What is vitamin A - “extract of youth and beauty” for?

What is vitamin A (retinol) for? to our body? How is it useful? Is it true that vitamin A is necessary for good vision, beautiful and smooth skin, strong and shiny hair? These and other questions arise for many of you. You will find the answers to them in this article...

Vitamin A for vision

Eyes are one of the five most important human sense organs. Vision helps us perceive new information various phenomena and the events of our lives, the people around us. Therefore, it is very important to maintain it throughout your life. It’s not for nothing that they say, “to protect it like the apple of your eye” (“apple” is the pupil, “eye” is the eye).

And vitamin A helps us with this. Its role is that it participates in the formation of a special pigment in the retina of the eye - rhodopsin (visual pigment or purple). Thanks to rhodopsin, our eyes perceive light signals. At every light contact a certain number of molecules of this pigment disintegrate. New rhodopsin molecules are formed from protein and vitamin A. This function of retinol was discovered in 1967 by George Wald, for which he received Nobel Prize.

Thus, adaptation of vision to different degrees of illumination lasts about 8 minutes with a sufficient amount of vitamin A, and with its deficiency - 30 - 40 minutes.

In addition, retinol prevents such an ancient disease as “night blindness” (impaired twilight vision).

Vitamin A for skin, hair and nails

What is benefits of vitamin A for skin? Retinol ensures the strength of collagen and elastin fibers (connective tissue proteins). These fibers are the main component of the dermis, the inner layer of the skin. The condition of our skin depends on their quantity and strength: its firmness and elasticity. As we age, collagen and elastin production decreases, strength decreases, and fibers break. This is the cause of wrinkles and, as a result, skin aging.

Thanks to its function, vitamin A slows down this process, maintaining youthful skin for many years. It is for this reason that retinol is included in many cosmetic creams.

The above-described effect of vitamin A also applies to hair, nails and teeth.

Vitamin A for bone growth and development

Retinol is a factor in bone growth and development, increasing protein production in bone and cartilage tissue, as well as ensuring their renewal. This applies not only to the bones of the skeleton, but also to the jaw bones. This is especially important for a young and growing body. Therefore, vitamin A is of particular importance for children. Their diet must include foods rich in retinol and beta-carotene (provitamin A).

Vitamin A against infections

Retinol is necessary for the normal condition of the mucous membranes of the nose, bronchi, and other organs. It stimulates special cells to produce mucus, thereby protecting the mucous membranes from drying out and forming a stratum corneum. This provides our body with reliable protection from various types of infections, diseases of the skin, lungs, intestines, stomach, and cancer.

In addition, vitamin A enhances the effect of the body’s own defense system – the sympathetic-adrenal system. Its mechanism is as follows: when foreign bacteria and microbes enter the body, adrenaline is produced from the adrenal medulla (its central part) to fight them. Sufficient supplies of vitamin A increase the amount of brain matter, and therefore adrenaline. Retinol also enhances the effect of leukocytes - white blood cells.

And another very important function of vitamin A... It restores the activity and performance of the thymus or thymus gland, protects it from destruction by free radicals. The thymus gland is the “substernal ganglion.” It is the place where T-lymphocytes or T-cells live and live, which also fight infectious agents. With age, the thymus gland decreases in size and becomes less active. Retinol in certain quantities can restore the growth of the thymus, thereby increasing its effectiveness.

Thus, vitamin A plays an important role in protecting the body from such viral diseases, such as flu, colds, chicken pox, measles, diseases of the digestive tract, respiratory tract and others.

Biological role of vitamin A

Biological role of vitamin A is as follows:

1. It takes part in providing the body with energy. So, retinol is necessary for continuous operation gluconeogenesis - the process of glucose formation.

Our body constantly needs glucose. Its main consumer is the brain. When the diet is poor in carbohydrates (the main source of glucose), the body begins to produce it from proteins, fats, acids and even alcohol (this explains the lack of appetite in alcoholics).

2. Necessary for better absorption of proteins.

3. Takes part in cholesterol metabolism. Vitamin A increases cholesterol levels in the blood by releasing it from atherosclerotic plaques and soft tissues. As a result, the absorption of cholesterol from the gastrointestinal tract slows down. intestinal tract, as well as its formation in the liver.

4. Participates in the production of adrenal hormones from cholesterol, as well as steroid hormones (including progesterone).

Vitamin A as an antioxidant

Vitamin A, as well as its predecessor, are the most important antioxidants. They protect cells, tissues and organs of the body from the destructive effects of active molecules - oxygen free radicals and polyunsaturated fatty acids. This is of great importance in preventing cardiovascular, cancer diseases, premature aging.

Vitamin A for the reproductive system

Firstly, retinol ensures the healthy condition of the mucous membranes of the genital organs. Secondly, it is involved in the production of steroid hormones (progesterone). Thirdly, it is necessary for the production of sperm and the development of eggs. And finally, vitamin A is very important during pregnancy. It increases the resistance of a pregnant woman to diseases of the mucous membranes of the intestines and respiratory tract. IN postpartum period participates in restoration processes in the mother’s body. Thus, the importance of retinol for procreation is very great. However, here you also need to observe moderation and be careful. The fact is that an overdose of vitamin A (namely, synthetic) can be dangerous during pregnancy and lead to birth defects in the child.

So, here we have answered the question, what is vitamin A for? to our body. Let's move on... You can find out which substances help retinol fulfill its beneficial mission in the body, and which ones try in every possible way to interfere and harm...

P.S. Live healthy! Magnificent vitamin A. A brick in the building of health.

What vitamin A is useful for, where it is easy to find and how to use it to maintain beauty and health, we decided to tell you in this article.

During the cold season, the topic gains particular relevance, since immunity decreases, the number of diseases increases, and the lack of sunlight affects frequent mood swings and a deterioration in general condition.

The very first and vital

The wonderful substance was discovered in 1913 independently by researchers McCollut-Davis and the Osborne laboratory. Since the vitamin was the very first of all discovered at that time, it was designated by the initial letter of the Latin alphabet - A.

The significance of the compound for restoring and preserving vision was so great that biochemist George Wald, who described its characteristics, received the Nobel Prize in 1967.

Wise nature has decreed that the human liver is capable of accumulating a certain amount of a unique substance, thereby ensuring the stable functioning of the body. This compound is fat soluble. It has two main forms - retinol (chemical name) and carotene (main source - plant foods).

Where to look for the miracle element

To maintain good health, you need to know how to maintain the amount important elements in the body where retinol is contained, except for the classic pharmacy version. It's simple. It’s easy to find vitamin A-rich foods on supermarket shelves:

These include:

• fish fatty varieties, including mackerel, trout, salmon;
• beef (pork) liver;
• various curds (often additionally enriched with a complex of vitamins);
• cheeses and butter;
• sour cream and fermented baked milk;
• eggs.

Carotenes are found in large quantities in plant foods.

Rich in useful components:

• parsley and spinach;
• sorrel and green salad;
• wild garlic and carrots;
• cabbage and bell pepper;
• green beans and tomatoes;
• dried rose hips;
• chanterelles (mushrooms).

Excellent sources of this important component are various fruits and berries: apricot and blackberry, melon and plum, sea buckthorn and peaches, rowan and papaya.

Freshly squeezed juices are also the richest storehouses of carotenes. Thus, they manifest themselves well when drinking juice, which contains large amounts of vitamin C. It is well known to everyone. We will only remind you that with ascorbic acid deficiency, the risk of cataracts increases, bone fragility is observed, and working capacity decreases.

Why is it necessary

We know that our body is a perfect invention of nature. Everything in it is balanced and interconnected. To learn how to use such a priceless gift, it is important to understand how to properly support and nourish it. Therefore, it is necessary to know why vitamin A is useful and what function it performs.

The spectrum of fat-soluble compound A is incredibly broad:

• Directly affects protein synthesis and metabolic processes.
• Improves regeneration processes in damaged tissues.
• “Responsible” for the strength of bone mass.
• Promotes uniform distribution of necessary fat deposits.
• Warns premature aging(decrepancy) of the body.

Perhaps we all know that a lack of vitamin A negatively affects vision - since childhood we have heard about the benefits of carrots! Many simple and original recipes, easy to find by following the link. After all, the bright orange liquid is a whole complex for the production of energy and a great mood.

Traditional healers advise to use for myopia and night blindness, and regularly include boiled liver in the diet. It is also undeniable for filling the body with the whole complex of useful substances.

Retinol has beneficial influence on the functioning of visual analyzers, the normal functioning of the retina. Contains retinol. They are able to quickly relieve fatigue and eliminate (prevent) corneal dystrophy.

Carotenes can increase the body's resistance to viral infections, promote the activity of leukocytes, protect against various infections of the gastrointestinal tract, genitourinary system, and respiratory tract.

During pregnancy, retinol is important for the full development and nutrition of the fetus; its deficiency can cause low weight in the baby. It is effective after long-term illnesses and surgeries, as it protects the body from relapse of the disease.

Urologists note that carotenes are necessary for the stronger half of humanity to improve potency. They are able to activate the production of testosterone (male hormone) and prevent the development of cancer.

Important: Carotenes are perfectly absorbed by the body in combination with calcium and zinc. A lack of tocopherol leads to poor absorption of retinol, so they should be taken together.

For female beauty

Liquid vitamin A is a proven and favorite remedy for many women for the beauty of their facial skin and healthy hair.

He helps:

• get rid of dryness and flaking of the skin;
• maintain epithelial moisture;
• eliminate;
• prevent acne.

The neutralizing characteristics of carotenes can provide protection to the face from the adverse effects of ultraviolet rays and various aggressive external influences. It is known that free radicals tend to accumulate and have a destructive effect on collagen fibers. As a result, early grooves appear and the skin loses its elasticity.

Your doctor will tell you how to take the drug in capsules for specific ailments, and for prevention you can take 1-2 capsules daily - morning and evening. Be sure to follow the rule - take capsules only after meals. Also, do not forget that vitamin C is beneficial for velvety skin and strong curls.

Note: Liquid retinol is excellent in treating dermatological diseases, as well as injuries, frostbite, and burns.

Vitamin A has been used in cosmetology for a long time. Retinoids are essential components in various cosmetic products. However, there is no need to visit expensive salon procedures. As we wrote above, the active component is found in various fruits and vegetables, which can be used to prepare healthy and effective mixtures.

So, we offer recipes for masks that are easy to make at home:

1. Carrot juice + rolled oats. Combine freshly squeezed vegetable juice with rolled oats flakes. The duration of the mask is 20 minutes. Can be used for all types of skin.
2. Avocado + apricot + olive oil. Grind the fruit pulp in equal proportions, add a few drops of olive oil. Apply to face for 30 minutes.
3. Anti-inflammatory. An oil solution of vitamin A (2-3 drops), combine with 0.5 teaspoon of aloe juice and a small amount of your favorite nourishing cream. The mask lasts 25-30 minutes.

What are the risks of deficiency (hypovitaminosis) and overdose?

During the First World War, xerophthalmia was a fairly common disease. Scientists have found that the cause of dry conjunctiva and cornea of ​​the eye is a lack of butter in the diet. Also, carotene deficiency can cause hemeralopia (night blindness), described in ancient Egypt. It is known that eye disease is often provoked by and.

An insufficient amount of retinol provokes dullness and fragility of strands, increased hair loss, often this common reason baldness in men. The skin peels off, becomes grayish, rashes and pimples appear.

Important: The daily dose of retinol is 1.5 mg per day. It increases during pregnancy (2 mg per day), with breastfeeding(2.5 mg per day).

Insufficient consumption of carotenes causes bad dream, weakness, fatigue, increased sensitivity to even the most minor ailments and pain. Children experience nervousness, frequent colds, and slow growth.

An overdose of retinol - especially with regard to excessive use of pharmaceuticals - also poses a number of dangers:

• the spleen and liver may increase in size,
• pigmentation often appears on the face, which is difficult to remove,
• there is pain in the bones and joints,
• women may experience a disruption in their menstrual cycle,
• attacks of nausea and headache are observed.

Eat high-quality and healthy foods, take care of yourself and always be healthy and cheerful!

• Why does our body need vitamin A and what functions does this substance perform in it?
• What organ systems does vitamin A affect and why is it primarily useful?
• How is vitamin A useful in cosmetology and in what forms of release is it optimally used for skin and hair care.

As well as a number of other interesting and useful nuances.

Vitamin A is the first vitamin discovered by scientists. Actually, for this reason it was named after a capital letter. English alphabet. After the discovery of the vitamin, physiologists, chemists and pharmacists carefully studied the properties of this useful substance, and today not only doctors, but also many ordinary citizens know well what vitamin A is used for and what effect it has on the body.

We will talk in more detail about what it affects, how it is useful and in what cases it can be prescribed by doctors.

This is interesting

Generally speaking, vitamin A refers to several related substances from the group of retinoids. The main one among them is retinol, which, in fact, takes an active part in the work of many internal organs and metabolism in the human body. Other substances from the group of retinoids, when they enter the body, are converted through biochemical processes into retinol.

Often, vitamin A is also called the precursor substances of retinoids - carotenes (you probably heard the so-called beta-carotene). Once in the body, they are also converted into vitamin A, due to which they are used for the same purposes for which retinol itself is used. However, if we talk about what vitamin A affects, then it would be correct to consider retinol, and not its predecessors.

It would not be an exaggeration to say that vitamin A affects, to one degree or another, almost all organs and systems of human organs. Accordingly, drugs containing it are used in the most different areas medicine, and in addition to them - in cosmetology and dietetics.

So, let's figure out why our body needs vitamin A...

The role of vitamin A in the human body

First of all, it should be noted that vitamin A is the most important component with the participation of which the formation cell membranes. This means that this substance is present in almost every cell of the body and is vital to ensure the cell’s protection from external influences.

In addition, retinol performs the following functions:

• Regulates the synthesis of many proteins, thus supporting the process of human growth, which is especially important for children (products with vitamin A are very useful for the growth of babies);
• Provides constant regeneration of mucous membranes and epithelial tissues, as well as the production of a number of hormones and enzymes;
• Protects the body from free radicals. As it is fashionable to say today, it is a powerful antioxidant that prevents the development of cancerous tumors, roughening of the skin and aging of the body as a whole (in many ways, this property of retinol is used today in cosmetology). Vitamin A is useful because it participates in redox reactions and, simply put, inhibits the excessive activity of oxidizing agents, preventing them from destroying cells;
• Participates in metabolism. With the participation of retinol, the synthesis and breakdown of certain proteins, organic acids and carbohydrates occurs, which ensures the occurrence of normal energy processes in the body, as well as the production of many structural components of various tissues and organs;
• Actively participates in the processes of growth and formation of the skeleton. It is especially useful for children (perhaps only vitamin D is more important for the formation of the skeleton);
• It affects the processes of formation and renewal of fat deposits, and for this reason is the focus of attention of nutritionists.

Listed above are only the most general properties vitamin A. Now let's look at its benefits for the body in more detail.

On a note

There is even an opinion that it is precisely thanks to a good supply of vitamin A that children in developed countries recover faster from measles and chickenpox.

Thanks to vitamin A, the immune system continues to work more or less even during AIDS, and therefore retinol is often included in therapeutic complexes for various immunodeficiencies.

The effect of vitamin A on the skin, nails and hair (including eyelashes and eyebrows) is so versatile and great that it is worth talking about its use in cosmetology separately.

Application in cosmetology

Vitamin A in cosmetology is used in the form of ointments and creams, masks and emulsions, serums and balms, as well as as part of food supplements and vitamin complexes. Retinol is often called the “master skin vitamin” – and for good reason.

Firstly, this substance is involved in the formation of epithelial cells, that is, thanks to it, our skin is regularly “renewed”. In practice, hypovitaminosis A manifests itself as follows: the skin becomes dry, dehydrated, quickly ages and flakes.

Vitamin A stimulates the formation of collagen, improves skin regeneration, helps to disappear or reduce the intensity of pigment spots. It restores elasticity to the skin, makes it smooth, elastic, eliminates minor imperfections (in particular, the same small pigment spots, acne). Vitamin A preparations can also be used to care for the skin of the lips, especially if cracks and peeling appear on them.

Next, since we are talking about skin, it is worth mentioning the antioxidant properties of retinol once again. It serves as a “trap” for peroxide radicals, which damage cell membranes, destroy collagen, cause premature aging of the skin and even provoke the growth of malignant tumors in it.

Free radicals have the most harmful effects on the skin, because it is the outer barrier that separates our body from aggressive influences. environment. Vitamin A traps free radicals and prevents their destructive effects on the body.

Vitamin A is useful for eyelashes and eyebrows: it helps strengthen the skin under them and, as a result, nourishes them, prevents hair loss, and makes eyelashes and eyebrows more viable.

Another problem that retinol can help cope with is acne (pimples, blackheads). In the treatment of this disease, vitamin A often has a very positive effect: it reduces the secretion of the sebaceous glands and reduces their size, normalizes the process of keratinization of the skin, and relieves inflammation.

Thanks to these properties, retinol is indicated for seborrhea, dermatitis, eczema, psoriasis, alopecia and others. skin diseases. In addition, thanks to retinol, the healing process of wounds, burns, frostbite and various skin damage is accelerated.

Vitamin A preparations and their areas of application

Since the scope of vitamin A is very wide, it is used in a wide variety of release forms - so that in any clinical case it is possible to deliver the beneficial substance to the necessary organs.

For example, in medicine they use:

• Drops for oral use, which are usually sold in 10 or 20 ml bottles. They are usually oil-based because vitamin A is a fat-soluble substance.
• Capsules in gelatin shell. This is the most common form of release. Intended for oral use, and each capsule provides the body with from one to 10 daily requirements of the vitamin (depending on the drug). They do not require chewing - their shell dissolves under the action of gastric enzymes. Often used in cosmetology due to its wide availability.
• Solutions for oral administration, differing from drops in packaging volume and partly in composition.
• Oil solutions for intramuscular administration. They are usually sold in ampoules, which are used for external use by especially resourceful home stylists. Before injection, this solution must be warmed to body temperature. They are used when it is necessary to administer large doses of the vitamin due to problems with its absorption in the gastrointestinal tract.
• And finally, dragees containing either retinol itself or its predecessors. Such dragees are very convenient for children to use, easy to store and usually taste good.

Vitamin A is found in a large number of multivitamin complexes - it finds its place in preparations of various types, from children's multivitamins to hair and skin support products.

Homemade skin and hair care products with vitamin A

Often, in search of an effective (and to some extent exclusive) skin and hair care product, resourceful girls use vitamin A preparations in a rather original way.

Let's look at a few examples:

• The drug is added to shampoos. For this, the contents of capsules are usually used, less often an oil solution for injection or for oral use. As a result of washing your hair with this shampoo, your hair becomes stronger and more voluminous and shiny, and the skin at its roots is softened and moisturized. Although, this effect is partly ensured by the oils themselves, in which the vitamin is dissolved as part of the drug.
• The drug is included in skin lotions. When treating the skin of the face and neck with this lotion, the skin is moisturized and softened, and metabolic processes in it are accelerated. Some try to fight wrinkles, acne and various rashes in this way. Vitamin A itself does not help against acne, but by healing the skin, it helps reduce the intensity of inflammation and normalize the functioning of the sebaceous glands. As a result, when treating the skin with vitamin A products, it is often possible to solve the acne problem to a certain extent.
• The drug is used in the preparation of various masks. This is the most popular way to use vitamin A in home cosmetology. Typically, injection solutions or capsules are used for this.

The recipes for homemade vitamin A care products themselves are very diverse, and many girls have their own secrets for preparing masks and shampoos that are best suited for a certain type of hair and skin.

Natural sources of vitamin

To obtain vitamin A in the required quantities, it is usually enough to eat foods rich in it. With a properly formulated diet, there will be no need to use artificial sources of retinol to prevent hypovitaminosis, nor will it be necessary to invent means for external use - the body will be provided with the vitamin in the quantities it needs.

Largest quantity Vitamin A is concentrated in the liver and kidneys of animals. There is also a lot of it in cod liver, which is fatty sea ​​fish. Vitamin A is rich in dairy products, butter, and eggs.

On a note

The liver of some animals contains so much vitamin A that you can get very seriously poisoned if you eat too much of it. For example, there are known cases of acute poisoning with a fatal outcome after eating liver polar bear, sharks and some marine animals.

Precursors of vitamin A - various carotenoids - are found in large quantities in vegetables and fruits (the very name “carotenoids” comes from the English “carrot” - carrot), greens, berries and legumes. It is not surprising that those who eat plenty of fresh vegetables and fruits almost never lack retinol and rarely suffer from diseases associated with its deficiency.

Interesting video about the benefits of vitamin A and its effect on human health

What food sources can you get enough vitamin A naturally?

The daily diet should be rich in organ meats, carrots, spinach and other foods containing retinol and carotene. It is not for nothing that vitamin A is the first, for which both women and men know this component is useful.

Retinol is involved in the body's redox processes and is also part of the cell membrane. It is especially necessary in winter time when a person's immunity weakens.

We will consider further how deficiency, excess and normal amounts of vitamin A affect the human body.

The need to take vitamin A

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The date of discovery of this vital substance goes back to 1913, when two scientists, Osborne and McColuth-Davies, independently discovered retinol. Since this was the first vitamin discovered, it was designated by the letter of the Latin alphabet - A.

The event of 1967 was significant. Then the biochemist J. Wald received the Nobel Prize for describing vitamin A and the benefits of this component of the visual apparatus.

The liver is able to accumulate the compound, ensuring stable functioning of the entire body. Vitamin A occurs in nature in two forms (retinol and carotene). This component is fat soluble.

The benefits of the compound for the body cannot be overestimated. Below is short list the main functions occurring in the human body for which this substance is simply necessary:

1. Visual function. The beneficial properties of vitamin A are manifested in the fact that it is an integral component of the retina of the eyes. It is prescribed for office workers who spend most of their time in front of a monitor screen. A normal concentration of the compound in the body helps to see better at dusk, to forget about fatigue and the feeling of “sand” in the eyes for a long time.
2. Protective function. Useful property vitamin is associated with the production of immune cells, which increase the body's defenses. Thus, the risk of colds, flu and ARVI is reduced.
3. Regenerative function. The substance is useful for restoring the skin and mucous membrane. Retinol is often included in creams and ointments intended for the treatment of burns, cuts and skin diseases.
4. Natural antioxidant. What vitamin A is useful for, among other things, is protecting cells from free radicals. This vital component prevents the development of cancerous tumors. It strengthens vascular walls, heart and brain.

The use of the compound depends on the age and gender of the person. Moreover, it is contained both in products and drugs. Vitamin A capsules can be purchased at any pharmacy, but first the instructions for use must be carefully studied. Daily dose of the component:

1. Men – 1000 mcg.
2. For women – 800 mcg.
3. Pregnant women - 1000 mcg.
4. nursing mothers – 1200 mcg.
5. Children (0-3 years) – 400 mcg.
6. Children (4-7 years old) – 500 mcg.

In addition, for middle-aged children and adolescents (over 7 years old) – 700 mcg.

The benefits of vitamin A for men and children

A man needs to watch his diet and remember to take the vital compound, be it food or vitamin A capsules. Normal level retinol has a beneficial effect on male sex hormones, increasing sexual desire.

It is a known fact that the male body is susceptible to various cardiovascular pathologies. But vitamin A reduces the likelihood of developing thrombosis, stroke or hypertension. The beneficial component is important for smokers, as it prevents the occurrence of lung and throat cancer.

Retinol should be taken by young children, because it is involved in the formation of new cells in bone structures. We can talk endlessly about the benefits for the eyes: vitamin A reduces the risk of developing myopia and moisturizes the mucous membrane.

It is very important to take the compound during cold weather, since children are the first to suffer from viral and infectious diseases. Even if sick, a child who takes vitamins properly, in particular retinol, will recover faster than his peers.

Since children often damage their skin, the component increases the regenerative abilities of the epithelium and helps you quickly forget about scratches, wounds, abrasions, burns, etc.

The benefits of vitamin A for women

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This component is also necessary for the female body. During pregnancy, retinol is responsible for natural development baby in the womb.

Vitamin A is beneficial for women who are breastfeeding. Since the mammary glands are composed of adipose tissue, they depend on fat-soluble elements. Retinol is a regulator of chemical processes occurring in female cells that are responsible for lactation. In this regard, doctors prescribe vitamin A capsules to nursing mothers.

A woman needs to take a substance to preserve her beauty, because it improves the condition of the epithelial integument:

1. Face. Vitamin A is especially useful for facial skin, as it improves blood flow, metabolic processes and stimulates cell renewal. Therefore, the skin on the face becomes smooth and moisturized. Retinol relieves inflammation, evens out tone and protects against external factors.
2. Hair. Thanks to vitamin A, you can achieve shine and elasticity of hair, restore normal function of the sebaceous glands, forgetting what oily, dry hair and dandruff are. Retinol also protects curls from the negative effects of UV rays and stimulates their growth.
3. Nails. When the body has enough retinol, the condition of the nails returns to normal. They do not flake or break and grow back quickly. As soon as the level of the beneficial vitamin decreases, the nails become brittle, ribbed, and with hangnails.

Vitamin A can be added to various homemade masks and creams.

But it is better not to overuse anti-aging masks before the age of 35, since the body produces a sufficient amount of collagen.

Vitamin A deficiency and excess

The benefits and harms of this compound are manifested in its content in the human body.

Lack of vitamin A leads to vitamin deficiency.

Vitamin deficiency in the human body manifests itself in different ways.

The main signs of manifestations of disorders in the body are:

• decreased performance;
• decreased immunity;
• development of diseases respiratory system– pneumonia, sinusitis, bronchitis;
• reproductive dysfunction, manifested by decreased libido;
• development of “night blindness”;
• deterioration of teeth;
• severe dry skin;
• loss of appetite, weight loss;
• deterioration of visual acuity;
• dry eye mucosa, conjunctivitis;
• premature skin aging.

Excess vitamin A is also bad. After excessive use of the component, unfavorable aspects appear instead of useful ones:

1. Intoxication of the body: vomiting, nausea, weakness, enlarged liver, general malaise
2. Carotene jaundice (yellowing of the skin as a result of excessive consumption of beta-carotene).

Among other things, there are some contraindications when consuming vitamin A. Often these are allergies and hypothyroidism. Those who take capsules that contain retinol and retinoids need to be careful, as such elements can cause toxic effects. The instructions always indicate the composition of the drug, contraindications and potential harm. This is especially true for expectant mothers, because retinol-based medications are prescribed individually by the attending physician so as not to harm the normal development of the fetus.

Therefore, it is important to use it correctly vitamin complex or food so as not to cause harm to the body. To replenish vitamin A reserves, the male and female body needs to take animal food (liver, fish fat, cheese) and vegetable (carrots, apricots, grapes) origin.

Drugs

Vitamin A is considered an excellent fighter against infections, dry skin and wrinkles. Therefore, this vitamin is very good for beauty and health.

Vitamin A or retinol - trans-9,13-dimethyl-7 (1,1,5-trimethylcyclohexen-5-yl-6) nonatetraene 7,9,11,13-ol. Chemically, vitamin A is a cyclic unsaturated (unsaturated) monohydric alcohol, consisting of a 6-membered β-ionone ring and a side chain consisting of two isoprene residues having a primary alcohol group. Vitamin A is fat-soluble, therefore, accumulating in the liver and other tissues when taken for a long time in high doses can have a toxic effect. This vitamin is not soluble in water, although some of it (from 15 to 35%) is lost during cooking, scalding and canning vegetables. Vitamin A can withstand heat when cooked, but can be destroyed when stored for long periods of time when exposed to light.

Vitamin A has two forms: prepared vitamin A and provitamin A or the plant form of vitamin A (carotene).

In total, about five hundred carotenoids are known. The most famous are β-carotene (it was isolated from carrots, therefore the name of the group of vitamins A carotenoids comes from the English carrot), α-carotene, lutein, lycopene, zeaxanthin. As a result of oxidative breakdown in the human body, they are converted into vitamin A.

Vitamin A includes a number of structurally similar compounds: retinol (vitamin A - alcohol, vitamin A1, a-xerophthol); dehydroretinol (vitamin A2); retinal (retinene, vitamin A - aldehyde); retinolic acid (vitamin A - acid); esters of these substances and their spatial isomers.

Free vitamin A predominates in the blood, and retinol esters predominate in the liver. The metabolic functions of vitamin A in the retina are provided by retinol and retinal, and in other organs by retinoic acid.

Vitamin A: Metabolism

Vitamin A is absorbed similarly to lipids - this process includes emulsification and hydrolysis of its esters in the lumen of the gastrointestinal tract, its adsorption and transport into the cells of the mucous membrane, re-esterification of retinol in them and the subsequent entry of vitamin A into the liver as part of chylomicrons.

Vitamin A absorption occurs mainly in the small intestine, mainly in its upper section. Vitamin A normal conditions when consumed in physiological doses, it is absorbed almost completely. However, the completeness of absorption of vitamin A largely depends on its amount (in particular, with increasing dose, absorption decreases proportionally). This decrease is apparently associated with increased oxidation and disruption of the mechanisms of active absorption of vitamin A in the intestine, which is due to adaptive mechanisms aimed at protecting the body from vitamin intoxication.

Emulsification of retinol is a necessary step in the process of its absorption in the gastrointestinal tract. In the presence of lipids and bile acids, free vitamin A is adsorbed by the intestinal mucosa, and its esters are adsorbed after hydrolysis by enzymes of the pancreas and small intestinal mucosa (carboxylic acid ester hydrolase).

Up to 40% of carotene is absorbed unchanged. The absorption of carotene is facilitated by complete proteins in the diet. The absorption of ß-carotene from boiled, homogenized foods together with an emulsion of fats (especially unsaturated fatty acids) and tocopherols is improved. β-carotene in the intestinal mucosa undergoes oxidation at the central double bond with the participation of a specific enzyme of the small intestine, carotene dioxygenase (carotinase), resulting in the formation of 2 molecules of active retinal. Carotinase activity is stimulated by thyroid hormones. In hypothyroidism, this process may be disrupted, leading to the development of carotenemic pseudojaundice.

In children under 1 year of age, carotinase is inactive, so carotene absorption is poor. Inflammation of the intestinal mucosa and cholestasis lead to the fact that carotenes and vitamin A are poorly absorbed.

In the intestinal mucosa on the inner surface of the villi, vitamin A, like triglycerides, undergoes resynthesis, forming esters with fatty acids. This process is catalyzed by the enzyme retinol synthetase. The newly synthesized retinol ester enters the lymph and, as part of chylomicrons (80%), is transported to the liver, where it is captured by stellate reticuloendotheliocytes and then by hepatocytes. The ethereal form, retinyl palmitate, accumulates in liver cells, and its reserves in an adult are sufficient for 23 years. Retinol esterase releases retinol, which is carried in the blood by transthyretin. The release of retinol by the liver is a zinc-dependent process. The liver is not only the main depot of vitamin A, but also the main site of synthesis of “retinol binding protein” (RBP), to which vitamin A specifically binds in the blood. RSB belongs to the prealbumin fraction, its molecular weight is 21 kDa. The concentration of RSB in human plasma is 4 mg per 1 ml. RSB in connection with retinol enters into a complex with a protein of much higher molecular weight - thyroxine-binding prealbumin and is transported in the form of a complex complex: vitamin A + retinol-binding protein + thyroxine-binding prealbumin.

The complex of vitamin A and RSB has a significant physiological significance, which consists not only in the solubilization of water-insoluble retinol and its delivery from the depot (liver) to target organs, but also in protecting the unstable free form of the retinol molecule from chemical decomposition (for example, vitamin A becomes stable to the oxidative effects of liver alcohol dehydrogenase). RSB has a protective function in cases of high doses of vitamin A entering the body, which is manifested in the protection of tissues from the toxic, in particular membranolytic, effects of the vitamin. Vitamin A intoxication occurs when vitamin A in the plasma and membranes is not in complex with RSB, but in another form.

In addition to the liver, vitamin A is also deposited in the retina, somewhat less in the kidneys, heart, fat depots, lungs, in the lactating mammary gland, in the adrenal glands and other endocrine glands. Intracellularly, vitamin A is localized mainly in the microsomal fraction, mitochondria, lysosomes, and in the membranes of cells and organelles.

In tissues, vitamin A is converted into retinyl palmitate, retinyl acetate (esters of retinol with palmitic and acetic acids) and retinyl phosphate (phosphoric ester of retinol).

Part of the retinol in the liver (vitamin A - alcohol) is converted into retinal (vitamin A-aldehyde) and retinoic acid (vitamin A - acid), that is, the alcohol group, vitamins A1 and A2, are oxidized, respectively, into aldehyde and carboxyl.

Vitamin A and its derivatives are found in the body in trans configuration (linear form), with the exception of the retina, where cisisomers (11-cisretinol and 11-cisretinal folded form) are present.

All forms of vitamin A have biological activity: retinol, retinal, retinoic acid and their ester derivatives.

Retinal and retinoic acid are secreted by hepatocytes in the bile in the form of glucuronides, retinol glucuronide is excreted in the urine.

Elimination of retinol is slow, so when used as medicinal product, accumulation with the development of an overdose is possible.

How does vitamin A affect the body?

Vitamin A restores the shape and strength of nails, it promotes good healing wounds, thanks to it hair grows faster, it looks healthier and shiny.

Vitamin A is an antioxidant; it fights aging, strengthens the immune system, and increases resistance to viruses and pathogenic bacteria.

Vitamin A is very good for the reproductive system of men and women, increases the activity of the production of sex hormones, and also fights such a serious disease as night blindness (hemeralopathy).

Biological functions of vitamin A

Vitamin A has a wide range of biological effects. In the body, vitamin A (its active form retinal) controls the following processes:

• Regulates the normal growth and differentiation of cells of a developing organism (embryo, young organism).
• Regulates the biosynthesis of glycoproteins of external cytoplasmic membranes, which determine the level of cellular differentiation processes.
• Increases protein synthesis in cartilage and bone tissue, which determines the growth of bones and cartilage in length.
• Stimulates epithelization and prevents excessive keratinization of the epithelium (hyperkeratosis). Regulates the normal function of single-layer squamous epithelium, which plays a barrier role.
• Increases the number of mitoses in epithelial cells, vitamin A regulates division and differentiation in rapidly proliferating (dividing) tissues, prevents the accumulation of keratohyalin in them (cartilage, bone, epithelium of the skin and mucous membranes, spermatogenic epithelium and placenta).
• Promotes the synthesis of RNA and sulfated mucopolysaccharides, which play an important role in the permeability of cellular and subcellular, especially lysosomal membranes.
• Due to its lipophilicity, it is integrated into the lipid phase of membranes and has a modifying effect on membrane lipids, controls the rate of chain reactions in the lipid phase, and can form peroxides, which in turn increase the rate of oxidation of other compounds. Maintains the antioxidant potential of various tissues at a constant level (this explains the use of vitamin A in cosmetology, especially in preparations for aging skin).
• Having a large number of unsaturated bonds, vitamin A activates redox processes, stimulates the synthesis of purine and pyrimidine bases, and participates in the energy supply of metabolism, creating favorable conditions for ATP synthesis.
• Participates in the synthesis of albumin and activates the oxidation of unsaturated fatty acids.
• Participates in the biosynthesis of glycoproteins, as a lipid carrier through the cell membrane of hydrophilic residues of mono- and oligosaccharides to the places of their connection with the protein base (to the endoplasmic reticulum). In turn, glycoproteins have a wide range of properties in the body biological functions and can be enzymes and hormones, participate in antigen-antibody relationships, participate in the transport of metals and hormones, and in blood clotting mechanisms.
• Participates in the biosynthesis of mucopolysaccharides that make up mucus, performing a protective effect.
• Increases the body's resistance to infection, vitamin A enhances the formation of antibodies and activates phagocytosis.
• Necessary for normal cholesterol metabolism in the body:
  • regulates the biosynthesis of cholesterol in the intestine and its absorption; with a lack of vitamin A, the absorption of cholesterol accelerates and it accumulates in the liver.
  • participates in the biosynthesis of hormones of the adrenal cortex from cholesterol, vitamin A stimulates the synthesis of hormones, and with a lack of vitamin, the nonspecific reactivity of the body decreases.
• It inhibits the formation of thyroid hormones and is an antagonist of iodothyronines, suppresses the function of the thyroid gland, and thyroxine itself promotes the breakdown of the vitamin.
• Vitamin A and its synthetic analogues can inhibit the growth of some tumors. The antitumor effect is associated with stimulation of the immune system, activation of the humoral and cellular immune response.

Retinoic acid is involved in stimulating the growth of bones and soft tissues only:

• Regulates the permeability of cell membranes, increasing their stability, by controlling the biosynthesis of their components, in particular individual glycoproteins, and thereby affects the barrier function of the skin and mucous membranes.
• Stabilizes mitochondrial membranes, regulates their permeability and activates enzymes of oxidative phosphorylation and coenzyme Q biosynthesis.

Vitamin A has a wide range of biological effects. It promotes the growth and development of the body, tissue differentiation. It also ensures the normal function of the epithelium of the mucous membranes and skin, increases the body’s resistance to infections, and participates in the processes of photoreception and reproduction.

Vitamin A's most widely known function is in night vision. It participates in the photochemical act of vision by producing the pigment rhodopsin, which can capture even minimal light, which is very important for night vision. Even Egyptian doctors in 1500 BC. e., described the symptoms of “night blindness” and prescribed ox liver as a treatment. Without knowing about vitamin A, relying on the empirical knowledge of that time.

First of all, vitamin A is a structural component of cell membranes, so one of its functions is its participation in the processes of proliferation and differentiation of various types of cells. Vitamin A regulates the growth and differentiation of cells in the embryo and young organism, as well as the division and differentiation of rapidly proliferating tissues, primarily epithelial cells, especially the epidermis and glandular epithelium, which produces mucous secretions, by controlling the synthesis of cytoskeletal proteins. Lack of vitamin A leads to disruption of the synthesis of glycoproteins (more precisely, glycosylation reactions, i.e., the addition of a carbohydrate component to protein), which is manifested by loss protective properties mucous membranes. Retinoic acid, having a hormone-like effect, regulates the expression of genes for certain growth factor receptors, while it prevents the metaplasia of glandular epithelium into keratinizing squamous epithelium.

If there is little vitamin A, keratinization of the glandular epithelium of various organs occurs, which disrupts their function and contributes to the occurrence of certain diseases. This is due to the fact that one of the main functions of barrier protection, the clearance mechanism, cannot cope with the infection, since the process of maturation and physiological desquamation, as well as the process of secretion, is disrupted. All this leads to the development of cystitis and pyelitis, laryngotracheobronchitis and pneumonia, skin infections and other diseases.

Vitamin A is necessary for the synthesis of chondroitin sulfates in bone and other types of connective tissue; its deficiency impairs bone growth.

Vitamin A takes part in the synthesis of steroid hormones (including progesterone), spermatogenesis, and is an antagonist of thyroxine, the thyroid hormone. In general, much attention in the world literature is currently paid to vitamin A derivatives – retinoids. It is believed that their mechanism of action is similar to steroid hormones. Retinoids act on specific receptor proteins in cell nuclei. Next, such a ligand receptor complex binds to specific regions of DNA that control the transcription of special genes.

Antioxidant effect of vitamin A

Vitamin A and, especially, carotenoids are the most important components of the body's antioxidant defense. The presence of conjugated double bonds in the vitamin A molecule promotes its interaction with free radicals of various types, including oxygen free radicals. This most important feature vitamin allows it to be considered an effective antioxidant.

The antioxidant effect of retinol is also manifested in the fact that the vitamin significantly enhances the antioxidant effect of vitamin E. Together with tocopherol and vitamin C, it activates the inclusion of selenium in glutathione peroxidase (an enzyme that neutralizes lipid peroxides). Vitamin A helps maintain SH groups in a reduced state (SH groups of a diverse class of compounds also have an antioxidant function). In particular, by preventing the oxidation of SH-containing proteins and the formation of SS cross-links in them in the composition of keratin, vitamin A thereby reduces the degree of keratinization of the epithelium (increased keratinization of the skin leads to the development of dermatitis and early skin aging). However, vitamin A can also act as a pro-oxidant, since it is easily oxidized by oxygen to form highly toxic peroxide products. It is believed that the symptoms of hypervitaminosis A are precisely due to its pro-oxidant effect on biomembranes; the process of lipid peroxidation in lysosomal membranes, to which vitamin A exhibits a pronounced tropism, is especially enhanced. Vitamin E, protecting the unsaturated double bonds of retinol from oxidation and the resulting formation of free radical products of retinol itself, prevents the manifestation of its pro-oxidant properties. It is also necessary to note the synergistic role with tocopherol ascorbic acid in these processes.

The antioxidant effect of vitamin A and β-carotene plays an important role in the prevention of heart and artery diseases; vitamin A has a protective effect in patients with angina pectoris, and also increases the level of “good” cholesterol (HDL) in the blood. They protect the membranes of brain cells from the destructive effects of free radicals, while β-carotene neutralizes the most dangerous species free radicals: polyunsaturated acid radicals and oxygen radicals. Being powerful antioxidants, vitamin A is a means of preventing and treating cancer, in particular, preventing the reappearance of tumors after surgery.

The carotenoid contained in red wine and peanuts, reservatol, has the most powerful antioxidant effect. Lycopene, which tomatoes are rich in, differs from all carotenoids in its pronounced tropism for adipose tissue and lipids; it has an antioxidant effect on lipoproteins and some antithrombogenic effect.

In addition, it is the most powerful carotenoid in terms of protection against cancer, especially breast, endometrial and prostate cancer.

Lutein and zeaxenthin are the main carotenoids that protect our eyes: they help prevent cataracts and also reduce the risk of macular degeneration, which is the cause of blindness in one in three cases. With vitamin A deficiency, keratomalacia develops.

Vitamin A and immunotropic effect

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. Due to the accelerated proliferation of cells of the immune system, the phagocytic activity of leukocytes and other factors of nonspecific immunity increases. β-carotene significantly increases the activity of macrophages, since they undergo specific peroxide processes that require large amounts of antioxidants. Macrophages, in addition to phagocytosis, present antigen and stimulate the function of lymphocytes. There are many publications regarding the effect of β-carotene on increasing the number of T-helper cells. The greatest effect is shown in persons (people and animals) experiencing stress (improper diet, illness, elderly age). In completely healthy organisms the effect is often minimal or absent. This is due, among other things, to the elimination of peroxide radicals that inhibit the proliferation of T cells. By a similar mechanism, vitamin A stimulates the production of antibodies by plasma cells.

The immunoactive effect of vitamin A is also associated with its effect on arachidonic acid and its metabolites. It is assumed that vitamin A suppresses the production of arachidonic acid products (related to omega fatty acids), thereby inhibiting the production of prostaglandin E2 (a lipid physiologically active substance). Prostaglandin E2 is a suppressor of NK cells, reducing its content; betacarotene enhances the activity of NK cells and stimulates their proliferation.

Vitamin A is believed to protect against colds, flu and infections of the respiratory tract, digestive tract, and urinary tract. Vitamin A is one of the main factors responsible for the fact that children in more developed countries tolerate such diseases much more easily. infectious diseases like measles, chicken pox, while in countries with a low standard of living the mortality rate from these “harmless” viral infections is much higher. Vitamin A prolongs the life of even AIDS patients.

Vitamin A: special properties

Vitamin A almost does not lose its properties during heat treatment, but in combination with air during long-term storage it is destroyed. When cooked, 15 to 30% of vitamin A is lost.

The content of vitamin A in these products depends on how vegetables with vitamin A are grown. For example, if the soils are too poor, then much less vitamin A remains in them. If vegetables are grown with a high content of nitrates, they tend to destroy vitamin A - both in the body and in the plants themselves.

Vegetables grown in winter have 4 times less vitamin A than those grown in summer. Greenhouse cultivation also depletes vegetables of vitamins by about 4 times. If vegetables do not contain vitamin E, then vitamin A will be absorbed much worse.

Milk (natural) contains a lot of vitamin A. But only if cows are fed plants grown in soils rich in fertilizers and if vitamin E is present in their diet. It protects vitamin A from destruction.

Vitamin A and retinol, which is part of it, are a recognized fighter against aging and for beauty. Vitamin A also contains many fat-soluble substances, retinoic acid, retinal, and retinol esters. For this property, vitamin A is also called dehydroretinol.

Vitamin A in the free state has the form of slightly colored yellow crystals with a melting point of 63640 C. It is soluble in fats and most organic solvents: chloroform, ether, benzene, acetone, etc., but insoluble in water. In a chloroform solution, vitamin A has an absorption maximum at λ = 320 nm, and dehydroretinol (vitamin A 2) at λ = 352 nm, which is used in its determination.

Vitamin A and its derivatives are unstable compounds. Under the influence of ultraviolet rays, it quickly decomposes with the formation of Rionon (a substance with the smell of violets), and under the influence of atmospheric oxygen it easily oxidizes with the formation of epoxy derivatives. Sensitive to heat.

Plant products contain a precursor to vitamin A – carotene. Therefore, the body is partially supplied with vitamin A through plant products, unless the process of converting food carotenoids into vitamin A is disrupted in the body (in case of gastrointestinal pathology). Provitamins are found in the yellow and green parts of plants: carrots are especially rich in carotene; satisfactory sources of carotene are beets, tomatoes, pumpkin; found in small quantities in green onions, parsley, asparagus, spinach, red pepper, black currants, blueberries, gooseberries, and apricots. Carotene from asparagus and spinach is twice as active as carotene from carrots, since carotene from green vegetables is more active than carotene from orange and red vegetables and fruits.

Where is vitamin A found?

Vitamin A can be found in foods of animal origin, where it is in the form of esters. Provitamins A look like orange substances; they color the vegetables they contain. Orange color. Plant foods also contain vitamin A. In vegetables, provitamins A are converted into lycopene and beta-carotene.

Vitamin A in combination with carotene is also found in egg yolks and butter. Vitamin A accumulates in the liver, this fat-soluble vitamin, so you don’t have to eat food with vitamin A every day; it’s enough to replenish your body with the necessary doses of vitamin A.

Vitamin A: natural sources

• This is the liver beef liver 8.2 mg vitamin A, in chicken liver– 12 mg of vitamin A, in pork liver 3.5 mg of vitamin A
• This is wild garlic - a green plant that contains 4.2 mg of vitamin A
• This is viburnum - it contains 2.5 mg of vitamin A
• This is garlic - it contains 2.4 mg of vitamin A
• This is butter - it contains 0.59 mg of vitamin A
• This is sour cream - it contains 0.3 mg of vitamin A

Vitamin A requirement per day

For adults it is up to 2 mg. Vitamin A can be obtained from pharmacy supplements (one third daily requirement), and two-thirds of this vitamin comes from natural products that contain carotene. For example, carrots.

The daily requirement for vitamin A is for an adult - 1.0 mg (carotene) or 3300 IU, for pregnant women - 1.25 mg (4125 IU), for breastfeeding - 1.5 mg (5000 IU). At the same time, at least 1/3 of the daily requirement of retinol should be supplied to the body in finished form; the rest can be covered by the use of yellow plant pigments - carotenes and carotenoids.

When does the need for vitamin A increase?

• For obesity
• During heavy mental work
• Under working conditions with insufficient lighting
• When constantly working with a computer or TV
• For diseases of the gastrointestinal tract
• For liver diseases
• In cases of viral and bacterial infections

How is vitamin A absorbed?

In order for vitamin A to be normally absorbed into the blood, it needs to come into contact with bile, like a vitamin that dissolves in fat. If you eat vitamin A, but there are no fatty foods in your diet, little bile will be secreted, and vitamin A loss will be up to 90%.

If a person eats plant foods with carotenoids, for example, carrots, no more than a third of beta-carotene is absorbed from it, and half of it is converted into vitamin A. That is, to get 1 mg of vitamin A from plant foods, you need 6 mg of carotene.