Vitamin A: Health Benefits, Sources, Risks and Features

 All about Vitamin A

In the previous article, the basic concept of vitamins has been discussed including their origin, characteristics, importance, classification, and various important physical situation related to vitamins. This article will be discussing vitamin A in detail.

Vitamin A

Chemical Introduction of Vitamin A: 

  • Vitamin A is chemically known as Retinol. 
  • Vitamin A is a compound made of carbon, hydrogen, and oxygen. 
  • The molecular symbol of vitamin A is [C20H30O]. 
  • It is unsaturated alcohol by nature. 
  • Retinol is also known as vitamin A1. 
  • A2 is another version of vitamin A. 
  • The molecular symbol of A2 is C20H28O. 
  • A1 and A2 have similarities but there are some differences too.  A2 has 6 bivalent bonds where A1 has 5 bivalent bonds of carbon. 
  • The unsaturation level of A2 is higher than A1 and vitamin A1 is more effective than A2.

Characteristics of Vitamin A

  • Vitamin A is soluble in fat and oil.
  • Vitamin A is also soluble in alcohol, Ether, Benjen, Chloroform, and Acetone.
  • The presence of Oxygen destroys Vitamin A. Though it stays intact for some time at 100°C along with oxygen.
  • Contact of light also destroys vitamin A.

Rich Sources of Vitamin A

Animal sources: Some rich sources of vitamin A in animal food are ghee, butter, whole milk, curd, egg yolk, and liver. Besides, there are cod, halibut, and shark liver oil which contain an ample amount of vitamin A.

The plant world also contains vitamin A in a huge amount. But in plants vitamin A stays as carotene which gets converted into retinol inside the human body. Carotene is the provitamin of vitamin A.

Carotene cannot be produced inside the human body. It was first discovered from Carrot which's why it was named after carrot as carotene. 

There are some variations of carotene - alpha, beta, gamma. Each variation produces a different amount of vitamin A. The process of synthesizing vitamin A from carotene takes place in the intestine and it gets stored in the liver.

Deep green and yellow vegetables are an excellent source of carotene. SpinachAmaranthus, coriander leaves, curry leaves among leafy vegetables and carrots, yellow pumpkin, ripe mango, papaya, and tomatoes among vegetables are valuable sources of carotene.

Besides, outer leaves of cabbage are greener than the inner ones and it contains more carotene. Green grasses are also rich sources of vitamin A that's why we get vitamin A from cow milk. 

Ghee made of cow milk contains more carotene than buffalo milk. Carotene creates the yellow colour of ghee. Red palm oil also contains enough amount of carotene.

Amount of Vitamin A in Some Food

(Microgram per 100 grams)

Food Items
Vitamin A

Fish liver oil

6000 - 100000

Liver (sheep, buffalo)

6000 - 10000 

Butter, Ghee

600 - 800

Egg, powder milk

300 - 500 

Amount of Carotene in Some Food

(Microgram per 100 grams)

Food Items
(per 100 grams)

Milk (Cow, Buffalo, human)

50 - 60

Red palm oil

25000 - 30000

Green Leafy Vegetables

1500 - 6000


1500 - 2000

Ripen mango and papaya

800 - 2000 

How much vitamin A do we need daily?

In Indian food, beta carotene is the main source of vitamin A. But the presence of fat has a great influence on the conversion of vitamin A from beta carotene and the absorption level of it into our body because vitamin A gets absorbed through the fat medium.

Generally, 25 to 50% of the beta carotene of food gets useful for our body. Mathematically, one mole of beta carotene produces o.25 moles of retinol. This means we need to consume beta carotene four times the amount of vitamin A required for the human body.

According to ICMR recommended daily food chart(1989) requirement of vitamin A is given below - 



Beta carotene

 Baby(0-12 months)

 350 mcg

 1200 mcg

 1 to 6 years

 400 mcg

 1600 mcg

 7 to adults

 600 mcg

 2400 mcg

 Pregnant woman

 600 mcg

 2400 mcg

 Maternity period

 950 mcg

 3800 mcg

Functions of vitamin A

  • Vitamin A contributes to a big portion of the growth and nutrition of the human body.
  • Vitamin A does the most significant work on the eyes. It is called anti-xerophthalmic vitamin as the retina fails to work properly in its absence.
  • The second most important function of vitamin A is keeping the epithelial tissue healthy. It keeps the epithelial tissue of the face, nose, throat, and lungs healthy and lessens the chances of getting diseases.
  • Vitamin A keeps the epithelial tissue of the mouth, stomach, and alimentary canal healthy and working. 
  • It supports the digestion process by helping the secretion of the digestive juice.
  • It helps to keep the skin bright, soft, and smooth.
  • Vitamin A also acts as an antiaging element for the skin.
  • It also protects the skin from various skin diseases.
  • Helps in structuring bones and teeth properly.
  • Keep the sweat glands functioning.
  • Helps to prevent stomach and breast cancer to a great extent.
  • Vitamin A is known as an anti-oxidant for its anti-oxidation properties.

Deficiency of Vitamin A

1. Problems of Eyes: 
  • Insufficiency of vitamin A affects the eyes in the very first place. 
  • Lacrimal glands get damaged. 
  • Nyctalopia happens due to the deficiency of vitamin A. 
  • Besides, there are Xeropthalmia, Bits spot, and Keratomalacia which also happens due to the scarcity of vitamin A. 
  • Keratomalacia is damage to the cornea. 
  • In Xeropthalmia, eyeballs become red, dry, and dim.

2. Damages of Epithelial tissue:
  • Skin becomes dry and rough. This is known as Xeroderma
  • The sebaceous gland and sweat gland get damaged. Skin pores get blocked by keratin. As a result, skin becomes extremely rough, full of patches and papules shaped like domes. Skin becomes toad-like. This disease is called phrynoderma.
  • The alimentary canal gets drier and the secretion of digestive juice decreases which causes indigestion and anorexia
  • Epithelial tissue of the respiratory system gets damaged as a result natural immunity power decreases and chances of getting various diseases increases.
3. Because of the disruption of the epithelial tissue, various parts of the body get exposed to different diseases.
4. The bone of the skull and spinal cord get increased in some places which cause damage to the nervous system.
5. The deficiency of vitamin A hampers growth.
6. Insufficiency of vitamin A affects the proper growth and development of teeth.
7. Vitamin A also has an influence on reproduction. Infertility can be a result of the deficiency of vitamin A.

Hypervitaminosis of vitamin A:

When we consume more vitamin A than the needed amount the excess vitamin A gets stored in the liver which further helps the body in the future. But when this situation happens regularly for a longer time it converts into hypervitaminosis and various symptoms of vitamin A toxicity start showing up. Such as - 
  • Scaly and rough skin.
  • Bones get prone to break.
  • The growth of bone and teeth get affected.
  • Vitamin K fails to do its work of clotting the blood.
  • headache, vomiting tendency.
  • Sleepiness.
  • Rude mentality.
  • Weight loss etc.

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