Nutrient Intake as a Predictor of Health Improvement on the Low Glutamate Diet in Veterans With Gulf War Illness (GWI)

OBJECTIVES: Gulf War Illness (GWI) is a chronic multi-symptom condition characterized by widespread chronic pain, fatigue, cognitive dysfunction, and mood dysregulation. Previous research found that the low glutamate diet can reduce overall symptoms of GWI, including systemic inflammation. Micronutrients thought to be protective against excitotoxicity include riboflavin, vitamins B6, C, D, and E, and magnesium. This research examined whether changes in these micronutrients after one month on the low glutamate diet could predict overall improvement in GWI symptoms, after accounting for changes in free glutamate intake. METHODS: Forty veterans with GWI were recruited, and three-day food diaries, among other health measurements, were collected at baseline and after one month on the low glutamate diet. Nutrition Data Systems for Research was used to analyze dietary intake data. Dietary adherence was measured with a glutamate food frequency questionnaire (FFQ), and improvement on the diet was defined as being “much/very much” improved on the patient global impression of change scale (PGIC) or as having ≥30% of their symptoms remit. Logistic regression was used to model improvement on the diet, after adjusting for age, sex, change in FFQ, and change in BMI. RESULTS: Increased vitamin C intake significantly predicted improvement based on ≥30% symptom remission (p = 0.02). Similarly, increased intake of vitamin E and magnesium each marginally predicted improvement based on the PGIC (both p = 0.06). CONCLUSIONS: These findings suggest that in addition to reduction in free glutamate consumption, improved intake of vitamin C, vitamin E, and magnesium, may be driving improvement in neurological symptoms on the low glutamate diet. Further research is warranted. FUNDING SOURCES: This work was supported by the Office of the Assistant Secretary of Defense for Health Affairs, through the Gulf War Illness Research Program under Award No. W81XWH-17-1-0457.