraindicated in case of individual hypersensitivity, acute or chronic glomerulonephritis, pancreatitis, hypervitaminosis A, obesity, chronic alcoholism.

Side effects of taking vitamin A supplements

The use of retinol in large doses or with hypersensitivity to it can cause the following symptoms:

• Damage to liver tissue with increased activity of liver enzymes.
• Cracks in the skin, lips, orange spots on the palms, soles, subcutaneous swelling and itchy rash.
• Weakness, fatigue, headache, impaired gait and vision.
• Irritability, insomnia.
• Scanty periods.
• Hemolysis of red blood cells.
• Bone pain, cramps.
• Hair loss.

When the drug is discontinued or the dose is reduced, side effects go away on their own.

special instructions

1. Retinol accumulates and remains in the body for a long time, so its use cannot be combined with other drugs that contain vitamin A.
2. With prolonged daily intake may cause hypervitaminosis.
3. Use with caution for diseases that are accompanied by blood clotting disorders or calcium loss. It is also recommended to prescribe in a limited manner when severe violations liver functions and hepatitis.
4. When treating with tetracyclines, retinol is not used.
5. After taking cholestyramine, you need to take a break of 4-6 hours before using retinol.

Vitamins A for pregnant women

For the full development of the fetus and normal course During pregnancy, vitamin A intake is important. This is due to such beneficial properties for a pregnant woman:

• Prevention of viral and colds, bronchitis.
• Prevention of thrush and cystitis.
• Prevents the appearance of stretch marks on the skin and hair loss, dryness and flaking of the skin.
• Ensures growth of the uterus.
• Supports vision.

New research has found a link between vitamin A deficiency during pregnancy and a child's risk of developing Alzheimer's disease later in life.

For the fetus, the benefits of taking the vitamin are manifested in the following effects:

1. Improving the development of the skeletal system.
2. Prevention of growth retardation.
3. Promotes the formation of the genitourinary system.
4. Prevention of hydrocephalus and developmental defects.

Retinol exhibits such properties when taken in a therapeutic dose, but taking more than 5000 IU can cause miscarriage and developmental defects. Pregnant women are strictly prohibited from taking Aevit, since it contains 20 times more vitamin A than necessary.

Since the use of any drugs during pregnancy must be agreed with a gynecologist, then self-administration vitamin preparations Not recommended.

Vitamin A for children

Retinol is important for children for the development of the musculoskeletal system, especially during periods of intense growth, when dietary intake cannot cover the need for it.

During puberty, vitamin A stabilizes the menstrual cycle in girls and promotes testicular development and spermatogenesis in boys.

Taking vitamin A protects against respiratory infections and weakened vision, prevents acne.

It is most appropriate to carry out treatment short cycles for 10-15 days with 3300 IU per day.

Vitamin A - instructions for use

Vitamin A is taken orally after meals, 10-15 minutes later.

The highest single dose for adults is 50 thousand IU, up to 1 year – 1650 IU, up to 6 years 3300 IU, over 7 years 5000 IU.

Children can have 20 thousand IU per day, adults – 100 thousand IU.

For adults, mild vitamin deficiency is treated with a dose of 33,000 IU per day.

For diseases of moderate severity, the following doses are indicated:

1. Skin diseases and retinitis pigmentosa, hemeralopia – 50-100 thousand IU.
2. Ulcers, burns, frostbite are treated by smearing with a retinol solution and covering sterile bandage. Such procedures are carried out 5-6 times a day until complete epithelization.
3. It is recommended to take vitamin A preparations orally at the same time in a dose of 33 thousand IU.

Treatment of children is carried out depending on age with doses from 5 to 20 thousand IU. For the treatment of rickets, exudative diathesis, acute or chronic diseases of the lungs and bronchi, respiratory diseases, underweight and collagenosis, vitamin A is used in the dosage (in thousands of IU):

• Children from 3 to 6 months – 1000.
• From 6 months to a year – 2000.
• From 1 year to 3 years – 3000.
• From 3 years to 7 – 4000.

The drug is used intramuscularly for inpatient treatment of diseases of the digestive system - atrophic gastritis, gastric ulcer, nonspecific ulcerative colitis, enterocolitis. Injections of 10-100 thousand IU per day are prescribed, every other day. The course of treatment is from 10 to 20 days.

Oil extract of 3.44% concentration is taken orally and externally. A drop of extract contains 5000 IU of retinol acetate, 1 ml - 100 thousand IU. For internal use, it is dripped onto a piece of black bread.

The course of treatment with retinol lasts from two weeks to a month. After which a break of 2-3 months is required. If necessary, courses can be repeated.

New Vitamin A Research

Recent studies have proven the ability of vitamin A to stabilize blood glucose levels. The mechanism of this action is associated with overcoming insulin resistance.

This may be important for the treatment of type 2 diabetes. In this variant of the course of the disease, insulin is produced in the pancreas in normal quantities, but cells lose sensitivity to it. Overcoming insulin resistance will have positive influence not only when diabetes mellitus, but also obesity and atherosclerosis, arterial hypertension, combined into the so-called metabolic syndrome.