Vitamin A is fat-soluble vitamins, and contains a number of compounds structurally related to:
Retinol (vitamin A alcohol, vitamin A1, akseroftol);
degidroretinol (vitamin A2);
retina (retinal, vitamin aldehyde);
retinolevaya acid (Vitamin acid);
esters of these substances and their spatial isomers.
It was first vitamin was isolated from the roots, so the British carrot (root), there was a name for vitamin A - carotenoids. Carotenoids found in plants, some fungi and algae, and when ingested can turn into vitamin A. Among ba d-carotene, lutein, lycopene, zea xanthin. The best known at the end of five hundred carotenoids.
The best-known carotenoid is b-carotene. He is the precursor of vitamin A (liver, changes in vitamin A, as a result of oxidative cleavage).
ER (retinol equivalent) = 1 mg retinol = 6 mg b-carotene. 1 mg = 3.33 IU (international units)
Vitamin A is a complex redox processes, protein synthesis parameter, the metabolism to promote a common, function of cellular and subcellular membranes and plays an important role for the formation of bones and teeth, and fat is essential to the growth of new cells slows down the aging process.
It has long been known effect of vitamin A value in the eyes, even in antiquity cooked liver - one of the main sources of vitamin A - as a place for night blindness used. Photo reception is necessary, to ensure normal functioning of the visual analyzer is involved in the synthesis of visual pigment into the retina, and eye sensitivity to light.
Vitamin A is necessary to normal functioning of the immune system and is an essential part of infection control. Application of retinol improves mucosal barrier function, increased phagocytic leukocytes unrest and other factors, non-specific immunity. Vitamin A protects next to colds, flu and respiratory infections, digestive, urinary tract infections. The presence of blood vitamin A is one of the major factors responsible for the details that child in developed countries is frequently simpler, diseases such as measles; chicken pox suffered, while in countries with low living conditions of much higher mortality of viral infections "innocent." Vitamin A life-long, straight and AIDS.
Retinol is essential in the maintenance and repair of epithelial tissue, thus the skin and mucous membranes. Not surprisingly, some modern cosmetics contain retinoids - its synthetic analogue. In fact, the vitamin is used in almost all skin diseases (acne, psoriasis, etc.) to handle. Skin lesions (wounds, burns), vitamin accelerates the healing process and stimulates collagen synthesis, improves the quality of tissue formed recently to reduce the risk of infection.
Due to the close of its merger with mucus and epithelial cells, vitamin A a beneficial effect on lung function and is a worthy addition in the treatment of certain diseases of the digestive tract (ulcers, colitis).
Retinol is essential for normal embryonic development, nutrition, and reduce the risk of fetal complications of pregnancy such as low birth weight.
Vitamin A is involved in the synthesis of steroid hormones (including progesterone), spermatogenesis is an antagonist of thyroxine - the thyroid hormone.
When AB-carotene and vitamins are powerful antioxidants, is a tool in the prevention and treatment of cancer, in particular, the prevention of recurrence after surgery.
"Vitamin AB-carotene and protect the brain cell membrane to the ravages of unrestrained radicals, and b-carotene neutralize the most dangerous forms of free radicals. Radical of polyunsaturated fatty acids and oxygen radicals'
Antioxidant activity of b-carotene plays an important role in the prevention of cardiovascular diseases, has a protective effect in patients with angina pectoris levels and high blood cholesterol "good" (HDL).
Lutein and zeaksentin - main carotenoids, which protect our eyes: they help prevent cataracts and reduce the risk of macular degeneration (the main organ of sight), in each case, the third meter is the cause of blindness.
However, another carotenoid - lycopene (the tomato-based) protects against atherosclerosis by preventing oxidation and accumulation of cholesterol in the arteries with low density. In addition to "strong" carotenoids in protecting against cancer, particularly breast cancer, endometrial and prostate cancer.
Symptoms of hypovitaminosis
Vitamin A deficiency is defined as the content of blood serum retinol below 0.35 micromoles / liter. However, even at the level of plasma from 0.70 to 1.22 mmol / l. Significant reduction of vitamin A in the liver, where they accumulate. Vitamin A in plasma begins when its concentration in the liver drops falling to 0.7 umol / g tissue.
Causes of hypovitaminosis:
Lack of vitamin A in food, especially during the winter-spring;
A balanced diet (protein lacks long-term high-grade conflict with the absorption of vitamin A);
reduce consumption of fats (vitamin A is fat-soluble);
liver and gallbladder;
diseases of the pancreas, short intestine;
significant removal of the small intestine, malabsorption syndrome;
Insufficient intake of vitamin E (vitamin E as an antioxidant, prevents oxidation of vitamin A).
Diagnostic clinically significant symptoms of vitamin A deficiency in the body
Premature aging of the skin to form wrinkles
Increasing pain and temperature sensitivity
Increased sensitivity of tooth enamel
watery eyes to the cold.
Accumulation of crusts and mucus in the corners of the eyes, a feeling of "sand" in the eyes, redness of the eyelids'
weak erections, rapid ejaculation, poor urinary sphincter, etc.
The best-known symptoms of hypovitaminosis so-called "night blindness (night blindness and day blindness) - rapid deterioration of vision in low-light conditions, Vitamin A deficiency leads to changes in almost all organs and body systems.
stain, xerophthalmia (dry mucous membranes, eyes), itchy eyes in the cold, bark structure and mucus in the corners of the eyes, a feeling of "sand" in the eyes, redness of the eyelids, xanthelasma century;
dry skin, premature aging of the skin folds, seborreyny, facial dermatitis, cancer and skin cancer form;
dry hair, dandruff;
hyperesthesia of tooth enamel;
atrophic gastritis, colitis, cholelithiasis, diarrhea, intestinal infections, cancer of the pancreas, liver cysts;
Weakness of the sphincter of the urinary bladder, erectile dysfunction, decreased libido;
cervical erosion, endocervicitis, polyps, adenomatosis, leukoplakia;
breast cancer, breast cancer;
respiratory infections, sinusitis, pneumonia, frequent colds, chronic bronchitis, bronchiectasis, lung cancer;
disorders, delayed growth;
increasing pain and temperature sensitivity;
Vitamin A is prescribed:
in various diseases of the skin and mucous membranes (thrush, Seborrheic dermatitis and other allergic symptoms);
in diseases of the eyes (conjunctivitis, keratitis), receiving daily retinol improve adaptation in the dark;
to activate the process of healing and regeneration in the treatment of burns, wounds, fractures;
Retinol is a member of comprehensive therapy for treatment of:
acute and chronic pneumonia
acute and chronic liver and gallbladder.
Use of a vitamin in the iron-deficiency anemia, because a direct correlation between plasma levels of retinol and iron concentrations in serum.
Vitamin A was appointed interior, intramuscular and local (government).
Vitamin A is used for prophylactic and therapeutic benefits. Preventive benefits are determined according to the daily needs of the human body vitamins. The use of vitamin A for therapeutic purposes should be strictly supervised by a physician.
Therapeutic doses of vitamin A deficiency disease of mild to moderate amounts to boost ME 33000 (0.01 g) per day for children - 1000 to 5000 hours daily. Skin disease in adults - 50000-100000 Me, Children - 5000 - 10.000 ME per day.
Single doses of vitamin A should not exceed 50 000 ME for adults and children at the European Championships 5000, diet - 100,000 adults and 20,000 children to MS.
Daily preventive dose of vitamin A for adults is 3,300 IU.
When pregnancy is not recommended during 6000 with vitamins, a day, in large doses, has teratogenic effects, may cause birth defects in children. Toxic effects were observed at doses more than 25,000 IU daily. Pregnant women should not use cod-liver oil.
When planning a pregnancy should also be borne in mind that retinol accumulates throughout the body, and if a woman treated by high doses of vitamin A during pregnancy is older than six months after discontinuance of retinol.
Children need more than 18,000 MS vitamin per day during the month.
Beware of vitamin A should be considered in patients with allergic diseases such as asthma symptoms in some cases the level of carotene and retinol levels increased.
With hypothyroidism should avoid the use of b-carotene because the body can convert into vitamin A.
Signs of hypervitaminosis
The overdose of vitamin A can be abdominal pain, delayed menstruation increased liver and spleen, gastrointestinal disorders, hair loss, itching, joint pain, nausea, vomiting, small cracks on the lips and corners.
In chronic hypervitaminosis said:
dryness and pigmentation to the skin, hair loss, brittle nails,
pain in joints and bones, scattered thickening of bones,
enlarged liver and spleen, and dyspeptic symptoms.
The long-term use of vitamin A is necessary to take vitamin E because of his absence at the same time prevents the absorption of vitamin A.
Conversion of vitamin A in its active form, contributes to zinc, as zinc deficiency leads to disruption of the absorption of vitamin A.
There is evidence of negative interactions with alcohol-carotene, a combination of liver damage as possible to a greater extent than when only alcohol, you must use an account in the general use and a range of alcoholic products.
When drugs that lower blood cholesterol levels should take into account that they can be fat to absorb vitamins and fat-soluble, and thus taking the vitamin should be discontinued performed in different time periods in hyperlipidemic agents.
Vitamin A should not be in accordance with retinoids, such as the combination is toxic.
When the laxative mineral origin impaired absorption of fat-soluble vitamins, including a vitamin A.
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