The Low Glutamate Diet Effectively Improves Pain and Other Symptoms of Gulf War Illness

Abstract

Gulf War Illness (GWI) is a multisymptom disorder including widespread chronic pain, fatigue and gastrointestinal problems. The objective of this study was to examine the low glutamate diet as a treatment for GWI. Forty veterans with GWI were recruited from across the US. Outcomes included symptom score, myalgic score, tender point count, dolorimetry and the Chalder Fatigue Scale. Subjects were randomized to the low glutamate diet or a wait-listed control group, with symptom score being compared after one month. Subjects then went onto a double-blind, placebo-controlled crossover challenge with monosodium glutamate (MSG)/placebo to test for return of symptoms. Symptom score was compared between diet intervention and wait-listed controls with an independent t-test and effect size was calculated with Cohen’s d. Change scores were analyzed with Wilcoxon Signed Rank tests. Crossover challenge results were analyzed with General Linear Models and cluster analysis. The diet intervention group reported significantly less symptoms (p = 0.0009) than wait-listed controls, with a very large effect size, d = 1.16. Significant improvements in average dolorimetry (p = 0.0006), symptom score, tender point number, myalgic score and the Chalder Fatigue Scale (all p < 0.0001) were observed after the 1-month diet. Challenge with MSG/placebo resulted in significant variability in individual response. These results suggest that the low glutamate diet can effectively reduce overall symptoms, pain and fatigue in GWI, but differential results upon challenge suggest that other aspects of the diet, or underlying differences within the population, may be driving these changes. Future research is needed to identify potential nutrient effects, biomarkers, and underlying metabolic differences between responders and non-responders.

Scope of Use and Effectiveness of Dietary Interventions for Improving Health-Related Outcomes in Veterans: A Systematic Review

“…Most studies were conducted in the USA ( n = 15 of 17), and there was one each from Australia and Taiwan. Of these, ten were randomised controlled trials (RCTs) [ 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ], three were dietary interventions in usual care that were evaluated using routinely collected data accessed retrospectively [ 36 , 37 , 38 ], three were single arm interventions [ 39 , 40 , 41 ], and one was a cohort study [ 42 ]. The trial intervention duration ranged from 1 to 24 months.…”

“…In a population of veterans with Gulf War Illness (GWI), a low-glutamate diet was implemented to examine its effectiveness on symptomatology [ 42 ]. A study in participants with amnestic mild cognitive impairment compared a low-saturated-fat/low-glycaemic-index diet to a high-saturated-fat/high-glycaemic-index diet [ 27 ].…”

“…One study reported that 87% of the intervention group, which received weekly mailings and phone calls, and 55% of the comparison group, which received “usual care” from a hospital clinic, attended 8-week follow-up [ 28 ]. Another study using dietary training via Skype reported that 87% completed the trial, and 74% completed the 3-month follow up [ 42 ]. Of these, 88% were still following the diet.…”

Exercise modifies glutamate and other metabolic biomarkers in cerebrospinal fluid from Gulf War Illness and Myalgic encephalomyelitis / Chronic Fatigue Syndrome

“…Instead, elevated glutamate may have been the result of an interaction of exercise with as yet unknown pathological mechanisms active in the STOPP phenotype. Glutaminergic excitotoxicity is highly relevant for interpreting the benefits of a low glutamate diet in GWI and irritable bowel syndrome [ 61 – 63 ].…”

Could Free Glutamic Acid in Processed Food be the Surprise Ingredient in Mood Disorders?

“…Holton and others have demonstrated the effectiveness of a low free-glutamate diet in reducing the symptoms Of Gulf War illness --symptoms that include mood disorders. 2 The possibility that free glutamate consumed in processed foods causes or exacerbates mood disorders might hold the key to a better understanding and treatment of these mental health problems.…”