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A child's body uses
calcium to constantly build and rebuild bones, teeth
and nails. As a young child grows into a teenager and
then an adult, thier body needs even more calcium so
it can make thier bones bigger and stronger -- that's
why they grow physically.
Your child's body needs a bit
of calcium that circulates around inside to help parts
of the body function. Nerves, organs, and certain tissues
all rely on calcium to help make them work.
Some
studies:
Physician scientists
do experiments to answer questions of whether or not
Calcium makes bones stronger. There are several kinds
of experiments used to answer these questions. One experiment
is called a randomized double-blind clinical trial.
A sample of people (in this case, children and teenagers)
are divided into two groups. The larger the number of
people, the more definite the results of the study.
All kids in one group take a pill that has calcium in
it; while kids in the other group take a placebo. Neither
the kids nor the doctors doing the study know which
person is taking the calcium and which one is taking
the placebo. Only a statistician knows which kids are
taking the calcium.
At the beginning
of the study all the kids have a measurement done of
their bone strength called bone density. Then during
the study they are asked to take thier pills. Believe
it or not, this study can last for several years. At
the end of the study everyone has another measurement
of the bone density. When, and only when, the experiement
is done the statistician tells informs everyone involved
in the study who was taking the real calcium and who
was taking the placebo. They can tell if the average
bone density was better in the group taking calcium
than in the group taking placebo.
This graph shows
the results of several such studies of calcium in young
people. Each bar on the graph is a different study,
and the height of the bar represents how much better
the bone density was (% increase since beginning of
study) in the calcium group than in the placebo group.
You can see that all of the studies found that the bone
density in the calcium group was better than the placebo
group.
The best study (the first bar
on the graph) was done by a doctor named Conrad Johnston,
from Indiana. His team studied 140 kids aged 6 to 14.
This study was really clever, because all of the kids
were identical twins. One twin got the calcium pill
and the other twin got the placebo. After three years
the bone density was better in the twins taking the
calcium. The reason this was such a good study is that
the groups had exactly the same age, and almost exactly
the same height and weight, because the kids were identical
twins. Another indication that it was a good study is
that the National Institutes of Health paid for the
study, and not the company which makes the calcium pills.
These results are then published
in medical journals so doctors can read all the details
of the study. Of course, the best studies are published
in the best journals. The summaries of the studies are
now available to anyone on-line through the National
Library of Medicine. Click on the link if you want to
read the summary of Dr. Johnston's study. To read the
entire study you would have to go to a medical library
to find the journal.
More information
Here are some links to more information about calcium:
1) Calcium
recommendations, the 1999 recommendations from the National
Academy of Science. Extremely detailed information!
2) U.S. Department of Agriculture, a data-base that
has composition of foods, including the amount of calcium.
Some of the information on these
calcium pages was taken from the "Calcium, Do you
get it?" program that was prepared by the U.S.
Food and Drug Administration.
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