All About Glutamic Acid, Glutamate, Glutamine and Glutathione

Amino acids are substances that the body uses to perform tasks like building proteins, secreting hormones and causing chemical reactions. There are 21 different amino acids — 11 of which are nonessential and nine of which are essential.

Nonessential amino acids are naturally produced by the body without food sources. Essential amino acids can't be synthesized from scratch and must be provided through diet or supplementation. Nonessential amino acids may become conditional, meaning they are essential in times of stress and illness, according to the U.S. National Library of Medicine.

Ali Webster, PhD, RD, the director of research and nutrition communications at the International Food Information Council, recommends getting essential amino acids from food sources before turning to supplements.

Glutamic acid, also known as glutamate, is an example of a nonessential amino acid. Glutamine is another nonessential amino acid, though it is conditional under certain circumstances. Though they sound the same, they are different.

The amino acids glutamic acid and glutamine are also sometimes confused with glutathione. This is a substance known as a tripeptide that is produced in the body from three amino acids: glycine, cysteine and glutamic acid. It acts as an antioxidant.

Glutamic acid belongs to a group of amino acids called nonessential amino acids — you need these types of acids to form proteins, and your body produces them on its own.

Glutamic acid turns into glutamate in the body. This chemical helps nerve cells in the brain send and receive information from other cells, which is why it may be involved in learning and memory, per the University of Rochester Medical Center.

Eating plenty of protein is key to getting enough amino acids — even nonessential ones. Glutamic acid is often considered the most common dietary amino acid as it is found in a wide variety of foods, including vegetable protein.

Glutamic acid may have blood pressure lowering effects, according to a large July 2009 study in ​Circulation​. There is minimal research on the health benefits of glutamic acid, and more research is needed to confirm these purported benefits.

Monosodium glutamate (MSG) is the sodium salt of glutamic acid, according to the FDA. While glutamic acid is naturally found in your body, MSG is not. You can get MSG naturally from certain foods (like cheese) but it's also a common additive used to enhance umami flavors.

The glutamate in MSG is chemically the same as glutamate in food proteins — like those in cheese — and the body metabolizes both sources in the same way. In fact, you get about 13 grams of ​natural​ glutamate each day from protein in food, while you only get around 0.55 grams per day of added​ MSG from foods like takeout and frozen TV dinners.

There is some controversy about whether MSG is unhealthy or unsafe due to allegations around MSG hypersensitivity. The FDA states that MSG is generally recognized as safe (GRAS). Some people may report experiencing sensitivities to foods with added MSG, such as headaches, flushing or sweating, per the Mayo Clinic, but this is rare. There is little supportive evidence of negative health risks from MSG, according to a May 2019 review in ​Comprehensive Reviews in Food Evidence and Food Safety​.

"MSG has undeservingly had a bad rap for a long time, but the reality is that it's safe to consume, and could be a helpful tool for lowering the overall amount of sodium people eat," Webster explains.

Of all the amino acids in the human body, glutamine is the most abundant and versatile. It's made internally like glutamic acid, so it's classified as a nonessential amino acid. Unlike glutamic acid, glutamine has the potential to become essential since it's also a conditional essential acid.

Glutamine is often a part of clinical nutrition supplementation — it helps people who undergo surgery and helps support athletes' immune functions, per a November 2018 review in ​​​​Nutrients​​​​.

Glutamine also supports the cells in the stomach and intestines, per the University of Michael Health. People can develop a glutamine deficiency when they go through extremely stressful situations, such as severe injury, surgery, infections and excessive exercise. Some dietary sources of glutamine include meat, fish, eggs and dairy products. It's also found in tofu, beans and lentils.

While glutamine is technically considered a nonessential amino acid, major events like severe injuries, surgery or infection can drastically reduce glutamine levels in the body, Webster says.

"In these situations, glutamine may be conditionally essential, meaning that the body's requirements for glutamine exceed its ability to produce enough of it. This makes getting glutamine from the diet especially important."

Together, three essential amino acids that are also conditional — glutamine, glycine and cysteine — form glutathione. It's a chemical with powerful antioxidant properties, protecting against oxidative stress.

Glutathione is naturally produced in the body, though production declines with stress and age. It can also be taken as a supplement.

One of the main benefits of glutathione is its ability to protect from cell-damaging molecules known as free radicals. Antioxidants are common in skincare products, and taking a glutathione supplement may have positive effects. Glutathione is observed to reduce wrinkles and increase skin elasticity, according to an April 2017 study in ​Clinical, Cosmetic and Investigational Dermatology​.

Though glutamic acid, glutamine and glutathione all occur naturally in the body, many people choose to take dietary supplements to increase their levels. But eating foods rich in protein is usually enough.