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How do truly natural glutamic acid and manufactured glutamic acid (MSG) differ?

Glutamic acid is an amino acid found in abundance in both plant and animal protein.  In humans it is a non-essential amino acid, i.e., the body is capable of producing its own glutamic acid, and is not dependent upon getting glutamic acid from ingested food.

Glutamate is glutamic acid to which a mineral ion has been attached.  (Researchers call this mineral ion a “salt”.)  If the mineral ion is sodium, the glutamic acid becomes sodium glutamate.  If the mineral ion is potassium, the glutamic acid becomes potassium glutamate.

In addition to its role as a building block of protein, glutamic acid serves as a neurotransmitter vital to the transmission of nerve impulses in many parts of the central nervous system.  Under certain circumstances, glutamic acid becomes a neurotoxin, causing neuron degeneration and cell death which may be followed by neuroendocrine disorders.

When protein is digested, the glutamic acid in that protein is released for use in the body.  If there is need, additional glutamic acid can be synthesized from other amino acids contained in ingested protein.  If an individual never ingested protein with glutamic acid in it, that individual could synthesize all the glutamic acid needed for body function from other amino acids. The human brain is also capable of synthesizing glutamic acid according to its metabolic needs, from endogenous materials.   Glutamic acid is referred to as a non-essential amino acid because a healthy human can manufacture/synthesize all the glutamic acid needed for normal body function from other amino acids.

What is MSG?

MSG is glutamic acid that has been produced outside of the human (or animal) body.  But when glutamic acid is produced or created in this way (outside of the human body), it differs significantly from the glutamic acid found in unadulterated, unprocessed, unfermented protein or released from unadulterated, unprocessed, unfermented protein during digestion.  Glutamic acid found normally in the human body (and in all higher organisms) is glutamic acid in the L form, i.e., L-glutamic acid.  Glutamic acid that is produced outside of the human body is made up of L-glutamic acid and an array of unwanted by-products often referred to as impurities. L-glutamic acid produced outside of the human body is always accompanied by impurities such as D-glutamic acid and pyroglutamic acid; and when L-glutamic acid is produced by way of acid hydrolysis, carcinogenic mono and dichloro propanols inevitably accompany it. 

All manufactured free amino acids are accompanied by impurities. The fact that glutamate produced outside of the human body is categorized as food grade or pharmaceutical grade (99% pure) attests to the fact that impurities always accompany amino acids produced outside the body.

MSG fed to the very young has been shown to cause brain damage and subsequent learning, behavior, and endocrine disorders such as reproductive disorders and gross obesity.  Ingestion of MSG by people of all ages will cause adverse reactions when people ingest amounts that exceed their individual tolerance levels.  Eating protein (which will contain bound glutamic acid that is L-glutamic acid, only) does not cause either brain damage or adverse reactions.   

Additional information, including relevant citations, can be found at

On the Subject of Manufactured vs Natural Glutamic Acid,

Evidence of MSG-induced Brain Damage and Endocrine Disorders: The Animal Studies,

Evidence of MSG-induced Human Adverse Reactions: The Human Studies, and

The Young are Particularly at Risk for Brain Damage from Ingestion of MSG:  Data