Effects of the low glutamate diet on PTSD symptoms and related biomarkers

Gulf War veterans commonly experience a multi-symptom disorder called Gulf War Illness (GWI) that sometimes co-occurs with post-traumatic stress disorder (PTSD). PTSD involves intrusive memories, avoidance of trauma-associated stimuli, and hyperarousal. Homocysteine, cortisol, and brain-derived neurotrophic factor may be important biomarkers for PTSD. Elevated homocysteine and low cortisol are commonly observed in PTSD, while conflicting evidence exists regarding brain derived neurotrophic factor. The low glutamate diet, which eliminates consumption of unbound glutamate to reduce excitotoxicity, has been shown to ameliorate GWI and PTSD symptoms. This study aimed to examine changes in serum homocysteine, cortisol, and brain-derived neurotrophic factor relative to PTSD severity in veterans with GWI after one month on the low glutamate diet. Data were analyzed for 33 veterans. PTSD scores significantly decreased post-diet. At baseline, homocysteine levels were higher in those with PTSD versus those without. There was no difference in cortisol or BDNF by PTSD status. There was a significant negative correlation between glutamate intake and change in cortisol, which held in a multivariable linear regression model, after adjustment for age, sex, and change in BMI. Cortisol increase was marginally associated (p=0.08) with PTSD reduction in a simple linear model. Change in BDNF and homocysteine were not significantly related to dietary adherence, nor were they significantly related to change in PTSD. Results suggest that the low glutamate diet effectively treats PTSD, and that dietary glutamate reduction and PTSD amelioration are associated with increased cortisol levels.