What does vitamin a mean? Vitamin A – where it is found and what it is useful for

Vitamin A (Retinol) is a representative of the class of fat-soluble vitamins that can accumulate in the body. Necessary for vision and bone growth, healthy skin and hair, normal functioning of the 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 in their effect. 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. This chemical compound 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, dicyclohexane, dichloroethane. Practically insoluble in water. It is unstable in the external environment - it is destroyed under the influence of 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 of 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 increases. 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 the growth and proper development of the 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

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 by frequent bronchitis, pneumonia, erosive-inflammatory processes in the gastrointestinal tract, inflammation of the genitourinary system with urinary incontinence.

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

General weakness, increased fatigue, drowsiness during the day and insomnia at night appear. On the mental side, unmotivated irritability, anxiety and depression are noted. The risk of malignant tumors increases, especially breast cancer, and for 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
• deficiency of other 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 the visual analyzer (long sitting at the computer, watching 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:

It is easy to notice that the largest amount of 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! A solution for external use is used in the treatment of skin diseases, and preparations for internal use are used for the prevention of vitamin A deficiency and the 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, and “heavier” dosage forms are used for therapeutic purposes.

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 burns and frostbite
• acute 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, passion for 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 of various metabolites it is removed 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 one remarkable case was described in medical practice, when a group of polar researchers decided to feast on the liver of a 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 it can provoke a 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.

Everyone knows that the benefits of vitamin A for the entire body are very great. Therefore, it is important to consume the required amount of foods containing it every day, while you need to take into account the rules of preparation and storage for better absorption of the vitamin.

According to its composition, vitamin A is classified into substances similar in composition - retinoids and carotenoids, and can be of different origins. The most common and useful substances are retinol and beta-carotene. The first can be obtained from animal products such as meat, liver, chicken eggs, butter and milk, while the second is rich in vegetables and fruits, especially those with bright colors.

Retinol is a vitamin A, has high biological activity, and therefore is of great value in human nutrition.

Beta-carotene entering the body breaks down into two molecules and produces pure vitamin A, the remaining part accumulates in the body and remains for a long time unchanged in the form of a carotenoid, which provides a temporary supply, and if necessary, beta-carotene produces vitamin A again.

What effect does vitamin A have on the body?

The group of vitamins A plays an invaluable role for the whole body. It helps improve the functioning of the organs of vision, strengthen bone tissue and skeleton, improves the functioning of the musculoskeletal system, promotes the formation of the mammary glands, improves metabolism, prevents the occurrence of cancer cells, promotes skin rejuvenation, improves the functioning of the thyroid gland, strengthens the immune system, improves hair condition and nails and much more. And these are just its main properties; it would take a very long time to list everything. Therefore, daily consumption of vitamin A in the diet is necessary for everyone, and especially for people who often suffer from colds and flu, eating disorders, who have poor vision, as well as under heavy physical and mental stress, especially children, pregnant and lactating women, and athletes.

How much vitamin A should you consume per day?

The daily average intake of vitamin A in the diet for a healthy adult is 5000 IU, which is 1.5 mg. However, this amount should be adjusted based on a number of characteristics of the body. It is important to take into account gender, body weight, age, and presence of diseases. For pregnant and lactating women, vitamin A intake is recommended slightly higher than the standard intake. For children, the norm is reduced to 800 micrograms.

When using synthetic vitamins, you must follow the instructions, where the dose has already been adjusted. Or you should take into account the recommendations of the doctor who prescribed you an individual norm for certain reasons.

Why is vitamin A deficiency dangerous in the body?

When there is a lack of vitamin A in the human body, many problems arise:

vision decreases, conjunctivitis appears, in some cases so-called “night blindness” may occur, when a person loses the ability to see in low light. In addition, the mucous membrane of the eye dries out, as a result of which pus and mucus accumulate in the corners of the eyes, tearfulness increases, and vision becomes blurred;

drying out of the skin occurs, which provokes its accelerated aging;

hair and scalp dry out, dandruff and seborrhea appear;

tooth enamel loses strength, begins to deteriorate, and caries develops;

the entire digestive system suffers;

a person suffers from colds and infectious diseases more often and suffers them more severely;

insomnia, lack of sleep, exhaustion, and general fatigue of the body appear.

for women, a lack of vitamin A is fraught with diseases of the reproductive organs;

In men, potency decreases.

What causes vitamin A deficiency

Improper, poor nutrition, frequent diets, diseases of the digestive system contribute to the development of vitamin deficiency, in particular vitamin A deficiency. Also, vitamin A is not absorbed by the body without vitamin E (without it, retinol quickly oxidizes in the human body). Therefore, these two vitamins need to be consumed in combination.

However, not only vitamin A deficiency, but also its excess has a negative effect on the body.

In this case, a number of negative consequences for the body may be observed, namely:

the liver and spleen may increase in size;

disturbances in the functions of the digestive system occur;

excessive hair loss occurs, dandruff, seborrhea appear, nails peel and become brittle;

pigment spots may appear on the skin;

often excess vitamin A is accompanied by nausea;

disruptions occur in the female menstrual cycle.

However, it is quite difficult to achieve a supersaturation of the body with vitamin A. This is mainly due to excessive consumption of synthetic multivitamins. When consuming large amounts of natural foods that are rich in vitamins A, as a rule, excess does not occur. But do not forget that it is strictly forbidden to eat one product for a long time, this can lead to serious irreparable consequences. And if symptoms of overdose are detected, you should immediately stop consuming foods rich in vitamin A, replacing them with foods rich in vitamin C.

What foods contain vitamin A?

Group A vitamins are found in plant and animal products. The largest amounts of retinol are found in fruits and vegetables that are bright orange or green in color. Vitamin A is rich in liver, butter, bird eggs, fish oil, and dairy products. Also, a large percentage of beta-carotene is also found in hawthorn and dandelions. For better absorption of vitamin A by the body, the presence of fat in small doses is necessary. This is necessary for the production of gastric juice, which ensures the synthesis of ready-made vitamin A. Tocopherol and choline are also necessary for the processing of this group of vitamins. That is why it is recommended to use a small amount of sour cream, vegetable or olive oil as a dressing for vegetable salads.

Interaction of vitamin A with other vitamins and drugs

For better absorption of this group of vitamins, it is recommended to take vitamin E, B, phosphorus, potassium, calcium, and zinc together.

Today you can see a wide variety of complex vitamins in pharmacies. However, not all of them contain the optimal ratio of microelements, so you should be very careful when choosing them. You should also not abuse their use, strictly follow the instructions and drink only when necessary, it is advisable to consult a doctor.

IMPORTANT! When taking vitamin A, try to avoid drinking alcohol, as their interaction can cause disturbances in the liver and also lead to serious liver diseases. In addition, when using any vitamins, including group A, you should not use laxatives, as they reduce their absorption (with the exception of herbal laxatives).

How to achieve better absorption of vitamin A

In order to get the maximum benefit from consuming foods, you must follow several rules for their storage and preparation. We already know what vitamin A contains, now let's talk about what is best to do with them.

In order for beta-carotene to be better absorbed by the body, it is recommended to boil or finely chop vegetables. But this rule is not suitable for all products; for example, when cabbage is cooked, the benefits of vitamin A are reduced, so it will be healthier to eat it raw.

Sun rays and oxygen contribute to the destruction of vitamin A, so it is not recommended to store food in an open place exposed to direct sunlight.

The benefits of vitamin A will be greater if you cook foods containing beta-carotene and tocopherol together.

Best cooked steamed or grilled.

The quantitative content of retinol in milk depends on the season. In spring and summer there is significantly more of it, since only natural fresh herbs are used in feeding cows, and artificial additives are very rarely used.

It is best to choose fruits that are bright red or orange in color; they contain the highest amount of vitamin A.

Adequate nutrition ensures health throughout the body, improves well-being and mood. It also makes it possible to avoid many diseases and illnesses. Therefore, it is important to correctly adjust your daily diet and consume all foods in sufficient quantities.

Undoubtedly, it is best not to consume synthetic vitamins, but to obtain them in natural foods in the diet.

Table of vitamin A content in foods

You can monitor this using a special table.

Hello my curious friends. Does your diet contain retinol - aka vitamin A? This is an incredibly useful element, and I intend to convince you of it today.

Vitamin A is a fat-soluble element that belongs to a group of substances called retinoids. It plays a key role in maintaining healthy vision, nervous system function and healthy skin. Like all antioxidants, this element is involved in reducing inflammation by fighting free radicals.

Knowing what vitamin A is good for, you can protect yourself from developing many serious diseases. This element takes part in the following processes:

• Forms a special pigment in the retina - rhodopsin. Thanks to this substance, the eyes are sensitive to light signals. If rhodopsin is present in sufficient quantities in the body, adaptation of the eyes to lighting occurs quickly.
• Increases the production of proteins in cartilage and joint tissues, which ensures their renewal and growth. This is why vitamin A is so important for a young, growing body.
• Ensures the normal condition of the mucous membranes of the bronchi and nose. Thanks to this, the intestines, lungs, and stomach are protected from infections.
• Strengthens the work of the sympathetic-adrenal system of the body. The essence of this function is this: after foreign bodies enter the body, the adrenal glands produce adrenaline. If retinol enters the body in sufficient quantities, it promotes the production of large amounts of adrenaline.
• Provides strength to dermal fibers. The condition of the skin depends on the elasticity of such fibers, so vitamin A is simply necessary for facial skin.

In cosmetology, the vitamin is also used for acne. It is also important for hair and eyelashes. This element strengthens hair follicles and accelerates hair growth.

Deficiency Symptoms

People with fat malabsorption are very susceptible to developing vitamin deficiency. The most common health problems that cause element A malabsorption include gluten sensitivity. This also includes leaky gut syndrome, autoimmune reactions, inflammatory bowel diseases, etc.

Element A deficiency has become a public health problem in more than half of all countries in the world. This problem is especially common in Africa and Southeast Asia. It primarily affects young children and pregnant women in low-income countries.

The following signs indicate a lack of vitamin A in the body:

• Premature skin aging. Peeling and follicular thickening of the skin are observed. Keratinization of the dermis occurs when epithelial cells lose moisture and become hard and dry. Such phenomena can occur on the mucous membranes of the respiratory tract, urinary tract, etc.
• Vision is impaired. Moreover, this problem can have different aspects of manifestation. One of them is xerophthalmia or “dry eye”. Another manifestation is keratomalacia or melting of the cornea. In addition, conjunctivitis may occur. Not receiving enough retinol can lead to the development of night blindness.

• Hair becomes brittle and dull. Lack of retinol in the body leads to early gray hair.
• Nail growth slows down. They begin to peel and break.
• Respiratory infections. This happens because the body's immunity is weak due to a lack of vitamin A.

What does vitamin A contain?

It comes in two different types: active and beta carotene. The active form comes from animal products and is called retinol. It is directly used by our body.

The other type, which we get from fruits and vegetables, in the form of “provitamin A,” is called a carotenoid. These substances are converted into retinol after food enters the body. For example, a type of carotenoid such as beta-carotene must first be converted into the active form A so that it can be absorbed by the body.

Research has repeatedly shown that retinol, as an antioxidant, is very important for good health. Nutrition experts recommend getting most of your vitamins from food. Eggs, milk, liver, carrots, and yellow or orange vegetables are common foods that are high in vitamin A. Foods that contain high amounts of vitamin A are listed in the table below. The percentage is given at a consumption rate of 900 mcg.

Remember that retinol is heat stable. However, during cooking, boiling and canning, about 15-30% of vitamin A is still lost.

This element is also destroyed under the influence of ultraviolet rays. And oxygen reduces its content in the product. Therefore, long-term storage of food in air leads to a partial loss of retinol.

Instructions for use

The daily intake of vitamin A depends on age and gender. Below I have listed the data with the official dosage accepted in Russia.

For children:

For adults:

Most people get enough of the vitamin from their diet. But if you are diagnosed with a deficiency, your doctor may recommend taking additional supplements. You can buy this drug at a pharmacy. Liquid Aevit is sold here, in capsules and ampoules. In addition, the pharmacy sells Retinol Acetate and Retinol Palmitate. The price depends on the form of release and dosage.

The formula of the drug varies slightly. Therefore, a doctor should select a pharmaceutical supplement and describe how to take it. He will also tell you the name of the drug that is optimal in your case. The doctor knows best how to take the drug correctly so as not to harm your health.

Additional vitamin A is needed for:

• strong physical activity;
• after x-ray irradiation;
• during a period of intensive growth;
• in too hot climates;
• due to prolonged exposure to a computer or TV;
• excessive stress, etc.

Side effects - overdose

High doses of element A may actually do more harm than good. Excessive consumption of additional supplements can lead to jaundice, nausea, loss of appetite, irritability, vomiting and baldness. Overdose is rare, but still. If you are considering taking vitamin A supplements, be sure to consult your doctor.

If you are using supplements that contain vitamin A, look at the amount of the element in one dose. And make sure it's appropriate for your gender and age.

Symptoms of a vitamin A overdose include dry skin, joint pain, vomiting, headaches and confusion. Due to increased intracranial pressure, severe headaches and even confusion may occur. In addition, gastrointestinal upset may occur.

Health Benefits of Vitamin A

This element is very important for the full functioning of individual organs and systems. It also helps prevent the development of certain diseases.

Moreover, retinol protects the body from the harmful effects of free radicals. This slows down the aging process and maintains elasticity for a long period of time. Retinol also protects the skin from aggressive ultraviolet exposure. It evens out the complexion, fights inflammation, and smoothes out wrinkles. Therefore, this vitamin is extremely important for the face.

Interaction with other drugs

Retinol has “friends” and “enemies”. Knowing them by sight, you can prevent a deficiency of this element. Thus, a lack of vitamin E impairs the absorption of retinol. Therefore, a balanced intake of these two components is important.

Zinc deficiency is also bad for the body. This situation makes it difficult to convert vitamin A into its active form.

Mineral oils dissolve fat-soluble substances. This includes retinol. With constant intake of mineral oils, vitamin A, passing through the intestines, is simply not absorbed. Therefore, the body experiences a shortage of this element.

Vitamin A supplements may interact with some birth control pills and blood thinners (such as Coumadin or warfarin). Retinol is detrimental to acne medications (such as Accutane) and drugs used to treat cancer.

You should not take retinol and alcohol at the same time. This duo will kill your liver. You should not take cholesterol-lowering drugs and vitamin A at the same time. Because they are incompatible and this may interfere with the absorption of retinol.

With long-term use of tetracyclines and vitamin A, hypertension develops. Therefore, such a duet is dangerous. The combination of retinol + glucocorticoids is fraught with antagonism.

I am sure that today’s article has helped you take a different look at vitamin A. It turns out that so much depends on this element. Therefore, they cannot be neglected.

Vitamin A (Retinol) was discovered in 1920 by a group of scientists, it is the first vitamin discovered.

Scientists, after much research, came to the conclusion that butter and chicken egg yolk contain a substance associated with lipoids necessary for the growth of animals; they also showed that it contains an active principle that is not destroyed by the action of alkalis and during saponification remains outside the saponified fraction . This substance was designated "fat soluble factor A" and was later renamed vitamin A.

Other names for vitamin A are Anti-infective vitamin, anti-xerophthalmic vitamin, retinol, dehydroretinol.

There are two forms of this vitamin: ready-made vitamin A (retinol) and provitamin A (), which is converted into vitamin A in the human body, so it can be considered a plant form of vitamin A.

It has a pale yellow color that is formed from red plant pigment. During heat treatment, it almost does not lose its properties (only 15-30%), but in combination with air during long-term storage it is destroyed.

Physicochemical properties of vitamin A

The vitamin A group includes the following compounds: Retinol, Retinal, Retinoic acid, Retinol palmitate, Retinol acetate.

Vitamin A is a cyclic unsaturated alcohol, which, when oxidized in the body, forms vitamin A-aldehyde and retinoic acid.

Cereal products and skim milk, even with vitamin supplements, are unsatisfactory sources, as are vitamin A in trace amounts.

Daily requirement for vitamin A

• Infants: 0-6 months. - 400 mcg; 7-12 months - 500 mcg
• Children: 1-3 years - 300 mcg; 4-8 years - 400 mcg
• Men: 9-13 years old - 600 mcg; 900 mcg (3000 IU) for 14-70 years
• Women: 9-13 years - 600 mcg; 700 mcg (2300 IU) for 14-70 years
• Pregnant women: less than 19 years old - 750 mcg; 19-50 years old - 770 mcg
• Women breastfeeding: under 19 years old - 1200 mcg; 19-50 years old - 1300 mcg

For diseases associated with retinol deficiency, the dosage can be increased to 10,000 IU per day (calorizer). (The above dosages apply exclusively to the retinoid form of vitamin A. The carotenoid form is not as toxic).

Retinol can be obtained from pharmaceutical supplements (which is 1/3 of the daily requirement), and 2/3 of this vitamin can be obtained from natural foods that contain carotene, such as bell peppers or carrots.

Vitamin A (retinol) is a fat-soluble vitamin, an antioxidant, essential for vision and bones, as well as healthy skin, hair and immune system function. Retinol 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 fights viruses and bacteria well, helps strengthen nails and speed up wound healing.

It has a good effect on the reproductive system of men and women, increases the activity of the production of sex hormones.

Harmful properties of vitamin A

Vitamin A can be harmful if overdosed. When there is an excess of it, the body is poisoned and manifests itself in the following symptoms: loss of appetite, nausea, headache, inflammation of the cornea, enlarged liver (calorizator).

Pregnant women should use this vitamin with caution, because An excess of Retinol can lead to developmental disorders of the fetus and the appearance of various congenital pathologies in the child.

Vitamin A absorption

Vitamin A is fat-soluble, so it requires fats as well as minerals to be absorbed by the digestive tract.

Its reserves remain in the body long enough that it does not need to be replenished every day.

Vitamin A deficiency in the body

With a deficiency of vitamin A, night blindness develops, a skin rash appears, the skin peels off, premature aging begins, increased susceptibility to various diseases, visual acuity decreases, dry eyes occur, conjunctivitis develops, dandruff and hair loss appear, and appetite decreases.

Excess vitamin A in the body

With an excess of vitamin A, the following symptoms appear: nausea, vomiting, drowsiness, headache, lethargy, redness of the face, pain in the bones of the lower extremities, menstrual irregularities.

Participation in the vision process of vitamin A

Carotenoids (ie plant sources of vitamin A) are the main sources of protection for our eyes, they help prevent cataracts, and also reduce the risk of macular degeneration, which is the main cause of blindness.

Participation in the body's antioxidant defense of vitamin A

Vitamin A is an essential component of the body's antioxidant defenses, especially carotenoids. It promotes its interaction with free radicals, including oxygen free radicals - this is the most important feature of the vitamin, which allows it to be considered an effective antioxidant.

The antioxidant effect of vitamin A plays an important role in the prevention of heart and artery diseases, also has a protective effect in patients with angina pectoris, and also increases the content of good cholesterol in the blood (calorie).

Due to the fact that Retinol is considered a powerful antioxidant, it is a means of preventing and treating cancer, and prevents the reappearance of tumors after surgery.

Interaction of vitamin A (Retinol) with other substances

Vitamin A significantly enhances antioxidant properties, but it can be destroyed completely if there is not enough zinc in the body, and it also acts in relation to vitamin A.

Mineral oil, which can sometimes be taken as a laxative, can dissolve fat-soluble substances (such as vitamin A and ). These vitamins then pass through the intestines without being absorbed because they are dissolved in mineral oil, from which the body cannot extract them. Chronic use of mineral oil can thus lead to vitamin A deficiency.

For normal absorption of Retinol, the presence of fats and proteins in the diet is necessary. The difference between edible oil and mineral oil is that the body can absorb edible fat along with the vitamin A dissolved in it; The body does not absorb mineral oil.

For more information about vitamin A, watch the video “Great Vitamin A. A Brick in the Building of Health”

Vitamins are valuable substances for the human body. That is why it is important for people to consume them not only in the form of drugs, but also in the form of food. Which foods contain a lot of vitamins A and B will be discussed in the article. Moreover, it is important to use them as normal, avoiding shortages and overdoses.

The simplest method of obtaining the necessary vitamins is considered to be proper nutrition. With them, the necessary components enter the body. To balance your diet, you need to consider which foods contain the most vitamins. Each substance has its own value for the body, so they are needed for every person. You just need to take the norm into account.

Benefits of Vitamin A

Retinol is required for the prevention and treatment of diseases of vision, bones, skeleton, mammary glands, respiratory system, cirrhosis, hypertension, atherosclerosis. Products with this vitamin help normalize metabolic processes in the skin and improve resistance to colds and infections. Therefore, if you have to deal with eye strain in everyday life, you should know which foods contain a lot of vitamin A. In this case, you will need animal and plant products.

If retinol is supplied with food in the required quantity, it improves the permeability of cell membranes and the synthesis of adrenal hormones. The component improves sexual function and thyroid function. Food with vitamin A reduces the effect of carcinogens, restores immunity, and suppresses malignant formations.

Where is vitamin A present?

What foods are high in vitamin A? Retinol is not found in plants, but it is found in animal products:

• cream;
• butter;
• yolks;
• kidneys;
• fermented milk products;
• fish liver.

What other foods are high in vitamin A? To treat night blindness, dishes made from half-raw liver (beef and pork) are used. Retinol is present in fish oil. Which foods contain a lot of vitamin A or carotenoids? This component is found in red and orange vegetables and fruits. Carotenodes are converted into retinol in the body. Spinach, parsley, lettuce, tomatoes, red peppers, zucchini, green peas, cabbage, and sea buckthorn are rich in beta-carotene. The component is found in rose hips, pumpkin, and peaches.

Daily norm

To establish the dose of a substance, the unit IU has been created by international agreements. Every day, the human body receives 5000 IU of vitamin A through food, which is equal to 1.5 mcg. When compiling a diet, you need to know that the retinol level is 1/3.

The remaining 2/3 of the daily requirement should be supplied to the body with plant foods that contain carotene. The biological activity of such food is 2-3 times lower, which compensates for the consumption of carotenes in 2-3 times more quantities. There are experts who believe that for prevention and treatment it is possible to exceed the maximum level by 3-4 times, but long-term overdose should be excluded.

Excess and deficiency of vitamin A

Excess retinol is indicated by headache, body itching, nausea, swelling, and nervous irritability. There is no overdose with the use of regular products. If there are signs of excess, then you need to avoid products with vitamin A, but you need vitamin B.

According to studies, it was revealed that due to prolonged overdose of retinol and fish oil, malignant formations appear. Retinol tends to accumulate between cell membranes, which contributes to disruption of their function. An overdose of synthetic drugs is dangerous during pregnancy.

With a lack of vitamin A, visual impairment occurs, immunity decreases, dry skin, rashes, and acne appear. This is evidenced by brittle hair, rough skin, and high fatigue. Due to the lack of foods with vitamin A, cellulite appears, the functioning of the nervous system and digestion are disrupted.

Vitamin B1

This component is necessary for the body just like other vitamins. Its presence will allow the body to function normally. Vitamin B1 (thiamine) helps convert food into energy. Its presence is required for healthy skin, hair, muscles, and brain.

The daily norm is 1.2 mcg for men and 1.1 mcg for women. But indicators may vary depending on age and lifestyle. Due to the lack of a component, nausea, constipation, insomnia, tearfulness, and deterioration in performance may occur.

Nowadays, component shortages are rare. Most of all it is present in food. What foods contain a lot of B vitamins? It is found in plant foods: soybeans, peas, spinach, beans, and products based on wholemeal flour. Less thiamine is present in potatoes, cabbage, and carrots. Among animal products, this valuable component is found in liver, brains, kidneys, pork and beef. Such products should be included in every person's diet.

Riboflavin. AT 2

It is also called riboflavin. The component is involved in metabolism and is necessary for the normal functioning of the visual system, skin and mucous membranes. It is needed in the synthesis of hemoglobin. A lack of vitamin contributes to decreased appetite, headaches, and burning skin. This also causes pain in the eyes.

To avoid unpleasant symptoms, it is necessary to include food rich in the menu. For men, 1.2 mcg of the component per day will be enough, and for women - 1.1 mcg. Most riboflavin is present in the liver, kidneys, and yeast. Smaller amounts are present in eggs and almonds. The substance is also found in mushrooms, cottage cheese, and cabbage.

A nicotinic acid. AT 3

Thanks to vitamin B3, or nicotinic acid, energy is released from all food components. The substance synthesizes proteins, fats, and is involved in the production of various hormones. When there is a deficiency, pellagra appears. Symptoms include aggression, dermatitis, confusion, paralysis and diarrhea. Lack of the substance causes disruption of the intestinal microflora.

To replenish the vitamin, 20 mcg of the component per day will be enough for men and women. It is found in meat, whole grains, mushrooms, potatoes, nuts, egg yolks, and green vegetables. Yeast is rich in it.

AT 5

The component is called pantothenic acid. With its help, wounds heal, it synthesizes antibodies and metabolizes proteins, fats, and carbohydrates. With a deficiency, a burning sensation in the legs and other neurological symptoms appear.

The norm for men and women is 5 mcg. The need for this component is satisfied by non-specialized nutrition, since it is found in many animal and plant products. The substance is also produced by the body. It is found in peas, hazelnuts, garlic, milk, and fish roe.

Pyrodoxin. AT 6

The component is necessary for the synthesis of hemoglobin and polyunsaturated fatty acids. With a lack of pyrodoxine, depression, dermatitis, and loss of appetite are observed. The norm for men is 1.7 mcg, and for women - 1.5 mcg.

What foods are high in vitamin B6? Most of this component is found in hazelnuts, walnuts, potatoes, and sweet potatoes. Vegetables, fruits, and berries are rich in it.

Biotin. AT 7

Biotin releases energy from caloric components. If there is a lack of substance, there will be dermatitis, hair loss, increased blood sugar, insomnia, and muscle pain.

The daily norm for a healthy person is 30-100 mcg. The component is present in small quantities in legumes, cauliflower, nuts, yeast, liver, and kidneys. A small amount of the substance is found in tomatoes, spinach, and mushrooms.

Folic acid. AT 9

Needed for cell division. Due to its deficiency, anemia, apathy, digestive difficulties, memory impairment, and graying are observed.

Needed during pregnancy. The daily norm is 200 mcg. Folic acid is found in green leafy vegetables, citrus fruits, legumes, honey, and flour products.

AT 12

Cyanocobalamin is necessary for the creation of red blood cells, maintaining growth and functioning of the nervous system. Lack of a component causes digestive disorders, liver enlargement, and nervous disorders. The daily norm is 3 mcg. The substance comes with food. Therefore, it is important to remember which foods contain a lot of vitamin B 12? This will allow you to saturate your body with the necessary substances.

What foods are high in vitamin B12? Most of this substance was found in beef liver. It is also found in chicken hearts and pork liver. What other foods contain a lot of vitamin B12? It is found in seafood and dairy products.

There are many other vitamins that are important for human health. These include C, PP, D. Each of these substances is necessary for the full development of a person. You should not allow a lack of nutrients to avoid hypovitaminosis. Therefore, nutrition should be balanced, which involves the supply of all necessary substances. Then the body is not at risk of various ailments.