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Glutamates 穀胺酸鹽

By: Joe Hing Kwok Chu

     Most processed food contains free glutamates. The most common glutamate in food is mono-sodium glutamate (C₅H₈NO₄Na), commonly called MSG, which actually is one of the trade names for mono-sodium glutamate.

Glutamates occur naturally in food, but it is the free glutamates that cause adverse health reactions for many people, estimated at 30% of the population. 

Among the products that contain glutamates as the main ingredient to enhance taste of food are miso, soy sauce, liquid amino and hydrolyzed protein, and bouillons. Liquid Aminos is incorrectly promoted as a non-fermented health product. Actually the healthier and tastier products of the same category are miso, fermented soy sauce, and fermented soy bean paste because they contain naturally occurring vitamin B group, fragrance, and color. In these products the taste enhancer is the sodium salt of glutamic acid. They cannot be used as a substitute for table salt for those on a sodium- restricted diet. The cheapest soy sauce is the non-fermented kind, which is extremely cheap to produce, like Liquid Aminos. These products are not labeled as mono-sodium glutamate because to be qualified as mono-sodium glutamate, the products must contain 99% mono-sodium glutamate, according to FDA regulations.

     Glutamates are metal compounds of glutamic acid. Glutamic acid C₃H₉O₄N is one of the amino acids found in proteins. Glutamates are found naturally abundant in sea weeds. Glutamates were isolated from sea weed by a Japanese scientist. Commercial productions usually are performed by hydrolyzing tapioca, grain or soy protein (byproduct in oil manufacturing), using enzyme or hydrochloric acid. 

The hydrochloric acid method is much faster and more economical, usually taking a few hours to hydrolyze the protein in soy byproduct, tapioca or grains, while the enzyme method might take days, weeks or months, depending on the kind of enzymes. Enzymes are used in making real soy sauce, and the better ones are made with enzymes where fermentation processes take as long as ten months. Enzymes cost much more than hydrochloric acid.

 When the author was studying chemical technology more than fifty years ago, the textbooks at that time usually mentioned that glutamates were good for cleansing the liver to get rid of toxins. This could be an unfounded opinion.  Glutamates are usually tasteless but they can enhance the taste of food, especially sea food and meat. They have little effect on vegetables and other plant products. Glutamates include mono-sodium glutamate, marketed as Aji no Moto 味之素,  Wei Jing 味精 , and MSG.

 Over-usage of glutamates can have adverse effects, including headache, on some people.S   Many  migraine sufferers, asthma sufferers, and patients of ALS (amyotrophic lateral sclerosis, now known as Lou Gehrig's Disease)  can be allergic to glutamates. Glutamates are neural toxins. Long term use with large amounts can cause memory loss according to various studies. It can induce obesity and diabetes with fatty liver and fatty liver hepatitis in lab mice. [1]

    Children over consuming food with high content of glutamates may suffer from growth retardation. Over consumption of food with high content of glutamates may result in the overproduction of δ-amino acid.  δ-amino acid  may inhibit the secretion of thyroid stimulating hormone from the pituitary gland and cause the underproduction of thyroid hormone. The underproduction of thyroid hormone causes  the loss of calcium and phosphate and causes growth retardation and may also cause obesity and lethargy.

    Breastfeeding mothers should not use mono-sodium glutamate. If breastfeeding mothers are using a high protein diet and using excessive mono-sodium glutamate, the glutamate will be absorbed by the babies through the mother's milk and combine with the trace mineral zinc. The compound of zinc will be expelled in the urine.  This effect causes zinc deficiency in the babies and will result in lack of appetite, impaired function of the brain, slowing growth, and slowing sexual maturity of the babies.

There are studies that show effects of glutamates on lab animals:

1. In 1957, when Dr. D. Newhouse and Dr. J.P. Lucas did rat studies, they found that ingested glutamates result in rapid irreversible destruction of retinal cells[2]. Later, Dr. John Olney of Washington University did further studies with rodents that revealed that glutamate can damage dendrites in the brain, damage the hypothalamus and cause obesity, behavioral disturbances, endocrine changes, stunted bodies, seizures and infertility.

2. Another study showed that obesity in baby animals resulted  if glutamate was included in the diet of the nursing mother animals

3. Another study showed that all small chickens died within 19 days after being fed feed containing 2.6% monosodium glutamate.  All chickens in the control group survived.

One health source recommended maximum dosages of mono-sodium glutamate / Body Weight in Kg

Avoid glutamates if you are allergic to them.

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[1] J Autoimmun. 2008 Feb-Mar;30(1-2):42-50. doi: 10.1016/j.jaut.2007.11.016.

[2] Archives of ophthalmology 58 (2): 193–201. PMID 13443577; AMA Arch Ophthalmol. 1957 Aug;58(2):193-201.

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Last update: October 26, 2013,  4 p.m. LAH