The textbook words swam before Emily’s eyes, refusing to stick in her memory. At 42, she had finally returned to college to study advanced psychology, but something wasn’t right. Despite hours of determined study, crucial details kept slipping away.

She would walk into a room and forget why, misplace her carefully organized notes, and draw frustrating blanks during exams. Simple tasks that had once been routine now required intense concentration. Emily wondered why she felt too old for this.

But the truth behind her mental fog had nothing to do with age—and everything to do with what was in her meals.

Emily thought she ate pretty healthfully, focusing on plenty of protein and vegetables every day. A chance conversation about diet with a friend led her to discover that her “healthy” meals—the convenient frozen dinners, ready-made sauces, protein bars, and occasional takeout that fueled her busy student-mom life–harbored hidden ingredients that were quietly sabotaging her learning ability and brain function.

Hidden Ingredients That Affect The Brain

To function properly, the brain relies on a balance between two main chemicals: glutamate—the main excitatory neurotransmitter, meaning that it stimulates nerve cells, making them more likely to fire an electrical signal—and gamma-aminobutyric acid (GABA), the main inhibitory neurotransmitter, meaning that it works to calm down or inhibit nerve activity.

Glutamate is both an amino acid (the building block of protein) and the most abundant neurotransmitter in the brain. It plays a vital role in health, responsible for about 40 percent of our nervous system activation and mood regulation. However, too much glutamate from food can cause overstimulation, leading to brain inflammation and various symptoms.

Kathleen Holton, a nutritional neuroscientist at American University in Washington, focuses her work on the effects of dietary excitotoxins—chemicals that “excite” neurons in the brain. Holton told The Epoch Times that certain amino acids, such as glutamate, found both naturally and artificially in modern foods, directly act on receptors in the brain.

Overconsumption of artificially made glutamic acid can cause sensitivity in some people, according to Holton. Reactions occur when the amounts ingested exceed an individual’s tolerance.

The hippocampus, the brain’s center for memory formation, is particularly vulnerable to manufactured glutamate found in processed foods. Research shows that chronic stress further increases glutamate release in the hippocampus, compounding learning and memory deficits.

Symptoms seen in research include headaches and problems with focus and attention. Holton said these cognitive issues can be frustrating and lead to irritability and mood problems when people can’t think clearly.

The Inflammation Connection

An individual’s inflammatory load—the overall level of chronic inflammation in the body—can significantly influence their sensitivity to glutamate. Inflammation can cause the body to produce more glutamate. This is why glutamate sensitivity can develop in someone previously unaffected after a major life stressor, such as psychological trauma, stroke, or physical brain injury.

Because foods with glutamate-rich ingredients can be addictive, stimulating the brain via tongue receptors and encouraging overconsumption, people may not readily connect their health issues to these ingredients. Many people love and crave them, as they “excite” neurons on the tongue and in the brain.

However, while glutamate activates taste receptors, it does not have the same neuroexcitatory effects on the tongue as it does in the brain. In the brain, chronic inflammation can weaken the blood-brain barrier, allowing excessive glutamate to accumulate, overstimulate, and potentially damage neurons. On the tongue, glutamate receptors simply enhance flavor perception without causing harm.

Natural Versus Manufactured Glutamate

In 1908, renowned Japanese chemist Kikunae Ikeda discovered glutamate while studying seaweed broth (kelp), identifying the savory taste we now call umami.

Food companies can make glutamate using acids by breaking down cells with enzymes or through fermentation.

Today, glutamate is most often associated with the flavor enhancer monosodium glutamate, produced through a fermentation process. However, Holton said most people’s exposure to the Western diet comes from manufactured free glutamate (MfG), also found in flavor-enhancing or sweetening food additives.

There are distinct differences in how natural and manufactured glutamate affects the brain and body.

Natural glutamic acid (L-glutamic acid) occurs in many whole foods we eat regularly, such as tomatoes, mushrooms, and aged cheeses. In these foods, it’s bound to other proteins, meaning that our bodies break it down and metabolize it gradually. When we consume glutamic acid in whole foods, our bodies can effectively regulate how it’s processed, allowing us to enjoy its natural umami flavor with minimal negative effects.

In contrast, manufactured glutamic acid exists in a different form called D-glutamic acid, commonly found in processed foods. Unlike its natural counterpart, this form exists in an “unbound” or “free” state. This means it can deliver much higher concentrations of glutamate to our system at once, potentially leading to rapid overstimulation in the brain.

The Hidden Names of Glutamate

Many products that involve the chemical processing of proteins that produce the manufactured glutamate ingredient are not clearly labeled as such, as there is no legal requirement for that in the United States. Katherine Reid, a biochemist and author of “Fat, Stressed, and Sick,” lists 40-plus food ingredients used in processed and ultra-processed foods containing MfG in her book.

Yeast extract, an ingredient in which proteins are physically or chemically broken down (e.g., modified by hydrolysis or autolyzed), is another plentiful source of manufactured glutamate. Other names include hydrolyzed proteins, maltodextrin, and soy protein isolate. Especially high levels are found in seasonings and condiments.

While the food industry holds that glutamate is safe in moderate amounts, growing concerns suggest that chronic exposure to such additives in ultra-processed foods may contribute to cognitive decline and other brain-related health issues.

The easiest way to reduce glutamate consumption is to avoid food products that have it.

Look for a short ingredients list free from complex-sounding names that your grandmother wouldn’t normally use in home cooking. Anything containing “hydrolyzed protein,” “autolyzed,” and any protein “isolate” and maltodextrin, to name just a few, will have glutamate.

Reversing Cognitive Decline

Many people initially fear their cognitive decline is age-related, but within one to four weeks of removing the processed food ingredients from their diet, some see remarkable improvements in memory, mood, and post-traumatic stress disorder symptoms, according to Holton.

She suggests avoiding or checking ingredient labels on ultra-processed foods, especially condiments, seasonings, ready-made meals, packaged meats, and protein powder or bars, as much as possible.

Holton suggests asking yourself, “Is this what the food/ingredient looks like in nature?” Alternatives found in organic products often contain fewer additives.

If quitting ultra-processed foods cold turkey isn’t feasible, start by removing processed plant protein foods, commercial sauces, soups, and condiments from your diet, as they are among the biggest sources of glutamate.

Other brain-healthy dietary suggestions include daily meals rich in omega-3 fats, such as salmon. Adding plenty of leafy green vegetables and blue fruits, such as blueberries, provides plenty of antioxidants to fuel the brain.

Emily’s Path to Recovery

Emily, willing to do anything to improve, agreed to switch her diet for four weeks and see how she felt.

Even though figuring out what not to eat was difficult—because glutamate is not required to be listed under that exact name on product labels—she became a “food detective” to remove the suspect ingredients. She stuck with it.

Emily was strict in following a low-processed glutamate diet, and as a result, she experienced transformative changes. Her focus and memory sharpened, and even her mood greatly improved.

She reconnected with her studies and enjoyed spending time with her family. She never went back to eating the same way as before—she felt too good to stop.