Vitamin A

Vitamin A

The proper chemical name of vitamin A is
retinol.It is found in food or animal origin. The orange pigment carotene,
familiar in carrots, and similar pigments called carotenes, are found widely in
plants and can be converted to vitamin A during digestion. Vitamin A is a pale
yellow primary alcohol derived from carotene. The structure of carotenes and
vitamin A is particularly well adapted for light absorption. Light brings about
a relativel large change in the structure of retinal, sufficient to trigger the
generation of a nerve impulse.

Principle Sources

Fish-liver oil
Liver
Milk and derivatives
Carrots
Spinach
Watercress
broccoli
squash
spinach, kale
sweet potatoes

Function

Controls normal epithelial structure and growth.
Used to make retinal, which is essential for the formation of the visual pigment rhodopsin.
Aids 'night vision'

Deficiency diseases and Symptoms

Skin becomes dry.

Cornea becomes dry

Mucous membranes degenerate.

Poor 'night vision'

Serious deficiency results in complete night blindness or Xerophthalmia

Permanent blindness or Keratomalacia may occur if the vitamin is not present
in the diet.

Excess Vitamin A?

Prolonged consumption of large amounts of vitamin pills can cause
certain matters. Some of the matters are listed below.

Bone damageHair lossDouble visioninterfere with growthstop menstruationHigh intakes (in excess of 3300micrograms per day) during pregnancy may
cause birth defectsdamage red blood corpusclescause skin rashes, headaches, nausea, and jaundice.

Right Amount you Should Take

Regular intakes should not exceed;

6000µg per day for adolescent

7500µg per day for adult women
9000µg per day for adult men