Vitamin A – sources, effects on the body, effects of deficiency and overdose

Proven content

Vitamin A is the common name for several organic compounds from the group of retinoids. It is also often referred to as retinol, beta-carotene, axophthol and provitamin A. It belongs to the group of fat-soluble vitamins. In plants, this compound accumulates in the form of carotenoids. In the body, vitamin A is stored as retinol in the liver and adipose tissue. It is one of the earliest discovered vitamins in the history of medicine. Much earlier, even before the discovery of vitamin A, the effects of its deficiency were symptomatically treated by the ancient Egyptians, Greeks and Romans. The disease was called night blindness or night blindness and the treatment consisted of eating raw or cooked animal liver.

The role of vitamin A in the body

Vitamin A is an extremely important vitamin that is essential for the functioning of our body. It plays a large part in the process of vision, influences growth, and regulates the growth of epithelial tissue and other cells in the body. In addition, it has anti-cancer properties, protects the epithelium of the respiratory system against microorganisms, strengthens the immune system, prevents infections, helps fight bacteria and viruses, maintains the proper condition of the skin, hair and nails, and also affects the proper functioning of cell membranes. Vitamin A regenerates dry skin, so it is worth using cosmetics with its addition, such as the revitalizing Vianek cleansing gel for mature and sensitive skin.

It is one of the most important compounds that builds the body’s immunity. Therefore, it is worth supplementing vitamin A deficiencies in the diet with dietary supplements with high vitamin A content, such as vitamin A 10.000 IU from Swanson and vitamin A supplement from Dr. Jacob’s.

Vitamin A – Health Benefits

Vitamin A is an important nutrient that benefits your health in many ways.

Vitamin A is a powerful antioxidant

Provitamin A carotenoids such as beta-carotene, alpha-carotene and beta-cryptoxanthin are precursors to vitamin A and have antioxidant properties.

According to the results of a study published in Pharmacognosy Reviews in 2010, carotenoids fight free radicals – highly reactive molecules that can harm our body by causing oxidative stress. Oxidative stress is linked to various chronic diseases such as diabetes, cancer, heart disease, and cognitive decline, in turn confirmed by studies such as those published in Oxidative Medicine and Cellular Longevity in 2017.

Diets high in carotenoids are associated with a lower risk for many of these conditions, such as heart disease, lung cancer, and diabetes.

See also: Alpha carotene is a good preventive medicine

Vitamin A is essential for eye health and prevents macular degeneration

Vitamin A is essential for maintaining eyesight. Vitamin A is needed to convert light reaching the eye into an electrical signal that can be sent to the brain. In fact, one of the first symptoms of a vitamin A deficiency may be night blindness, known as night blindness.

Night blindness occurs in people who are deficient in vitamin A, as this vitamin is the main ingredient in pigment rhodopsin. Rhodopsin is found in the retina of the eye and is extremely light sensitive. People with this condition still see normally during the day, but have limited vision in the dark because their eyes have difficulty picking up light at lower levels.

As confirmed by a 2015 study published in JAMA Ophthalmology, in addition to preventing night blindness, consuming the right amounts of beta-carotene can help slow down the deterioration in eyesight that some people experience with age.

Age-related macular degeneration (AMD) is the leading cause of blindness in developed countries. Although its exact cause is unknown, it is believed to be the result of cellular damage to the retina, attributed to oxidative stress (as confirmed in a 2000 study in the Survey of Ophthalmology).

Another 2001 study published in the Archives of Ophthalmology on age-related eye disease found that giving people over the age of 50 with some visual degeneration an antioxidant supplement (including beta-carotene) reduced the risk of developing advanced macular degeneration by 25 %.

However, a recent Cochrane review found that beta-carotene supplements alone will not prevent or delay the visual impairment caused by AMD.

See also: Innovative therapy for patients with exudative AMD

Vitamin A may protect against certain types of cancer

Cancer occurs when abnormal cells start growing or dividing uncontrollably.

Since vitamin A plays an important role in cell growth and development, its effects on cancer risk and role in cancer prevention are of interest to researchers.

In observational studies (e.g. published in the Annals of Hematology in 2017 or Gynecologic Oncology in 2012), consuming higher amounts of vitamin A in the form of beta-carotene was associated with a reduced risk of certain types of cancer, including Hodgkin’s lymphoma, and also cancer of the cervix, lung and bladder.

However, while high intake of vitamin A from plant foods is associated with a reduced risk of cancer, animal foods containing active forms of vitamin A are not related in the same way (a 2015 study published in the Archives of Biochemistry and Biophysics).

Similarly, according to a 1999 study published in the Journal of the National Cancer Institute, vitamin A supplements did not show the same beneficial effects.

In fact, in some studies, smokers taking beta-carotene supplements have experienced an increased risk of lung cancer (including a study published in Nutrition and Cancer in 2009).

At the moment, the relationship between vitamin A levels in our body and cancer risk is still not fully understood. However, according to a 2015 study published in BioMed Research International, obtaining adequate vitamin A, especially from plants, is important for healthy cell division and may reduce the risk of certain types of cancer.

See also: A drug that reduces the risk of developing breast cancer. Research is ongoing

Vitamin A reduces the risk of acne

Acne is a chronic, inflammatory skin disease. People with this condition develop painful pimples and blackheads, most often on the face, back, and chest.

These pimples appear when the sebaceous glands become clogged with dead skin and fats. These glands are found in the hair follicles on the skin and produce sebum, the oily waxy substance that keeps the skin hydrated and waterproof.

Although pimples are physically harmless, acne can have a serious impact on people’s mental health and lead to low self-esteem, anxiety and depression (as a 2016 study published in Clinical, Cosmetic and Investigational Dermatology seems to confirm). The exact role that vitamin A plays in the development and treatment of acne remains unclear.

A study like the one published in the 2015 Journal of Nutrition & Food Sciences has suggested that vitamin A deficiency may increase the risk of developing acne because it causes an overproduction of keratin protein in the hair follicles. This would increase the risk of acne by making it difficult to remove dead skin cells from the hair follicles, leading to skin blockages.

Some vitamin A acne medications are now available by prescription.

Isotretinoin is one example of an oral retinoid that is effective in treating severe acne. However, this drug can have serious side effects and must only be taken under medical supervision.

See also: How to get rid of acne?

Vitamin A is essential for the fertility and development of the fetus

Vitamin A is essential for maintaining a healthy reproductive system in both men and women, and for the proper growth and development of embryos during pregnancy.

A study in rats published in Nutrients in 2011 on the importance of vitamin A in male reproduction found that deficiency blocks sperm development, causing infertility. The same study mentioned suggests that vitamin A deficiency in females may affect reproduction by reducing the quality of the egg and influencing the implantation of the egg in the uterus.

In pregnant women, vitamin A is also involved in the growth and development of many major organs and structures of the unborn baby, including the skeleton, nervous system, heart, kidneys, eyes, lungs, and pancreas.

However, although much less common than vitamin A deficiency, excess vitamin A during pregnancy can also be harmful to the developing baby and can lead to birth defects (as confirmed by studies such as those published in the Archives de Pédiatrie in 1997).

Hence, many health authorities have advised women to avoid foods that contain concentrated amounts of vitamin A, such as pate and liver, and supplements that contain vitamin A during pregnancy.

See also: 22q11.2 deletion syndrome. A defect with which one in two to four thousand is born. kids

Vitamin A strengthens the immune system

Vitamin A supports the health of the immune system by stimulating responses that protect the body against disease and infection. Vitamin A is involved in the formation of certain cells, including B and T lymphocytes, which play a key role in immune responses to protect against disease.

As confirmed in a 2012 study in the Proceedings of the Nutrition Society, deficiency of this nutrient leads to increased levels of pro-inflammatory molecules that weaken the response and functioning of the immune system.

Vitamin A supports bone health

The key nutrients needed to maintain healthy bones as you age are protein, calcium, and vitamin D. However, consuming enough vitamin A is also essential for proper bone growth and development, and a deficiency of this vitamin has been linked to poor bone health.

According to a 2017 study published in the International Journal of Environmental Research and Public Health, people with lower blood levels of vitamin A are more likely to develop bone fractures than those with healthy levels. In addition, a recent meta-analysis of observational studies found that those with the highest total dietary vitamin A content have a 6% lower risk of fractures.

However, low vitamin A levels may not be the only concern when it comes to bone health. Some studies, such as the 2013 one published in the Journal of Clinical Densitometry, found that people who consume high amounts of vitamin A also have a higher risk of fractures.

Even so, all of these findings are based on observational studies that cannot pinpoint cause and effect. This means that the link between vitamin A and bone health is currently not fully understood and more controlled studies are needed to confirm what was observed in observational studies.

Keep in mind that vitamin A status alone does not determine fracture risk, and the effect on the availability of other key nutrients, such as vitamin D, also plays a role.

See also: Diet after bone fractures

The presence of vitamin A.

Vitamin A can be found, among others, in butter, milk and dairy products, some fatty fish, liver and animal offal, eggs, sweet potatoes, kale, spinach and pumpkin. The most desirable carotenoids, among which beta carotene plays the most important role, are found in spinach, carrots, tomatoes, red pepper and lettuce. Fruits that are particularly rich in carotenoids are, for example, cherries, apricots, peaches and plums. The product that is most often used for supplementation and contains the most vitamin A is fish oil. Try, for example, Moller’s Tran Norwegian Fruit, which you can buy in a safe and convenient way at Medonet Market. Also try Familijny fish oil with vitamins A and D – Health and immunity, available at a promotional price.

Vitamin A supplementation should be consulted with your family doctor. You can now make your visit comfortably from home in any form you choose via the halodoctor.pl portal.

You can also reach for corn flour, which is also a source of vitamin A. It is used as a substitute for traditional wheat flour. Pro Natura corn flour is available on Medonet Market.

Symptoms of vitamin A deficiency

People who work at the computer, pregnant and breastfeeding women, premature babies, people with cystic fibrosis, alcoholics and smokers, and the elderly are all in need of more vitamin A.

Vitamin A deficiency is most often manifested by:

1. poor night vision, or so-called “night blindness” (according to the WHO, vitamin A deficiency is the leading cause of preventable blindness in children around the world),
2. hair loss and brittleness,
3. stunted growth,
4. chapped skin and rash
5. drying out of the cornea and conjunctiva of the eye,
6. the presence of brittle and slowly growing nails,
7. increased susceptibility to bacterial and viral infections (vitamin A deficiency increases the severity and risk of death from infections such as measles and diarrhea),
8. acne, eczema,
9. hyperkeratosis,
10. prone to diarrhea.

In addition, vitamin A deficiency increases the risk of anemia and death in pregnant women and negatively affects the fetus, slowing its growth and development.

In the diagnosis of vitamin deficiencies, it is worth taking a blood test for the level of vitamins and minerals. Such a test can be purchased at private Arkmedic medical facilities.

Vitamin A can be found in the composition of GlowMe Health Labs – for skin thirsting for radiance – a dietary supplement that positively affects the complexion.

Vitamin A excess – symptoms

Nowadays, we use vitamin supplements more and more often, but it must be remembered that excessive consumption of vitamin A, due to the fact that it accumulates in the liver, may be toxic to the body and dangerous to health (high consumption of carotenoids in the diet is not related to toxicity although studies link beta-carotene supplements to an increased risk of lung cancer and heart disease in smokers). Therefore, fish oil should be taken strictly according to the doctor’s instructions or according to the pharmaceutical leaflet.

Taking too much vitamin A can lead to serious side effects and can even be fatal if consumed in very high doses.

While it is possible to consume excess amounts of preformed vitamin A from animal sources such as the liver, toxicity is most often associated with excessive supplementation and treatment with certain medications such as isotretinoin. Acute vitamin A toxicity occurs in a short time when a single, excessively high dose of vitamin A is consumed, while chronic toxicity occurs when doses in excess of 10 times the RDA are taken for prolonged periods.

Symptoms of excess (hypervitaminosis) include:

1. hyperactivity and irritability,
2. nausea, vomiting
3. blurred vision,
4. reduced appetite,
5. sensitivity to sunlight,
6. hair loss,
7. dry skin,
8. jaundice,
9. delayed growth,
10. confusion,
11. itchy skin
12. headaches,
13. joint and muscle pain,
14. enlargement of the liver and disorders of its functions,
15. yellowish skin lesions,
16. lower calcium content in bones,
17. birth defects in children of mothers who experienced hypervitaminosis during pregnancy.

Although less common than chronic vitamin A toxicity, acute vitamin A toxicity is associated with more severe symptoms, including liver damage, increased cranial pressure, and even death.

Moreover, vitamin A toxicity can negatively impact maternal and fetal health and can lead to birth defects.

To avoid toxicity, high-dose vitamin A supplements should be avoided. Since too much vitamin A can be harmful, it is recommended that you consult your doctor first before taking vitamin A supplements.

Tolerable upper intake levels for vitamin A apply to animal sources of vitamin A as well as vitamin A supplements.

What to do in case of vitamin A deficiency or excess?

In the event of a deficiency or excess of vitamin A in the body, we should analyze our daily diet and modify it in a possible way. In case of deficiency – add products rich in vitamin A to the diet, and excess – limit their consumption. If an excess is detected, you should reduce, and in special cases stop taking vitamin supplements containing vitamin A.

Sometimes, even in the case of a properly balanced diet, vitamin A deficiency is found. In such a situation, additional supplementation should be considered. The best solution, however, is to consult a dietitian who will arrange an appropriate diet and recommend appropriate steps.

See also: How much do vitamin supplements harm us?

Vitamin A toxicity and dosage recommendations

Just as vitamin A deficiency can have a negative impact on your health, too much can also be dangerous.

The Recommended Daily Allowance (RDA) of vitamin A is 900 mcg and 700 mcg per day for men and women, respectively – which is easily accomplished by following a complete diet. However, it is important not to exceed the Tolerable Upper Intake Level (UL) of 10 IU (000 mcg) for adults to prevent toxicity.

See also: Eat with common sense

Vitamin A – interactions

Possible interactions include:

1. Anticoagulants. Oral use of vitamin A supplements while taking these medications used to prevent blood clots may increase the risk of bleeding.
2. Bexarotene (Targretin). Taking vitamin A supplements while using this topical anti-cancer drug increases your risk of side effects such as itching, dry skin.
3. Hepatotoxic drugs. Taking high doses of vitamin A supplements can damage the liver. Combining high doses of vitamin A supplements with other medications that can harm your liver can increase your risk of liver disease.
4. Orlistat (Alli, Xenical). This weight loss drug may reduce the absorption of vitamin A from food. Your doctor may suggest taking a multivitamin with vitamin A and beta-carotene while you are taking this medication.
5. Retinoids. Do not use vitamin A supplements and these prescription oral medications at the same time. This can increase the risk of high levels of vitamin A in the blood.