Gulf War Illness is characterized by a range of symptoms, including chronic fatigue, cognitive problems, pain, and gastrointestinal symptoms—which persist up to 30 years after deployment—affecting quality of life. This study, which builds on earlier pilot studies by the same team, further supports the link between gut microbiome imbalances and Gulf War Illness.

Saurabh Chatterjee, MSc, Ph.D., corresponding author and professor in the Joe C. Wen School of Population & Public Health at the University of California, Irvine, and his colleagues found distinct differences in the composition of gut bacteria between people with Gulf War-related illness and those who did not.

The study used stool samples and data from the Multidimensional Fatigue Inventory from 89 Gulf War veterans, 63 of whom served as the study group with Gulf War-related illnesses and 26 as controls who did not have Gulf War-related illnesses.

The study was published in International Journal of Environmental and Public Health Research.

Interestingly, veterans with Gulf War disease had a noticeably different mix of gut bacteria, often expressed as Bray-Curtis beta diversity, compared to those without disease. This mix is ​​important because it affects gut, immune, and brain health.

Specifically, Gulf War veterans had higher levels of certain bacteria that are typically less beneficial, such as Blautia, Streptococcus, Klebsiella, and Clostridium, and lower levels of beneficial bacteria, such as Akkermansia and Bacteroides.

The team used advanced machine learning algorithms to identify two bacteria called Coprococcus and Eisenbergiella as critical predictors of Gulf War Illness. The results were impressively accurate—in nearly 75% of cases, the algorithm was able to correctly distinguish veterans with Gulf War Illness from those without, using these two bacteria.

Furthermore, higher fatigue scores in affected veterans were associated with altered gut bacterial diversity, particularly species such as Lachnospiraceae and Blautia.

These findings not only advance our understanding of Gulf War veterans’ disease, but also suggest potential therapeutic targets that focus on the veterans’ gut microbiome to alleviate specific disease symptoms.

“This study offers hope that new treatments for Gulf War-related illnesses that specifically target gut health could potentially improve the quality of life for veterans who have been suffering for decades,” said Chatterjee, who is also based at the University of California, Irvine School of Medicine and the Veterans Affairs Medical Center in Long Beach.

“We’ve only just gotten to the bottom of our understanding of the link between microbiome imbalance and chronic fatigue, but we see this as a breakthrough that leads to more in-depth research on Gulf War veterans.”