“A key neurotransmitter in central sensitization is glutamate; which is the most ubiquitous excitatory neurotransmitter in mammals. In animal models, experimentally high glutamate levels have been shown to overexcite a neuron to the point of death.”1
Research shows a relationship between consumption of dietary glutamate and increased symptoms of fibromyalgia (FM) and irritable bowel syndrome (IBS). Study subjects maintained a daily symptom checklist throughout a four-week diet and two-week double-blind placebo-controlled crossover challenge. Significant decreases in symptoms were seen in participants who received the placebo rather than the dietary glutamate.
Fifty-seven people diagnosed with both FM and IBS participated in a 4-week diet that omitted dietary additive excitotoxins, including monosodium glutamate (MSG) and aspartame. The subjects received a group diet training session prior to the study and had access to professional dietary counseling throughout the study. They also maintained food/symptom journals during weeks one and four, and also Monday through Wednesday of the second part of the study.
Thirty-seven people completed the four-week diet and were eligible for the next portion of the study. Of those patients, 84% reported more than 30% of their symptoms were resolved. Eight participants reported fewer than 12 symptoms by the end of the four-week diet and on average 11 symptoms remitted in the subjects.
The second part of the study included a double-blind placebo-controlled challenge with MSG. The subjects received MSG or placebo for three consecutive days each week. Each subject tracked their symptoms daily on a checklist, which consisted of 28 symptoms of FM, IBS, and four ‘Chinese Restaurant Syndrome’ symptoms. All fibromyalgia symptoms were reported more frequently during the MSG challenge in the second part of the study. Severe fatigue was reported by 70 percent of the participants receiving MSG while only 30 percent of those receiving the placebo reported this side effect. All IBS symptoms were reported more frequently during the MSG challenge, except for straining during BM which remained the same as reported by 30 percent of the subjects. Significant differences were seen in abdominal pain and diarrhea between the MSG and non-MSG groups. Only 9% of those receiving the placebo reported these symptoms, while 32% of MSG recipients reported abdominal pain and diarrhea.
Conclusion: Patients whose symptoms improved during the (first part of the study) four-week diet saw the symptoms return when they received MSG in the second part of the study. Clinically significant symptom improvement was reported by 84% of the participants who completed the four-week diet and suggests a diet free of excitotoxin is not only feasible for individuals, but that it improves symptoms of FM/IBS. This indicates excitotoxins may evoke symptoms in some FM/IBS patients.
1. Holton, K, Taren D, Thomson C, Bennett R, Jones K. The effect of dietary glutamate on fibromyalgia and irritable bowel symptoms. Clin and Exper Rheumatology. 2012 Vol 30 No. 6. Suppl 74.