In 1991 Deb Mariya, a US Navy chaplain, deployed to Kuwait with Operation Desert Storm. She remembers black clouds of burning oil and sandstorms heavy with debris, as she told Gabby Landsverk of Business Insider. Her symptoms grew worse in the years after she came home, and the war stayed with her.

For more than three decades she lived with PTSD and fibromyalgia. A persistent brain fog kept her from thinking clearly. An autoimmune condition attacked her bones and joints. She needed a hip replacement and then could not heal properly, and the complications nearly killed her. She tried medication and acupuncture, and every other treatment she could find.

In 2024 she joined a trial of a diet.

An illness of the returned

According to the Department of Veterans Affairs, as many as 300,000 servicemembers who deployed to the Persian Gulf in the early 1990s, in Operations Desert Shield and Desert Storm, went on to report chronic health problems: fatigue, dizziness, headaches, joint pain, breathing trouble and memory loss. The cluster is called Gulf War Illness, a group of neurological complaints with joint problems, severe fatigue and mood disturbances among them. More than three decades on, it remains poorly understood.

A reflection, not a finding: states keep careful records of what they send to war and much poorer ones of what the war sends back. The veterans’ complaints never fitted any single ministry’s forms. Pain, exhaustion, forgetfulness and fear arrived together.

The evidence so far points to three processes feeding one another in the central nervous system: inflammation, excitotoxicity and oxidative stress. Kathleen Holton, a nutritional neuroscientist at American University in Washington, DC, calls this the “neurotoxic triad.” “Currently, we don’t have any medications that can treat the neurotoxic triad, but nutrition is perfectly suited to do just that,” she said.

The flavour that excites

Glutamate is an amino acid, one of the building blocks of protein. The body makes it, and it works as a neurotransmitter, carrying chemical messages through the nervous system. It is also in food. Since the early 1900s it has been added to food as monosodium glutamate, or MSG, which gives soups, snacks, cured meats and condiments an umami taste. “Glutamate is really the ultimate flavor enhancer in the diet,” Holton said. “It has the ability to excite neurons in your tongue.”

MSG has been linked to possible harms such as headaches and nausea. The FDA still considers it safe, partly because the blood-brain barrier stops glutamate in food from moving freely into the brain. Since the 1950s researchers have known that too much glutamate overexcites nerve cells and can damage or kill them. This is excitotoxicity, and it occurs in Parkinson’s disease, seizure disorders and some types of stroke.

Holton’s approach is called precision nutrition: the idea that some people are especially sensitive to particular compounds. After a brain injury or under stress, she argues, the barrier can become more permeable and let too much glutamate through. Glutamate also acts on the gut, which helps regulate neurotransmitters such as serotonin. She began working in this area as a graduate student around 2006. Few others were there, because neurology rarely studies food and nutrition science rarely studies the brain.

Forty veterans, then more

Her team’s diet does two things. It cuts food sources of glutamate, and it adds nutrients thought to calm inflammation and protect the brain, such as omega-3 fatty acids and fresh produce. In 2020 she published her first randomized controlled trial, in the journal Nutrients, on 40 veterans with Gulf War Illness. After a month, 73% had improved. On a symptom scale running from 0 to 33, the diet group averaged 11.7 and the control group 18.1, which the researchers called a “very large” effect. The published study then put participants through a double-blind, placebo-controlled challenge with MSG or a placebo to see whether symptoms returned. A later paper from the same pilot trial looked at anxiety, PTSD and depression.

In 2022 the Department of Defense gave Holton $6.4 million to study more than 100 veterans and a wider set of symptoms, including anxiety, depression and migraines. Hundreds of veterans have followed the programme since 2020. Up to 80% of them improve, according to their own reports and the team’s data: less chronic pain, fewer symptoms of depression, anxiety and PTSD, and sharper thinking. “The people who go onto this diet usually don’t come off it due to how much better they feel,” Holton said.

Pasta, cereal, beans

Wendy Fite, a 68-year-old Army veteran, scored about 40 on a PTSD assessment before the diet. The clinical threshold for diagnosis is 31 to 33. After 30 days her score had fallen by 30 points. Patients are usually counted as responding to treatment if their score drops by at least 10. She said her marriage improved and her mind felt sharper, and extensive cognitive testing by Holton’s team backed her up. Her biggest change was giving up pasta with cheese and tomato sauce, all high in glutamate and her staple through more than 70 marathons. She now eats beans as often as she can and takes cod liver oil. Two years after her study ended, she is still on the diet.

Robin Runkle, 60, an Army veteran from Ohio, cut out snacks and sweets and swapped cereal for yogurt. Her migraines went from several a week to “once in a blue moon.” She says her cholesterol, sleep and energy have all improved, and she spends the energy trying out recipes that fit the plan.

What remains unproven

The research on low-glutamate diets is still young, and individual stories are not proof. Deanna Kelly, a psychiatry professor at the University of Maryland who has published work on gluten-free diets, said there is precedent for diet affecting mental and cognitive health. “You can imagine in a brain that’s just on the edge of not working so well, there are a variety of manifestations that could be seen or worsened if you had inflammation,” she said. The open question is which compounds overload a sensitive brain. Holton’s studies on migraines and traumatic brain injuries are underway, and she hopes to run more veteran trials with the Department of Defense.

Mariya had been on the diet for a month when she went in for another surgery. This time, she said, she healed quickly and was walking within weeks. The fog lifted, and she had the energy to finish physical therapy. “I couldn’t believe it,” she said. “It was like an answer from God.”

She still has trouble getting around and will probably need a wheelchair one day. For now she can walk a lap around the block, climb a flight or two of stairs without losing her breath, and fetch her own mail. She wants to pass the diet on to her niece and to the home health aides the VA sends her. “It changed my life,” she said. “I wish I had found it sooner.”