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.
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