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Vitamin A is a fat-soluble vitamin, which is naturally present in certain food items. It is derived from provitamin A and is quite essential for the optic health (eyesight). 

Vitamin A is also called retinol because it aids in producing the pigment which helps in the formation of the retina in your eyes. You may be surprised to know that the deficiency of vitamin A is the most common cause of blindness worldwide.

Vitamin A is a powerful antioxidant, which helps to protect you from the harmful effects of free radicals. It is considered to have an important role in the proper growth and development of your body and is thus highly required in infants and children.

It helps in maintaining the health of your skin, tissues, mucous membranes, bones and teeth, and is also important for maintaining several cellular functions. Vitamin A also has an essential role in improving the functioning of your immune system, which helps you in fighting infections.

This article discusses the important functions of vitamin A for different age groups, along with the daily requirement of it, food sources and the side effects of taking an excess of vitamin A supplements.

  1. Vitamin A side effects
  2. Vitamin A recommended daily intake
  3. Vitamin A rich foods
  4. Health benefits of vitamin A

Excess of vitamin A in the form of retinol is likely to cause the following side effects:

Severe side effects like liver damage can occur if vitamin A is stored in larger amounts by the body. Disorders of the nervous system are also likely to occur in such cases, and the risk of developing osteoporosis is increased.

An excessive dosage of vitamin A can cause lower oxygen saturation levels in the blood, which is likely to cause breathlessness in children. Vitamin A must thus not be excessively given to children, particularly those suffering or recovering from pneumonia.

(Read more: Treatment for shortness of breath)

The recommended daily intake of vitamin A depends on your weight, height, gender, and age. It also depends on the area you reside in. Individuals living in an area with a higher prevalence of vitamin A deficiency or malnutrition require a higher dosage of this vitamin.

It is also required more by women during stages of lactation (breastfeeding) and pregnancy to prevent deficiencies in infants and children. While the range of dosage highly varies, the upper limits of consumption of this vitamin are mentioned below. It is highly recommended not to take beyond the prescribed dosage. 

Generally, a dosage of more than 3000 IU (1 IU = 0.6 mcg beta-carotene) is not suggested for daily intake. It is also recommended not to take any additional supplements without doctor consultation since this vitamin is present in ample amounts in food and is also stored by the body. 

While taking external supplements, if any, it is advisable to take those of beta-carotene instead of retinol, since carotene is a precursor (is responsible for forming vitamin A) of vitamin A and will be naturally converted into vitamin A by the body, which is then stored. However, retinol is likely to cause side effects and can even cause hypervitaminosis, that is toxicity when consumed in higher amounts. The side effects of vitamin A are discussed in the later sections.

Age and Upper limit of dosage:

  • Birth to 3 years: 600 mcg
  • 4 years to 8 years: 900 mcg
  • 9 years to 13 years: 1700 mcg
  • 14 years to 18 years: 2800 mcg
  • Adult dosage: 3000 mcg
  • Pregnancy and lactation: 3000 mcg
  • Single maternal dosages of 120,000 mcg are also given to prevent deficiencies in infants. They are usually well-tolerated and do not affect the quality of mother's milk.

Following are the dietary sources of vitamin A:

  • Carrots and other vegetables containing natural coloured pigment (beta-carotene) like bell peppers (capsicum) red, green and yellow.
  • Green leafy vegetables like broccoli, kale, spinach, zucchini, squash.
  • Cod liver oil
  • Fruits like mangoes, papayas, apricots
  • Pumpkin
  • Dairy products like (milk, cheese, yogurt).
  • Animal products like meat, poultry and fish, particularly salmon.
  • Egg yolks
  • Liver
  • Certain packaged foods like breakfast cereals

It is recommended to include more of the natural sources of this vitamin in your diet. You are advised to refrain from taking any supplements without a physician’s consult. Pregnant women must especially avoid taking them since it can cause birth defects in newborns.

Vitamin A has very significant benefits for your health, particularly your visual health and immunity. It is a powerful antioxidant and has different benefits for individuals in different age groups, which will be discussed ahead.

  • Preserves vision: Vitamin A is most well-known for its benefits in preventing vision loss and age-related degeneration of eyes. It is made up of carotenoids, which prevent oxidative damage to your eyes thus protecting vision.
  • Prevents ageing: Vitamin A has an important role in the formation of new skin cells, which along with its antioxidant action is effective in preventing premature ageing of skin. So, if you are taking your recommended dosage of this vitamin you can stop worrying about fine lines and wrinkles.
  • For pregnant women: Deficiency of vitamin A can not only cause preterm labour but also it is associated with birth defects such as learning disability.
  • For infants and children: Vitamin A helps prevent diseases in children and aids in their proper growth and development. It also improves immunity in newborns.
  • Improves brain function: Vitamin A facilitates the proper growth and development of brain cells in children and it also aids in maintaining circadian rhythms in adult brain, which is helpful in avoiding stress an enhancing brain function.
  • Reduces morbidity in measles: Intramuscular injection of vitamin A has been found to reduce the risk of measles in malnourished children. It is also suggested to prevent morbidity and increase their survival rate.
  1. Vitamin A benefits for skin
  2. Vitamin A for cancer
  3. Vitamin A in pregnancy
  4. Vitamin A for children
  5. Vitamin A for the brain
  6. Vitamin A for measles
  7. Vitamin A for the elderly
  8. Vitamin A benefits for eyes
  9. Vitamin A prevents night blindness

Vitamin A benefits for skin

Vitamin A is a common constituent of the epidermis (topmost layer of the skin) and takes part in the epidermal turnover (replacing of old skin cells with the newer). The epidermal turnover rate is higher in infants and young children, and it gradually diminishes with age. This gives the skin an old and wrinkled appearance.

Vitamin A helps to form and maintain your skin cells, which helps in reducing fine lines and creases on the face. Since epidermal vitamin A is vital for this process, treatments aimed at increasing its level can be highly beneficial. Topical (applied on the skin) retinoid solutions are one such alternative.

They help in reducing oxidative damage (damage caused by free radicals) and the damage caused to your skin by UV rays. UV rays are further known to reduce the levels of epidermal vitamin A. So, protecting the skin from direct sunlight can also be helpful in reducing skin damage. As of topical retinoid agents, natural retinoic acid precursors like retinaldehyde or retinol are more beneficial and less irritant than acidic retinoids.

However, you are highly recommended not to make the use of these agents without your physician’s consult. Some over-the-counter products like creams and moisturizers, which already have vitamin A added in them can be opted for.

Vitamin A for cancer

Vitamin A is essential for cell growth, differentiation, proliferation and apoptosis (programmed death of cells on their own). It also regulates the process of organogenesis (formation of various body organs) and has a significant role in the immune response of the mucosa. For these reasons, it has been used for the prevention and treatment of cancer and certain metabolic diseases.

Individuals who consume foods containing beta-carotene in high amounts have a lower risk of cancer, as demonstrated by various studies. However, these studies have also suggested that carotenoids help in the prevention of certain kinds of cancer, but mixed results have been obtained. Risks of some cancers have been known to increase with these supplements, so, their role is still debatable.

Vitamin A in pregnancy

As already stated, deficiency of vitamin A is fairly common during pregnancy, due to higher demands. This can cause several birth defects in the fetus. Other than fetal defects, a deficiency of vitamin A may also increase the risk of preterm labour (birth of the child before the full term of 39 to 40 weeks). This is further a threat to the health and survival of the infant. Such babies are more prone to serious health problems and learning disabilities, which may continue until adulthood.

Thus, it is essential to supplement your diet with vitamin A rich foods during pregnancy, so that you do not require a supplement, having similar side effects. You can simply increase the number of food items that you consume from the above list. In addition to protecting the health of your infant, vitamin A will also help you reduce the risk of developing maternal anemia or hypertension, and will ensure your best maternal health.

Vitamin A has other benefits during pregnancy and breastfeeding. According to one study, topical application of carrot poultice helps in reducing breast engorgement. Breast engorgement refers to tender, swollen and hard lump-like structures in the breast, due to an excessive amount of breast milk.  However, other research suggests that breast engorgement is self-limiting, so it is not obvious that the topical application of carrot on breasts has any treatment efficacy.

(Read more: Breast lump causes)

Vitamin A for children

Vitamin A is essential for infants and children to aid in their proper growth and development. It helps in avoiding childhood infections and illnesses. Vitamin A reduces various health-related risks in the infants and children.

Dietary supplementation of vitamin A is appropriate for children who have already started with a solid diet. However, in case of infants, adequate levels of vitamin A have to be maintained by improving the maternal intake of the vitamin. So, the recommended daily intake of vitamin A is higher in lactating women. They are recommended to take at least 1300 mcg of retinol rich foods per day to enhance the levels of carotenoids in the milk.

Dietary supplementation of vitamin A during lactation is known to improve immune function and antioxidant actions in children. No known risks are observed in infants even at a higher dosage, however, a dosage higher than 3000 mcg must be avoided.

Vitamin A for the brain

Vitamin A is quite an essential vitamin for your brain. Its effects on the brain are pronounced in all stages of life. It has a very important role during childhood and infancy, as it helps in proper growth, development and differentiation of the brain cells. This helps in ensuring optimal function and capacity of the brain even during adulthood.

(Read more: Poor memory)

In a fully grown adult brain, differentiation is less likely to occur. However, certain changes are possible even in adults, termed as neural plasticity, which regulates memory and function in adults. Other than this, vitamin A also helps in maintaining the circadian rhythm, which helps in regulating your sleep and feeding cycle. Thus, it is a good idea to include more vitamin A in your diet to enhance your brain function. It will also help in regulating the circadian clock, enhancing several body functions and helping to regulate sleep.

(Read more: Insomnia causes)

Vitamin A for measles

Measles is a highly infectious disease, which is fairly prevalent in India, despite the availability of vaccinations and preventive measures. It is a serious viral disease and increases the risk of death in infants. More than 5000 cases are reported in India each year, and have been invariably noticed in malnourished children who had a vitamin A deficiency.

Intramuscular injections of vitamin A have been tried in malnourished children. They have been found to significantly reduce the incidence of measles. A reduced rate of mortality and a better survival rate has also been observed among them.

(Read more: Treatment of infection)

Vitamin A for the elderly

Supplementation with vitamin A has several health benefits for the elderly. Being a powerful antioxidant, vitamin A is known to reduce the effects of ageing on the skin. It helps in keeping the skin tight and supple as individual ages.

Vitamin A also helps in avoiding vision-related disorders in the elderly and also reduces retinal degeneration and blindness. Other than this, vitamin A is known to prevent cognitive (related to brain functioning and memory) disorders in the elderly by reducing oxidative stress in the brain.

Oxidative stress is responsible for diminished memory and cognition as an individual ages. So, Vitamin A is vital for the elderly since it improves their mental and physical functioning required for daily acitvities.

Vitamin A benefits for eyes

As already stated, vitamin A is essential for proper vision and eyesight. Its deficiency can result in various eye-related problems, particularly dryness of the eye and diminished vision at night. Vitamin A is made of carotenoids, which are known for their antioxidant activities and protective functions.

As we age, the effects of biological oxidation get higher and the eyesight gets affected. Supplementation with vitamin A is known to reduce age-related macular degeneration (slowly progressing disease advancing to blindness), which helps in maintaining good vision even as an individual ages. Dietary supplementation with foods rich in carotenoid is found to be more effective than vitamin A supplements.

Other than in the advancing age, vitamin A is known to have beneficial effects on the vision for all. It helps in reducing retinal degeneration (degeneration of cells in the retina), which is responsible for blindness. It is particularly essential to maintain adequate levels of this vitamin during pregnancy. Deficiency of vitamin A during pregnancy is a significant risk factor for birth defects in infants. However, supplements may not be taken, since they pose a similar risk.

Vitamin A prevents night blindness

Night blindness is the first symptom of retinal degeneration, caused due to retinitis pigmentosa (a group of inherited disorders). The retina of the eye is responsible for converting light signals into vision. Degeneration of the retina in this condition begins during adolescence (teenage) or young adulthood, following which, affected individuals may progress to blindness in their 40s.

It is an inheritable disorder and can be transferred to offsprings, which makes it all the more essential to avoid this condition. Since treatment of this condition is not equally successful, it is advisable to reduce its risk by adding more of vitamin A in your diet. It is often said that vitamin A is fuel for the retina (and vision), so load up on it!

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References

  1. MedlinePlus Medical Encyclopedia: US National Library of Medicine; Vitamin A
  2. Duerbeck NB, Dowling DD. Vitamin A: too much of a good thing? Obstet Gynecol Surv. 2012 Feb;67(2):122-8. PMID: 22325302
  3. MedlinePlus Medical Encyclopedia: US National Library of Medicine; Vitamin A
  4. National Institutes of Health; Office of Dietary Supplements. [Internet]. U.S. Department of Health & Human Services; Vitamin A.
  5. World Health Organization [Internet]. Geneva (SUI): World Health Organization; Vitamin A deficiency.
  6. Clare Gilbert. The eye signs of vitamin A deficiency. Community Eye Health. 2013; 26(84): 66–67. PMID: 24782581
  7. MedlinePlus Medical Encyclopedia: US National Library of Medicine; Vitamin A
  8. Eggersdorfer M, Wyss A. Carotenoids in human nutrition and health.. Arch Biochem Biophys. 2018 Aug 15;652:18-26. PMID: 29885291
  9. Wu J, Cho E, Willett WC, Sastry SM, Schaumberg DA. Intakes of Lutein, Zeaxanthin, and Other Carotenoids and Age-Related Macular Degeneration During 2 Decades of Prospective Follow-up. JAMA Ophthalmol. 2015 Dec;133(12):1415-24. PMID: 26447482
  10. Zhou YM, Huang YF. Research on natural antioxidants in the treatment of retinal degeneration. Zhonghua Yan Ke Za Zhi. 2018 Apr 11;54(4):312-315. PMID: 29747361
  11. Kaukonen M et al. Maternal Inheritance of a Recessive RBP4 Defect in Canine Congenital Eye Disease.. Cell Rep. 2018 May 29;23(9):2643-2652. PMID: 29847795
  12. Sorg O, Saurat JH. Topical retinoids in skin ageing: a focused update with reference to sun-induced epidermal vitamin A deficiency. Dermatology. 2014;228(4):314-25. PMID: 24821234
  13. Radhika MS, Bhaskaram P, Balakrishna N, Ramalakshmi BA, Devi S, Kumar BS. Effects of vitamin A deficiency during pregnancy on maternal and child health. BJOG. 2002 Jun;109(6):689-93.
  14. Oliveira LM, Teixeira FME, Sato MN. Impact of Retinoic Acid on Immune Cells and Inflammatory Diseases. Mediators Inflamm. 2018 Aug 9;2018:3067126. PMID: 30158832
  15. World Health Organization [Internet]. Geneva (SUI): World Health Organization; Vitamin A supplementation in infants and children 6–59 months of age.
  16. Drugs and Lactation Database (LactMed) [Internet]. Bethesda (MD): National Library of Medicine (US); 2006-. PMID: 30000990
  17. McCaffery P, Zhang J, Crandall JE. Retinoic acid signaling and function in the adult hippocampus. J Neurobiol. 2006 Jun;66(7):780-91. PMID: 16688774
  18. Shearer KD, Stoney PN, Morgan PJ, McCaffery PJ. A vitamin for the brain. Trends Neurosci. 2012 Dec;35(12):733-41. PMID: 22959670
  19. Ransom J, Morgan PJ, McCaffery PJ, Stoney PN. The rhythm of retinoids in the brain. J Neurochem. 2014 May;129(3):366-76. PMID: 24266881
  20. Bichon A et al. Case report: Ribavirin and vitamin A in a severe case of measles. Medicine (Baltimore). 2017 Dec;96(50):e9154. PMID: 29390321
  21. Stephensen CB et al. Adverse effects of high-dose vitamin A supplements in children hospitalized with pneumonia. Pediatrics. 1998 May;101(5):E3. PMID: 9565436