Vitamin A content in fruits and vegetables. Vitamin A: what foods contain it and why does a person need it

Content:

The importance of this vitamin What is the danger of its deficiency. Daily rate. What products does it contain?

The answer to the question - "what foods contain vitamin A" - is not as simple as it might seem at first. Let's analyze what is meant by this element and where it can be found.

Varieties

The term refers to several different but similar nutrients that can be divided into two main categories:

• Retinoids (or retinol) is a biologically available form of the vitamin found in animal foods.
• Carotenoids- provitamin A, present in plant foods.

The only type of this element that the human body can use relatively easily is retinoids. Common foods containing retinol include liver and eggs. If we consume carotenoids found in plant foods, then the body will need to convert them into a biologically available form, that is, into retinol, in order to be used further. If you are in excellent health, then there will be no problems with this process.

There may be a number of factors that can hinder the body's ability to absorb carotenoids and convert them to retinol. These issues include:

• genetic factors;
• problems with the digestive system;
• alcohol consumption;
• certain types of medicines;
• exposure to toxins;
• certain diseases that interfere with the digestion of fats (for example, granulomatous disease, cystic fibrosis, diseases of the gallbladder and liver).

For most people, this transformation is very difficult. To the greatest extent, this applies to infants, diabetics and people experiencing problems with bile formation. Also, this kind of ability depends on the general composition of the human diet. In people using a low-fat diet, the effectiveness of this process will be clearly low.

Many people think that vitamin A is just beta-carotene. At the same time, people often think that by consuming a sufficient amount of carrots and some other plant products, they provide themselves with this element. But if your body is not able to fully convert carotenoids into retinol, then avoiding animal foods (for example, with a vegetarian diet) can lead to a deficiency of this substance.

Scarcity Risks

This vitamin is important for vision, immune system function and cell growth. It works in conjunction with other vitamins and minerals including D, K2, zinc and magnesium.

Usually, the population of developed countries rarely encounter a shortage of this element. The earliest sign of deficiency is night blindness, which can lead to permanent blindness if left untreated. Deficiency of this compound also suppresses the immune system, which can cause complications from infectious diseases. Other consequences are:

• Hormonal imbalance.
• Infertility.
• affective disorders.
• Skin problems (such as eczema and acne).
• Thyroid dysfunction.

Vegetarians and alcoholics are among the most deficient populations.

Element Importance

Vitamin A is very important for good vision, especially for preventing age-related changes in the cornea. It affects vision primarily through the regulation of gene expression. For this mechanism to work correctly, it is necessary to convert retinol to retinal and then to retinoic acid.

To optimize metabolism, it is important to eat natural foods that are rich in vitamins in general, and not just A.

What products have it?

As in the case of other elements, it is not just the fact of its presence in the product that is important, but the level of its concentration. Here is a list of foods rich in vitamin A.

• Beef liver - 8,2 .
• Chicken eggs - 0,25 .
• Butter - 0,4 .
• Whole cow's milk - 0,03 .
• Cream - 0,06 .
• Fresh fish - 0,05 .

Sources of provitamin A (carotenoids):

• Carrot - 9,0 .
• Parsley - 5,7 .
• Rose hip - 2,6 .
• Dill - 4,0 .
• Salad - 1,75 .

Several studies have shown that taking vitamin A supplements in excess of acceptable levels can be toxic to the body, increasing the risk of heart disease, cancer, and other health problems. For this reason, it is safer to use foods containing the vitamin rather than supplements.

The risk of toxic effects is especially high when using dietary supplements containing a biologically available form - retinol or retinoic acid. Signs of such an impact include:

• Hair loss.
• Confusion of consciousness.
• Osteoporosis.
• Liver damage.

Daily dose

• Daily allowance for adult men and women - 900 and 700 mcg respectively.
• In pregnant women it is 750–770 mcg, and in lactating women it is almost twice as high - 1200–1300 .
• In children, the picture is the opposite - only 300–400 mcg/day.

Conclusion

The element in question is necessary for the normal functioning of many organs and systems of the body. Vitamin A is found in both plant and animal products. Their correct selection, as well as the use of any nutritional supplements, require prudence and knowledge of the current state of health of a particular person.

Scientists have proven that vitamin A affects almost all organs and systems of the human body, and its deficiency negatively affects our health.

It is important for each person to know what foods and how much vitamin A is contained in order to properly organize their diet.

Vitamin A includes a whole group of substances that are similar in their chemical properties. The most common are two of them:

1. Retinol is often called the “correct” vitamin A due to its high biological activity, and therefore it is considered the most valuable in nutrition.
2. Beta-carotene is vitamin A that has not yet been prepared for absorption by the body. The use of this substance by the body is possible only after it has been converted into retinol.

In order to always know exactly where A is contained, it is necessary to remember that retinol is usually found in large quantities in animal foods, while sources of beta-carotene are found in plant foods.

Daily rate

Retinol is known to many as a substance that promotes the growth and development of bone tissue. It is for this reason that experts recommend consuming foods with vitamin A for children.

In order to avoid vision problems, improve immunity, take care of heart health, it is important to know which foods contain vitamin A and beta-carotene in sufficient quantities. With a lack of retinol in the human body, there is a risk of early aging, vision “falls”, the perception of colors worsens, skin rashes appear, excessive hair loss is activated, increased tooth sensitivity occurs, and immunity problems are characteristic.

The daily requirement of vitamin A for an adult is 1500 - 2000 mcg. For children, depending on their age, the daily norm is in the range of 375-700 mcg. Doctors recommend that one-third of the daily value be consumed as a complete retinol, and the rest from foods high in beta-carotene.

In products

Retinol

Fish oil is the leader in retinol content, 100 grams contains 1900 mcg, followed by beef liver - 8000 mcg, pork and cod liver - 4000 mcg each. Much less retinol is found in eggs - 400 mcg, dairy products: butter - 400 - 500 mcg, and in milk - only 25 mcg. Not all types of milk contain retinol, but only the milk of cows whose diet consisted of grass and hay. Due to the high content of beta-carotene in cow feed, in summer or autumn, the proportion of retinol increases significantly both in the milk itself and in the butter. It is thanks to retinol that milk (as well as butter) acquires a characteristic yellowish tint, indicating a high content of beta-carotene in animal nutrition.

Carotene

Beta-carotene is found in plant foods. Most beta-carotene in carrots - 8320 mcg, red hot peppers, green onions - 2000 mcg each, pumpkin - 4750 mcg, apricots - 1600 mcg.

A large amount of beta-carotene is found in almost all orange or dark green vegetables, potatoes, carrots, mangoes, cabbage and other foods. For the transformation, in our body, of beta-carotene into a full-fledged retinol, a small amount of fat is required in food. Fat is needed in order for bile to occur in the digestive tract. The use of beta-carotene without fat leads to its loss - by almost 90%. To synthesize ready-made vitamin A from beta-carotene, the body also needs a number of other substances, including tocopherol and choline. Therefore, nutritionists recommend seasoning vegetable salads with vegetable oil or sour cream.

Amount in food: table

Studies by employees of the Russian Academy of Medical Sciences do not recommend exceeding the daily allowance of vitamin A. Using the table of retinol content in food, you can adjust your diet by choosing the necessary products for its sources.

How to increase digestibility

1. By destroying the shell, you can increase the absorption of beta-carotene from plant products. For example: vegetables can be boiled or eaten raw.
2. Boiled carrots contain more bioavailable beta-carotene than raw ones, but it must be remembered that boiling or frying some other vegetables (for example, cabbage), on the contrary, reduces the level of nutrients.
3. Heat treatment of products containing retinol leads to vitamin losses by an average of 20-40%.
4. Our body is able to store small amounts of vitamin A in the liver (and sometimes tissues) and use it as needed.
5. Foods containing beta-carotene and tocopherol are best cooked together. Vegetables containing beta-carotene should be eaten with some fat content for its best absorption.

A balanced diet is the guarantee of our health and well-being. Knowing which foods have enough vitamin A, you can adjust your daily diet, avoid the lack of this important substance in the body.

If vitamins were given awards for their health benefits, vitamin A would undoubtedly be in first place: its impact on human health is truly colossal. will introduce you to the main features of such an important element, and will also explain in detail how to properly “build relationships” with this vitamin so that its use brings the body maximum benefits.

Vitamin A is not just listed at the very beginning of the “vitamin alphabet”: it was the first of its brethren discovered by scientists. Why does the body need this element so much?

Multifunctional doctor

The range of useful properties of vitamin A is really impressive in its vastness: when it enters the human body in sufficient quantities, it works wonders. One of his most famous superpowers is support and restoration of vision: that we need to use carrots rich in carotene as often as possible, we were told from early childhood. Vitamin A fights cataracts. In addition, vitamin A guards the health of the skin: with its help get rid of acne and psoriasis he is excellent heals wounds and burns, activating the accelerated epithelial recovery.

Separately, it is worth noting the direct effect of vitamin A on the immune system: if a person consumes this element in sufficient quantities, it immunity is getting stronger practically before your eyes. The mucous membranes of the body become more resistant to various viruses, and in the respiratory tract, genitourinary system and gastrointestinal tract almost no infections occur. Needs vitamin A and thyroid- deficiency of this element in the body can trigger the development of leukemia and other diseases of the endocrine system.

You can not do without vitamin therapy for those people who regularly encounter diseases gastrointestinal tract and cardiovascular system. Vitamin A active fights atherosclerosis, thrombophlebitis and hypertension, increasing the content of "good" cholesterol in the body and not allowing the "bad" to accumulate. This element normalizes the process of protein synthesis, promotes growth of new cells and improves metabolism; healthy teeth and bones- also his handiwork.

Another valuable benefit of vitamin A is its antioxidant properties: with their help, this element significantly slows down the aging of the body and increases resistance to cancer. It is this vitamin that builds active protection against the negative effects of stress and eliminates the consequences of contact with polluted air. In addition, vitamin A is vital for normal functioning of the sex glands and even capable protect against infertility.

Where to look: Top Sources of Vitamin A

It is immediately worth noting that the human body receives vitamin A from two different sources: animal products saturated retinol, whereas vegetable - carotene(provitamin A). Each of these elements is of great value to the body, but it must always be remembered that vitamin activity of carotene is about 3 times weaker than that of retinol. And since carotene contained exclusively in vegetables, fruits and herbs, their amount in the human diet should three times the volume of animal products, saturated retinol.

So what foods should you eat regularly to get the right dose of vitamin A?

So that your body does not know what a lack of retinol is, be sure to include in your daily diet butter with a fat content of more than 82% and others dairy(the shorter the shelf life, the better). In addition, you should regularly use beef liver and cod liver, as well as egg yolks and kidneys. But at the same time, do not forget about moderation: if the body experiences a constant overabundance of retinol, the chances of facing oncology and cardiovascular diseases will increase significantly.

As for the use of foods high in carotene, you can be calm here: you can lean on them in almost any amount - the more, the better. Particularly valuable sources of carotene are apricots(both fresh and dried) and carrot(especially carotel varieties, which gave the name to provitamin A). Emphasis should also be placed on the use vegetables and fruits in yellow and orange, all kinds cabbage(especially broccoli) and potatoes. Plus, a real storehouse of carotene is considered greens(parsley, watercress, etc.) and lettuce.

Important nuances: how to use vitamin A correctly?

If everything is very simple with retinol, then carotene requires a special approach. The thing is that this vitamin is fat-soluble - in other words, in order for the body to absorb it normally, fats must certainly be present in the dish. It is important to strike a balance: recent studies have shown that provitamin A is best absorbed when it is combined with a very small amount of vegetable oils.

Also carotene loses its beneficial properties during the heat treatment of products and is destroyed if left in the open air for a long time.

What is the daily requirement for vitamin A?

Numerous medical studies have shown that Adult men need approximately 900 micrograms of vitamin A per day., while women - about 700 mcg. For children, the norm can be safely divided by two. Nutritionists recommend including in your daily diet 2 raw carrots(ideal for these purposes is the Korean carrot dish), as well as 200 g broccoli, one serving beef liver and handful of pumpkin seeds- this combination will provide the perfect balance of vitamin A in your body.

Significantly increase the consumption of foods high in retinol and carotene should be those people who have hard, exhausting work, weakened immune system and experience constant stress. In addition, a lot depends on climatic conditions: residents of hot sunny countries, where the incidence of cancer is many times higher, vitamin A should be consumed in much larger quantities.

About deficiency: how to know that the body lacks vitamin A?

The most common symptom of vitamin A deficiency has always been considered vision problems. If you began to notice that in low light it became more difficult to see and read, dryness and pain are regularly felt in the eyes (as if sand has got in), lacrimation occurs in cold air - then it's time to reconsider your diet. In addition, vitamin A deficiency is one of the main enemies of beauty: the skin becomes dry, premature wrinkles appear on the face, hair dries and splits, dandruff and itching of the scalp occurs, tooth enamel is destroyed.

Other organs get no less - a lack of retinol and carotene provokes serious diseases of the gastrointestinal tract and genitourinary system, and also leads to protracted and complex colds, sleep disturbances and mental balance, general weakness.

What causes this deficiency? First of all - malnutrition. Most often, such problems are faced by people who consume too little fat, protein and foods containing vitamin E - a deficiency of the latter leads to accelerated oxidation of vitamin A in the body. In a separate risk zone, those who decide to completely abandon fats, because they help carotene to be absorbed.

About Overdose: Symptoms of Too Much Vitamin A

First of all, it should be noted that ordinary foods are practically not capable of leading to an overdose of vitamin A: if the diet is balanced, the body will take from it only what it needs, and simply remove the rest. But who should be feared is pharmacy vitamin complexes containing synthetic vitamin A - if used improperly, it can easily accumulate in the body in an unacceptable volume, causing malfunctions in the functioning of many vital organs and systems. So, excess synthetic vitamin A in the body leads to problems with the stomach and intestines, enlargement of the spleen and liver, nausea, pain in the bones and joints. In addition, the nails become brittle, there is drying, itching and pigmentation of the skin, hair begins to actively fall out.

Vitamin A belongs to the group of fat-soluble compounds (lipovitamins). It is able to be deposited in the body, mainly in the liver.

According to the WHO, with hypovitaminosis in vitamin A, none of the food products can cover its deficiency, and therefore the intake of retinol in the form of pharmacological preparations is required.

Vitamin A is formed in the body from provitamins - "carotenoids" coming from outside. The term comes from carrot (carrot, English), since these precursor substances were first discovered in carrots. Related compounds are present in a wide range of vegetables and fruits (especially yellow, red and orange), as well as in algae and certain types of fungi.

Currently, more than half a thousand carotenoids are known to science.

The most common of these are:

• a-, b- and d-carotene;
• zeaxanthin;
• lutein;
• lycopene.

Beta-carotene undergoes oxidation in the human liver, and, splitting, forms vitamin A.

The unit of measurement for retinol is 1 ER, which corresponds to 1 µg of retinol, 6 µg of b-carotene, or 12 µg of other carotenoids.

1 mcg is 3.33 IU for retinol or 10 IU for b-carotene.

Important:it has been experimentally proven that beef, skimmed milk, and cereals contain insufficient amounts of carotene and retinol, i.e., they cannot serve as full-fledged sources of vitamin A.

Animal foods containing vitamin A:

• beef liver;
• Cod liver;
• fish fat;
• sea ​​fish caviar;
• whole milk;
• cream;
• egg yolk.

Plant Sources:

• carrot;
• tomatoes;
• pepper ("Bulgarian" and hot cayenne);
• spinach;
• broccoli;
• parsley;
• parsley;
• peas;
• soya beans;
• apples;
• (kelp seaweed).

Important:in large quantities, provitamin A is present in herbs such as alfalfa, horsetail, pepper, lemongrass, nettle, sage, hops, and plantain.

Vitamin A is involved in a number of metabolic processes in the human body. It plays an important role in the regulation of protein biosynthesis and ensures the stability of cell membranes. The connection is necessary for the formation of bone tissue, as well as enamel and dentin. Thanks to him, the fat reserves necessary for a person are formed.

Note:It has been known since ancient times that liver consumption improves visual acuity and helps prevent or cure night blindness.

Retinol is necessary for adequate photoreception (perception of light); it takes part in the biosynthesis of retinal pigment. The most important carotenoids prevent cataracts and significantly reduce the likelihood of developing macular degeneration, a pathology that is one of the main causes of blindness.

Vitamin A is one of the most effective natural antioxidants. It minimizes the harmful effects of free radicals, which allows the use of retinol and carotenoids for the prevention and treatment (as part of complex therapy) of oncological diseases. In clinical studies, it has been proven that b-carotene reduces the likelihood of recurrence of malignant neoplasms after surgery.

The antioxidant effect helps prevent the development of a number of serious pathologies of the heart and blood vessels.

Vitamin A is able to increase the serum concentration of high density lipoproteins necessary for the body.

The carotenoid lycopene, which is found in large quantities in tomatoes, prevents the deposition of cholesterol on the vascular walls, thus protecting a person from its dangerous consequences. This provitamin also reduces the likelihood of developing malignant and breast cancer, as well as prostate cancer.

The state of non-specific depends largely on vitamin A. The compound is able to increase the body's resistance against infectious agents of a bacterial and viral nature (the phagocytic activity of leukocytes is significantly increased).

Sufficient intake of vitamin A with food reduces the likelihood of developing colds, as well as infections of the genitourinary and respiratory systems and organs of the gastrointestinal tract.

Children who eat well and regularly receive retinol and carotenoids in the right amount are much easier to tolerate "" and.

The constant presence of a sufficiently high level of retinol in the serum significantly increases the life expectancy of patients suffering.

Vitamin A is actively involved in the process of regeneration of the epithelial layer of the skin and mucous membranes. Its preparations are widely used in the treatment of any (, etc.), as well as skin damage due to mechanical injuries or burns. Due to the stimulation of the collagen biosynthesis process, retinol ensures the fastest healing, greatly reducing the risk of developing secondary infectious complications. Vitamin A significantly improves the quality of tissue that is newly formed at the site of significant damage.

Note:many modern cosmetic preparations include retinoid substances, which are nothing more than synthetic analogues of vitamin A. Retinoid creams are very good for sunburn.

The beneficial effect of retinol on epithelial cells improves the functional activity of the bronchi and lungs. Receiving vitamin A preparations for patients can speed up recovery from such pathologies of the digestive tract as peptic ulcer and colitis (inflammation of the mucous membranes of the walls of the large intestine).

Retinol is one of the most important organic compounds needed for the normal intrauterine development of the unborn child.

Women who are preparing to become mothers are advised to consume sufficient amounts of vitamin A to improve the nutrition of the fetus and reduce the likelihood of having an underweight baby.

For pregnant women, the daily intake of retinol should be 750-770 micrograms. For nursing mothers, the norm recommended by Russian doctors is higher - 1200-1300 mcg.

Important: during childbearing, you can not consume more than 6000 IU per day, because high doses have a teratogenic effect on the fetus. For the same reason, during pregnancy, women are categorically contraindicated in fish oil.

How much vitamin A is required per day?

The average intake of vitamin A for an adult is 3300 IU (1000 mcg) per day. Against the background of pathologies caused by hypovitaminosis A, it is recommended to increase consumption by 3 times (up to 10,000 IU).

Important:climatic conditions can affect the body's need for vitamin A. Cold weather has no effect on retinol metabolism, but a hot climate makes its own adjustments: the need for this vitamin increases significantly.

Babies in their first year of life need 400 micrograms of retinol per day. Children from 1 to 3 years old need 450 mcg of the vitamin, those aged 4 to 6 years need 500 mcg, and from 7 to 10 years old 700 mcg per day.

For teenagers, the rules are the same as for adults.

Note:the need is reduced in women who take birth control pills.

Hypovitaminosis: causes and symptoms

Plasma vitamin A levels are considered insufficient if they are below 0.35 µmol/L.

Even at a level of 0.70-1.22 µmol / l, the amount of retinol in its main “storage”, i.e., in the liver, is noticeably reduced.

The main reasons for the development of hypovitaminosis include:

For the full assimilation of vitamin A, it is necessary to consume a sufficient amount of fat and complete protein. It must be present in food, the absence of which makes it difficult to absorb retinol.

Important:hypovitaminosis A is often observed in vegetarians who do not replace animal products with the necessary amount of high-grade vegetable protein.

The characteristic manifestations of hypovitaminosis include:

• increased temperature sensitivity;
• lowering the pain threshold;
• early aging of the skin (the appearance of wrinkles);
• dryness and peeling of the skin;
• redness of the eyelids;
• feeling of "foreign body" or "sand" in the eyes;
• accumulation of mucus and the formation of crusts in the corners of the eyes;
• urinary incontinence (sphincter weakness);
• hyperesthesia (pathologically high degree of sensitivity) of tooth enamel;
• deterioration of erectile function;
• early ejaculation.

A very characteristic manifestation of retinol deficiency is hemeralopia - a significant deterioration in vision at dusk.

Consequences of vitamin A deficiency:

• xerophthalmia (dryness of the cornea of ​​​​the eyes);
• clouding of the cornea;
• precancerous pathologies and skin cancer;
• atrophic gastritis;
• intestinal inflammation;
• pancreatitis;
• decrease in sexual desire;
• mastopathy;
• malignant tumors of the mammary glands;
• gynecological diseases (etc.);
• cachexia (exhaustion);
• anemia (anemia);
• frequent respiratory infections;
• cystic formations of the liver;
• insomnia.

Indications for taking vitamin A

Vitamin A is prescribed orally, for injection (IM) or for topical application, if diagnosed:

• pathology of the skin and mucous membranes;
• inflammation of the cornea and conjunctiva of the eyes;
• burns, fractures and other injuries (to accelerate regeneration).

Mild and moderate hypovitaminosis require doses up to 33,000 IU for adult patients and from 1,000 to 5,000 for children. For skin diseases, the dosages are higher - 50000-100000 and 5000-10000 IU, respectively.

Hypervitaminosis

Important:vitamin A has a toxic effect on the body when consumed 25,000 IU per day.

Symptoms of hypervitaminosis:

• pain in the abdominal region;
• hepatosplenomegaly;
• alopecia;
• arthralgia;
• "Zaedy" in the corners of the mouth;
• delay of menstruation;
• dry skin;
• increased fragility and thickening of the nail plates.

Important:a lack of zinc leads to a violation of the absorption of retinol.

The combination of vitamin A and ethanol causes more significant liver damage than alcohol exposure.

International name - Vitamin A, in the form of a dietary supplement is also called retinol.

A fat-soluble vitamin, an essential component for healthy growth, bone and tooth tissue formation, and cell structure. It is of great importance for night vision, it is necessary to protect against infections of the tissues of the respiratory, digestive and urinary tracts. Responsible for the beauty and youthfulness of the skin, the health of hair and nails, visual acuity. Vitamin A is absorbed in the body in the form of retinol, which is found in liver, fish oil, egg yolk, dairy products and added to margarine. Carotene, which is converted into retinol in the body, is found in many fruits and vegetables.

Discovery history

The first prerequisites for the discovery of Vitamin A and the consequences of its deficiency appeared as early as 1819, when the French physiologist and psychologist Magendie noticed that dogs that receive poor nutrition are more likely to get corneal ulcers and have a higher mortality rate.

In 1912, British biochemist Frederick Gowland Hopkins discovered hitherto unknown substances in milk that did not look like fats, carbohydrates, or proteins. Upon closer examination, it turned out that they contributed to the growth of laboratory mice. Hopkins received the Nobel Prize in 1929 for his discovery. In 1917, Elmer McCollum, Lafayette Mendel, and Thomas Burr Osborne also saw similar substances when studying the role of dietary fats. In 1918, these "additional substances" were found to be fat-soluble, and in 1920 they were finally given the name Vitamin A.

Foods rich in vitamin A

Estimated availability in 100 g of product

Daily requirement for vitamin A

Recommendations for daily intake of vitamin A are based on the amount needed to provide a supply of retinol for several months in advance. This reserve maintains the normal functioning of the body and ensures the healthy functioning of the reproductive system, immunity, vision and gene activity.

In 1993, the European Scientific Committee on Nutrition published data on the recommended intake of vitamin A:

Many European nutritional committees, such as the German Nutrition Society (DGE), recommend 0.8 mg (800 mcg) of vitamin A (retinol) for women and 1 mg (1000 mcg) for men per day. Since vitamin A plays a significant role in the normal development of the embryo and newborn, pregnant women are advised to take 1.1 mg of vitamin A starting from the 4th month of pregnancy. Women who are breastfeeding should receive 1.5 mg of vitamin A per day.

In 2015, the European Food Safety Authority (EFSA) established that the daily intake of vitamin A should be 750 mcg for men, 650 mcg for women, for newborns and children - from 250 to 750 mcg of the vitamin per day, taking into account age . During pregnancy and lactation, the additional amount of the vitamin that should be ingested due to the accumulation of retinol in the tissues of the fetus and mother, as well as the intake of retinol in breast milk, was indicated at 700 and 1,300 mcg per day, respectively.

In 2001, the American Food and Nutrition Council also set the recommended intake for vitamin A:

As we can see, although the amount varies according to different organizations, the approximate daily intake of vitamin A remains at the same level.

The need for vitamin A increases with:

1. 1 weight gain;
2. 2 strenuous physical labor;
3. 3 work in night shifts;
4. 4 participation in sports competitions;
5. 5 stressful situations;
6. 6 work in conditions of improper lighting;
7. 7 additional eye strain from monitors;
8. 8 pregnancy, breastfeeding;
9. 9 problems with the gastrointestinal tract;
10. 10 SARS.

Physical and chemical properties

Vitamin A is a fat-soluble vitamin that is part of a group of molecules with a similar structure - retinoids - and occurs in several chemical forms: aldehydes (retinal), alcohol (retinol) and acid (retinoic acid). In animal products, the most abundant form of vitamin A is an ester, primarily retinyl palmitate, which is synthesized to retinol in the small intestine. Provitamins - biochemical precursors of vitamin A - are present in plant products, they are components of the carotenoids group. Carotenoids are organic pigments found naturally in plant chromoplasts. Less than 10% of the 563 carotenoids known to science can be synthesized into vitamin A in the body.

Vitamin A is a fat-soluble vitamin. This is the name of a group of vitamins, for the assimilation of which the body needs the intake of dietary fats, oils or lipids. These include, for example, cooking oils, nuts, fish, meat, avocados.

Vitamin A dietary supplements are often available as oil-filled capsules to ensure that the vitamin is fully absorbed by the body. People who don't eat enough dietary fat are more likely to be deficient in fat-soluble vitamins. Similar problems can occur in people with poor absorption of fats. Fortunately, fat-soluble vitamins naturally occur naturally in foods that contain fat. Thus, with a good diet, the lack of such vitamins is rare.

In order for vitamin A or carotene to enter the bloodstream in the small intestine, it is necessary that they, however, like other fat-soluble vitamins, are combined with bile. If the food at this moment contains little fat, then little bile is secreted, which leads to malabsorption and loss of up to 90 percent of carotene and vitamin A with feces.

Approximately 30% of beta-carotene is absorbed from plant foods, about half of beta-carotene is converted into vitamin A. From 6 mg of carotene, 1 mg of vitamin A is formed in the body, so the conversion ratio of the amount of carotene to the amount of vitamin A is 1:6.

Useful properties of vitamin A

Vitamin A performs several functions in the body. The most famous is its effect on vision. Retinyl ester is transported to the retina, which is located inside the eye, where it is processed into a substance called 11-cis-retinal. Further, 11-cis-retinal is in the rods (one of the photoreceptors), where it combines with the protein opsin and forms the visual pigment "rhodopsin". Rods containing rhodopsin can detect even very small amounts of light, making them essential for night vision. The absorption of a photon of light catalyzes the transformation of 11-cis-retinal back to all-trans-retinal and results in its release from the protein. This sets off a chain of events leading to the generation of an electrochemical signal to the optic nerve, which is processed and interpreted by the brain. Lack of retinol available to the retina leads to impaired dark adaptation, known as night blindness.

Vitamin A in the form of retinoic acid plays an important role in the regulation of gene expression. Once retinol is taken up by the cell, it can be oxidized to retinal, which is oxidized to retinoic acid. Retinoic acid is a very powerful molecule that binds to various nuclear receptors to initiate or inhibit gene expression. Through the regulation of the expression of specific genes, retinoic acid plays an important role in cell differentiation, one of the most important physiological functions.

Vitamin A is needed for the normal functioning of the immune system. Retinol and its metabolites are needed to maintain the integrity and function of skin cells and mucous membranes (respiratory, digestive and urinary systems). These tissues serve as a barrier and are the body's first line of defense against infections. Vitamin A plays a central role in the development and differentiation of white blood cells, lymphocytes, which are key agents in the immune system's response.

Vitamin A is indispensable for embryonic development, being directly involved in the growth of limbs, the formation of the heart, eyes and ears of the fetus. In addition to this, retinoic acid affects the expression of the gene responsible for growth hormone. Both deficiency and excess of vitamin A can cause birth defects.

Vitamin A is used for the normal development of stem cells into red blood cells. In addition, vitamin A probably improves the mobilization of iron from reserves in the body, directing it to the developing red blood cell. There, iron is incorporated into hemoglobin, the oxygen carrier in red blood cells. Vitamin A metabolism is thought to interact with zinc and iron in several ways. Zinc deficiency can lead to a decrease in the amount of transported retinol, a decrease in the release of retinol in the liver, and a decrease in the conversion of retinol to the retina. Vitamin A supplements have a beneficial effect on iron deficiency (anemia) and improve iron absorption in children and pregnant women. The combination of vitamin A and iron appears to treat anemia more effectively than supplemental iron or vitamin A alone.

Recent studies have shown that vitamin A, carotenoids, and provitamin A carotenoids may be effective antioxidants in preventing heart disease. The antioxidant activity of vitamin A and carotenoids is provided by the hydrophobic chain of polyene units, which can quench singlet oxygen (molecular oxygen with higher activity), neutralize thiyl radicals, and stabilize peroxyl radicals. In short, the longer the polyene chain, the higher the stability of the peroxyl radical. Because of their structure, vitamin A and carotenoids can be oxidized with increasing O2 tension and thus are the most effective antioxidants at low oxygen tensions, which are characteristic of the physiological levels found in tissues. Overall, epidemiological evidence suggests that vitamin A and carotenoids are important dietary factors in reducing the incidence of heart disease.

The European Food Safety Authority (EFSA), which provides scientific advice to policy makers, has confirmed that the following health benefits have been seen with vitamin A intake:

• normal cell division;
• normal development and functioning of the immune system;
• maintaining the normal condition of the skin and mucous membranes;
• maintaining vision;
• normal iron metabolism.

Vitamin A has a high compatibility with vitamins C and E and the minerals iron and zinc. Vitamins C and E protect vitamin A from oxidation. Vitamin E increases the absorption of vitamin A, but only in cases where vitamin E is consumed in a small amount. A high content of vitamin E in the diet, in turn, impairs the absorption of vitamin A. Zinc helps the absorption of vitamin A, taking part in its conversion to retinol. Vitamin A enhances the absorption of iron and influences the utilization of the iron reserve present in the liver.

Vitamin A also pairs well with vitamins D and K2, magnesium, and dietary fat. Vitamins A, D and K2 work synergistically to support immune health, promote adequate growth, maintain bone and dental health, and protect soft tissues from calcification. Magnesium is essential for the production of all proteins, including those that interact with vitamins A and D. Many of the proteins involved in vitamin A metabolism and the receptors for both vitamins A and D only function properly in the presence of zinc.

Vitamins A and D also work together to regulate the production of certain vitamin dependent proteins. Once vitamin K activates these proteins, they help mineralize bones and teeth, protect arteries and other soft tissues from abnormal calcification, and protect against cell death.

Foods containing vitamin A are best consumed with foods that contain “healthy” fat. For example, spinach, which contains a high content of vitamin A and lutein, is recommended to be combined with avocado. The same goes for lettuce and carrots, which pair well with avocados in salads. As a rule, animal products rich in vitamin A already contain a certain amount of fat, sufficient for its normal absorption. As for vegetables and fruits, it is recommended to add a small amount of vegetable oil to a salad or freshly squeezed juice - this way we will be sure that the body will receive the necessary vitamin in full.

It is worth noting that the best source of vitamin A in particular, as well as other useful substances, is a balanced diet and natural products, and not dietary supplements. When using vitamins in medicinal form, it is very easy to make a mistake with the dosage and get more than the body needs. And an excess of one or another vitamin or mineral in the body can have very serious consequences. The risk of developing oncological diseases may increase, the general condition of the body may worsen, metabolism and the functioning of organ systems may be disturbed. Therefore, the use of vitamins in tablets should be carried out only if necessary and after consulting a doctor.

Application in medicine

Intake of a large amount of vitamin A is prescribed in such cases:

• with vitamin A deficiency, which can occur in people with a protein deficiency, diabetes, an overactive thyroid gland, fever, liver disease, cystic fibrosis, or an inherited disorder called abelatipoproteinemia.
• in breast cancer. Premenopausal women with a family history of breast cancer who consume high levels of vitamin A in their diet are thought to reduce their risk of developing breast cancer. It is not known whether taking vitamin A as a dietary supplement has a similar effect.
• with cataracts. Studies show that a high intake of vitamin A in the diet leads to a reduced risk of developing cataracts.
• with diarrhea caused by HIV. Taking vitamin A along with conventional medications appears to reduce the risk of death from diarrhea in HIV-infected children with vitamin A deficiency.
• with malaria. Taking vitamin A by mouth reduces the symptoms of malaria in children under 3 years of age in areas where malaria is common.
• with measles. Taking vitamin A by mouth reduces the risk of complications or death from measles in children who have measles and are deficient in vitamin A.
• with precancerous lesions in the mouth (oral leukoplakia). Research shows that taking vitamin A can help treat precancerous lesions in the mouth.
• in recovery after laser eye surgery. Taking vitamin A orally along with vitamin E improves healing after laser eye surgery.
• with complications after pregnancy. Taking vitamin A reduces the risk of diarrhea and fever after pregnancy in malnourished women.
• with complications during pregnancy. Oral vitamin A supplementation reduces the risk of death and night blindness during pregnancy in malnourished women.
• in eye diseases affecting the retina (retinitis pigmentosa). Studies show that vitamin A supplementation can slow the progression of eye diseases that cause damage to the retina.

The pharmacological form of vitamin A can be different. In medicine, it is found in the form of dragees, drops for oral administration, drops for oral administration in oily form, capsules, oily solution for intramuscular administration, oily solution for oral administration, in the form of coated tablets. Vitamin A is taken for prevention and for medicinal purposes, as a rule, 10-15 minutes after eating. Oil solutions are taken in case of malabsorption in the gastrointestinal tract or in severe illness. In cases where long-term treatment is necessary, the solution for intramuscular injection is combined with capsules. In pharmacology, the amount of vitamin A is often indicated in International Units. With mild to moderate beriberi, adults are prescribed 33 thousand International Units per day; with hemeralopia, xerophthalmia - 50-100 thousand IU / day; children - 1-5 thousand IU / day, depending on age; for skin diseases in adults - 50-100 thousand IU / day; children - 5-20 thousand IU / day.

Traditional medicine advises the use of vitamin A as a remedy for flaky and unhealthy skin. To do this, it is recommended to consume fish oil, liver, butter and eggs, as well as vegetables rich in vitamin A - pumpkin, apricot, carrots. A good way to make up for the deficiency is freshly squeezed carrot juice with the addition of cream or vegetable oil. Another folk remedy for obtaining a vitamin is considered to be a decoction of tubers high - it is used as a tonic, tonic and antirheumatic agent. Also a valuable source of vitamin A, as well as other useful substances, are flax seeds, which are consumed orally and as part of external masks, ointments and decoctions. According to some reports, a high amount of vitamin A is contained in the tops of carrots, even more than in the fruit itself. It can be used in cooking, as well as making a decoction, which is used internally as a course for a month.

Latest scientific research on vitamin A:

Researchers at the Case Western Reserve University School of Medicine have found that an uncontrolled metabolism of vitamin A in the gut can cause dangerous inflammation. The discovery establishes a link between dietary composition and inflammatory diseases such as Crohn's disease and irritable bowel syndrome.

Researchers have found a branch point in the vitamin A metabolic pathway that depends on a specific protein called ISX. The beginning of the journey is beta-carotene, a pigmented, highly nutritious substance, thanks to which the color of sweet potatoes and carrots is formed. Beta-carotene is converted to vitamin A in the digestive tract. From there, the largest proportion of vitamin A is delivered to other tissues, providing good vision and other important functions. When studying mice that had had ISX removed, scientists noticed that this protein helps the body balance this process. Protein helps the small intestine determine how much beta-carotene it needs to meet the body's need for vitamin A. Immune cells rely on this control mechanism to properly respond to foods entering the small intestine. This provides an effective barrier against potential food hazards. Researchers have found that when ISX is absent, immune system cells in the digestive tract overreact to the beta-carotene-rich diet. Their results prove that ISX is the main link between what we eat and gut immunity. The scientists concluded that removing the ISX protein speeds up the expression of the gene that converts beta-carotene to vitamin A by 200 times. Because of this, ISX-deleted mice received an excess of vitamin A and began to convert it into retinoic acid, a molecule that regulates the activity of many genes, including those that form immunity. This caused localized inflammation as immune cells filled the area in the gut between the stomach and colon and began to multiply. This severe inflammation spread to the pancreas and caused the mice to become immunodeficient.

A recent study shows that vitamin A increases the activity of insulin-producing β-cells. Scientists have found that insulin-producing beta cells have a high number of receptors on their surface that are sensitive to vitamin A. Researchers believe that the reason for this is that vitamin A plays an important role in the development of beta cells in the early stages of life. , as well as for correct and functioning during the rest of life, especially during pathophysiological conditions - that is, with certain inflammatory diseases.

To study the importance of vitamin A in diabetes, the researchers worked with insulin cells from mice, healthy people, and people with type 2 diabetes. The scientists fragmentarily blocked the receptors and gave the patients some sugar. They saw that the cells' ability to secrete insulin was deteriorating. The same trend could be observed when comparing insulin cells from donors with type 2 diabetes. The cells of patients with type 2 diabetes were less able to produce insulin compared to those of people without diabetes. Scientists have also discovered that the resistance of beta cells to inflammation is reduced in the absence of vitamin A. When it is completely absent, the cells die. This study may also be relevant for some types of type 1 diabetes, where beta cells are poorly developed in the early stages of life. “As it became clear after research with animals, newborn mice need vitamin A for the full development of their beta cells. We are pretty sure that the same thing happens in humans. Children need to get the right amount of vitamin A in their diet,” said Albert Salehi, senior researcher at the Diabetes Center at Lund University in Sweden.

Scientists at the University of Lund in Sweden have discovered a previously unexplored effect of vitamin A on human embryonic development. Their research demonstrates that vitamin A has an effect on the formation of blood cells. A signaling molecule known as retinoic acid is a vitamin A derivative that helps determine how different types of tissue will form in a growing fetus.

An unprecedented study by Prof. Nils-Bjarn Woods' laboratory at the Lund Stam Cell Center in Sweden showed the effect of retinoic acid on the development of red blood cells, white blood cells and platelets from stem cells. Under laboratory conditions, stem cells were influenced by certain signaling molecules, transforming into hematopoietic cells. Scientists have noticed that high levels of retinoic acid rapidly lower the number of blood cells produced. The decrease in retinoic acid, in turn, increased the production of blood cells by 300%. Despite the fact that vitamin A is needed for the normal course of pregnancy, it has been found that an excess of vitamin A harms the embryo, introducing the risk of developing a malformation or stopping the pregnancy. In view of this, pregnant women are strongly advised to control the intake of foods containing a large amount of vitamin A in the form of retinoids, such as, for example, liver. “The results of our study show that vitamin A in large quantities negatively affects blood formation. This suggests that pregnant women should additionally avoid excessive intake of vitamin A,” says Niels-Bjarn Woods.

This is one of the main components that provide a healthy and toned skin. With the intake of a sufficient amount of vitamin, you can forget about such problems as skin laxity, age spots, acne, acne, dryness.

Vitamin A in its pure, concentrated form can be easily found in pharmacies, in the form of capsules, oil solutions and ampoules. It is worth remembering that this is a fairly active component, so it should be used with caution, and preferably after 35 years. Cosmetologists advise making masks containing vitamin A during the cold season and once a month. If there are contraindications to the use of pharmacy vitamin A as part of masks, you can replace it with natural products that are rich in this vitamin - viburnum, parsley, spinach, egg yolks, dairy products, pumpkin, carrots, fish oil, algae.

There are many recipes for masks with vitamin A. They often contain fat-containing substances - olive oil, fat sour cream, burdock oil. Vitamin A (oil solution and retinol acetate) has good compatibility with aloe juice, oatmeal and honey. To eliminate mimic wrinkles and bruises under the eyes, you can use a mixture of vitamin A and any vegetable oil, or Aevit, which already contains both vitamin A and vitamin E. A good preventive and therapeutic remedy for acne is a mask with ground lentils, vitamin A in an ampoule or a small amount of zinc ointment, applied 2 times a month. In the presence of allergic reactions, open wounds and skin lesions, any of its diseases, you should refrain from using such masks.

Vitamin A is also good for nail health when mixed with other ingredients. For example, you can prepare a hand mask with liquid vitamins A, B, and D, oily hand cream, coconut oil, lemon juice, and a drop of iodine. This mixture should be applied to the skin of the hands and nail plates, massaged for 20 minutes and left to be absorbed. Regular implementation of this procedure will improve the condition of nails and hands.

The impact of vitamin A on the health and beauty of hair should not be underestimated. It can be added to shampoos (immediately before each procedure, in order to avoid oxidation of the substance when added to a whole package of shampoo), to masks - to increase shine, softness and strength of hair. As in face masks, vitamin A is recommended to be combined with other ingredients - vitamin E, various oils, decoctions (chamomile, horsetail), starch (for softness), mustard or pepper (to accelerate hair growth). These products should be used with caution for those who are allergic to pharmacy vitamin A and for those whose hair is prone to increased oiliness.

Vitamin A in animal, crop and industry

Found in green grass, alfalfa, and some fish oils, vitamin A, otherwise known as retinol, is one of the nutrients essential for poultry health. Vitamin A deficiency leads to poor plumage along with weakness, eye and beak problems, up to and including damage. Another important factor for production is that lack of vitamin A can slow down growth.

Vitamin A has a relatively short shelf life and, as a result, dry foods stored for extended periods of time may not contain sufficient amounts of the vitamin. After illness or stress, the immune system of birds is very weak. By adding a short course of vitamin A to feed or water, further illness can be prevented, as without sufficient vitamin A, birds are susceptible to a number of harmful pathogens.

Vitamin A is also essential for the healthy growth of mammals, to maintain a good appetite, coat condition and immunity.

• it is the first vitamin discovered by man;
• polar bear liver is so rich in vitamin A that eating a whole liver can be fatal to humans;
• approximately 259 to 500 million children lose their sight every year due to vitamin A deficiency;
• in cosmetics, vitamin A is most often found under the names retinol acetate, retinyl linoleate and retinyl palmitate;
• rice fortified with vitamin A, developed about 15 years ago, could prevent hundreds of thousands of cases of blindness in children. But due to concerns about genetically modified foods, it was never put into production.

Dangerous properties of vitamin A, its contraindications and warnings

Vitamin A is quite resistant to high temperatures, but is destroyed in direct sunlight. Therefore, it is necessary to store vitamin-rich foods, as well as medical nutritional supplements, in a dark place.

Signs of Vitamin A Deficiency

Vitamin A deficiency usually results from inadequate intake of foods high in vitamin A, beta-carotene, or other provitamin A carotenoids; which are metabolized into vitamin A in the body. In addition to dietary problems, excess alcohol intake and malabsorption can be the cause of vitamin A deficiency.

The earliest sign of vitamin A deficiency is blurred vision in the dark, or night blindness. Severe or prolonged vitamin A deficiency causes changes in corneal cells that eventually lead to corneal ulcers. Vitamin A deficiency among children in developing countries is the leading cause of blindness.

Vitamin A deficiency is also associated with immunodeficiency, decreasing the ability to fight infections. Even children with mild vitamin A deficiency have a higher incidence of respiratory disease and diarrhea, as well as a higher mortality rate from infectious diseases (especially measles) compared with children who consume adequate amounts of vitamin A. In addition, vitamin A deficiency can cause impaired growth and bone formation in children and adolescents. In smokers, vitamin A deficiency can contribute to chronic obstructive pulmonary disease (COPD) and emphysema, both of which are thought to increase the risk of lung cancer.

Signs of Too Much Vitamin A

Acute vitamin A hypervitaminosis caused by very high doses of retinol, which is rapidly absorbed and slowly excreted from the body, is relatively rare. Symptoms include nausea, headache, fatigue, loss of appetite, dizziness, dry skin, and swelling of the brain. There are studies that prove that prolonged excess of vitamin A in the body can lead to the development of osteoporosis. Some synthetic retinol derivatives (eg, tretinate, isotretinoin, tretinoin) may cause fetal defects and therefore should not be used during pregnancy or when trying to conceive. In such cases, beta-carotene is considered the safest source of vitamin A.

Results from the Beta-Carotene and Retinol Efficacy Study (CARET) suggest that long-term vitamin A (retinol) and beta-carotene supplementation should be avoided in the long term in people at high risk of developing lung cancer, such as smokers and people exposed to asbestos.

Interaction with other drugs

Vitamin A, which has already entered the bloodstream, begins to quickly break down if the body lacks vitamin E. And if there is a lack of vitamin B4 (choline), then vitamin A is not stored for future use. Antibiotics are thought to somewhat reduce the effects of vitamin A. In addition, vitamin A can increase the effects of a substance called isotretinoin and lead to severe side effects.

We have collected the most important points about vitamin A in this illustration and would be grateful if you share the picture on a social network or blog, with a link to this page:

Reprint of materials

Use of any material without our prior written consent is prohibited.

Safety regulations

The administration is not responsible for attempting to apply any recipe, advice or diet, and also does not guarantee that the information provided will help and will not harm you personally. Be prudent and always consult the appropriate doctor!