Vitamin A - where it is found, what it is useful for, symptoms of deficiency 41624 3

The benefits of foods rich in vitamin A

Vitamin A is an essential component of many chemical reactions occurring in the body. A deficiency of this substance can lead to disruption of metabolic processes, which can lead to malfunction of many organs and systems.

The most important functions of retinol:

• regulates the amount of proteins and steroid hormones;
• promotes maturation of germ cells;
• increases immunity;
• participates in the formation of the musculoskeletal system;
• improves the condition of skin, hair and nails;
• acts as an antioxidant, fighting excess free radicals;
• necessary for harmonious intrauterine development;
• regulates twilight vision;
• eliminates dry skin and mucous membranes.

Vitamin A and fatty acids are the most important components necessary for the synthesis of sex hormones.

Steroids are involved in many processes, including the synthesis of gametes. Therefore, with a deficiency of retinol, disturbances in sexual and reproductive functions are possible.

Also, all substances from the retinoid group have a stimulating effect on the immune system. At the same time, resistance to bacterial and viral infections increases.

Special attention should be paid to the antioxidant effect of this substance. It binds free radicals that have a damaging effect on the body's cells. This property increases antitumor immunity, allowing you to prevent cancer.

Vitamin A has a beneficial effect on the skin and its appendages. It prevents dryness of the skin and mucous membranes, accelerates reparative processes. Retinol also helps accelerate the growth of hair and nails, making them stronger and healthier.

The benefits of vitamin A have also been proven for a growing body. It participates in the formation of all organs and systems, including bone and endocrine.

Retinol is essential for maintaining eye health. It prevents the occurrence of corneal dryness and the development of keratoconjunctivitis. It is also part of the visual pigment rhodopsin, which is found in rods and cones. These are neurosensory cells located in the retina. They cause twilight vision.

Products containing vitamin A stimulate and regulate metabolic reactions in tissues and skin, increase resistance to colds and infections. They are included in the menu to prevent “night blindness” - poor vision at dusk.

With regular intense visual work, it is useful to diversify your diet with foods of animal and plant origin that contain vitamin A.

The intake of retinol with food increases the permeability of cell membranes, the synthesis of hormones of the adrenal cortex, stimulates sexual function, and the activity of the thyroid gland.

Products with vitamin A reduce the effect of carcinogens, strengthen the immune system, prevent malignant formations, and reverse them.

Signs of overdose:

• Strong headache;
• nausea, vomiting;
• cracks in the corners of the lips;
• itching of the body or scalp;
• painful swelling;
• increased nervous excitability.

Typically, traditional products do not cause overdose. But there is a known death from eating one carrot for a month.

If there are signs of overdose, exclude foods containing vitamin A. Include fruits and vegetables rich in ascorbic acid in the diet.

According to studies, long-term overdose of retinol and fish oil is the cause of malignant formations.

The accumulation of excess retinol between cell membranes disrupts their function.

An overdose of a synthetic drug is especially dangerous during pregnancy.

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Signs of shortage:

• visual impairment (conjunctivitis, night blindness);
• decreased immunity;
• dry and pale skin, rash, acne;
• fragility, hair loss;
• roughness of the skin;
• dysfunction of the sweat and sebaceous glands;
• loss of strength, increased fatigue;
• slow reactions;
• deterioration of attention;
• delayed growth and development in children.

Lack of foods containing vitamin A is the cause of cellulite, dysfunction of the liver, nervous system, breathing, digestion, deterioration of visual acuity, dryness and clouding of the cornea.

The causes of hypovitaminosis are eating canned food without receiving fresh vegetables and fruits rich in carotenoids.

The role of vitamin A is to maintain proper metabolism and normal immune system function. This component in the form of retinol is found in the skin, hair, teeth, bones, muscles, and regulates the process of regeneration and tissue growth.

It has a unique ability to limit the negative effects of free radicals on the body. Thanks to this property, this most important organic compound for humans resists the growth of cancer (malignant) cells and significantly slows down the aging process. Retinol increases the effectiveness of other antioxidants, in particular vitamins E.

Beneficial 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. Next, 11-cis-retinal ends up 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. 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.

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 potent molecule that binds to various nuclear receptors to initiate or inhibit gene expression.

Vitamin A is needed for the normal functioning of the immune system. Retinol and its metabolites are needed to maintain the integrity and functioning 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 is essential during 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 a deficiency and an excess of vitamin A can cause birth defects.

Vitamin A is used for the normal process of stem cells developing 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 included in hemoglobin, the oxygen carrier in red blood cells.

Vitamin A metabolism is thought to interact with zinc and iron in several ways. Zinc deficiency may result in decreased amount of retinol transported, decreased release of retinol in the liver, and decreased conversion of retinol to the retina. Vitamin A supplements have a beneficial effect on iron deficiency (anemia) and improve iron absorption among 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 the development of 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.

Briefly, the longer the polyene chain, the higher the stability of the peroxyl radical. Because of their structure, vitamin A and carotenoids can be oxidized when O2 tension increases and are thus the most effective antioxidants at low oxygen tensions, which are typical of the physiological levels found in tissues.

The European Food Safety Authority (EFSA), which provides scientific advice to policymakers, has confirmed that the following health benefits have been observed from consuming vitamin A:

• 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 small amounts. High levels of vitamin E in the diet, in turn, impair the absorption of vitamin A.

Vitamin A also combines 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 tooth health, and protect soft tissue from calcification. Magnesium is essential for the production of all proteins, including those that interact with vitamins A and D.

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.

Products containing vitamin A are best consumed with foods that contain “healthy” fat. For example, spinach, which is high in 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 salad or freshly squeezed juice - this way we will be sure that the body will receive the necessary vitamin in full.[8]

It is worth noting that the best source of vitamin A in particular, as well as other beneficial substances, is a balanced diet and natural foods, rather than dietary supplements. When taking 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 a particular vitamin or mineral in the body can have very serious consequences. The risk of developing cancer may increase, the general condition of the body may deteriorate, metabolism and the functioning of organ systems may be disrupted. Therefore, the use of vitamin tablets should be carried out only when necessary and after consultation with a doctor.

Value for human health

Skin tissues and mucous membranes need vitamin A not only as an element that supports their functionality, but also as a substance that helps restore the epidermis and mucous membranes after receiving various types of damage. This is due to the fact that this compound improves the production of collagen, which is a building material for connective tissues in the human body.

Anti-aging and cosmetic products intended for the treatment of skin problems, as a rule, contain retinoids - a synthetic analogue of vitamin A. These are not only creams and lotions, but also pharmaceutical preparations for stretch marks and rashes.

Retinol is an essential component in every person's diet. A sufficient amount of vitamin increases the body's resistance to adverse factors, prevents a decrease in immunity and promotes rapid recovery.

Vitamin A is especially useful for pregnant women. It helps the body adapt to changes, and also takes part in the formation of fetal organs. That is why expectant mothers should include oil, fruits, vegetables, fish and other foods rich in this vitamin in their diet.

How to take vitamin A capsules for adults

Instructions for using vitamin A in capsules depend on the specific drug. But on average, 1 capsule of retinol contains from 33,000 to 100,000 IU of the active substance, and the same daily amount of the substance is prescribed by doctors for medicinal purposes to patients. For children, the dosage is calculated individually depending on age and weight, but usually does not exceed 20,000 IU.

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Thus, usually an adult needs to take only 1 capsule per day. Take the supplement on a full stomach, 15 minutes after eating. In total, you need to use retinol for a month - vitamin A accumulates in the body, and if you take it for too long, it will begin to cause harm.

Advice! Since an overdose of retinol is dangerous, only a doctor should determine why vitamin A in capsules is useful and prescribe dosages.

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.

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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).

Daily requirement for vitamin A

Determined by age and gender. A child needs about 300-400, a teenager - 600, an adult woman - 700, a man - 900 mcg. Pregnant and breastfeeding women need much more retinol.

Vitamin A accumulates in body tissues and its excessive intake with food can lead to poisoning. The safe upper limit of the daily value for children is 900 mcg, for adults - 3000 mcg. It is allowed to consume no more than 9000 mcg at a time. A higher dosage is fraught with poisoning.

Vitamin doses depend on a number of factors:

• age;
• floor;
• anthropometric parameters;
• initial vitamin level;
• the presence of additional needs (heavy physical labor, pregnancy and lactation, acute and chronic diseases).

If the gastrointestinal tract is normal and there is no chronic deficiency, a person can receive the required amount of retinol from food.

Vitamin A is found in plant and animal products. Therefore, getting the required amount of vitamin from your diet is quite possible. However, if the absorption of nutrients is impaired, with total vitamin deficiency or increased need, the use of nutritional supplements will be rational.

Every day, an adult body should receive foods containing 5000 IU of vitamin A.

The biological effect of 1 mg of retinol is equivalent to 3300 IU. Therefore, the daily requirement is covered by 1.5 mg of retinol.

When compiling a diet according to the vitamin table, take into account that the proportion of retinol should be 1/3.

The body should receive the remaining 2/3 of its daily requirement from plant foods rich in carotene.

The biological activity of plant products containing vitamin A is 2-3 times lower. It is compensated by increasing the amount of carotenes by 2-3 times.

For the prevention and treatment of diseases, a short-term excess of the daily norm by 3-4 times is acceptable. Long-term overdose is harmful.

Table of products and the amount of vitamin A in them and video

For convenience, when preparing your daily diet, use a table indicating foods that contain a lot of vitamin A:

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This video talks about the role of vitamin A in the body, the daily requirement for it and foods that contain a lot of it:

Symptoms of Vitamin A Deficiency

• intolerable headaches;
• gagging;
• cracks in the corners of the mouth;
• burning of the skin (for example, scalp);
• swelling accompanied by pain;
• syndrome of increased nervous excitability.

Overdose is a rare phenomenon for people who eat traditionally. But excessive (more than 100 g per day) consumption of carrots over several months can lead to death.

If there are signs of excess of the substance, vitamin A in foods and preparations is excluded from the diet or limited. Consumption of vitamin C is beneficial.

A number of experiments have shown that prolonged excess of retinol and fish oil provokes the development of cancerous tumors. Retinol accumulated between cell membranes can disrupt their functioning. Excess synthetic vitamin A is dangerous for pregnant women. Negatively affects the intrauterine development of the fetus.

Deficiency of this beneficial vitamin is common in children around the world, usually in developing countries. Causes blindness and even death of small inhabitants of the planet.

• conjunctivitis, poor vision in low light conditions;
• decreased immunity;
• dryness, roughness, pallor of the skin, acne;
• fragility, hair loss;
• disruptions in the functioning of the external secretion glands;
• weakness, drowsiness;
• slow reactions, distracted attention;
• growth and development of children with delays.

To avoid these disorders, you should know which foods contain vitamin A. After all, its deficiency also causes cellulite, malfunctioning of the liver, respiratory organs, and digestive system. Vision decreases, the cornea becomes cloudy and dry.

Hypovitaminosis appears when eating canned food, when there are not enough fresh vegetables and fruits in the diet.

Let's look at what vitamin A contains. How to avoid trouble and eat right.

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.

Vitamin A hypovitaminosis is a serious pathological condition. Most often, it develops over many years, without making itself felt for a long time.

The main causes of retinol deficiency:

• nutritional – vitamin deficiency is often caused by an inadequate diet;
• pregnancy and lactation;
• growth and puberty;
• impaired digestion and absorption in the intestine;
• severe debilitating diseases, including cancer.

It is extremely difficult to recognize hypo- or vitamin deficiency. Symptoms usually appear with severe deficiency. The general condition may not be disturbed. Such patients rarely complain and consult a doctor. They most often attribute their condition to other reasons.

Vitamin A deficiency has the following symptoms:

• twilight vision impairment;
• xerophthalmia (hypertrophic and degenerative processes in the cornea);
• dry skin, jams and cracks;
• premature appearance of wrinkles;
• fragility of nails;
• hair loss;
• decreased sense of smell due to dry nasal mucosa;
• frequent inflammatory diseases of the respiratory system due to impaired barrier function of the bronchial mucosa;
• violation of hormonal regulation, infertility.

Important! Even vitamin deficiency (an extreme degree of vitamin deficiency) can be asymptomatic for a long time.

The diet of a typical city dweller consists of cutlets, sausages and other semi-finished meat products, white rice, pasta, bread, buckwheat and other grains. Such a diet does not allow you to obtain vitamin A in the required amount, which leads to its deficiency. Eating low-fat foods makes the situation even worse.

A constant lack of retinol negatively affects the body's protective functions. Reduced immunity leads to the fact that a person more often suffers from colds, infectious diseases, and loses visual acuity. The latter is especially important in the dark. The nail plate and hair become fragile, and the skin becomes excessively dry. The lack of this important organic compound is indicated by the appearance of dandruff.

TOP 20 products with high retinol content

Vitamin A is a vital element of plant origin for the health of the body. It, like all useful substances, improves immunity. And this is far from his only prerogative. Almost everyone has heard about the benefits of retinol for vision. However, little is known about the beneficial effects of carotenoids on:

• bones;
• Hair Growth;
• healthy complexion;
• skin condition
• teeth;
• cellular renewal.

Now Foods, Vitamin A, 10,000 IU, 100 Capsules

Therefore, all beauties should take note of the properties of such a nutrient. In addition, a sufficient amount of micrograms of vitamin A helps slow down aging and prevent cancer.

On a note! Retinol is well absorbed with fats and minerals.

Children's daily allowance “A” depends on the age category:

1. Up to 12 months - 400 mcg.
2. One - three years - 450 mcg.
3. From 4 to 6 - 500 mcg.
4. 7-10 years - 700 mcg.

The recommended dose for children over 10 years of age and adults also depends on gender characteristics.

The daily norm for men of all ages is 1000 mcg. For women over 11 years old - 800 mcg. It is recommended to add 200 mcg for pregnant women, and 400 mcg for lactating women.

In imported supplements, Vitamin A is often indicated not in grams or mcg, but in conventional international units IU (in English - IU). 0.6 micrograms of retinol is equivalent to 1 IU.

It is advisable to receive one third of the dose in its natural form. The rest is multivitamin complexes. Table 1 will help you find out which foods contain a lot of vitamin A.

Table 1. Which foods contain a lot of vitamin A.

Swiss cheese and Camembert are the products richest in retinol in the fermented milk category.

Good to know! Long frying, boiling, etc. evaporates all beneficial properties, including nutrients.

All products rich in vital vitamin A are quite affordable and are often found on shelves at reasonable prices. This makes it easier to replenish the body with nutrients. According to the list in Table 1, you can see where vitamin A is found in mcg the most. Fish oil is made from different components. Before purchasing, read the ingredients, we need cod liver.

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Vitamin A overdose

Retinol intoxication from consuming plant-based products is unlikely. The amount of vitamin A in the table above is given in pure form, that is, the data does not need to be divided by “12” or “24”, since the resulting percentage absorption will be slightly lower.

The real danger is the combination of dietary nutrition with vitamin-rich foods and retinol capsules. To further aggravate the situation, the symptoms of hypervitaminosis with retinol, without consulting a specialist, can be mistaken for vitamin deficiency (lack of vitamin A).

It is extremely difficult to get hypervitaminosis by consuming large amounts of vitamin A from food. To do this, you need to eat 3 kg of beef liver at one time. Most acute conditions develop due to incorrect dosage of medications. A clinical picture of severe poisoning develops.

Chronic hypervitaminosis is often a consequence of taking tablet forms and a large number of products containing retinol.

Symptoms of vitamin A overdose:

• weakness;
• emotional lability;
• headache;
• myalgia;
• nausea;
• vomit;
• disturbance of consciousness;
• convulsions.

In such cases, urgent consultation with a doctor and detoxification measures are necessary.

What foods contain vitamin A?

Vitamin A can be found in the form of retinol in the following animal products:

• liver - pork, beef, chicken, rabbit;
• chicken egg yolk;
• Cod liver;
• fish roe;
• butter;
• hard cheese;
• mackerel, sardine.

Vitamin A is found in foods of plant origin in the form of carotenoids, these include:

• carrot;
• parsley and celery;
• spinach;
• lettuce leaves;
• rose hip;
• red bell pepper;
• leek;
• apricots;
• pumpkin;
• tomatoes.