How Do Excitotoxins Harm the Body
How tissues are affected by excitotoxins
All excitotoxins harm the body. They cause a lot of ailments and diseases that may cause death.
What are excitotoxins?
Excitotoxins are substances, usually amino acids that react with receptors in the brain and destroy certain types of neurons. One of these excitotoxin is monosodium glutamate. It comes from natural glutamic acid.
Glutamic acid is one of the many amino acids that are building blocks of proteins. It is naturally found in tomatoes, milk, mushrooms, and in many food in varying concentrations. It is also found in mother’s milk. Glutamic acid is found in the cells of the body and is involved in a variety of brain functions as a neurotransmitter. It is the most commonly used neurotransmitter by the brain, and the most important neurotransmitter in the hypothalamus. This natural glutamate in plants and animals is called L-glutamic acid. The digestive system breaks down this natural glutamic acid, and delivers this to the glutamate receptors in our body and brain. When broken this way, it is harmless. But when it undergoes processing with the use of strong chemicals, bacteria, and enzymes, it becomes “free” and harmful, and this is what is commonly known as MSG or monosodium glutamate. It is 78.2% glutamate, 12.2% sodium, and 9.6% water. Its chemical formulation has been altered, and is technically called as D-glutamic acid. It also contains L-glutamic acid, pyroglutamic acid, and contaminants. Take note that plant and animal proteins do not contain D-glutamic acid, pyroglutamic acid, nor contaminants.
Free glutamate or monosodium glutamate is the product of certain chemical processes such as hydrolysis, autolysis, and fermentation with the use of strong chemicals, bacteria, and enzymes. They come from various raw materials mostly from corn.
How do excitotoxins harm the body?
Glutamate and other excitatory amino acids attach to special receptors such as NMDA, AMPA, kainate, and metabotropic. These in turn opens the calcium channel on the neuron cell membrane, allowing calcium to flood into the cell. This calcium will trigger various reactions including free radical generation, eicosanoid production, and lipid peroxidation which will destroy the cell. With this calcium-triggered stimulation, the neurons become very excited, firing its impulses repetitively up to the point of death. This activation of calcium channel also involves other membrane receptors like zinc, magnesium, phencyclidine, and glycine receptors.
Glutamate acts on its receptors via a nitric oxide mechanism. Over stimulation of glutamate receptor produces an accumulation of reactive nitrogen species which result in the generation of several species of dangerous free radicals including peroxynitrite. This is how excess glutamate damages the nerve cells. Many studies have demonstrated the link between free radical generation and excitotoxity.
Free radicals have been shown to damage cellular proteins (protein carbonyl product), and DNA. The most immediate DNA damage is the mitochondrial DNA, which controls protein expression within a particular cell and its progeny. Parkinson’s disease, a neurodegenerative disease is suspected to be affected in this way. Chronic free radical accumulation can result in an impaired functional reserve of antioxidants, vitamins, minerals, enzymes, and thiol which are needed in neural protection.
Monosodium glutamate penetrates the blood-brain barrier. This barrier is a system of specialized capillary structures designed to exclude toxic substances from the brain. But the brain has areas that normally do not have a barrier system. These unprotected areas are in the hypothalamus, the subfornical organ, organium vasculosum, area postrema, pineal gland, and the subcommisural organ. There is a most consistent finding that monosodium glutamate can penetrate the blood-brain barrier. It was found out that exposure to MSG damages the arcuate nucleus of the hypothalamus. This area of the hypothalamus controls many neuroendocrine functions, and is intimately connected to several hypothalamic nuclei. It was demonstrated that high concentration of glutamate and aspartate can enter the blood-brain barrier by seeping through the unprotected areas, such as in the hypothalamus or in other circumventricular organs. This is the situation when individuals consume foods high in excitotoxins on a daily basis. Conditions associated with the seepage of toxic substances into the blood-brain barrier include hypertension, head trauma, diabetes, strokes, collage-vascular diseases, multiple sclerosis, AIDS, brain infections, Alzheimer’s disease, and premature aging.
Besides monosodiun glutamate, a growing list of excitotoxins are being discovered. One of these is aspartame . It contains approximately 40% aspartic acid, 50% phenylalanine, and 10% of methyl ester. Aspartame, like monosodium glutamate can cause brain lesions, brain tumors, and brain cancer.
Another excitotoxin is L-cysteine. It is a powerful excitotoxin that is added to certain bread dough, and is sold in health food store as a supplement. Also, hydrolyzed vegetable protein contains cysteic acid, another excitotoxin.