Updated: Feb 2
It may be surprising that foods such as bone broth and sauerkraut are so popular and among the most recommended healthy additions to your diet but could actually have a dark side. If you have any sort of digestive distress, you’re likely to have heard of the power of bone broth, gelatin and fermented foods. And protein drinks have moved beyond usage by athletes to become mainstream as a portable snack and sometimes-meal for busy people. A common ingredient in these foods is glutamic acid, also known as glutamate. And for certain people, it may increase anxiety. Understanding its effects can be a game changer for many who struggle.
What Is Glutamate and What Is Its Role In The Body?
Glutamate is the most common amino acid (a protein building block) in the body. We each have about four pounds of it. It’s considered non-essential because the body can make it if needed, but it’s very easy to get enough of it from many plant and animal food sources. The term glutamate is often used interchangeably with glutamic acid.
Glutamate is also a neurotransmitter that acts within the brain and central nervous system to enhance neuroplasticity. Neurotransmitters are chemical messengers between nerve cells (neurons). Specifically, glutamate helps the brain to change and grow as it performs cognitive functions. Its classified as a an excitatory neurotransmitter, as opposed to an inhibitory one. It is actually the brain’s primary excitatory neurotransmitter. Excitatory neurotransmitters have stimulating effects on the nerve cells, meaning they increase the likelihood that the nerve cell will send information. Dysfunctions in the glutamate system have been linked to many psychological and neurodegenerative disorders.
The Glutamate – GABA Balance
GABA (gamma-aminobutyric acid), on the other hand, is classified as an inhibitory neurotransmitter that can prevent the transmission of the nerve message. GABA inhibits brain activity, resulting in a relaxed state. GABA and glutamate have an intricate relationship that should ideally be balanced in the brain so that a person is neither overly excited nor overly calm.
Adding to the complexity is that glutamate is the precursor to GABA. An enzyme called GAD (glutamic acid decarboxylase) triggers the creation of GABA from glutamate. Conversely, GABA can turn back into glutamate if needed.
When Imbalance Occurs
The balance of these two neurotransmitters is important. Excess excitability, termed “excitotoxicity”, can occur when the level of glutamate is too high. There are two main causes of this:
Too much glutamate has accumulated in the brain, or
Glutamate receptors have become overly sensitive
Symptoms that could indicate a glutamate imbalance include anxiety, depression, restlessness, headaches, insomnia, fatigue, and an increased sensitivity to pain.
At an extreme, and particularly when glutamate receptors are severely dysfunctional, psychological or neurodegenerative disorders can occur, including:
Chronic fatigue syndrome
The Causes of Excess Glutamate
Typically, brain tissue accumulates glutamate, and there are safeguards that keep it from reaching dangerous levels. First, there are transporter molecules that can move it out of the brain. The brain also has a border of cells called the blood-brain barrier that prevents glutamate in the bloodstream from entering the brain. And lastly, when the system is functioning properly, excess glutamate can simply convert to GABA. But there are many situations where the system does not function as it’s supposed to, including:
An autoimmune reaction to GAD, causing a poor conversion of glutamate to GABA
Vitamin B6 deficiency, which is an essential cofactor in the conversion of glutamate to GABA
Traumatic stress can elevate glutamate
Mood-altering substances can disrupt the GABA-glutamate balance
Excess caffeine can increase glutamate activity at the expense of GABA
Brain injury or stroke can cause excessive glutamate in the injured area
Glutamate In Food
It is a hotly debated topic as to whether consuming food containing glutamate can affect a person’s GABA-glutamate balance. Let’s first discuss how glutamate appears in food.
There are many foods that naturally contain glutamate, including:
Glutamate can also be added to foods as MSG (monosodium glutamate), a controversial flavor enhancer.
It’s also important to understand the two different forms of glutamate, bound and free. Bound glutamate is attached to other amino acids, whereas free is not attached. Bound glutamate has no flavor and is digested and absorbed slowly. Free glutamate does have a savory or umami flavor and it digests quickly, leading to spikes in the bloodstream
Bound glutamate is what’s naturally in foods, but free glutamate is released if a food that contains bound glutamate has been adulterated, cured or fermented. MSG is a processed food additive that is pure, free glutamate, but it is not synonymous with free glutamate. When a food has free glutamate, it doesn’t necessarily mean that it contains MSG.
Issues of MSG Versus Free Glutamate
MSG has clearly been shown to be toxic. The Journal Toxicology Mechanisms and Methods reported in its May 2019 issue that several studies concluded “MSG has toxic effects on fetal development/fetus in children, adolescents, and adults. Physiological complication associated with MSG toxicity are hypertension, obesity, gastrointestinal tract troubles, and impairment of function of brain, nervous system, reproductive, and endocrine system.” For many people, the reported reactions to added MSG are unmistakable. They can experience a myriad of different symptoms including migraines, flushing, and even heart palpitations. Because of this, some restaurants and other companies have made an effort to decrease the use of MSG in their prepared foods; however, it is still a common additive.
As for free glutamate in foods causing unwanted symptoms, science has not confirmed a cause and effect. Regardless, some people still seem to react to foods that have high levels of free glutamate such as bone broth, gelatin, cheeses, and protein drinks even though they don’t have the diagnosed conditions that cause excess glutamate. Reported symptoms can be milder than those experienced with MSG but are still concerning and may include:
Middle of the night wakening with a racing heart
Exacerbated pain in pre-existing chronic pain
Because the cause cannot be directly identified in research studies, it’s a controversial topic among doctors and scientists. To be clear, there is no conclusive research that links free glutamate to adverse reactions in the general population.
In many cases, reported glutamate sensitivity coincides with other health issues, such as gastrointestinal disorders or autoimmune diseases. I suspect that glutamate is not the primary cause of sensitivity, but rather a secondary reaction caused by a related condition. The so-called condition of “leaky brain syndrome”, where the blood brain barrier fails to keep out certain substances is related to “leaky gut syndrome”, a common condition among sufferers of gastrointestinal disorders and autoimmune diseases.
The high levels of free glutamate in certain foods may be enough to overwhelm someone with leaky brain syndrome. For example, the amount of glutamate in bone broth increases with the length of time it’s cooked. Cheeses and other fermented foods as well as protein drinks with added isolated proteins like whey protein have a higher concentration of free glutamate. The elevated levels in these foods may trigger those who are sensitive while being harmless to those without specific conditions.
While MSG has been implicated in psychiatric distress such as anxiety, clearly more research is needed to determine if glutamate’s mechanism extends beyond excitatory neurotransmission in central processes. If you experience anxiety or any of the symptoms described above, I recommend you consider glutamate because of its increased presence in our diets. Do you notice feeling worse after supplementing with gelatin or collagen? Do you experience insomnia after consuming fermented foods or protein drinks?
Given the clear identification of glutamate-containing foods, try eliminating sources you consume often or in abundance, and certainly avoid foods with added MSG. It shouldn’t require more than a week or two to reveal a correlation. And if you notice a link, it doesn’t necessarily mean that glutamate is a lifelong issue. If glutamate is a probem, I would encourage you to seek out the help of a functional doctor to understand whether you have conditions that may increase glutamate sensitivity.
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