Vitamin A

International name – , as a dietary supplement also called Retinol.

 

Fat-soluble vitamin, an essential component for healthy growth, bone and dental 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 youth of the skin, health of hair and nails, visual acuity. Vitamin A is absorbed in the body in the form of Retinol, which is found in the liver, fish oil, egg yolk, dairy foods and added to margarine. Carotene, which is converted into Retinol in the body, is found in many vegetables and fruits.

History of discovery

The first prerequisites for the discovery of Vitamin A and the consequences of its deficiency appeared back in 1819, when the French physiologist and psychologist Magendie noticed that poorly nourished dogs 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 resemble fats, carbohydrates, or proteins. On closer inspection, it turned out that they promoted the growth of laboratory mice. For his discoveries, Hopkins received the Nobel Prize in 1929. 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 named Vitamin A.

Vitamin A rich foods

Indicated approximate availability in 100 g of product

Curly cabbage500 μg
Cilantro337 μg
Soft goat cheese288 μg
+ 16 more foods rich in vitamin A (the amount of μg in 100 g of the product is indicated):
Basil264Quail egg156Mango54A tomato42
Raw mackerel218Cream124Fennel, root48prunes39
Rosehip, fruit217Apricot96Chilli48Broccoli31
Raw egg160Leek83grapefruit46oysters8

Daily requirement for vitamin A

The recommendations for daily vitamin A intake are based on the amount needed to provide a supply of Retinol for several months in advance. This reserve supports 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:

AgeMen (mcg per day)Women (mcg per day)
6-12 months350350
1-3 years400400
4-6 years400400
7-10 years500500
11-14 years600600
15-17 years700600
18 years and older700600
Pregnancy700
Lactation950

Many European nutrition committees, such as the German Nutrition Society (DGE), recommend 0,8 mg (800 mcg) of vitamin A (Retinol) per day for women and 1 mg (1000 mcg) for men. 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 from the 4th month of pregnancy. Women who are breastfeeding should get 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, and for newborns and children 250 to 750 mcg of vitamin A per day, taking into account age. … During pregnancy and lactation, the additional amount of vitamin that must enter the body 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 in the amount of 700 and 1,300 mcg per day, respectively.

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

AgeMen (mcg per day)Women (mcg per day)
0-6 months400400
7-12 months500500
1-3 years300300
4-8 years400400
9-13 years600600
14-18 years900700
19 years and older900700
Pregnancy (18 years old and younger)750
Pregnancy (19 years and older)770
Breastfeeding (18 years old and younger)1200
Breastfeeding (19 years and older)1300

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 on 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 ARVI.

Physical and chemical properties

Vitamin A is a fat-soluble vitamin that belongs to a group of molecules with a similar structure – retinoids – and is found in several chemical forms: aldehydes (retinal), alcohol (Retinol), and acid (retinoic acid). In animal foods, the most common form of vitamin A is an ester, primarily retinyl palmitate, which is synthesized into Retinol in the small intestine. Provitamins – biochemical precursors of vitamin A – are present in plant foods, they are components of the carotenoid group. Carotenoids are organic pigments that occur naturally in the chromoplasts of plants. 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 edible fats, oils or lipids. These include, for example, for cooking,,,, avocados.

 

Vitamin A dietary supplements are often available in oil-filled capsules so that the vitamin is fully absorbed by the body. People who do not consume enough dietary fat are more likely to be deficient in fat-soluble vitamins. Similar problems can occur in people with poor fat absorption. Fortunately, naturally occurring fat-soluble vitamins are usually found in foods that contain fat. Thus, with adequate nutrition, 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, like other fat-soluble vitamins, combine with bile. If the food at this moment contains little fat, then little bile is secreted, which leads to malabsorption and the loss of up to 90 percent of carotene and vitamin A in the feces.

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

 

We recommend that you familiarize yourself with the assortment of Vitamin A at the largest in the world. There are more than 30,000 environmentally friendly foods, attractive prices and regular promotions, constant 5% discount with promo code CGD4899, free worldwide shipping available.

The beneficial properties of vitamin A

Vitamin A has several functions in the body. The most famous is its effect on vision. Retinyl ester is transported to the retina, which is inside the eye, where it is converted into a substance called 11-cis-retinal. Further, 11-cis-retinal ends up in rods (one of the photoreceptors), where it combines with the opsin protein and forms the visual pigment “rhodopsin”. Rhodopsin-containing rods 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 leads to its release from the protein. This triggers a chain of events leading to the generation of an electrochemical signal to the optic nerve, which is processed and interpreted by the brain. The lack of Retinol available to the retina leads to impaired adaptation to darkness 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 absorbed 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 response of the immune system.

Vitamin A is indispensable in embryonic development, taking a direct part in the growth of the limbs, the formation of the heart, eyes and ears of the fetus. In addition, retinoic acid affects the expression of the growth hormone gene. Both lack 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 appears to improve the mobilization of iron from reserves in the body, directing it to the developing red blood cell. There, iron is included in hemoglobin – the carrier of oxygen in erythrocytes. Vitamin A metabolism is believed to interact with and 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 heal more effectively than just supplemental iron or vitamin A.

Recent studies have shown that vitamin A, carotenoids, and provitamin A carotenoids may be effective in preventing the development of heart disease. The antioxidant activity of vitamin A and carotenoids is provided by a 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 when the O2 stress is increased and are thus the most effective antioxidants at low oxygen pressures that are characteristic of physiological levels found in tissues. Overall, epidemiological evidence suggests that vitamin A and carotenoids are important dietary factors in reducing heart disease.

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

  • normal cell division;
  • normal development and functioning of the immune system;
  • maintaining the normal state of the skin and mucous membranes;
  • maintenance of 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. A high vitamin E content in the diet, in turn, impairs the absorption of vitamin A. Zinc helps the absorption of vitamin A by taking part in its conversion to Retinol. Vitamin A enhances the absorption of iron and affects the utilization of the iron reserve present in the liver.

Vitamin A also works 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 tissue 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 the metabolism of vitamin A and the receptors for both vitamins A and D function correctly only 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.

Vitamin A foods 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. The same goes for lettuce and carrots, which go well with avocados in salads. As a rule, animal foods rich in vitamin A already contain some 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.

It should be noted 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. Using vitamins in a medicinal form, it is very easy to make a mistake with the dosage and get more than the body needs. An overabundance 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 deteriorates, the metabolism and the work of organ systems are disrupted. Therefore, the use of vitamins in tablets should be carried out only when necessary and after consulting a doctor.

Application in medicine

Consumption of large amounts of vitamin A is prescribed in the following cases:

  • for vitamin A deficiency, which can occur in people with protein deficiency, an overactive thyroid gland, fever, liver disease, cystic fibrosis, or an inherited disorder called abelatipoproteinemia.
  • with 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 if vitamin A supplementation has a similar effect.
  • … Research shows that a high intake of vitamin A in the diet leads to a reduced risk of developing cataracts.
  • with diarrhea caused by. Taking vitamin A along with conventional medications appears to reduce the risk of dying from diarrhea in HIV-infected children with vitamin A deficiency.
  • … Taking vitamin A orally reduces the symptoms of malaria in children under 3 years of age in areas where malaria is common.
  • … Taking vitamin A orally reduces the risk of complications or death from measles in children with measles who are deficient in vitamin A.
  • with precancerous lesions in the mouth (oral leukoplakia). Research shows that taking vitamin A can help treat premalignant lesions in the mouth.
  • when recovering from 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. Taking vitamin A orally reduces the risk of death and night blindness during pregnancy in malnourished women.
  • for eye diseases affecting the retina (retinitis pigmentosa). Research shows that taking vitamin A can slow the progression of eye diseases that damage the retina.

The pharmacological form of vitamin A can be different. In medicine, it is found in the form of pills, 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 film-coated tablets. Vitamin A is taken for prophylaxis and for medicinal purposes, as a rule, 10-15 minutes after a meal. Oil solutions are taken in case of malabsorption in the gastrointestinal tract or in severe disease. In cases where long-term treatment is necessary, a solution for intramuscular injection is combined with capsules. In pharmacology, vitamin A is often quoted in International Units. For mild to moderate vitamin deficiencies, 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 for adults – 50-100 thousand IU / day; children – 5-20 thousand IU / day.

Traditional medicine advises using vitamin A as a remedy for flaky and unhealthy skin. For this, it is recommended to use fish oil, liver, oil and eggs, as well as vegetables rich in vitamin A – pumpkin, apricot, carrots. Freshly squeezed carrot juice with the addition of cream or vegetable oil is a good remedy for deficiency. Another folk remedy for obtaining vitamin is considered to be a decoction of the tubers of the potbelly tuber – it is used as a tonic, restorative and antirheumatic agent. Flax seeds are also considered a valuable source of vitamin A, as well as other useful substances, which are used internally 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 make a decoction, which is used internally as a course for a month.

Latest Scientific Research on Vitamin A:

Researchers at Case Western Reserve University School of Medicine have found that uncontrolled metabolism of vitamin A in the gut can cause dangerous inflammation. The discovery establishes a link between dietary composition and inflammatory diseases – and sore gut syndrome.

Read more

Researchers have found a branching point in the vitamin A metabolic pathway that is dependent on a specific protein called ISX. The beginning of the path is beta-carotene – a highly nutritious pigmented 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 transported to other tissues, ensuring good vision and other important functions. In a study of mice that had ISX removed, scientists noticed that the protein helps the body balance this process. Protein helps the small intestine determine How long beta-carotene is needed to meet the body’s need for vitamin A. Immune cells rely on this control mechanism to properly respond to food entering the small intestine. This provides an effective barrier against potential food-related threats. The researchers found that when ISX is absent, immune cells in the digestive tract become over-responsive to beta-carotene-laden meals. Their results prove that ISX is the main link between what we eat and gut immunity. The scientists concluded that removing the ISX protein accelerates the expression of a gene that converts beta carotene to vitamin A 200-fold. Because of this, ISX-removed 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 intestine between the stomach and colon and began to multiply. This intense inflammation spread to the pancreas and caused immunodeficiency in the mice.

Recent research 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 this is because vitamin A plays an important role in the development of beta cells in the early stages of life. , as well as for correct and work during the rest of life, especially during pathophysiological conditions – that is, with some inflammatory diseases.

Read more

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. Scientists fragmentarily blocked receptors and gave patients some sugar. They saw that the ability of cells to secrete insulin was deteriorating. The same trend could be observed when comparing insulin cells from donors with type 2 diabetes. Cells from patients with type 2 diabetes were less capable of producing insulin compared to cells from people without diabetes. Scientists have also discovered that beta cells’ resistance to inflammation is reduced in the absence of vitamin A. When vitamin A is absent, cells die. This study may also have implications for some types of type 1 diabetes, when beta cells are poorly developed in the early stages of life. “As it became clear after studies with animals, newborn mice need vitamin A for the full development of their beta cells. We’re pretty sure it’s the same in humans. Children need to get enough vitamin A in their diet, ”said Albert Salehi, Senior Research Fellow 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.

Read more

An unprecedented study by the laboratory of Professor Niels-Bjarn Woods 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. In the laboratory, stem cells were influenced by certain signaling molecules, transforming into hematopoietic cells. Scientists have noticed that high levels of retinoic acid rapidly decrease 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 excess vitamin A harms the embryo, introducing the risk of malformation or pregnancy termination. In view of this, pregnant women are strongly advised to control the consumption of foods containing a large amount of vitamin A in the form of retinoids, such as, for example, the liver. “The results of our research show that large amounts of vitamin A have a negative effect on hematopoiesis. This suggests that pregnant women should additionally avoid excessive vitamin A intake, ”says Niels-Bjarn Woods.

Vitamin A in cosmetology

It is one of the main ingredients for healthy and toned skin. When you receive a sufficient amount of vitamin, you can forget about problems such as lethargy of the skin, age spots, 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, therefore, it must 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 in the composition of masks, you can replace it with natural foods that are rich in this vitamin – kalina, parsley, spinach, egg yolks, dairy foods, pumpkin, carrots, fish oil, algae.

There are many recipes for masks with vitamin A. They often include fat-containing substances – fatty sour cream, burdock oil. Vitamin A (oil solution and Retinol acetate) works well 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 the drug Aevit, which already contains both vitamin A and vitamin E. A good preventive and therapeutic remedy for acne is a mask with ground, 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 damage to the skin, 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, lemon juice, and a drop of iodine. This mixture should be applied to the skin of the hands and nail plates, massage for 20 minutes and leave to absorb. Performing this procedure regularly will improve the condition of your nails and hands.

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

Vitamin A in livestock, crop and industry

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

Vitamin A has a relatively short shelf life and, as a result, dry foods stored for extended periods of time may not contain enough vitamin A. After illness or stress, the bird’s immune system 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 good appetite, coat health and immunity.

Interesting facts about vitamin A

  • it is the first vitamin discovered by humans;
  • 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 eyesight each year due to vitamin A deficiency;
  • in cosmetics, vitamin A is most often found under the names Retinol acetate, retinyl linoleate and retinyl palmitate;
  • Vitamin A-fortified rice, 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, store vitamin-rich foods and medical supplements in a dark place.

Signs of Vitamin A Deficiency

Vitamin A deficiency usually occurs due to insufficient intake of foods high in vitamin A, beta-carotene or other provitamin A carotenoids; which are metabolized to vitamin A in the body. In addition to dietary problems, excess alcohol consumption and malabsorption can be responsible for vitamin A deficiency.

The earliest sign of vitamin A deficiency is blurred vision in the dark, or night blindness. Severe or long-term vitamin A deficiency causes changes in the cells of the cornea, which ultimately lead to corneal ulcers. Vitamin A deficiency among children in developing countries is the leading cause of blindness.

Vitamin A deficiency is also linked to immunodeficiency, decreasing the ability to fight infections. Even children with mild vitamin A deficiencies have a higher incidence of respiratory disease and diarrhea, as well as a higher mortality rate from infectious diseases (especially), 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, a lack of vitamin A can contribute to chronic obstructive pulmonary disease (COPD) and emphysema, which are thought to increase the risk of lung cancer.

Signs of excess 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 cerebral edema. There are studies that prove that prolonged excess of vitamin A in the body can lead to the development of osteoporosis. Certain synthetic Retinol derivatives (eg tretinate, isotretinoin, tretinoin) can cause defects in the embryo 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) indicate that long-term vitamin A (Retinol) and beta-carotene supplementation should be avoided in the long term in people at high risk of lung cancer, such as smokers and people exposed to asbestos.

Interaction with other medicinal foods

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

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

Information sources
  1. Wikipedia article “Vitamin A”
  2. The British Medical Association. A-Z Family Medical Encyclopedia
  3. Maria Polevaya. Carrots against tumors and urolithiasis.
  4. Vladimir Kallistratov Lavrenov. Encyclopedia of Traditional Medicinal Plants.
  5. Protein regulates vitamin A metabolic pathways, prevents inflammation,
  6. The role of vitamin A in diabetes,
  7. Previously unknown effect of vitamin A identified,
  8. Walter A. Droessler. How delicious to eat and look great (p. 64)
  9. USDA Food Composition Databases,
Reprint of materials

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

Safety regulations

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

Read also about other vitamins:

Leave a Reply