Artificial sweeteners
Posted: Mon Sep 20, 2004 3:56 am
Does anyone find that their symptoms get worse after ingesting the
artificial sweetener Aspartame?
It is widely known that caffeine makes RLS worse, but I think there is
a theoretical reason why just the Aspartame - as found in Diet Coke,
Diet Pepsi, Equal, NutraSweet etc. - would contribute to the RLS
problem.
Aspartame is a widely used artificial sweetener - a billion dollar industry
according to some sources. It is composed of two amino acids -
Aspartic Acid and Phenylalanine - plus a small methyl group:
http://www.chm.bris.ac.uk/motm/aspartam ... tameh.html
Aspartame breaks down quickly and goes into the bloodstream as these
two amino acids. Normally, humans eat proteins which contain these
amino acids and many or all of the 18 others. There is no precedent in
Nature for a "food" which gives us just one or both these amino acids.
Amino acid levels in the blood fluctuate hour-by-hour according to what
has been recently ingested. There is are several transport systems which
take amino acids through the blood-brain barrier into the brain, and
presumably the spine and Cerebro-Spinal Fluid (CSF) as well.
The brain is carefully protected from most things in the blood, and there is
a specific transport system (which is still not properly understood) for a
subset of amino acids called the "Large Neutral Amino Acids" - LNAA. The
main amino acids of interest which use this LNAA Transporter are
Tryptophan, Tyrosine and Phenylalanine. This transporter system has a
limited capacity, and the amino acids compete with each other to be
carried into the brain (and presumably the spine and CSF). If all three are
present at the same concentration in the blood, they are all transported at
about the same rate. But if there is a lot more of one, then this will
diminish the quantities of the others which are carried into the brain.
It is well known that Tryptophan levels in the brain have a direct affect on
the ability of neurons to produce the neurotransmitter Serotonin, because
Tryptophan is converted into 5-HTP and then 5-HTP is converted to
Serotonin in the neurons which need Serotonin. (Consequently Selective
Serotonin Re-uptake Inhibitor drugs like Prozac are used to make the
most of the limited quantity of Serotonin in patients with depression, and
supplements of Tryptophan, or 5-HTP, can be used to help the neurons
produce more Serotonin.)
Most RLS drug treatments (which, I understand, all have various
problems) involve drugs which make the most use of available Dopamine.
So clearly RLS involves some problem in neurons which produce or sense
Dopamine as a neurotransmitter.
Neurons which produce Dopamine must take in Tyrosine from the fluid
between the cells. This is converted with an iron-dependent enzyme into
DOPA, which is then converted with another generally reliable enzyme
into Dopamine.
It seems to me that if RLS involves, to some extent, difficulties in
producing enough Dopamine, then a cause could be lower than ideal
levels of Tyrosine in the brain (and probably the spine and CSF).
We would expect that eating or drinking Aspartame (Diet Coke etc. etc.)
would lower Tyrosine levels in the brain, due to Aspartame being digested
into high levels of Phenylalanine which reduces the amount of Tyrosine
which is carried into the brain by the LNAA transporter.
So people with RLS and/or Depression have good theoretical reasons not
to drink or eat Aspartame!
The test of this theory would be to drink Aspartame sweetened
non-caffeinated drinks for a few days to see if this makes RLS worse.
Alternatively, if an RLS suffer usually drinks or eats Aspartame, then to cut
it out entirely, and see if this improves their condition.
Googling Aspartame leads to all sorts of critiques, not least:
http://www.holisticmed.com/aspartame/
I haven't considered all the other arguments against Aspartame, but it
seems clear that it would reduce Tyrosine levels in the brain, and so
presumably the spinal cord and CSF.
The material at:
http://www.holisticmed.com/aspartame/aspart.p11
on amino acid digestion and transport into the brain seems correct to me,
based on what I have been reading in various neuroscience books and
papers. However, as far as I know, the exact nature of the LNAA
transport mechanism has not been discovered.
- Robin rw@firstpr.com.au
artificial sweetener Aspartame?
It is widely known that caffeine makes RLS worse, but I think there is
a theoretical reason why just the Aspartame - as found in Diet Coke,
Diet Pepsi, Equal, NutraSweet etc. - would contribute to the RLS
problem.
Aspartame is a widely used artificial sweetener - a billion dollar industry
according to some sources. It is composed of two amino acids -
Aspartic Acid and Phenylalanine - plus a small methyl group:
http://www.chm.bris.ac.uk/motm/aspartam ... tameh.html
Aspartame breaks down quickly and goes into the bloodstream as these
two amino acids. Normally, humans eat proteins which contain these
amino acids and many or all of the 18 others. There is no precedent in
Nature for a "food" which gives us just one or both these amino acids.
Amino acid levels in the blood fluctuate hour-by-hour according to what
has been recently ingested. There is are several transport systems which
take amino acids through the blood-brain barrier into the brain, and
presumably the spine and Cerebro-Spinal Fluid (CSF) as well.
The brain is carefully protected from most things in the blood, and there is
a specific transport system (which is still not properly understood) for a
subset of amino acids called the "Large Neutral Amino Acids" - LNAA. The
main amino acids of interest which use this LNAA Transporter are
Tryptophan, Tyrosine and Phenylalanine. This transporter system has a
limited capacity, and the amino acids compete with each other to be
carried into the brain (and presumably the spine and CSF). If all three are
present at the same concentration in the blood, they are all transported at
about the same rate. But if there is a lot more of one, then this will
diminish the quantities of the others which are carried into the brain.
It is well known that Tryptophan levels in the brain have a direct affect on
the ability of neurons to produce the neurotransmitter Serotonin, because
Tryptophan is converted into 5-HTP and then 5-HTP is converted to
Serotonin in the neurons which need Serotonin. (Consequently Selective
Serotonin Re-uptake Inhibitor drugs like Prozac are used to make the
most of the limited quantity of Serotonin in patients with depression, and
supplements of Tryptophan, or 5-HTP, can be used to help the neurons
produce more Serotonin.)
Most RLS drug treatments (which, I understand, all have various
problems) involve drugs which make the most use of available Dopamine.
So clearly RLS involves some problem in neurons which produce or sense
Dopamine as a neurotransmitter.
Neurons which produce Dopamine must take in Tyrosine from the fluid
between the cells. This is converted with an iron-dependent enzyme into
DOPA, which is then converted with another generally reliable enzyme
into Dopamine.
It seems to me that if RLS involves, to some extent, difficulties in
producing enough Dopamine, then a cause could be lower than ideal
levels of Tyrosine in the brain (and probably the spine and CSF).
We would expect that eating or drinking Aspartame (Diet Coke etc. etc.)
would lower Tyrosine levels in the brain, due to Aspartame being digested
into high levels of Phenylalanine which reduces the amount of Tyrosine
which is carried into the brain by the LNAA transporter.
So people with RLS and/or Depression have good theoretical reasons not
to drink or eat Aspartame!
The test of this theory would be to drink Aspartame sweetened
non-caffeinated drinks for a few days to see if this makes RLS worse.
Alternatively, if an RLS suffer usually drinks or eats Aspartame, then to cut
it out entirely, and see if this improves their condition.
Googling Aspartame leads to all sorts of critiques, not least:
http://www.holisticmed.com/aspartame/
I haven't considered all the other arguments against Aspartame, but it
seems clear that it would reduce Tyrosine levels in the brain, and so
presumably the spinal cord and CSF.
The material at:
http://www.holisticmed.com/aspartame/aspart.p11
on amino acid digestion and transport into the brain seems correct to me,
based on what I have been reading in various neuroscience books and
papers. However, as far as I know, the exact nature of the LNAA
transport mechanism has not been discovered.
- Robin rw@firstpr.com.au