Autism and Monosodium Glutamate: The Theory and The QuestionsIncr

Posted on

In the 1950's and 1960's, the food industry found that if they added a special additive to their processed food, the favor was enhanced.  This additive was monosodium glutamate.  Also about that time, other additives, pesticides, chemical compounds, and vaccinations have been introduced to the populace, with the goal of making our lives better.  Recently, I read an article online regarding a "new" theory that places the blame of Autism on monosodium glutamate.  This little additive has been pegged as the smoking gun, now that the argument against vaccinations is losing steam.  Keep in mind that I have a specific bias toward genetic brain cell development, and I want to be sure I state that right at the beginning of this analysis.  The research into monosodium glutamate and the brain actually started back in the 1950's, with a resurgence of that research in the 1970's.  It seems that glutamate is a chemical compound that surrounds the neuron before it fires its synapsis through the neurotransmitter.  The presence of too much glutamate in the brain can cause neuron death, which leads to a number of neurological disorders.  In all the articles in Google Scholar that I have read, there is no mention of metabolizing glutamate within the body, the levels of glutamate that would be necessary to cause such damage, or anything like that.  Just that it is possible, and has been proven in post-natal lab rats.  Okay, so glutamate is in fact an important compound for brain function.  From the research that has been done, there is ample evidence that it would effect pruning, and cause damage to the neurons through overloading those neurons.  But I'm not convinced that there is a definite link between consuming monosodium glutamate in the real world and the development of an autistic brain. As you all know (those that have followed my blog, at any rate), I assert that autism is caused by increased gray matter and decreased white matter in the brain, and by the lack of or delayed pruning in the brain by age 6.  This means that autistic children have increased communication within their brain because of an increase of neurons, which causes sensitivity to any incoming stimuli.  This has been proven through MRI scans of the brains of autistic children and comparing them to their control, or "normal" children (see previous blog entries for the resources). In order for monosodium glutamate to be somehow responsible for this overgrowth of neurons at such a young age for some children and not for others would require the following: 
  1. The increased presence of monosodium glutamate within some children's diet rather than others.  As most families have a mixture of autistic and "normal" children, this would mean somehow an unequal portion of glutamate would have gone to the autistic child. 
  2. Levels of monosodium glutamate high enough at such a young age to cause such a transformation.  As of yet, I have been unable to find the actual research data outlining the proportion and dosage of glutamate used in laboratory rats for the oft-cited study.  
  3. The source of the monosodium glutamate.  Children are typically diagnosed at age 2, or have regression around age 6.  For the 2-yr old, it would suggest that the monosodium glutamate would be in either the formula being consumed, or the baby food being consumed.  Most children are not on "people" food by this time, or at least not in a significant quantity.  For 6-yr olds, this is possible, though it still brings up the problem of some children showing autism tendencies, and some not, though both may have a very identical meal. 
  4. Cultures that do not use monosodium glutamate as a food additive also have children that are autistic, which brings the whole theory into question.  
Now, I don't want to sound closed minded about this theory, because there is a kernel of truth regarding glutamate and its effect on the brain.  I would love to see actual clinical research that outlines the dosages of monosodium glutamate used, the duration, and the results compared to the "placebo" effect.  Unfortunately, as with most theories about autism, such information is never available, only anecdotal evidence.  So, if there are any neurobiologists that are familiar with the proposed theory and have research either fore or against it, I would be happy to read!  Remember, I want to know the details of the research, and not just the conclusions.  Much of the research I have been able to find so far is from the 1950's and 1970's, about the same time when it was determined that cancer was caused by cranberries, eggs, water, and various other compounds when taken in humanly impossible doses.