In the United States, nine million tons of
sugar are sold each year. Most of it is used to
prepare foods sold in supermarkets. Every-
one knows sugar is added to jellies, syrups,
soft drinks, cookies, and ice cream. You may
be surprised to learn that some foods that
do not even taste sweet have sugar added to
them. For instance, sugar is added to bacon,
bread, ketchup, and hamburger buns.
Cavities are one of the biggest problems
caused by sugar. The bacteria that naturally
live on your teeth get together with the food
you eat to cause cavities. Every time you eat,
some bits of food stick to your teeth. The
bacteria feast on these bits and produce acid.
This acid slowly eats away the hard enamel
that covers your teeth. When the acid has
worn a hole in a tooth, you have a cavity.
Acid + Tooth Enamel = Cavities
Sugar is the only food the bacteria can
use. All sugars can cause cavities. A sub-
stance in your saliva can change starch into
a type of sugar. Therefore, starch also can
cause cavities, but not as easily as sugar can.
Whether or not you might get cavities
depends on the answers to these questions.
• How much sugar and starch do you
eat? If you eat lots of these (and
they are not removed from your
teeth), the bacteria in your mouth
have plenty of food and can make
large amounts of acid.
• How often do you eat sugar and
starch? If you eat them often, the
bacteria have many chances to make
acid. Suppose you had 10 gumdrops.
You could eat them all at once
or one every 20 minutes. By eating
one every 20 minutes, the sticky candy
is on your teeth more often than if you
ate them all at once. The more often
you eat sugar and starch, the more
likely you are to have cavities.
• How sticky are the sugar and
starch you eat? Soft or chewy foods
that stick to your teeth are more
likely to cause cavities than liquid or
crunchy foods. That is because soft,
sticky foods such as taffy and jelly
beans stick to your teeth. They give
bacteria more time to make acid than
sugary liquids and crunchy foods
such as popcorn. Sugary liquids, like
soft drinks, pass through the mouth
quickly. Crunchy foods do not stick
to your teeth. These foods give the
bacteria less time to form acid.
• How often do you brush and floss
your teeth? Bacteria are removed
when you brush and floss your teeth.
If you brush and floss often, the
bacteria you remove have less time
to make acid. Plus, fewer bacteria
remain in your mouth. Less time and
fewer bacteria mean less acid, and less
acid means fewer cavities.
An experiment with an eggshell and
vinegar can show you how cavities form.
Eggshells are made of some of the same
substances as teeth. Vinegar is an acid
like that produced by the bacteria on your
teeth. Place an eggshell in a cup. Then, pour
vinegar into the cup until the eggshell is
covered. Cover the cup with plastic wrap.
After three days, check the eggshell. How
does it feel? What happens to teeth when
they are exposed to acid?
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Chapter 3 Your Nutrition Toolbox 53
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