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Hello. My name's Susan
Fairweather-Tait.
I'm a 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 riboflavin,
which is also known
as vitamin B2.
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Riboflavin is the
integral part of
the coenzymes flavin
adenine dinucleotide, FAD,
and flavin mononucleotide, FMN.
These two act as
proton carriers in
redox reactions involved in
energy metabolism and
metabolic pathways.
They're involved
in carbohydrate,
lipid, and protein metabolism,
in electron transport in
the respiratory chain,
in the metabolism of
drugs and toxins,
working together with
cytochrome P450,
and they have
antioxidant functions
involved in
glutathione reductase,
glutathione peroxidase,
and xanthine oxidase.
FAD is required as a cofactor
for methylenetetrahydrofolate
reductase,
which is a key enzyme
in the folate cycle.
FAD is also required
for the formation of
5-methyltetrahydrofolate,
which is involved
in the remethylation of
homocysteine to methionine.
Riboflavin is also involved in
the metabolism of
niacin and vitamin B6.
So you can see riboflavin has
a wide range of metabolic
functions within the body.
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The main food sources
of riboflavin are milk,
milk products, eggs, and offal.
It's not found in many foods,
so it's not widely
distributed in the diet.
More than 90% of dietary
riboflavin is in
the form of FAD or FMN,
and the remaining
10% is comprised of
the free form of riboflavin
and glycosides or esters.
Riboflavin is destroyed
when exposed to light.
So milk in glass
bottles on the doorstep
there won't be much riboflavin
by the end of the day.
It's also water-soluble,
so there will be losses
when cooking in water.
