What is Vitamin A – Sources, Function & Deficiency

Vitamin A is a group of unsaturated organic compounds (retinol, retinoic acid, and some provitamin A) which is fat soluble and also Heat stable so it can’t destroy by cooking. Vitamin found in vegetable in form of carotene, Carotene also has known as provitamin A. Provitamin A convert in retinol in the mucosa of the small intestine. Provitamin A acts as an antioxidant vitamin because it destroys free radical present in our body. It has many functions such as growth and development, essential for normal vision and protects from epithelial cancer. It can also be made in a laboratory. This is also found in animal sources like meats, fish, poultry, milk and dairy products.

Sources of vitamin A

Found in both sources animals and plants. In animal sources, it found in form of retinol and in plant sources, it found in form of Beta-carotine.

Plant sources-

Dark green leafy vegetable, yellow and orange fruits vegetable esp. carrot, pumpkin, zucchini sweet potatoes and a green vegetable like broccoli and spinach, tomatoes, mango, apricots, peaches etc.

Animal sources-

The best sources of vit-A are Cod liver oil, Eggs, Fortified breakfast cereals, Butter, Fortified skim milk, Milk and dairy products, Meats and poultry.

Vit. A can also be made in laboratory.

Characteristics of vitamin A-

Vitamin A is a fat-soluble and heat stable vitamin, so it can’t be destroy by cooking. Our body can store vitamin A in the liver and our body use this for 6 to 9 month but body can not eliminate vitamin A in urine so it may reach a toxic level. This is necessary for our eye sight. It appears in the ratina of the eye in some components called retinoids.

Functions of vitamin A-

Vitamin A helps to maintains epithelial membranes, forms and maintain healthy teeth, skeletal and bone tissue. It is also known as retinol because it produce rhodopsin (pigment found in retina). Vitamin A is necessary for good vision, it prevents night blindness. Beta-carotene is an anti-oxidant.Antioxidants protect cells and remove free redicals. Vitamin A reduce the risk of cancer. facilitates RNA transcription. Vitamin A provide resistance from Infection.

Vitamin A deficiency disease-

  1. Night blindness-
    Night blindness is a condition making difficult to see in relatively low light and night. It’s first clinical symptom is the deficiency of Vitamin A.
  2. Bitot’s spot-
    Triangular, pearly white or yellowish, foamy spots on the conjunctiva.
  3. Conjunctival xerosis-
    Dryness of conjunctiva is the first clinical sign of Vitamin A deficiency.
  4. Corneal xerosis-
    It is a serious condition in it cornea becomes dryness of cornea.
  5. Keratomalacia-
    liquefication of cornea or exessive softening of cornea called keratomalacia.

Vitamin A Overdose

A fat-soluble vitamin so it can’t be eliminated by the kidney, it can store in fatty tissue. consuming a large amount of vitamin A can cause some health problems like- Hypervitaminosis A. Hypervitaminosis A may be acute or chronic.

Acute Hypervitaminosis A

Irritable Mood.
Abdominal pain.
Loss of appetite .
Visual disturbances.

Chronic Hypervitaminosis A

Mouth ulcers.
Respiratory infection.
Dizziness, confusion.
Loss of hair or alopecia.
Peeling, oily or itching skin.
Cracked skin or fingernails.
Cracked skin at the corners of the mouth.
Bone abnormalities and joint pain.

An excess intake during pregnancy can increase the risk of fetal abnormalities developing.

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