Vitamin a
Vitamin A is an essential human nutrient. Its important part is the retinol group, which can be found not in a single compound, but in several forms. In foods of animal origin, the major form of vitamin A is an alcohol (retinol), but can also exist as an aldehyde, or as an acid (retinoic acid). Precursors to the vitamin (provitamins) are present in foods of plant origin as some of the members of the carotenoid family of compounds.
All forms of vitamin A have a Beta-ionone ring to which an isoprenoid chain is attached. This structure is essential for vitamin activity.The orange pigment of carrot - Beta-carotene - can be represented as two connected retinyl groups.
Retinyl group, being attached to a protein, is the only primary light absorber in visual perception, and the compound name is related to retina of eye.
Vitamin A may be found in various forms:
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retinol, the animal form of vitamin A, is a yellow, fat-soluble, vitamin with importance in vision and bone growth. Since the alcohol form is unstable, the vitamin is usually produced and administered in a form of retinyl acetate or palmitate.
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other retinoids, a class of chemical compounds that are related chemically to vitamin A, are used in medicine.
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Foods high vitamin A
apricots
eggs
pumpkin
liver
collard greens
carrots
sweet potatoes
papaya
broccoli
mango
peas
Broccoli leaves
spinach
butter
leafy vegetables
apple source vitamin c
banana rich vitamin b1
graves rich vitamin c
oranges rich vitamin c