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Vitamin A

The fat soluble vitamin A, as such is present only in foods of animal origin. However, its provitamins carotenes are found in plants. 

Sources 

  • Animal sources contain (preformed) vitamin A. The best sources are liver, kidney, egg yolk, milk, cheese, butter. Fish (cod or shark) liver oils are very rich in vitamin A. 
  • Vegetable sources contain the provitamin A-carotenes. Yellow and dark green vegetables and fruits are good sources of carotenes e.g. carrots, spinach, pumpkins, mango, papaya etc. 

Deficiency_ 

  • Night blindness (nyctalopia) is one of the earliest symptoms of vitamin A deficiency. The individuals have difficulty to see in dim light. 
  • Severe deficiency of vitamin A leads to xerophthalmia. This is characterized by dryness in conjunctiva and cornea, and keratinization of epithelial cells. 
  • In certain areas of conjunctiva, white triangular plaques known as Bitot's spots are seen. 
  • If xerophthalmia persisits for a long time, corneal ulceration and degeneration occur. This results in the destruction of cornea, a condition referred to as keratomalacia, causing total blindness. 




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