Glutamic acid is an amino acid that is produced naturally in the human body and the bodies of many animals. The amino acid plays a number of important roles in the human anatomy and functions as a neurotransmitter or chemical messenger. When released by the brain, glutamic acid excites the nervous system to allow messages to be transmitted throughout the body. The amino acid plays a crucial role in learning and memory.
In addition to glutamic acid's important functions as a brain chemical, the substance can also be used by the cells of the body to create the energy necessary to move, power the heart and lungs and keep organs functioning properly. The body also breaks glutamic acid into smaller components, which are used to manufacture other important brain chemicals and materials for proper cellular functioning.
The German scientist Karl Heinrich Leopold Ritthausen first discovered glutamic acid in 1866 while he was studying the substances found in ordinary wheat. A Japanese chemistry professor, Kikunae Ikeda, established glutamic acid as a flavoring agent by publishing the results of testing that he performed on kombu broth in 1907. Glutamic acid is now used as an additive in many foods, including soy sauce, cheese and fermented bean paste. The amino acid can also be made into monosodium glutamate salt with the addition of sodium. Commonly known as MSG, this food additive is used widely in Chinese cuisine.
In addition to use as a food additive, glutamic acid is an ingredient in some skin and hair care products, and is currently found in the formulas of more than 300 products sold in the United States. When used in food and skin care product manufacturing, glutamic acid is manufactured industrially from wheat. Approximately 1.7 million tons of glutamic acid are used worldwide each year in various foods and other products.
When used in the beauty industry, glutamic acid is primarily added to products because of its ability to condition the skin and hair. The chemical structure of glutamic acid makes the substance attractive to water molecules. Because moisture is naturally drawn to glutamic acid, when it is applied to the skin or hair, the ingredient has the ability to pull water from the air and transfer it to the tissue. Both the skin and hair are constantly subjected to the drying effects of evaporation, and glutamic acid helps to restore the moisture balance that is necessary to keep the skin soft and smooth.
Due to its skin conditioning abilities, glutamic acid is used in eye creams, lipsticks and treatments, shaving creams and moisturizers for the face, body, hands and feet. For those with dry skin, products that contain glutamic acid can help reduce redness, itching and irritation as well as the flaking and peeling that occurs when the tissue becomes extremely dehydrated.
The amino acid is also added to hair conditioners, to styling products used to reduce frizz and to solutions used for coloring, perming and straightening the hair to prevent over-drying. When mixed with zinc, glutamic acid forms zinc glutamate, an additive used to prevent bacteria and other microbes from colonizing in skin and hair care products.
Some studies have raised concerns about the overall safety of glutamic acid, finding that the ingredient may cause gastrointestinal or cardiovascular side effects when consumed in high quantities as an additive in foods. The U.S. Food and Drug Administration still lists glutamic acid on its list of ingredients that are safe for use in foods, and other studies have produced conflicting results that suggest the risks involved with consuming glutamic acid are minimal.
The safety of glutamic acid when used in skin and hair care products has not been widely assessed. The ingredient has not been evaluated by any major panels that review beauty products; however, a 1994 study using white rabbits found that even with prolonged exposure to a dressing coated with glutamic acid and water over a period of 4 hours, the ingredient did not cause any symptoms of skin irritation, including redness or swelling. The test subjects also did not develop any type of delayed reaction from glutamic acid in the 72 hours that followed the initial test. This suggests that even people with sensitive skin should be able to safely use glutamic acid on their skin or hair.