Excitotoxins #2: MonoSodium Glutamate and Your Brain

June 01, 2010

Excitotoxins #2: MonoSodium Glutamate and Your Brain 

 Reference: Russell Blaylock Excitotoxins, the Taste That Kills Competency:  Brain Health 

 Glutamate is not just an amino acid from which our proteins are constructed.  It turns out to be a critical and one of the most abundant neurotransmitters.  Here is how your brain works.  When a nerve impulse fires from one nerve cell, it passes on its message to another cell at a connection called a synapse.  At the connection, the first cell pushes out a tiny packet of different chemicals, often glutamate.  The glutamate floats across to the second cell where there are receptors into which the glutamate fits nicely, just like a lock and key.  That fires off the second cell to do its action.  We used to think there were just a few neurotransmitters but we now know there are dozens (about 50).  And glutamate is one of the central ones.  Aspartate and cysteine are two more amino acids that seem to attach to the glutamine receptors and turn them on too.   

Around each synapse there are bunches of "nurse" cells that keep soak up extra glutamate and make sure the level is just right.  Like Goldilocks, their job is to make sure the porridge is not too cold or not too hot, that the glutamate level is just right.  It takes a ton of energy to do that. You can imagine how you could mess up this delicate computer if the food we ate went directly into the brain.  Well, it doesn't.  We have a very handy little feature called the blood-brain barrier which filters our blood and only lets just the right stuff through.  That way, the food we eat can't just get right in there.  This blood-brain barrier does a great job of keeping extra glutamate out when it's not meant to be there.  BUT.... and there seems to always be buts, there are times when it doesn't work so well.  Like when we have a fever, or are stressed, or are very young, or very old, or have had a head injury, or chemotherapy when our blood-brain barrier breaks down and extra stuff gets in.  

One key time is when we are hypoglycemic.  With low blood sugar, our nurse cells don't get enough energy to clean up extra glutamate, and then a tiny extra dose just seems to become magnified.  That leaves some of our cells exposed to more glutamate than they were meant to be.  Another leaky occasion might be a mini-stroke.  With the cell death from a mini-stroke, the glutamate can soak across many other cells and travel across the brain.  And finally, there are parts of the brain that just hardly have a blood-brain barrier at all.  The hypothalamus (the part of the brain that controls your pituitary gland - your master endocrine gland) doesn't have a very good blood-brain barrier.  Nor does your pineal gland that sets your day-night cycle.  Nor does your locus ceruleus or circumventricular organ areas. Here is the next rub.  

When some cells get exposed to too much glutamate, they fire, and fire, and fire again, and again, and again.....and then they die.  Yes, they die.  Our brain cells get so fired up they just spin into a spiral of damage they just can't get away from.  We know the exact chemical reactions how that occurs.  The glutamate receptor called the NMDA receptor requires glutamate as well as glycine, magnesium, and zinc.  When all are present, as they usually are in a healthy brain, the cell fires just right and messages get passed on perfectly.  It's when they aren't in balance that we get in trouble.  With too much glutamate (or aspartate) they turn signals on too far, and can't turn off.  Calcium floods into the cell and overwhelms all the delicate chemical balances.  And the nerve cell dies.  Taking down other cells around it in doing so. 

 WWW.  What will work for me?  My brain can get damaged?  You mean eating the wrong food can make my brain get into trouble?!!   Is this like plugging my computer into 220 voltage when it's meant to run on 110?  Yup. That's it.  Well, then we better know more about this.  My blood-brain barrier works most of the time, protecting me from this chemical.  But I love the taste of glutamate.  Can I afford to be exposed to it when I’m not sure when I’m safe or when not?  Never before in human evolution have we had so much glutamate flooding into our bodies.  Do you think there might be a clue that many folks get a headache when they eat too much of the stuff on an empty stomach?   Tune in next week.  The plot unfolds.

 Column written by Dr. John E Whitcomb, MD, Brookfield Longevity, Brookfield, WI (262-784-5300)