Book Review
Excitotoxins --- The Taste That
Kills
Russell L. Blaylock, M.D.
(264 pp., $27.00, ISBN: 0-929173-14-7,
Santa Fe, NM, Health Press, 1994)
What do monosodium glutamate (MSG), hydrolyzed vegetable protein and
Aspartame (Nutrasweet) all have in common? They are all common taste-enhancing
additives found in a variety of foods and beverages, and they all contain
Excitotoxins. In his book, Excitotoxins --- The Taste That Kills,
Dr. Russell L. Blaylock provides an extensive review of the literature supporting
his hypothesis that these excitatory amino acids can promote death of neurons
in the brain and spinal cord. Dr. Blaylock defines excitotoxins as a
"group of excitatory amino acids that can cause sensitive neurons to
die." The most common ones are glutamate, aspartate, and cysteine.
Dr. Blaylock is in private practice and is a board-certified neurosurgeon,
clinical assistant professor at the University of Mississippi Medical Center,
and President of the Mississippi Chapter of the Association of American
Physicians and Surgeons (AAPS). His book tackles a very complex and controversial
topic. Much of the research he reviews seems to support the age-old adage,
"you are what you eat." The discussion of mechanisms of neuronal
cell death and their relation to excitotoxins is detailed and well-referenced,
yet is written in such a fashion the non-medical person will come away with
a good understanding of the subject. Numerous illustrations, drawn quite
expertly by the author himself, enhance the understanding of the gross and
microscopic anatomy and membrane transport mechanisms involved.
Although excitotoxins are widely distributed in our food supply, the
author points out we may not be able to depend upon the Food and Drug Administration
(FDA) to protect us from these toxic, excitatory amino acids. The author
tells us that a powerful food lobby, known as the Glutamate Association,
works diligently to counteract any negative reports or publicity. In reviewing
the "glutamate story," Dr. Blaylock reveals that the FDA was made
aware of research showing MSG added to baby food posed a danger to developing
infants. Yet, it required Congressional testimony by a dedicated scientific
researcher before MSG was removed from all baby foods. The author also reviews
some of the problems he sees with research data purportedly showing the
safety of MSG --- research which was funded by the glutamate industry. His
discussion of truth in scientific research and bias (based on source of
grant support) is quite thought-provoking, and it remains a concern for
many of us who are faced with trying to interpret scientific studies in
many areas of medicine today. He also points out new labeling guidelines
promulgated by the FDA allow many of these excitotoxins to be disguised
using such benign sounding names as "natural flavoring." This
makes it even more difficult for the consumer to tell what the product actually
contains.
The very young and the very old appear to be most susceptible to the
deleterious effects of excitotoxins. A built-in protective mechanism known
as the blood brain barrier excludes many of these substances from the central
nervous system to some degree. The blood brain barrier, however, is not
fully developed in the very young, and it can be damaged by a variety of
brain insults that are common and often asymptomatic in older people. Those
with neuro-degenerative conditions or those who are at risk for developing
conditions such as Parkinson's disease, Huntington's chorea, Alzheimer's
disease and Amyotrophic Lateral Sclerosis (ALS), may be especially vulnerable
to the toxic effects of glutamate and Aspartame (Nutrasweet). Those who
have suffered strokes may also be at high risk because of disruption of
the blood brain barrier. Various common metabolic conditions including hypoglycemia
and hypoxia also place people at risk due to dysfunction of energy --- requiring,
protective, cell transport mechanisms.
The damage produced by these excitotoxins seems to selectively involve
areas of the brain which have a high density of glutamate receptors. This
includes important structures like the hypothalamus and the hippocampus.
The former structure is, in turn, involved in the regulation of many important
endocrine functions in the body, and the latter structure is intimately
involved in memory function. Nerve cells in the substantia nigra (Parkinson's
disease) and anterior horn cells in the spinal cord (ALS) are also susceptible
to damage via glutamate toxicity.
The author develops his hypothesis noting that neuronal damage caused
by excitotoxins may be rather insidious, occurring over many years. The
brain has a rather remarkable ability to compensate for nerve cell damage
and cell loss so that many diseases are not clinically apparent until a
very high percentage of cells have been lost. This is particularly relevant
in the case of such diseases as Parkinson's and Alzheimer's disease. He
suggests there may be few, if any, signs of a clinical problem at the time
excitotoxin damage is occurring during the course of one's lifetime.
Although the author suggests a number of things which the FDA could do,
including requiring that MSG and other food additives be specifically listed
on the product, he stops short of advocating a total ban of these flavor-enhancing
substances. It is clear unbiased research in this area should be presented
in an open forum setting so that people can be informed and thus be able
to make up their own minds about the safety of these compounds. Dr.
Blaylock's book on Excitotoxins goes a long way toward accomplishing this
goal and serves to disseminate this important information to the public.
Reviewed by Lawrence R. Huntoon, MD, PhD
Jamestown, NY
Dr. Huntoon, a board-certified neurologist with a Ph.D. in physiology
(neurophysiology), practices in Jamestown, New York, and is a member of
the AAPS Board of Directors.
