Definition - Vitamins are organic substances that are required in small amount in diet for optimum health and growth.
They are usually not synthesised by humans, hence must be obtained through diet.
Classification of Vitamins
Vitamins are classified based on their solubility as fat soluble and water soluble .
Vitamins are grouped into 2 groups:
I.) Fat soluble vitamins: These are vitamins A, D, E and K.
II.) Water soluble vitamins: These are vitamin B complex group and vitamin C.
FAT SOLUBLE VITAMINS
Vitamin A
Three forms of vitamin A is - Retinal
Retinol
Retinoic acid
Fat soluble vitamin A is available in two forms for human needs. retinol in animal foods and as b-carotene in plant foods.
Function of Vitamin A
1) Formation of rod cells during the dim light.
2) responsible for normal function of grandular and epithelial tissue which lines intestinal respiratory as well as skin and eyes.
3) It supports skeleton growth.
4) It is anti - infective or it may protect against cancer.
Sources:-
Animal origin :- Milk ,meat,fish ,egg,liver.
Plant origin:- green vegetables, mango,papaya,carrot.
RDA of vitamin A - The Recommended Dietary Allowance (RDA) for men and women is 900 and 700 μg retinol activity equivalents (RAE)/day, respectively.
Vitamin A deficiency
1) Night blindness
Lack of vitamin A first causes night blindness.
It is inability to see in dim light.
It is due to impairment in dark adaptation.
2) Conjuctival xerosis
It is the first sign of Vitamin A deficiency.
The conjunctive becomes dry and non -wettable.
It becomes muddy & wrinkled(instead of smooth and shiny.
3) Bitot's spot's
are triangular ,pearly -white or yellowish ,foamy spots on the conjunctiva.
4 ) Corneal xerosis
The cornea becomes dull, dry and non - wettable.this stage is very serious.
In more severe deficiency there may be Corneal ulceration.
5) Keratomalacia
It is Liquification of cornea.
This is an medical emergency.
The cornea may become soft ,and may brust open.
THANKYOU 😊
