| 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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