Is Glutamate Sensitivity Real? Myths About Glutamate, MSG: Part 1

Originally Medically Reviewed by Dr. Sony Sherpa, (MBBS) - September 09, 2024

Fact Checked and Updated by Abinaya Muralidharan, M. Pharm - August 11, 2026

Introduction

Dietary glutamates, particularly MSG, have received both praise for their flavor - enhancing properties and criticism over potential adverse effects.

While most evidence highlights the safety of ordinary glutamate consumption, some studies have shown that a fraction of the population may be at risk for glutamate sensitivity. These results have encouraged many health advocates to avoid dietary glutamates entirely, despite very little being known about glutamate sensitivity in general.

This article reviews the current literature on dietary glutamates, MSG, and glutamate sensitivity:

• Part 1 (below) introduces glutamate and its functions in the body, possible benefits, and myths pertaining to MSG consumption.
• Part 2 covers the safety and toxicity of glutamate, possible side effects, risk factors, and tips for supporting optimal glutamate metabolism

What Is Glutamate?

Glutamate is the salt of glutamic acid, a non-essential amino acid. Both can be synthesized in the body from a variety of amino acid precursors belonging to the glutamate family of amino acids, including glutamine, proline, and arginine. Approximately one-quarter of dietary amino acids are derived from this amino acid family.

In the body, glutamate serves as both a vital neurotransmitter and cellular signaling peptide, with a broad range of actions across various body tissues. Glutamate may also be made from GABA (Gamma-Aminobutyric Acid), to which it is the main precursor. Foods may contain glutamate in free and bound forms or may offer glutamate precursors.

Infographic Added - August 11, 2026

What Are the Roles of Glutamate in the Body?

The roles of glutamate in the body are extensive and still being studied. A few of its better-known functions are detailed below:

• Cellular Respiration

Glutamate can be used to generate alpha-ketoglutarate, an intermediate in Krebs’ cycle that is involved in cellular respiration. Other areas of study suggest that glutamate (along with its family of amino acids, such as glutamine) is likely to be important for maintaining mitochondrial calcium transport in many cells pertaining to calcium signaling and mitochondrial function.

• Digestive Tract

Dietary glutamate is mostly consumed by the gut and used as fuel for enterocytes, in conjunction with GABA and butyric acid. Studies reveal that glutamine is required for enterocyte growth and for regulating their metabolism. This indicates that glutamate is essential for the turnover and repair of the gut, a process that occurs every 2-5 days on average.

• Gut Microbiome

Lactic acid bacteria make use of glutamate in order to produce GABA. Through this process, a charge gradient is generated that enhances their metabolism and promotes their growth. Other organisms make use of glutamate in order to produce metabolites, some of which exert antibiotic actions.

• Liver

In the liver, glutamate is an important component of protein metabolism and urea synthesis. It helps convert nitrogen from protein breakdown into ammonia, which the liver then turns into urea - a safer substance the body removes through urine.

• Nervous System

Glutamate constitutes the main excitatory neurotransmitter in the brain and nervous system. It is required for neurotransmission and also facilitates neuronal growth and plasticity. As it is the precursor to the main inhibitory neurotransmitter, GABA, it is also required for reducing activity in the nervous system.

• Immune System

In the right physiological concentrations, glutamate increases the growth and activity of immune cells, as well as being a central component of glutathione, a vital cellular antioxidant.

• Bone

Bone cells may rely on glutamate to function, as it may play a role in the signaling linked to maintaining adequate bone mineral density.

• Umami Taste

Glutamate is the amino acid primarily responsible for triggering umami taste. It is also known to improve the flavor of foods by improving their overall palatability, though the exact mechanism is not yet fully understood. It is also thought to play a supporting role in how taste signals are processed within taste buds.

Forms of Glutamate

There are many forms of glutamate found in food, which are typically classified according to whether they are free or bound to other proteins.

Bound Glutamates are found widely across many foods in varying amounts. Animal protein contains roughly between 11-22% glutamate by protein weight, and plant-based protein can contain up to 40%, comprising mainly bound glutamate. They are released during digestion and are not associated with any known adverse effects. The gut rapidly metabolizes dietary glutamate, which has been shown to have little to no effect on blood glutamate concentrations.

Free Glutamates are found naturally in a wide variety of foods, as well as directly added to refined foods as a flavor enhancer. They activate glutamate receptors in the taste buds to signal for umami taste. Free glutamates (including MSG) can be found in higher quantities in various food additives, including hydrolyzed protein, protein isolates (especially soy), and yeast extracts. When consumed in large concentrations, they may be associated with adverse effects in some individuals, such as anxiety and gastrointestinal discomfort in the stomach and intestines - though evidence for a consistent causal relationship remains limited and mixed.

Glutamate Isomers. In nature, free glutamates are present in two forms: L-glutamate and D-glutamate. They are chemically identical yet represent “left-handed” and “right-handed” 3D orientations (chirality). L-glutamate is responsible for activating receptors, while D-glutamate is far less effective. Fermented natural foods contain relatively higher proportions of D-glutamate, reducing the receptor-active (L-glutamate) fraction of the total free glutamate pool; non-fermented natural foods, however, contain relatively low D-glutamate levels, similar to MSG-added foods. By contrast, glutamates found in additives are produced via a controlled single-strain fermentation using Corynebacterium glutamicum, which yields 100% pure L-glutamate. MSG (monosodium glutamate) is the most famous of the free glutamates found in the diet, both naturally and added as a flavor enhancer. Commercial MSG is typically sold at 99% purity as L-glutamate salt.

Are There Actual Benefits to Consuming Glutamate?

In a healthy diet plan, the majority of ingested glutamate is either neutral or beneficial for health. A few possible benefits include:

• Enhancing Metabolism

Bound glutamate serves as a healthy fuel for most of the cells in the digestive tract. Consuming whole foods high in glutamate can be beneficial when the gut needs repair. The body can make use of glutamine during periods of intensive activity to replenish reserves, including for muscle building, neurogenesis, and tissue repair. Glutamine can become an essential amino acid when depleted, as seen in intensive surgery, trauma, chemotherapy, and sepsis.

• Lowering Acidity

Glutamine and glutamate also play important roles in regulating the acid-base balance in the body by producing ammonia (an alkali). This is in contrast to dietary proteins containing sulfur amino acids, which produce acid during metabolism and require glutamate and glutamine to help buffer the resulting acid load.

• Aiding Enteral Nutrition

Animal studies suggest that dietary-free glutamate may be able to protect against diarrhea caused by liquids, while glutamine has been shown to improve gut permeability markers in critically ill patients. Further research is needed to determine whether either benefit translates to people receiving enteral nutrition.

3 Myths About MSG: Health Claims or Health Hype?

Current research indicates that MSG is not completely free of adverse health effects. However, some public concerns about MSG’s safety are not fully supported by the available evidence.

Below is a discussion of three common health myths pertaining to MSG.

MSG Will Make You Fat

There may be some truth to this myth, yet much remains to be explored on the topic.

Lab vs. real-world MSG intake and obesity

MSG has been widely used in research to induce obesity in lab rats when studying the condition. The quantities of MSG used are typically a lot larger than what one would consume in a natural setting, and in some studies, it is even injected into the test subjects. Therefore, the scientific model of MSG-induced obesity alone is not enough to suggest that ordinary MSG consumption can produce the same result in humans.

Long-term MSG intake may increase obesity risk

Despite reports demonstrating its safety as a food additive, there is a possible connection between MSG consumption and obesity:

• MSG and the spleen. Recent rodent studies highlight that high doses of MSG can alter the profile of immune cells in splenocytes and the spleen. The vagus nerve and spleen form a neuroimmune axis that modulates systemic inflammation and metabolic signals. Disruption of this vagal-splenic axis is being investigated in injection-based animal models of MSG-induced hypothalamic obesity for its potential role in altered adiposity and weight gain.
• Hypothalamus. A rise in blood concentrations of MSG can potentially damage areas of the hypothalamus (e.g., arcuate nucleus) involved in regulating appetite. These areas lack a fully intact blood-brain barrier. Studies showing this used injected MSG, whereas real intake does not usually affect blood levels. More research is required to ascertain whether generally elevated blood glutamate may induce similar effects.

Long-term consumption is underexplored

If consumed in excessively high quantities over long periods, some observational data suggest it might be linked to metabolic imbalance or weight gain, though the time frame, individual variability, and true causal mechanisms remain unproven.

Some studies have revealed an association between chronic intake at safe levels and being overweight. More data is required regarding the long-term consumption of MSG and obesity.

Nutrition serves to regulate potential side effects. It has been noted in animal studies that oxidative stress induced by high doses of MSG in the spleen can be offset to a degree by dietary antioxidants, which helps restore normal immune responses.

Thus, MSG is highly unlikely to pose an immediate concern when consumed as part of a balanced diet. Long-term MSG intake may exacerbate metabolic risks when combined with a high- fat or nutrient-poor diet. Many MSG-fortified foods tend to be lower in overall nutritional value.

A Diet High in Glutamate Is Neurotoxic

While in vitro experiments clearly show the connection between glutamate overload and neurotoxicity, it is not necessarily true that dietary sources will pose the same adverse effects.

The brain glutamate cycle

Glutamate production is tightly regulated in the central nervous system. It typically relies on the cycling of glutamic acid from a finite store that is conserved across neuronal cell types. Dietary glutamate is unlikely to pose a risk unless the individual's glutamate cycle is already disrupted.

Brain glutamate uptake appears limited

Ingesting unusually large single doses of glutamate may exceed the gut’s capacity to process it, allowing a bit more glutamate than usual into the bloodstream. However, studies show that a significant rise in blood glutamate generally occurs when MSG is consumed in liquid form or on an empty stomach, whereas consuming it alongside a solid meal prevents this spike in healthy individuals. Even in such cases, glutamate is unable to pass the blood-brain barrier. Blood glutamate may enter the brain if the blood-brain barrier is severely compromised.

Glutamate may promote neuroinflammation and eventual toxicity

Dietary glutamate may be able to exert an indirect inflammatory effect on the nervous system through several mechanisms:

• Blood ammonia. Excess glutamate and protein intake are able to increase blood ammonia concentrations in some individuals. Blood ammonia can pass the blood-brain barrier and be converted into glutamate or glutamine in the brain. Excessive concentrations may lead to neuroinflammation. The body normally maintains strict, low physiological concentrations of blood ammonia through urea metabolism, preventing significant amounts from reaching the brain. Therefore, it is unlikely that ingested MSG would be able to cause an excess of ammonia in healthy individuals.
• Direct brain exposure. Elevated neuronal glutamate (non-dietary) has been shown to increase the permeability of the blood-brain barrier. This may make an individual more sensitive to elevated blood glutamate, as it could contribute towards a pre-existing imbalance that serves to increase neurotoxicity. Abnormal glutamate metabolism has been seen in those with neurodegenerative diseases, who are prone to excess brain glutamate irrespective of dietary consumption. Research is scarce regarding the impact of dietary glutamate on such individuals.

Despite these effects, dietary glutamate is unlikely to promote neurotoxicity in healthy individuals. This is not necessarily the case for individuals with epilepsy, where the underlying excitatory-inhibitory (glutamate- GABA) balance is already disrupted, and blood-brain barrier permeability may be altered- a proposed mechanism by which dietary glutamate could influence brain excitability, though clinical evidence for this remains preliminary and inconclusive.

Eating Chinese Food Is Unhealthy

Chinese food has a reputation for inducing Chinese Restaurant Syndrome in some people. Whether this is due to MSG-enriched food or not is still a matter of debate.

Chinese Restaurant Syndrome was first reported over 50 years ago, featured in the editorial section of a journal at that time. Someone who consumed a large amount of Chinese food showed all the classic symptoms, such as headache, neck pain, and digestive complaints. Since then, other reports have emerged, denoting similar symptoms in a small subset of individuals frequenting Chinese restaurants. Breathing problems, sinus problems, fatigue, flushing, skin rashes, and swelling of the glands have also been observed in these individuals. These symptoms were ascribed to the glutamate in the food, which is known to be higher, on average, in Chinese cuisine.

Chinese food is not the problem

The majority of people consuming Chinese food do not experience any symptoms at all. It should be noted that Chinese food itself is not inherently unhealthy due to the glutamate content. On the contrary, Chinese vegetables and traditional Chinese foods have a reputation for their health benefits. Therefore, MSG-related symptoms are likely only relevant when high amounts of free glutamates are ingested on an empty stomach. Chinese Restaurant Syndrome was renamed to MSG sensitivity or the MSG symptom complex.

MSG sensitivity is debatable

Researchers are still debating whether this phenomenon is a valid health concern. Most studies have drawn neutral results regarding MSG consumption, though a few observational studies among the highest average intakes amongst frequent consumers have reported mixed findings. Other studies point to sensitive individuals who experienced a reaction when consuming MSG; however, rigorous trials demonstrate these responses are inconsistent and depend directly on dose, fasting state, and route of administration. Consequently, the results are difficult to interpret and prone to inaccuracy. Much remains to be explored.

MSG does not appear to enhance immune reactivity in high-risk individuals

Although MSG has been hypothesized to heighten sensitivity to other allergens even when it does not trigger reactions on its own, this has been directly tested in both human and animal studies and has not been confirmed, though rare individual cases of true allergic reactions to MSG itself have been reported. Some refined MSG-enhanced products contain a whole host of other ingredients that may also trigger allergic reactions in sensitive individuals. More research is required before it can be ascertained why some individuals report reactions to MSG-containing foods and whether other factors are involved.

Toxicity & Safety: Are There Side Effects to Consuming Glutamate?

Continue to part 2 for more.

To search for the best Gastroenterology Healthcare Providers and Doctors in Germany, India, Malaysia, Spain, Thailand, Turkey, the UAE, and the USA, please use the Mya Care search engine.

To search for the best doctors and healthcare providers worldwide, please use the Mya Care search engine.

 

First Published: June 01, 2022

References:

Show More ▼

 

Disclaimer