T Nation

Amino Acids and Neurotoxicity

We all know that amino acids are the building blocks of proteins, and we know they naturally occur in many foods. But to what extent could they be harmful to mental health, particularly if taken in large doses after having been extracted from their food sources or used as food additives - like MSG for instance?

After reading some of the research conducted by Dr. Russell Blaylock, I was shocked to learn that some amino acids are considered excitotoxins. What are excitotoxins? Here is Dr. Blaylock’s definition. “These are substances, usually acidic amino acids, that react with specialized receptors in the brain in such a way as to lead to destruction of certain types of neurons.” Here is another quote from Dr. Blaylock explaining the function of excitotoxins:

“Subsequent studies have shown that glutamate, and other excitatory amino acids, attach to a specialized family of receptors (NMDA, kainate, AMPA and metabotrophic) which in turn, either directly or indirectly, opens the calcium channel on the neuron cell membrane, allowing calcium to flood into the cell. If unchecked, this calcium will trigger a cascade of reactions, including free radical generation, eicosanoid production, and lipid peroxidation, which will destroy the cell. With this calcium triggered stimulation, the neuron becomes very excited, firing its impulses repetitively until the point of cell death, hence the name excitotoxin.”

According to Blaylock, “There are a growing number of clinicians and basic scientists who are convinced that a group of compounds called excitotoxins play a critical role in the development of several neurological disorders including migraines, seizures, infections, abnormal neural development, certain endocrine disorders, neuropsychiatric disorders, learning disorders in children, AIDS dementia, episodic violence, lyme borreliosis, hepatic encephalopathy, specific types of obesity, and especially the neurodegenerative diseases, such as ALS, Parkinson’s disease, Alzheimer’s disease, Huntington’s disease, and olivopontocerebellar degeneration.”

Aside from glutamate, here are some other excitotoxins: L-cysteine, aspartame, aspartic acid, and cysteic acid. Please note that these amino acids are not typically found in BCAA products, but are found in other amino acid blend and protein supplements. Beware that some whey and soy protein supplements may have high concentrations of glutamate and L-cysteine.