17 August, 1998

Aspartic acid (aspartate) has been known to be a neurotoxin for 30
years. Rodent studies demonstrated that when ingested at doses of 0.5 g/
kg or greater, the circumventricular organs that surround the ventricles
of the brain become necrotic. The critical time of vulnerability is the
first 10 days of a rodents life but animals remain susceptible
throughout life--sensitivity will be lessened as they mature.

Circumventricular organs function, among other things, as neuroendocrine
control organs. i.e. they control the outflow of hormones from the
pituatary, adrenal and other glands. Rodents that have ingested too much
aspartate as infants are stunted as adults, obese and have sexual and
reproductive dysfunctions.  Aspartate is additive in its effects with
glutamate and other excitotoxins.  In other words, a subtoxic dose of
aspartate added to a subtoxic dose of glutamate may add up to a toxic
dose. Unfortunately it is hard to find food that does not contain added
glutamate and for some categories of food it does not have to be listed
on the label. I hope that people aren't taking the vitamin that contains
aspartate with food, which is very likely laced with glutamate (MSG,
hydrolyzed vegetable protein, autolyzed yeast, casein,natural flavoring
etc.  The food industry has innumerable ways of obfuscating the fact
they are adding glutamate).

Since the late 1960's when the first report of aspartate toxicity was
published, these effects have been reproduced in every species studied,
including primates.

Obviously we can't study this in humans as it is necessary to view the
brains within 4-6 hrs of ingestion to see the damage.

After that the brain heals over the wound and it is almost impossible to
detect histologically the loss of neurons in these brain regions which
have ill defined boundaries.  One must see the lesion when it is
evolving. What is particularly disturbing is that everything we know
that relates animal studies to humans tells us that human sensitivities
are generally greater than that of animals and there is far more
variability among individuals so that some individuals may be far more
sensitive to these toxic agents than animal studies would indicate.  For
instance we know that blood levels of  glutamate are far higher in
humans than in rodents or monkeys following a given dose and that some
individuals are very susceptible to Chinese restaurant syndrome after
ingesting glutamate and others are not.. Because of these 2 factors
(heightened sensitivity & varaibility in humans), FDA's rule is that 
doses of agents appropriate for humans must be 100 fold higher than the
toxic threshold dose generated in animal studies. 

Since glutamate and aspartate are still on the GRAS list (they may be
added in unlimited amounts to food and drugs) FDA is obviously not too
interested in following their own rules. Unfortunately a powerful food
industry lobby keeps them on the GRAS (generally regarded as safe) list.

Madelon Price