Vitamin A

pre formed-retinol

pro vitamin-beta carotene-some converted into retinol in intestinal mucosa

IU of vit A is equivalent to .3 microgram of retinol

1mcg retinol=1mcg of RE

1mcg of B-carotene=.167 mcg of RE

1mcg of other carotenoids=.084 mcg of RE

Functions:

-indispensable for normal vision-production of retinal pigments

-necessary for maintaining normal integrity & normal function of glandular & epithelial tissues

-supports growth, especially skeletal growth

-anti infective

-may protect against epithelial cell cancres like bronchial cancers

Sources:

-animal foods-halibut liver oil richest> cod liver oil

-plant foods-carrot>green leaves

-fortified foods-vanaspati,margarine,milk

Storage:

liver-retinol palmitate

well fed person-normal circumstances-reserves may last 6-9months

retinol binding protein-produced in liver-production decreases in deficiency

Deficiency:

-night blindness

-conjunctival xerosis

-bitot's spots-bilateral-triangular-foamy-in children deficiency-in older indicates earlier disease

-corneal xerosis- serious

-keratomalacia-liquefaction of cornea- rapid-most serious-medical emergency

Treatment:

-all early stages of xerophthalmia-2,00,000 IU-on 2 successive days

-all children of corneal ulcer should take vit A

Prophylaxis:

-NIN,Hyderabad-200,000 IU every 6 monthly in preschool kids(1-6yrs)

-100,000 IU to children of 6months-1yr

Recomended alllowance:

600 microgram for adult men/women/pregnancy/children>6yrs

950 microgram for lactating mother

350 for 0-12 minths

400 for 1-6yrs

Toxicity:

-nausea, vomiting,anorexia,sleep disorders, papillar edema