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Hello. My name is Susan
Fairweather-Tait.
I'm Professor of Human Nutrition
at the Norwich Medical School in
the University of East
Anglia in the UK.
Today, I'm going to
talk to you about iron.
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Iron exists in two stable
interchangeable forms.
Ferrous iron which is Fe^2+
and ferric iron Fe^3+.
It has redox reactivity
and is part of
the electron transport chain
which is required for
energy production.
It's mainly present in red blood
cell haemoglobin
where its role is
to transport oxygen and it's at
the centre of the
haemoglobin molecule.
It's also present
in muscle myoglobin
where it provides
short-term oxygen storage.
Oxygen is taken up
from the lungs,
transported in the blood,
and released to
the tissue cells.
It is also a component of
various tissue enzymes such
as the cytochromes which are
required for energy
production and
enzymes needed for the
functioning of the immune system.
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Iron is present in
a lot of foods.
The rich food sources
include meat,
fish, cereals, beans,
nuts, egg yolks,
dark green vegetables, potatoes,
and fortified food
products where
the manufacturers add iron
and declare it on the label.
The iron content
of these foods is
quite high but it isn't
necessarily well absorbed.
I'll go on to explain to you
about iron bioavailability
in a minute.
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Iron is present in the diet as
three different forms,
mainly as non-haem iron.
That's the natural form
that's found in foods.
Also as iron fortification
which is the added iron
and a small amount
of contaminant iron
which is rust, for example.
90% of our diet will
be non-haem iron.
About 10% will be
haem iron which is
found in meat and fish.
But of course, omnivores
would take haem iron,
but vegetarians won't,
of course, have
any haem iron because they
don't eat meat and fish.
There's a very small
amount of iron present as
ferritin which is found in
beans and animal
ferritin in liver.
The absorption of haem and
non-haem iron is carried out by
two separate pathways which
I'll explain in a minute.
But the proposed mechanism of
ferritin isn't well known,
but they think it's endocytosis.
