Many
Eastern cultures, and perhaps some Western cultures, believed
that a baby should be exposed to the sun so that the baby will
develop strong bones. This belief is now backed by science.
What actually happens is that the sun’s ultraviolet rays activate
a certain substance in the skin. This substance is a precursor
of vitamin D. Once vitamin D is formed, it helps the body absorb
all the calcium it needs for forming and strengthening the bones,
the cartilage, and the teeth. In an indirect way, vitamin D
or calciferol helps a person have strong bones and teeth.
However,
not everyone can use sunlight in forming the needed vitamin
D. Some people live in places (such as North Pole) where there
is no sun for quite a long period. And some people live in places
(such as Gobi desert) where the rays of the sun are dangerous,
even in the early morning. Luckily, there are other sources
of vitamin D, such as fishes and egg yolks. Milk, which is often
described as a complete food, usually does not have vitamin
D. But to make milk a true complete food, some manufacturers
fortify their milk and other dairy products with vitamin D.
A lack
of vitamin D leads to imbalances in the biochemical and physiological
make-up of the human body. The formation and mineralization
of bones and teeth go awry. As a result, children suffer from
rickets while adults develop osteomalacia.
To detect
early the presence of rickets in a child, a parent must look
for known symptoms such as restlessness, profuse sweating and
lack of muscle tone. The child or baby will take a long time
before he or she learns to sit, crawl or walk. A child with
rickets may have bowlegs or knock-knees. It was through the
study of rickets that Edward Mellanby discovered vitamin D in
1922.
Osteomalacia
is a condition in which the bones of adults are progressively
losing the calcium mineral. Aside from this disease, a person
who lacks vitamin D may also suffer osteoporosis. This disease
will make the bones of a person prone to fracture.
Since vitamin
D is fat soluble, it is a vitamin that can be stored by the
body. It implies that vitamin D should not be ingested in large
doses. When there is too much of it, vitamin D becomes toxic.
It will make a person lose his appetite and his weight. He will
experience nausea, vomiting, and a general weakness. And he
will suffer diarrhea.
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