Understanding the Importance of Glutamate in the Human Diet

Glutamate is the most abundant amino acid available in the human diet and also the most concentrated amino acid in the brain. It’s similar to the other 19 amino acids because it’s used to make proteins, facilitate metabolic functions and for energy production. But what makes the glutamate amino acid unique is that it’s considered the primary excitatory neurotransmitter of the human nervous system.

While it plays a role in many aspects of normal brain function, including learning and memory, too much of it in the brain can actually be toxic. According to the Center for Molecular Biology and Neuroscience:

Glutamate has to be present in the right concentrations in the right places at the right time. Both too much and too little glutamate is harmful. This implies that glutamate is both essential and highly toxic at the same time.

What Is Glutamate?

Glutamate, or glutamic acid, is a non-essential amino acid found in a variety of foods, including both plant- and animal-derived foods — such as bone broth, meats, mushrooms and soy products. It is the most common form of glutamic acid in our bodies and considered a non-essential amino acid because our bodies are able to synthesize it from other amino acids. This means we don’t require this amino acid from food sources, unlike with essential amino acids.

This amino acid also functions as a neurotransmitter. This means it helps nerve cells communicate with one another. It’s still not entirely agreed upon whether or not glutamate can cross the blood-brain barrier at all.

Some believe it can in very small amounts when someone’s brain barrier is “leaky” (similar to having a leaky gut), while others believe the blood-brain barrier shields the brain from glutamate in the blood. This means it must be generated inside the brain from glutamine and other precursors.

Bound vs. Free Glutamate

Bound glutamate is the form of the amino acid found naturally in unprocessed foods, especially foods high in protein. It is bound to other amino acids, and when you eat it, your body breaks it down slowly and is able to closely regulate the amount that you take in. Excess amounts can simply be excreted through the waste to prevent toxicity.
Free glutamate on the other hand is the modified form that is absorbed more rapidly. The modified, free form is the type linked to more potential health problems. This form is found in some whole/unprocessed foods but more commonly in many ultra-processed and packaged foods. One example is monosodium glutamate, the sodium salt of glutamic acid.

What does too much glutamate do? This depends on how much is present. “Glutamate sensitivity” is described as one possible cause of a group of symptoms that occur in some people who are sensitive to glutamate founds in foods.

While “glutamate dominance” is still controversial in the medical community, some researchers believe it’s tied to a number of health problems, including serious neurological disorders.

While the jury is still out on this topic, too much glutamate (glutamate dominance) has been linked to some psychiatric condition, such as anxiety, sleep disorders, epilepsy and others.

What causes too much glutamate? One contributing factor is consuming processed foods that are made with modified, free form glutamate. For example, glutamate is used to make MSG (or monosodium glutamate), a synthetic chemical that is added to many modified foods to increase their savory, appealing taste.

Studies have found that MSG and many other modified ingredients that are made from broken-down proteins seem to have the potential to cause side effects in certain people, although the extent of MSG’s harmful effects have been debated for decades.

What does too little glutamate do? Too much of this amino acid may be a problem, but so is too little. That’s because it is not only an important neurotransmitter, but also is involved in many functions of the digestive system and immune system.

Some research shows that glutamate levels are lower in adults with schizophrenia and certain other major psychiatric disorders. However, on the flip side, levels may be too high in children and adults with certain neurological conditions.

Health Benefits

Glutamate is found in high concentrations in the brain, along with in the gut and muscles. The human body produces it, and it plays an essential role in normal body functioning.

Some of the most important glutamate functions and benefits include:

Acting as an important neurotransmitter in the brain — it has excitatory effects, meaning it makes neurons more likely to fire
Serving as a precursor for the neurotransmitter GABA (gamma-aminobutyric acid), which is the main inhibitory neurotransmitter in the central nervous system
Supporting growth and development of the brain
Helping cells survive and differentiate and supporting formation and elimination of nerve contacts (synapses)
Supporting cognitive functions, including learning and memory, as well as neuroplasticity (the ability of neuronal connections to strengthen or weaken depending on experience, learning and memory)
Helping with cellular energy production
Facilitating protein synthesis
Supporting the “gut-brain connection” by activating the vagus nerve and serotonin secretion in the gut
Stimulating gut movement by increasing gut serotonin levels
Producing the antioxidant glutathione
Regulating inflammatory processes
Helping with bone formation and muscle tissue repair

Supports Cognitive Functions

Neurotransmitters are brain chemicals that communicate information throughout the brain and body. Glutamate is an excitatory neurotransmitter, which means it has stimulating actions and makes neurons more likely to fire.

Research shows that it is involved in many aspects of normal brain function. It is important for memory, learning capacity, mood stabilization and potentially overcoming effects of brain injuries.

What does glutamate do to neurons? Its signaling function works by binding to and activating certain receptors, including the kinds called NMDA, AMPA/kainate and metabotropic receptors.

Glutamate signaling has been shown to be critical in brain regions, including the cortex and hippocampus, which are responsible for high level functions like planning and organization, as well formation of new memories and regulation of emotions. Glutamate signaling also affects glial cells, which provide support and protection of neurons.

Risks and Side Effects

The World Health Organization has stated that glutamate is non-hazardous when used as an additive in foods. According to Yale Scientific, the FDA and the Food and Agriculture Organization of the United Nations both agree. However, there is some evidence that it may have the potential to be damaging to nerve cells and the brain when not processed normally or not present in normal amounts.

What are symptoms of high glutamate? Signs that someone may be sensitive to this amino acid include burning sensations or tingling of the skin, headaches or migraines, nausea and digestive upset, and chest pains.

Does glutamate cause anxiety? It’s possible. There’s evidence from some studies that high levels in the brain may be a contributing factor to many mental health conditions, including anxiety, depression, epilepsy, bipolar disorder, migraines, Huntington’s disease, memory loss, multiple sclerosis, ADHD, autism and others.

Some research suggests that children with autism spectrum disorder and ADHD may be more sensitive to the effects of glutamate, although this is still up for debate.

What causes glutamate excitotoxicity? Excitotoxicity refers to the pathological process by which neurons are damaged and killed by the overactivations of receptors, such as the NMDA receptor and AMPA receptor.

Some studies have found that excessive accumulation of glutamate in the synaptic cleft has been associated with excitotoxicty. Accumulation of this non-essential amino acid is now associated with disruption of normal transport systems and uptake mechanisms in the brain, leading to neuronal injury, trauma and associated metabolic failures.

High glutamate in proportion to another neurotransmitter called GABA may contribute to a number of mental health conditions. GABA is a calming neurotransmitter that can have anti-anxiety effects, while glutamate is more stimulating. An imbalance in these two neurotransmitters is suspected to be at play in some neurological conditions.

Food Sources

Believe it or not, glutamate has been used as food additive for enhancing flavor for over 1,200 years. In places such as Japan, fermenting and aging foods like soybeans has long been used to increase glutamate concentration and enhance umami flavor.

Over the past 100 years, more and more glutamate additives have been widely used in the food supply and mass marketed.

This amino acid is found is both natural and processed foods. Not all glutamate foods are unhealthy or problematic for the majority of people.

In fact, many (like bone broth, meat and some vegetables) are nutrient-dense. It’s all about striking a balance with how much you consume and being aware of your personal tolerance.

Naturally high-glutamate foods include:

Foods that have been fermented, aged, cured, preserved or pressure cooked. These include aged cheeses and cured meats
Bone broths
Slow-cooked meats and poultry
Eggs
Soy sauce
Soy protein
Fish sauce
Certain vegetables, like mushrooms, ripe tomatoes, broccoli and peas
Walnuts
Malted barley

As mentioned above, glutamate derivatives are also added to many foods to give them a pleasing “umami” taste, which is described as a combination of sweetness, saltiness, sourness and bitterness. This non-essential amino acid goes by many different names when listed on ingredient labels.

What foods increase glutamate in the brain the most?

If you’re looking to avoid free glutamate, check for the ingredients below, which all contain modified forms of glutamate.

These ingredients are found in many packaged foods, including meat substitutes, dairy products, cheeses, jams, yogurts, desserts, milk substitutes, chips, instant noodles, etc.:

MSG
Monopotassium glutamate
Wheat gluten
Dairy casein
Maltodextrin
Milk powder
Modified food starch
Soy sauce
Corn starch and corn syrup
Yeast extract
Hydrolyzed proteins
Textured proteins, including soy protein, soy isolate and soy concentrate
Meat flavorings (chicken, beef etc.)
Dough conditioner
Barley malt
Calcium caseinate
Rice syrup and brown rice syrup
Xanthan gum
Autolyzed yeast
Gelatin
Pectin
Whey protein isolate and concentrate
Carrageenan
Bouillon, used to make quick stocks
Many “flavors” or “flavoring” like natural vanilla flavor
Citric acid

What MSG does to your body?

MSG that is made from glutamic acid has been controversial for years. MSG seasoning is produced through a fermentation process and brings a savory taste to dishes.

Some evidence has linked MSG consumption with health problems like headaches, numbness/tingling, weakness, flushing, hormonal imbalances, high blood pressure, GI issues, cravings and weight gain.

Some people appear to be more sensitive to the effects of MSG than others. The manufacturing process of MSG creates contaminants that seem to trigger reactions in certain people (but not all). It’s theorized that eating large amounts can cause small amounts of glutamate to cross the blood-brain barrier, interacting with the neurons to cause swelling and cell death.

On the other hand, MSG and other related glutamates are generally perceived by the scientific community to be harmless. Plus, pairing MSG with a small amount of salt in some foods is estimated to help cut down on sodium intake, which some research suggests could be beneficial for certain people.

Overall it’s best to limit or avoid top foods with MSG, which include:

Potato chips
Fast food
Seasonings
Convenience meals
Cold cuts
Iced tea mixes
Salty snacks
Instant noodles
Sports drinks
Processed meats
Canned soups
Soy sauce
Broth/bouillon
Salad dressings
Crackers

How to Lower It in the Diet

The most practical step to take if you are sensitive to glutamate and suspect you have high levels, or if this applies to your child or a family member, is to eliminate sources of added free glutamate.

Glutamate supplements are not recommended for most people because the majority of people get enough from their diets, plus the human body makes some on its own.

However, in some cases a glutamate supplement may be used by people who suffer from protein deficiency.

What increases glutamate in your diet?

As mentioned above, processed foods that are modified to taste better are the biggest source of free glutamate. This means cutting out processed and packaged foods from your diet and opting for whole, unmodified foods instead is the best way to bring your level back within the normal, healthy range.

People who appear to be particularly sensitive to this amino acid’s effects may also need to be careful about consuming natural sources of free glutamate, such as certain high-protein foods that may otherwise be healthy for people who are less sensitive.

In addition to monitoring your intake of foods that provide this amino acid, it’s beneficial to increase your intake of anti-inflammatory foods, since these may help offset the effects of excess glutamate to some extent. Some examples of anti-inflammatory foods to include in your diet regularly are:

Dark leafy greens
Other vegetables, including cruciferous veggies, beets, celery, peppers, etc.
Berries
Spices like turmeric and ginger
Chia seeds and flaxseeds
Wild-caught fish like salmon, which provide omega-3s
Coconut oil and olive oil
Probiotic foods, like yogurt, kefir, etc.

Another method of balancing the ratio between glutamate and GABA is using GABA supplements. Chris Masterjohn, Ph.D, recommends taking 750 milligrams of GABA before meals, one to three times daily, in order to offset effects of glutamate sensitivity. While this protocol hasn’t yet been extensively studied or proven to work, considering it’s debatable whether GABA supplements are effective, there’s little risk involved in trying.

Final Thoughts

Glutamate is the most abundant amino acid available in the human diet. It’s a non-essential amino acid found in a variety of foods, including both plant- and animal-derived foods like meat, eggs, broths, soy, mushrooms and others.
Too much of it may be a problem, but so is too little. That’s because this amino acid is not only an important neurotransmitter, but also is involved in many functions of the digestive system and immune system.
Too much (especially in relation to GABA) may lead to overexcitation of receiving nerve cells, which has been linked to cell damage and death — the reason that glutamate is referred to as an “excitotoxin.”
Processed foods that are modified to taste better are the biggest source of free glutamate, including those with MSG. Some studies have linked MSG to weight gain, high blood pressure, asthma attacks, metabolic syndrome and short-term side effects in those who are sensitive.
Cutting out processed and packaged foods from your diet and opting for whole, unmodified foods instead is the best way to bring your level back within the normal, healthy range.