Vitamin A "Fat Soluble Vitamin " - Sources, RDA, Functions, Uses, Deficiency, Disadvantages.

Structure of Vit A

Various names of Vitamins-A
1    Retinol
2    Retinal
3    Retinol  Acid

Pro-Vitamins Form:

Pro Vitamins called carotenoid
They have different types depending on structure

• α Carotenoid, B carotenoids and carotenoids (Carotene)
• β -    Carotenoid is more common
• β -    Carotene makes two molecule of Vitamins-A while α and γ form only one molecule of Vitamins-A

In liver these carotene change in to Vitamins-A

Vitamins-A is a major component of carrot.
Basic Ring Structure (β-ionone) tri-methylecyclohexenyl ring

Sources:

• Richest sources is Fish (Fish liver oil specially big fish)
• other is egg yolk, butter, milk, 
• carrots, green yellow vegetables (carrot, tomatoes), 
• fruits (Mango)

RDA/RDI:   

900mcg/900 µg as in international unit
        Upper limit = 3000 mcg
        1iU = 0.3 micro gm of Retinol
Do µgm is to IU of Vitamins-A, wedevide it by 0.3
        900/0.3 = 3000 IU    or
        3000 * 0.3 = 900µg

Retinol Equivalent: (RE)

Micro grams of retinol can be called retinol equivalent
1µgm = 1RE

Functions of Vitamins-A:

1    Vitamins-A is very important for the formation of Glycolipid & Glycoprotein (Important for skin)
Vitamins-A deficiency can be decrease in mucus cells (secret mucces which moist skin or spithelium which is secreted by Globlet Cell which is made up of it Glycoprotein and then iti leads to Creatinized the skin (Creating hard protein) or skin become scaly or dry.
2    Vitamins-A is important for the visions and in vision it is important in vision in darkness.

HOW?

Retina contain 2 types of cells (1 Rods    2:Cones)
Rods contain a corrugated protein (combination) which is called Rhodospsin it contain ospin (protein) and Retinene (Vitamins-A form)  11csis retinal (isomeric aldehyde form of Vitamins-A present in retina)
When the light falls on Rhodopsin it break into Opsin and retinal. This retinal will be trans retinal by action of enzyme which convert 11 trans retinal.

This 11 trans retinal is converted in to aldehydic with two enzymes.
1:    RetineneReductase    2:    Retinal Dehydrogenase
In darkness, syntheses of Rhodopsin starts and if the Vitamins-A is not available the person become unable to see in the dim light. The disease called Nyctalopia (Night Blindness)

• Cones  containsIodopsin
• Vitamins-A is important for reproduction
• Formation of cilia (in lungs), is Vitamins-A is not available then cilia work and Keratinization occur increase suspectibility to infection.

Over/Upper intake Limit (UIL):   

10,000 IU x 032 = 3000mg

Adverse Effect:

1    if your take more quantity of Vitamins-A it cause liver abnormality
2    nausea / Vomitting
3    CSF pressure increase
4    Vertige
5    Blurred Vission
6    Muscular inoco-ordination
7    Fontana in Infants    (gap in the bones of cranium) this is anatomic features in infants seen as soft spots. It is a normal process ans can be developed in 3-4 months but if Vitamins-A
8    Vitamins-A is teratogenic:    (all those components are teratogenic which interface with normal development of embryo teratogenic effect.

Vitamins A Deficiency

1    Vitamins-A deficiency cause Xeropthalamia (xeros>dryness) dryness of eyes – xeropthalamia leas to bitots spots it own around the cornea of eye.
2. Vitamins-A Deficiency also called Xerosisos skin (dryness of skin)and Xerostomia (dry mouth)

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