Harmful Effects Of Excitotoxins
What are excitotoxins? These are substances, usually acidic amino acid that react with receptors in the brain that destroy certain types of neurons. One of the common excitotoxins is glutamate. MSG or monosodium glutamate is the sodium salt of glutamate. This is an amino acid commonly used by the brain as a neurotransmitter. Then how could this harmless neurotransmitter become harmful to the body? Because glutamate exists only in a very small concentration, no more that 8 to 12 uM, such that when it exceeds this amount, the neurons begin to fire abnormally to exhaustion until death.
Excitotoxins are very harmful substances that causes a lot of neurological disorders. These were discovered in 1957 by Lucas and Newhouse, while experimenting on mice to study a particular eye disorder. It was found during the experiment that newborn mice fed with MSG have widespread destruction of the inner nerve layer of the retina. In 1969, Dr. John Olney of the Department of Psychiatry at Washington University in St. Louis, repeated Lucas and Newhouse ’s experiment. His assistant found that newborn mice fed with MSG became grossly obese, and short in stature. The mice also developed hypoplastic organs including thyroid, adrenal, pituitary, and reproductive dysfunction. They demonstrated multiple endocrine deficiencies, such as TSH, growth hormone, LH, FSH, and ACTH. Discrete lesions of the arcuate nucleus, and less severe destruction of the hypothalamic nuclei were discovered when the mice brain were examined. Later studies showed that damaged by MSG is much more widespread, including the hippocampus, circumventricular organs, locus cereulus, amygdala-limbic system, subthalamus and striatum. Studies have shown that glutamate, and other excitatory amino acids attach to a family of receptors (NMDA, kainate, AMPA, and metabotropic), which in turn either directly or indirectly opens the calcium channel on the neuron cell membrane, allowing calcium to fllood into the cell. When not checked, this calcium will triggere a cascade of reactions including free radical generation, eicosanoid production, and lipid peroxidation, which will destroy the cell. The neuron become very excited with this calcium-triggered stimulation, firing its impulses repetitively until the point of cell death, thus the name excitotoxin.The activation of the calcium channel via the NMDA type receptors also involves other membrane receptors such as magnesium, zinc, phencyclidine, and glycine receptors.
MSG and other excitotoxin taste enhancers become more toxic when added together. Excitotoxins in subtoxic concentrations can become fully toxic to specialized brain cells when in combination.
Among the disorders caused by the use of MSG are migraines, seizures, abnormal neural development, infections, certain endocrine disorders, learning disorders in children, neuropsychiatric disorders, hepatic encephalophathy, obesity, episodic violence, ALS, Alzheimer’s disease, Parkinson’s disease, Huntington’s disease.
Glutamate acts on its receptor via a nitric oxide mechanism. Overstimulation of the glutamate receptor produces an accumulation of reactive nitrogen species, resulting in the generation of dangerous free radicals including peroxynitrite. Studies have shown that this is how excess glutamate damages the nerve cells.
MSG damages an area of the hypothalamus known as arcuate nucleus. This controls a multitude of neuroendocrine functions. High concentrations of glutamate and aspartate can penetrate the brain by seeping through hypothalamus or other circumventricular organs. Chronic elevations of blood glutamate can also seep through the normal blood-brain barrier whenthese high concentrations are maintained over a long period of time. This is the situation when foods high in excitotoxins are consumed on a daily basis. The harmful effects associated with the barrier disruption are hypertension, diabetes, strokes, head trauma, multiple sclerosis, brain tumors, collagen-vascular diseases, AIDS, brain infections, and Alzheimer’s disease.
Excitotoxins are present in almost all processed food. They come in the form of monosodium glutamate, cysteic acid, L-cysteine, homocysteine and aspartame. Almost all junk foods are loaded with MSG, and softdrinks and other carbonated drinks are also mixed with aspartame. And some o fhtese junk foods or drinks have two or more excitotoxins in them, which make them more dangerously toxic.