SAN DIEGO -- Veterans with Gulf War Illness experienced significant improvement in migraine symptoms after following a diet low in glutamate, a component of flavor enhancing food additives commonly found in processed foods, according to new research presented by Georgetown University and American University scientists. Brain scans also revealed decreased cortical thickness in patients on the diet — providing evidence, for the first time, that the improvement in symptoms was linked to measurable changes in the brain.
The findings point to a potential low-cost treatment option for veterans struggling with chronic neurological symptoms since the 1990-1991 Gulf War. Because cortical thickening has previously been linked to migraines more broadly, the study also suggests that a low-glutamate diet could provide relief to a much larger population.
"This was exciting, because it shows that the brain itself is responding and changing," said the study's senior author Ashley VanMeter , PhD, professor of neurology at Georgetown University School of Medicine . "This isn't a psychological reaction. These are actual changes in the brain related to the diet."
The findings were presented November 16 during at the annual meeting of the Society for Neuroscience in San Diego.
Gulf War Illness is a chronic condition affecting more than a quarter of veterans who served in the first Gulf War. It can cause an array of debilitating musculoskeletal, gastrointestinal, and neurologic symptoms, including migraines, and is thought to be caused by exposure to neurotoxic chemicals during the war.
Glutamate, which is found in high levels in processed foods and also occurs naturally in some foods like tomatoes and mushrooms, is the most abundant excitatory neurotransmitter in the nervous system, where it is known to play a role in mediating pain.
The new research, which was funded by the Department of Defense (DOD W81XWH1710457), grew out of a collaboration with Kathleen Holton, PhD, MPH, a nutritional neuroscientist at American University, who developed the low-glutamate diet and has been researching it as an approach to managing neurological conditions. The low-glutamate diet is currently being studied in a large multi-site clinical trial to confirm these findings in patients with Gulf War Illness.
"This was an exciting opportunity to see if we can do something for these veterans who have literally been suffering since the 1990s," VanMeter said.
For the study, researchers first used brain scans to compare differences in cortical thickness between patients with Gulf War Illness and a group of healthy patients. Those with Gulf War Illness had a significantly thicker right visual cortex. This group was also significantly more likely to report experiencing migraines than the healthy group.
Then in a follow-up study, researchers had patients with Gulf War Illness follow a low-glutamate diet. After a month, scans showed that cortical thickness in this group was significantly reduced.
Researchers also observed a "big, big decrease" in migraines and headaches, VanMeter noted.
"More than half of the Gulf War veterans had migraines before the diet, and that dropped to under 20% after following the diet for one month," she said. "So it was a very significant drop."
Holton said the findings support the team's theory that glutamate may be contributing to the symptoms of Gulf War Illness by driving excitotoxicity, neuroinflammation, and oxidative stress in the brain; and that these three processes then continue to trigger each other in an ongoing cycle.
"We think this is one of the reasons people who are susceptible to dietary glutamate tend to have prolonged symptoms over time," she explained.
The researchers noted that other symptoms also improved in the low-glutamate group, including significant reductions in widespread pain, fatigue, mood issues, and cognitive dysfunction. The team plans to publish additional findings from their current ongoing study.
While not universal, thickening of the visual cortex, part of the brain linked to vision, is common among migraine sufferers, especially those whose migraines occur with aura, or visual disturbances.
That raises the question of whether a low-glutamate diet could also benefit the wider population of migraine sufferers, potentially even as an alternative to medication, VanMeter said.
"This is a very doable diet," she said. "It's a healthy diet, it's not that hard to follow, and it's a very low-cost way of treating what for some individuals is a chronic and debilitating condition."
Holton noted that the study also adds to a growing body of evidence about how ultra-processed foods impact health.
"This speaks to the fact that diet can not only make us sick, but can also acutely treat our symptoms," she said.
Follow-up research is underway to expand on the findings and investigate if weakening of the blood-brain barrier plays a role in glutamate sensitivity.
