Vitamin A – Sources, Deficiency and Prevention

Vitamin A – Sources, Deficiency and Prevention

Vitamin A offers several benefits to humans like promoting good eye health, helping us to see in the dark, supporting the growth and remodelling of bones, fighting against infections etc.
One of the most important essential vitamins, Vitamin A or Retinol is a “fat soluble” vitamin. This article will deal with the functions and sources of Vitamin A, the conditions associated with its deficiency, and strategies to prevent and treat Vitamin A deficiency.


  • It is an integral component of normal vision. They are responsible for the production of retinal pigments which are needed for vision in dim light. This is the most important function of Vitamin A because the deficiency of this vitamin is becoming one of the major reasons of preventable blindness in the world.
  • It is necessary for the normal functioning of the tissue lining the respiratory tract, urinary tract, our intestines, eyes and skin.
  • Vitamin A has protective characters against infections.
  • Vitamin A can prevent cancers like Bronchial cancer.
  • Promoting skeletal growth is yet another important function of Vitamin A.


There are 2 main sources of vitamin A in the nature and they are : animal and plant sources.
In Animal sources they are found as pre formed vitamin A or Retinol. The major animal sources are : liver, egg, butter, cheese, fish, meat and milk. All of us are familiar with the fish liver oil vitamin A supplements. In fact, they are the richest source of Retinol.

In Plant sources vitamin A is found as pro vitamins or Carotenes. The main plant sources include :
green leafy vegetable like spinach, papaya, pumpkin, mango, winter squash, sweet potato, peaches, carrot.


Bitot spot vitamin a deficiency
Bitot Spot
  1. Night blindness : The condition first manifests as inability to see in dim light.
  2. Drying up of the conjunctiva of the eyes, result in a condition called “Conjunctival Xerosis”.
  3. Bitot spots – triangular yellowish or pearly white spots on the conjunctiva,
  4. Loss of smoothness and shine of the cornea leading to drying up of the cornea,resulting in a condition called as “Corneal Xerosis”.
  5. Abnormal bursting of the cornea due to thinning and liquefaction resulting in a dangerous condition called “Keratomalacia”.
  6. Deficiency of vitamin A can lead to darkening and loss of smoothness of the skin surface, a condition called as Follicular Hyperkeratosis.
  7. Deficiency can also result in growth retardation and cause several morbidities in children.

Treatment and Prevention

It is clear that vitamin A deficiency can lead to dangerous eye diseases which can eventually cause blindness. In order to prevent this from happening, a strategy has been adopted that includes administering vitamin A to pre school and younger children. This strategy was first developed at the National Institute of Nutrition at Hyderabad, India and has since been adopted by many other countries.
The strategy includes giving a single massive dosage of 2 lakh vitamin A units orally every 6 months to pre-school children aged from 1 year to 6 years. One lakh vitamin A units are given to children aged between 6 months and one year.

Role of Vitamin A in treating Measles in children has been studied. The World Health Organization recommends to give 2 lakh units of Vitamin A (1 lakh for infants) to children suffering from Measles for two days. This should be done in all areas where Vitamin A deficiency is known to occur.

Recommended Daily intake of vitamin A is 600 micrograms for adults. Care must be taken while taking Vitamin A supplements. In case of persons with Diabetes or those suffering from Liver diseases, the supplements should be taken only under the direct supervision of a health care provider.

Vitamin A Toxicity

Excess intake of vitamin A is also dangerous. Supplements should be taken only after consulting your doctor in case you have any liver diseases. Liver enlargement, skin diseases, blurring of vision due to papillar oedema, anorexia are some of the common manifestations of vitamin A toxicity.

Hope you found this article informative.

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