Vitamin a

Definition

noun

(biochemistry) A fat-soluble vitamin found in liver, orange, ripe yellow fruits, leafy vegetables, carrots, pumpkin, squash, spinach, fish, soya milk, milk, etc. and is essential for the protection of epithelium and the prevention of night blindness


Supplement

Vitamins are essential for normal growth and metabolic processes. One of them is vitamin A. Vitamin A is a fat-soluble organic compound that helps protect the epithelium and prevents night blindness. It can be obtained from liver, orange, ripe yellow fruits, leafy vegetables, carrots, pumpkin, squash, spinach, fish, soya milk, milk, etc. The recommended dietary allowance in males aged 19-70 is 900 µg.1 In females of the same age group, it is 700 µg. Inadequate amount of vitamin A in the diet may eventually lead to night blindness, hyperkeratosis, and keratomalacia.2 Overdosage of vitamin A may lead to hypervitaminosis A.

Vitamin A may occur in different forms such as retinol or vitamin A1 and dehydroretinol or vitamin A2. The formula of retinol is C20H30O whereas the formula of dehydroretinol is C20H28O. Both of them have a beta-ionone ring where an isoprenoid chain is attached.


See also:

Reference(s):
1 Dietary Reference Intakes: Vitamins. The National Academies, 2001.
1 Vitamin and Mineral Supplement Fact Sheets Vitamin A. Dietary-supplements.info.nih.gov (5 June 2013). Retrieved from [[1]]

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