Definition

Vitamin A deficiency exists when the chronic failure
to eat sufficient amounts of vitamin A or beta-carotene
results in levels of blood-serum vitamin A that are below
a defined range. Beta-carotene is a form of pre-vitamin
A, which is readily converted to vitamin A in the body.
Night blindness is the first symptom of vitamin A deficiency.
Prolonged and severe vitamin A deficiency can
produce total and irreversible blindness.

Description

Vitamin A (called retinol in mammals) is a fat-soluble
vitamin. The recommended dietary allowance (RDA)
for vitamin A is 1.0 mg/day for the adult man and 0.8
mg/day for the adult woman. Since beta-carotene is converted
to vitamin A in the body, the body