Biological role and use of L-glutamic acid and its influence on the body
Authors: Korytko O. O. 
Published: December 2024

L-glutamic acid (GA) is an non-essential ubiquitous amino acid present in most foods in either the free form (as free glutamate, Glu) or bound to peptides and proteins. Animals and реорle receives L-glutamic acid from the diet as a result of the breakdown of proteins in the intestine. This review contains new information important for a better understanding of the physiological functions of L-glutamic acid in the body, the use of monosodium glutamate MSG – a food supplement, with a characteristic taste called umami (“savoury deliciousness”), which is considered distinct from the four other basic tastes (sweet, sour, salty, and bitter), and the metabolism of L-glutamic acid. Glutamate occupies a central place in the metabolism of animals and humans.  Glutamate supplies the amino group for the biosynthesis of all other amino acids, is a substrate for glutamine and glutathione synthesis; important key neurotransmitter in the brain and energy source for certain tissues. L-glutamic acid is important precursor of compounds used in the development of new drugs based on the knowledge of neurodegeneration caused by high doses of this acid. Despite the high daily turnover, the total pool of glutamic acid in the blood is quite small due to its rapid removal and use by various tissues, including muscle and liver. L-glutamic acid is transformed in the cells of the intestinal mucosa into alanine, and in the liver – into glucose and lactate. The blood-brain barrier effectively excludes the passive flow of plasma glutamate to the central nervous system. Glutamate occurs naturally in virtually all foods, including meat, fish, poultry, breast milk and vegetables, and does not cause health problems, However, obtained by industrial methods L-glutamic acid can have a toxic effect on living cells. Various processed and prepared foods, such as traditional seasonings, sauces and certain restaurant foods can also contain significant levels of free glutamate, both from natural sources and from added MSG (flavor enhancers in food). MSG - sodium salt of L-glutamic acid, food additive E620 with umami taste, which is considered different from the other four basic tastes (sweet, sour, salty and bitter), enhances the intensity of taste and improves the palatability of food. Due to these properties, monosodium glutamate is often purposefully added to various products, which can be the cause of a number of adverse reactions in people who have consumed products with this additive. MSG has been implicated as the causative agent in the symptom complex known as Chinese restaurant syndrome and also as a trigger for bronchoconstriction in some asthmatic individuals. The European Food Safety Agency (EFSA) and the Joint FAO/WHO Committee on Food Additives (JECFA) have evaluated MSG and determined it to be safe for consumption within specified limits. MSG is usually produced as a white crystalline powder by microbial fermentation. Corynebacterium glutamicum is widely used for the biotechnological production of amino acids. Amino acid producing strains have been improved classically by mutagenesis and screening as well as in a rational manner using recombinant DNA technology. MSG is typically produced  from fermentation processes using molasses from sugar cane or sugar beet, as well as starch hydrolysates. We established that content of some amino acids and L-glutamic acid into of peat is increased under the influence of incubation and of sodium sulfate introduction. It is well known that peat amino acids are metabolites of accompanying microflora. Feeding such peat to broiler chickens in the form of a feed supplement to the main diet improved the metabolism in the body, growth and weight gain.