Beta carotene is a compound that
occurs naturally in carrots and gives this vegetable its orange
color. It was first isolated by Wackenroder in 1831 and its chemical
structure was explained by Karrer, who won the Nobel Prize for
it. Then, another scientist, named Steenbock, suggested that beta-carotene
is a pro-vitamin. A pro-vitamin is a compound that can be changed
by the human body to form a vitamin. Beta-carotene is a pro-vitamin
or precursor of Vitamin A, which is also known as retinol.
Vitamin A is known for three important functions. It is excellent
for maintaining good vision. It helps in bone and teeth development.
And it is effective in maintaining the youthfulness of the skin.
There is, however, another important function of vitamin A.
This vitamin can help the body build resistance against certain
types of cancer. Studies have revealed that among people who
are deficient in vitamin A, most of them suffer from lung cancer.
And many scientists tend to believe that it is the effect of
vitamin A which is responsible for the anti-cancer action of
beta-carotene.
The known sources of vitamin A are eggs, milk, spinach, sweet
potatoes, apricots, cantaloupe, and carrots. Since beta-carotene
is a precursor of vitamin A, cruciferous vegetables that are
rich in beta-carotene can also be considered as sources of vitamin
A. Some cruciferous vegetables are broccoli, cauliflower, brussels
sprouts and cabbage. Vitamin A can also be found in butter.
The margarine, a substitute for butter, is fortified with vitamin
A so that the margarine’s nutritional value will nearly be equal
to that of butter. Both beta-carotene and vitamin A are used
as food additives – as vitamin additive and as color additive.
Children who eat foods rich in vitamin A can store this vitamin
in their bodies for many years. As they grow older and develop
their bones, they use up some vitamin A. Thus it is important
for adults to replenish their stock of vitamin A in the body.
But for children who had less intake of vitamin A, they suffer
abnormal bone development. They have rough and dry skin. And
they experience night blindness, a blurring of vision that starts
at every dusk and this may eventually lead to a complete loss
of sight. They develop xerophthalmia, a condition in which the
cornea of the eye has dried.
However, too much vitamin A can be toxic. A vitamin A poisoning
is indicated by nausea, fatigue, and drowsiness. A person may
also feel pain in his bones, and may lose his hair. His skin
also becomes dry and scaly. Some adults will have blurred vision
and headache. While children become irritable. The children’s
growth becomes stunted and their livers will be abnormally large.
