New Study Shows Mediterranean Diet May Reduce or Prevent Post-Traumatic Stress Disorder (PTSD) Symptoms

According to a study published this week in the journal Nature Mental Health, a Mediterranean diet rich in vegetables, fruits, and fish may help reduce or prevent symptoms of post-traumatic stress disorder (PTSD).

The reviewed results are based on data from two studies—one in 2008 and another in 2013—in which tens of thousands of women participated. Researchers behind these studies collected stool samples, as well as information on the mental health and dietary habits of the women.

These findings could help in formulating dietary recommendations for people vulnerable to PTSD, such as those serving in the military, says Carol Shively, a professor of pathology at the Wake Forest School of Medicine, who was not involved in the study.

Shively's own research has shown that the Mediterranean diet protects monkeys from excessive stress reactions.

"When you look at this in the context of PTSD, I think if you have an obvious stressor, if you are on a Mediterranean diet, you won't have those awful stress reactions that can be very destructive," Shively said.

For the latest study, researchers from Brigham and Women's Hospital and the Harvard T.H. Chan School of Public Health selected 191 women from the previous groups: 44 with symptoms of PTSD, 119 who had experienced trauma but had no PTSD symptoms, and 28 who had neither.

Overall, women in this group who adhered to a Mediterranean diet, including fresh fruits, vegetables, nuts, seeds, olive oil, and fish, experienced fewer symptoms of PTSD.

Plant-based foods, in particular, were negatively associated with PTSD symptoms, while red and processed meats were positively linked to PTSD symptoms.

Link Between Diet and PTSD About 4% of the world's population suffers from PTSD during their lifetime. The disorder develops in some individuals who have experienced or witnessed traumatic events such as serious injuries, violence, or death, but researchers have yet to fully understand why.

"Many people are exposed to trauma, but only a small percentage develops PTSD. It has always been somewhat of a puzzle," said Christopher Lowry, an associate professor in the Department of Integrative Physiology at the University of Colorado Boulder, who was not involved in the study.

According to him, diet may be a crucial part of the explanation.

The brain and the gastrointestinal system, or "gut," which includes the stomach, intestines, and colon, send signals back and forth through a complex system of nerves, hormones, and chemicals. As a result, poor gut health has been linked to various mental disorders, including anxiety and depression. Last year, a study even identified signs of gut inflammation in people with PTSD.

PTSD, in particular, is associated with the disruption of brain circuits that regulate responses to stress and fear. For example, research has shown that individuals with PTSD have overactive amygdalae—the part of the brain that helps process emotions.

According to Yan-Yun Liu, the lead author of the study, the gut microbiome—or microorganisms, including bacteria, residing in the digestive tract—affects both the development and the response of the amygdala.

"This might be why the gut microbiome is important for PTSD," said Liu, an associate professor at Harvard Medical School and a researcher at Brigham and Women's Hospital.

Certain components of the Mediterranean diet, such as fiber and omega-3 fatty acids, support gut health, which in turn can influence brain function.

In particular, Liu and his research team identified a species of gut bacteria that appears to be associated with the Mediterranean diet and protects against PTSD symptoms.

"Perhaps these enriched components of the Mediterranean diet help this particular bug thrive in the gut environment," Liu said.