Vitamin A, Function, Sources, Requirement, Deficiency & Diseases, Excess

Vitamin A is essential for normal growth and development. It is also known as retinol. It has given this name due to its role in the formation of pigment of the retina. The retina is the innermost layer present in the eyeball on which visual image is formed. Vitamin A exists in both pure and pro form. When you take the pro form of vitamin A, It converts into Vitamin A inside the body.

Functions of Vitamin A

Vitamin A has a major role in vision. It is essential for the proper functioning of the retina. Moreover, vitamin A promotes the growth of hair, teeth and skin. It boosts immunity and protects from infectious diseases. Moreover, it has also a role in the proper functioning of the reproductive system.

Sources of Vitamin A.

Vitamin A is mainly found in the following substances.
Dark green leafy vegetables e.g, spinach, pumpkins, Lettuce, Carrots are rich in beta-carotene which is a pro-vitamin A substance and It converts into vitamin A inside the body. Sweet potatoes, yellow coloured ripe yellow fruits e.g, orange, apricot and grapes are also rich sources of preformed and pro-vitamin A. Meat, fish liver oil, poultry and dairy products also are the rich sources of vitamin A.

Daily Requirement of Vitamin A.

Adults need 700 – 900 micrograms of vitamin A per day. Children need 300 – 600 micrograms per day and infants need 400-500 micrograms of vitamin A per day.

Deficiency of Vitamin A and the diseases.

As vitamin A is required for vision, growth, immunity, skin, hair and reproductive health, therefore, its deficiency results in vision problems (night blindness), skin diseases (hyperkeratosis), hair loss, and vulnerability to infections.

Excess or overdose of Vitamin A.

Excess of an overdose of vitamin A cause headache, dizziness, nausea and vomiting, in short words it makes you sick. Usually, overdose means taking more than 25,000 international units of vitamin A per day for one to two weeks. This is a large amount and usually, we don’t get an overdose of vitamin A by taking normal foods. Overdose occurs in those who are taking vitamin A rich supplements, or by accidental ingestion of vitamin A tablets by children.