Mechanisms of Gulf War Illness

Since 2001, more than 2.2 million US veterans have served in Operation Enduring Freedom (OEF) in Afghanistan and Operation Iraqi Freedom (OIF) in Iraq. The Gulf Registry of the VA Environmental Epidemiology Service identified the majority of these veterans as having chronic health complaints of undetermined etiology. Among the symptoms most frequently reported by veterans with Gulf War Illness (GWI) were chronic fatigue, frequent or persistent headache, frequent or persistent muscle or joint pain, and gastrointestinal (GI) symptoms. GI symptoms (e.g., diarrhea, bloating, and abdominal pain) reported by these veterans accounted for most complaints. Indeed, up to 33% of veterans with GWI suffer from chronic GI symptoms. We have shown that veterans with GWI and GI symptoms have increased intestinal permeability that drives GI symptoms (Zhang et al., 2019). Our research group recently completed a clinical trial demonstrating the effectiveness of oral glutamine supplementation in diarrhea-predominant IBS patients with increased intestinal permeability (Zhou et al., 2019). We now have obtained preliminary evidence that oral glutamine supplementation may restore intestinal permeability in veterans with GWI and GI symptoms. Based on these new findings, we hypothesize that oral glutamine supplementation will improve the Symptom Severity Scale and restore intestinal permeability in veterans with GWI and chronic GI symptoms. We propose to conduct a randomized, double-blind, placebo-controlled clinical trial studying oral glutamine supplementation compared to placebo in veterans with GWI and GI symptoms. The human GI tract is the major site of glutamine utilization in the body. Glutamine is a major energy source for rapidly dividing intestinal mucosal cells of the digestive tract. Glutamine helps to protect the lining of the GI tract. Its depletion results in epithelial atrophy and a subsequent increase in intestinal permeability. Glutamine supplementation has been shown to decrease bacterial translocation and intestinal permeability after intestinal injury. Glutamine supplementation has also been shown to decrease intestinal permeability and improve GI function in patients with Crohn’s disease, advanced esophageal cancer, or metastatic cancer undergoing radio chemotherapy. There are no published studies to date to support the use of glutamine for veterans with GWI and chronic GI symptoms. However, given our published studies, preliminary data demonstrating restoration of intestinal permeability with oral glutamine therapy, and the mechanisms of action of glutamine on the GI tract, research testing whether oral glutamine is an effective therapy in veterans with GWI is needed. Given that there are no effective treatments for these veterans and that current treatment approaches are far from ideal, this proposed clinical trial would be extremely important as it would not only have a beneficial impact on the health of many of our veterans, but also it would substantially reduce the negative economic effects on the VA Health Care System.