Vitamin A role in human life

Vitamin A is a fat soluble vitamin. Its chemical name is Retinol. It is also known as retinol because it produces the pigments in the retina of the eye.  It is well known for its important role in vision. Vitamin A is found in two primary forms: active Vitamin A or “pre-formed” Vitamin A and Pro-vitamin A or beta carotene.

Active Vitamin A is also called retinol and it comes from animal-derived foods such as meat, fish, beef, liver, eggs, shrimp, and fortified milk. Pro-vitamin A is found in plant-based foods  such as Orange and yellow vegetables and fruits. Other sources of beta-carotene are sweet potatoes, carrots, pumpkins, squash, spinach, mangoes, turnip greens, broccoli, and most dark green, leafy vegetables.

The more intense the color of a fruit or vegetable, the higher the beta-carotene content. Vegetable sources of beta-carotene are fat- and cholesterol-free.

Health benefits

Vitamin A promotes good vision, especially in low light. Vitamin A helps maintenance of healthy teeth, skeletal and soft tissue, mucus membranes, and skin.
It is also a powerful antioxidant and as an antioxidant, it helps building strong bones, regulating gene regulation, maintaining healthy clear skin, facilitating cell differentiation, and supporting immune function.
Vitamin A keeps the lines and wrinkles in your skin away by producing more collagen, which is responsible for keeping the skin looking young.
Vitamin A can also contribute to healthy hair.
Vitamin A eye drops are effective for the treatment of dry eyes.

Deficiency of vitamin A causes increased risk for eye problems like reversible night blindness and non-reversible corneal damage known as xerophthalmia. Lack of vitamin A also causes hyperkeratosis or dry, scaly skin.
Lack of vitamin A in children causes severe visual impairment and blindness;

Overconsumption of vitamin A can lead to lower bone density, jaundice, nausea, loss of appetite, irritability, vomiting, headaches, muscle and abdominal pain and weakness, drowsiness, altered mental status and even hair loss.
In chronic cases, it causes hair loss, dry skin, drying of the mucous membranes, fever, insomnia, fatigue, weight loss, bone fractures, anaemia, and diarrhoea.

The Food and Nutrition Board of the Institute of Medicine -- Dietary Reference Intakes (DRIs) Recommended Intakes of Vitamin A are,
Infants (average intake)
0 To 6 months: 400 micrograms per day (mcg/day),
7 to 12 months: 500 mcg/day
Children (Recommended Dietary Allowance RDA)
1 to 3 years: 300 mcg/day
4 to 8 years: 400 mcg/day
9 to 13 years: 600 mcg/day
Adolescents and Adults (RDA)
Males age 14 and older: 900 mcg/day
Females age 14 and older: 700 mcg/day (770 during pregnancy and 1,300 mcg during lactation)