Vitamin A
Vitamin A, otherwise known as retinol, is a fat-soluble vitamin that is an antioxidant. It was opened one of the first in 1913 and, in accordance with this, received the designation of the first letter of the Latin alphabet. For the first time, vitamin A was obtained from carrots - therefore all vitamins of group A are called carotenoids (from the English carrot). Carotenoids are found in mushrooms, meat, plants and, when ingested, are converted to vitamin A.
Vitamin A in foods
The best sources of vitamin A are liver and fish oil. Further descending are egg yolks, butter, whole milk (not skimmed) and cream. Foods-suppliers of this vitamin of plant origin are yellow and green vegetables (carrots, bell peppers, pumpkin, spinach, green onions, parsley), apricots, peaches, apples, watermelons, melons, grapes, cherries, rose hips, legumes (peas and soybeans) … In addition, some medicinal herbs contain vitamin A: fennel, horsetail, hops, lemongrass, nettle, mint, raspberry leaves, sage, sorrel.
Vitamin A in animal products is represented by fish oil, caviar, beef liver, butter, margarine, whole milk, sour cream, cottage cheese, egg yolk, cheese.
Vitamin A action
The effect of vitamin A on the human body is enormous. It actively participates in redox processes, contributes to the regulation of protein synthesis, the normal functioning of metabolism, the performance of the functions of subcellular and cell membranes, the formation of teeth and bones, and fat deposits as well. Vitamin A is essential for the proper growth of new cells in the body and slows down the aging process. In addition, the vitamin is an essential element that allows the normal functioning of the human immune system.
The use of retinol in sufficient quantities can increase the protective function of the mucous membranes, increase the activity of leukocytes and other elements of nonspecific immunity. This substance protects our body from infections, colds, flu, diseases of the urinary system and gastrointestinal tract. The presence of a sufficient amount of vitamin A in the blood of children from developed countries explains the fact that they more easily tolerate infectious diseases such as chickenpox, measles, while in countries with a low standard of living, mortality from these seemingly harmless childhood diseases is widespread.
Vitamin A or its synthetic analogs - retinoids - are an integral part of all cosmetics aimed at restoring the tissues that make up the mucous membranes and skin. Vitamin is used as a medicine to eliminate skin diseases of various etiologies (psoriasis, acne, acne). For sunburns, vitamin A stimulates collagen production, accelerating regeneration processes and reducing the risk of infection.
A powerful antioxidant, vitamin A is an excellent prophylactic against cancer, protects the body's cell membranes from the damaging effects of free oxygen radicals and polyunsaturated acids. In addition, the effect of retinol extends to the cardiovascular system, preventing the onset of heart disease and increasing the level of "good" cholesterol in the blood.
The main carotenoids - zeaxanthin and lutein - play a critical role in protecting our eyes, reducing the risk of cataracts and macular degeneration.
Vitamin A requirement
According to research, no food can make up for the lack of vitamin A in the body, if any, therefore, in order to eliminate the deficiency, it must be supplemented. The recommended daily intake of vitamin A is:
- 3000 IU (900 mcg) for men;
- 2300 IU (700 mcg) for women.
For diseases associated with a lack of retinol in the body, the daily dosage of the vitamin can be increased to 10,000 IU. It is not recommended to take more than 6,000 IU of vitamin per day for pregnant women, since retinol in large quantities can have a teratogenic effect on the intrauterine development of the fetus.
Vitamin A should be taken with caution in patients with asthmatic manifestations of allergic diseases. You should also avoid the use of retinol for people suffering from hypothyroidism.
Indications for Vitamin A
The use of retinol is advisable when:
- Diseases of the mucous membranes and skin lesions (burns, seborrheic eczema, candidiasis, allergic dermatoses);
- Eye diseases (keratitis, conjunctivitis);
- The need to activate the processes of regeneration and healing of tissues after surgery, fractures, burns, wounds.
In addition, vitamin A is an integral component of complex therapy in the treatment of:
- Acute and chronic diseases of the biliary tract and liver;
- Acute and chronic pneumonia;
- Iron deficiency anemia.
Signs of vitamin A deficiency (hypovitaminosis)
Retinol deficiency is characterized by serum vitamin A levels below 0.35 μmol / L. The clinically significant symptoms of vitamin A deficiency in the body are:
- Dandruff;
- Premature aging of the skin;
- Increased temperature and pain sensitivity;
- Sensitivity (hyperesthesia) of tooth enamel;
- Accumulation of mucus or hardened crusts in the corners of the eyes, increased tearing in the cold;
- Accelerated ejaculation, weak erection in men;
- Weakness of the sphincter of the bladder;
- Hemeralopia ("night blindness");
- Frequent colds, respiratory infections, chronic pneumonia;
- Anemia, exhaustion, insomnia.
The causes of a lack of vitamin A in the body are:
- Unbalanced diet;
- Insufficient intake of retinol with food;
- Limiting fat intake;
- Diseases of the digestive tract;
- Malabsorption syndrome;
- Small bowel resection;
- Insufficient intake of vitamin E, an antioxidant that prevents retinol oxidation.
Signs of excess vitamin A (hypervitaminosis)
Signs of a retinol overdose are similar to those of a vitamin A deficiency. These include:
- Pigmentation and dry skin, brittle nails, hair loss;
- Delayed menstruation, abdominal pain, dyspeptic disorders;
- Joint pain, diffuse thickening of the bones;
- Enlargement of the spleen and liver.
special instructions
According to medical research, the interaction of vitamin A with alcohol leads to liver damage to a greater extent than drinking alcohol alone. This fact should be borne in mind when using alcohol-containing drugs.
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