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Hello. My name is Susan
Fairweather-Tait.
I'm professor of
Human Nutrition in
the Norwich Medical School at
the University of East
Anglia in the UK.
I'm going to be talking
to you about fluoride.
0:15
Fluoride has no known
essential function
in human growth and development.
It's mainly associating
in the body
with calcified tissue that's
bones and teeth and it's found
as calcium fluorapatite.
It's been known for more
than 100 years that
it's useful in the control of
dental caries development.
Apart from incorporating
fluoride into
forming enamel of
teeth before eruption,
dietary fluoride will exert
an anti-caries effect on
erupted teeth and
this happens through
contact with enamel
during ingestion,
excretion into saliva,
and uptake into
biofilms on teeth.
This is the mechanism
whereby fluoridated
toothpaste works.
In bones, the partial
substitution of
fluoride for hydroxyl
groups of apatite alters
the mineral structure of the
bone and this results in
increased density
and hardness of
the bone but it doesn't affect
the mechanical strength.
In fact, no
associations have been
found between serum
fluoride concentrations
which reflect intake and
bone mineral density
or osteoporotic fractures.
In other words, it may
make the bones harder but
it doesn't actually stop
the fractures occurring.
1:26
The major food
sources of fluoride
are water and
water-based beverages,
particularly from high
fluoride water and foods
reconstituted with
fluoridated water
or using fluoridated salt.
These examples would be
soup or infant formulae.
The levels can be very high in
fish products that
contain bones.
If you eat the bones
which are soft
such as in canned
salmon and sardines,
you'll get fluoride and
also tea contains quite
a lot of fluoride.
Now in a number of countries,
water fluoridation
is carried out
and this is because the
water is naturally low
in fluoride and it's known
to help with dental
caries prevention.
That's the reason
for doing this.
The optimal
concentration they're
aiming for in drinking water
is in the range of 0.5-1
milligrams per liter.
You can see the maps of
the world showing the probability
of naturally occurring
fluoride in
groundwater exceeding
the WHO drinking water
guideline which is
1.5 milligrams per liter and
the green areas showing
there's very low probability.
As you go up to
yellow and orange
and red and pink, the
probability increases.
You can see there are
some countries where for
example Western US and Mexico,
South America, South
Africa and South Asia,
there are very high
probability of
fluoride being very high
levels in the groundwater.
But the map shows
quite nicely that it's
a very varied distribution
across the world and
also within countries,
which means that
water fluoridation
has to be carried out
at a very local level.
In the world probably
the highest area of
