Vitamin A: Sources, uses and deficiency

    Vitamin A: Sorces, Uses and deficiency

Vitamin A is a fat soluble vitamin means it requires fat for its absorption and storage in the body. It plays several important roles in the body and is essential for normal growth and development.

Uses of Vitamin A:
Vitamin A plays an important role in vision specially the dim light vision. It is important for growth, reproduction and maintenance of healthy skin, bones and other body tissues. It is an anti oxidant.

Sources of Vitamin A:
Vitamin A is present in our diet in two forms

1. ) Preformed Vitamin A in the form of retinol which is present in animal sources
2. ) Pro vitamin A in the form of beta carotenoids which is present in plant sources.

Foods rich in vitamin A include;

• Cod liver oil
• Liver
• Egg yolk
• Ghee and other dairy products
• Carrots
• Sweet potatoes
• Pumpkin

Yellow orange fruits and vegetables are rich in Vitamin A.
Dark green leafy vegetables are also good sources.

Daily requirements of vitamin A for different age groups:

• 0-6 months : 400 mcg (1333 IU/day)
• 6-12 months : 500 mcg (1666 IU/day)
• 1-3 years : 300 mcg (1000 IU/day)
• 3-8 years : 400 mcg (1333 IU/day)
• 8-13 years : 600 mcg (2000 IU/day)
• 13-18 years : 900 mcg (3000 IU/day)
• Adult males : 900 mcg (3000 IU/day)
• Adult females : 700 mcg (2330 IU/day)
• >18years pregnant women : 750-770 mcg       (2500-2600 IU/day)
• >18years lactating mother's : 1300 mcg   (4330 IU/day)

Deficiency of Vitamin A:
According to WHO, around 2.5 lakh- 5lakh vitamin A deficient children become blind each year and about half of them die within 12 months of loosing their sight.
Vitamin A deficiency in pregnant women causes night blindness and may increase the risk of maternal death.

 Vitamin A deficiency occurs mostly in; 

1) malnourished children,

2) adults due to poor food intake,

3) chronic diarrhoea (prolonged loose     motions), 

4) malabsorption,

5) when there is an increased demand like during pregnancy and lactation,

 6) when nutrition is totally provided     through the blood (parenteral nutrition), 

7) chronic alcoholism and smoking,

8) zinc deficiency

Signs and Symptoms:

• Effect on Eye-

1. ) Night blindness: It is the earliest symptom of Vitamin A deficiency. The person is unable to see properly in dim light.
2. ) If the deficiency persists, night blindness progresses to xerophthalmia. It is the dryness of conjunctivae of the eyes. Eyes become smoky, further they become dull and hazy. These changes occur because the tear glands (lacrimal glands) and mucous secreting epithelium is replaced by keratinized epithelium.
3. ) Bitot's Spots : If the deficiency persists then triangular glistening white spots are formed near the angle of eye lateral to cornea.
4. ) Keratomalacia : persistent deficiency leads to corneal scarring and ulceration.

Vitamin A deficiency should be treated as early as possible otherwise it may soon lead to blindness.

Other body effects of deficiency of Vitamin A are:

• Dry and thick skin
• Frequent and serious infections of the eyes, lungs, urinary tract and other parts of the body.
• Poor wound healing
• Delayed growth

Treatment:

Prevention is always better than cure. A diet rich in Vitamin A should be given to children and pregnant and lactating mothers.

When vitamin A deficiency is diagnosed, vitamin A doses are started immediately by the doctor.

Note:
Over doses of vitamin A should be avoided as it may lead to hypervitaminosis or toxicity.


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