This clinical trial aims to confirm previous findings from a smaller study which demonstrated significant improvements in all symptoms among veterans with Gulf War Illness after one month on the dietary intervention. The main objectives of this study are: 1) to confirm previous findings of treatment response to the diet in a larger and more diverse group; 2) to examine how changes in the nervous system may be the reason for improvement; and 3) to identify markers which change in the blood after one month on the diet. Participants will have baseline measures collected and then will be randomized into the intervention or wait-listed control group, which they will follow for one month before being reassessed.

The rationale for the proposed research comes from observations from a smaller study which demonstrated profound widespread symptom improvements in veterans with Gulf War Illness (GWI) after one month on the diet. Improvements were noted in every symptom domain and included significant reductions in overall symptom number (with an average of 9 symptoms going away), reduced pain, fatigue, depression, anxiety, and post-traumatic stress disorder (PTSD); and concurrent significant improvements in cognitive function and quality of life. Results also demonstrated that those who improved on the diet had a significant reduction in peripheral inflammation, as compared to those who did not improve on the diet. These benefits have been observed without any negative side effects and the majority of participants continued to follow the diet three months after study completion, suggesting continued improvement and good feasibility. The objectives of this study are: 1) to evaluate whether or not the substantial benefits observed in the recently completed clinical trial hold in a larger group of more diverse veterans with GWI, and 2) to identify blood and/or brain measures which predict improvement on the diet. By recruiting a large group of veterans which are representative of those with GWI, the findings of this research should be applicable to the larger GWI community. The impact of this research could be quite profound, with the diet being a no-risk, low-cost treatment option with no side effects, which allows each individual veteran to take back control of his/her health. There are no direct risks to following the diet since it is a healthy whole-food dietary approach which provides all necessary nutrients. The potential benefits of the diet include improvement in GWI symptoms; improvement in quality of life, potential for improvement in other health markers related to diet (such as obesity, diabetes, cardiovascular disease, high blood pressure) and the possibility of benefit to the larger community. If positive results are confirmed in the proposed study, then the next step would be to teach all Veterans Administration (VA) dietitians how to administer the low glutamate diet so that all veterans have access to it, which should be possible within 1-2 years of the completion of this study.

Inclusion Criteria:

• Males and Females of all races and ethnicities who are ≤75 yrs of age
• Served in the 1990-1991 Persian Gulf War
• Fulfill both Center for Disease Control (CDC) and Kansas definitions of Gulf War Illness
• Stable medication regimen for ≥1 month and willing to keep medications and supplements stable throughout study participation

Exclusion Criteria:

• Recent substance use disorder (past year)
• Unwilling to stop using alcohol, tobacco (including vaping) and/or marijuana; or unwilling to change diet
• Diagnosed seizure disorder or severe asthma requiring past hospitalization
• Currently taking medication which affects glutamatergic or GABAergic neurotransmission (but can work with their physician to wean off of these medications prior to participating)