From: Brian D Williams (talon57@well.com)
Date: Thu Dec 28 2000 - 09:34:02 MST
From: "Emlyn" <emlyn@one.net.au>
>My daughter (5 yo) just asked me a question which I can't answer
>(not the first time for that!). I thought someone on the list
>might be able to help.
>She knows a bit about bacteria. We've talked about cells & other
>little things too... I'm going to get my hands on a microscope
>ASAP.
>Anyway, I've told her about plaque in your mouth, and how it is
>bacteria chomping on your teeth, which are promoted by sugary
>foods. I could be wrong about that, I've just been pedalling the
>standard parent party line.
>Also, she knows that sugar is used as a preservative in foods,
>like jam.
The sugar is not primarily a preservative in this case
>Another piece; she interogated me recently about food rotting; why
>does it happen? I told her that bacteria eat it.
>So she has put these things together, and asks this question...
>If sugar is a preservative, and stops bacteria from eating food,
>why does it cause decay in teeth, which is due to promotion of
>bacteria?
>I'm stumped. Help!
The sugar is not really a preservative, but as someone already
explained it's properties as an osmotic in the thick jam would draw
the water out of the bacteria, killing them.
In your mouth the sugar is food for the bacteria, just as it is for
us, the waste product of the bacteria is an acid, which weakens
tooth enamel.
It is interesting to note that honey can last for many years
without going bad because of this same effect.
Brian
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