Vitamin A is an essential nutrient for all humans. It is a complex compound made up of several forms of the same vitamin. The major source of vitamin A is derived from food sources.
Vitamin a is an important nutrient for
- Bone growth
- Cell division and differentiation
- Development of the immune system
- Promotion of surface lining of the eyes, respiratory, urinary and intestinal tract.
These linings are important barriers to the prevention of bacteria entering the body
Sources of Vitamin A include:
- colored fruits and vegetables (carrots, sweet potatoes, spinach and cantaloupes)
- whole milk
- fortified food products (cereals)
- whole eggs
A healthy diet should consist of 3-5 servings of fruits and vegetables per day and includes dark green leafy vegetables, oranges or other lime products to provide sufficient beta-carotene and other carotenoids.
Vitamin A deficiency is uncommon in North America but common in areas of the world where the intake of animal meat, sea food, green leafy vegetables, eggs, and whole milk products is inadequate.
Any medical disorder that affects the absorption of fats via the intestines can cause vitamin A deficiency. Other causes of vitamin deficiency include surgery on the intestine or pancreas. Liver disorders can interfere with the storage of vitamin A.
The first early symptom of vitamin A deficiency is inability see at night (night blindness). The whites (sclera) and corneas of the eyes may become dry and itchy - a condition called xerophthalmia. Xerophthalmia is common disorder in children in tropical Africa and South America, where there is a severe deficiency of protein intake and malnutrition. When the condition is not treated, it often progresses and causes corneal ulcerations and blindness.
Vitamin A deficiency is a common cause of blindness in developing countries.
The diagnosis is based on clinical symptoms and a low levels the vitamin in the blood.
Supplements are highly recommended for individuals at risk for developing Vitamin A deficiency.