Saturday, March 13, 2010

Vitamin A


Vitamin A

Vitamines

Vitamines are important chemical compounds. Vitamines do not have any nutritional value but they are required in minute quantity in the body for proper functioning of the body.improper quantiy of vitamines in the body leads to several defficences in the body.some vitamines are produced in the while other must be taken in the diet.vitamines are classified into two types

1. Fat soluble vitamines

2. Water soluble vitamines

Vitamin A

Vitamin A is a fat soluble vitamin.Vitamin A is also called retinol,retinoic acid and retinal.the precursor of the vitamin A is beta carotene.Beta carotene is converted into the vitamin A in the body.

Role/Functions of Vitamin A

1. Vision

Vitamin A has a great role in the vision.Vitmin A combines with the opsin(which is protein)and form an important compound called Rhodopsin which plays a vital role in yhe vision

2. Vitamin A is a part of certain co-enzymes

3. Vitamin A has an important role in the development of bones

4. Vitamin A has aslo a role in groth of the body

5. Vitamin A is very important in the good looking of the skin

6. Vitamin A has roles in gene expressing and cell defferentiation.

Source

Vitamin A is found in the carrots,fruits and fresh vegetables and cod liver oil

Defficiences of the Vitamin A

Malnutirtion of Vitamin A leads to several defficiences in the body

1. Night blindness

2. Xeropthalmia

3. Defficiency in growth and bone development

4. Keratinization of skin

5. Cell defferentiation and gene expression does not occur

Life Stage Group

Recommended Dietary Allowances (RDA)

Adequate Intakes (AI*)
μg/day

Upper Limit

μg/day

Infants

0–6 months
7–12 months


400*
500*


600
600

Children

1–3 years
4–8 years


300
400


600
900

Males

9–13 years
14–18 years
19 - >70 years


600
900
900


1700
2800
3000

Females

9–13 years
14–18 years
19 - >70 years


600
700
700


1700
2800
3000

Pregnancy

<19>50 years


750
770


2800
3000

Lactation

<19>50 years


1200
1300


2800
3000






















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