Living with Post-Traumatic Stress Disorder (PTSD) can feel like an uphill battle, affecting not just the mind but the entire body. Trauma rewires the nervous system, disrupts sleep, heightens anxiety, and weakens digestion. While PTSD is often addressed with therapy and medication, an emerging body of research shows that nutrition plays a key role in recovery. Science confirms that targeted nutrition can reduce PTSD symptoms by improving brain chemistry, reducing inflammation, and supporting gut health. The concept of the gut as a “second brain” or a “hidden organ” is an emerging focus in scientific research.
The Gut-Brain Axis and PTSD: An Emerging Link
The human gut microbiome has a significant impact on our health. Research has shown that it can influence the development and response of emotions, but the relationship between post-traumatic stress disorder (PTSD) and the gut microbiome has been unexplored. PTSD is a fear-based mental health disorder that develops in some individuals who experience a disturbing and horrifying situation involving severe injury, actual or threat of death, or violence.
As Harvard Associate Professor of Medicine, Yang-Yu Liu told Psychiatrist.com, the digestive tract plays a primary role in the enteric nervous system (ENS) found within the gut’s walls. “Those neurons communicate with the central nervous system through channels like the vagus nerve which connects the brain to the gut,” he explained. In fact, previous work suggests the gut produces about 90 percent of the body’s serotonin. Additionally, the microbiome independently creates its own neurotransmitters and other bioactive molecules that can cross the gut-brain barrier.
A new study by investigators from Brigham and Women’s Hospital and Harvard T.H. Chan School of Public Health systematically investigated the relationship between PTSD, diet, and the gut microbiome. “There is a very intriguing relationship between the human gut microbiome and the brain,” said co-corresponding author Yang-Yu Liu, of the Channing Division of Network Medicine within the Department of Medicine at Brigham and Women’s Hospital. “Through our study, we examined how factors, like diet, are associated with PTSD symptoms. The burden of PTSD often extends beyond the individual; family members, the health care industry, and society are also affected by the mental health disorder. In addition, individuals with PTSD have an increased risk of developing chronic diseases such as coronary heart disease, stroke, diabetes, autoimmune diseases, and premature death. “Examining the gut-brain axis can provide insights on the interdependence of mental and physical health,” said co-corresponding author Karestan Koenen, professor of psychiatric epidemiology at the Harvard Chan School.
Mediterranean Diet and PTSD Symptoms
A Mediterranean diet that's rich in vegetables, fruits and fish may help reduce or stave off symptoms of post-traumatic stress disorder, according to research published this week in the journal Nature Mental Health. A study conducted by Dr. Stephanie Smith, a recent graduate of the Behavioral Health Fellowship at the College of Community Health Sciences also suggests that the Mediterranean diet could help reduce the severity of Post-Traumatic Stress Disorder (PTSD) symptoms and improve overall health.
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The peer-reviewed findings are based on patient data from two studies - one in 2008 and another in 2013 - which collectively involved tens of thousands of female participants. The researchers behind those studies gathered stool samples, as well as information about the women's mental health and dietary habits.
For the latest study, researchers at Brigham and Women’s Hospital and the Harvard T.H. Chan School of Public Health selected 191 women from the earlier cohorts: 44 with PTSD symptoms, 119 who had experienced trauma but no PTSD symptoms and 28 who had experienced neither. Overall, women within that group who followed a Mediterranean diet - which includes fresh fruits, vegetables, nuts, seeds, olive oil and fish - experienced fewer PTSD symptoms. Plant-based foods in particular were negatively associated with PTSD symptoms, whereas red and processed meats were positively associated with PTSD symptoms.
The team collected data from 191 participants in sub-studies of the Nurses’ Health Study-II, which included the Mind-Body Study and the PTSD Substudy. Participants were assigned to three groups: probable PTSD, exposed to trauma but no PTSD, and no trauma exposure. All the participants submitted two sets of four stool samples, once at the beginning of the study and again six months later. The team evaluated the associations between overall microbiome structure and host factors, including PTSD symptoms, age, body mass index (BMI) and dietary information. Next, the researchers assessed the relationship between the available dietary information and PTSD symptoms. The team found that participants who adhered to a Mediterranean diet experienced fewer PTSD symptoms.
“The Mediterranean diet isn’t just about what you eat - it’s about how you live,” Smith said. Originating from such countries as Spain, France and Italy, the Mediterranean diet emphasizes plant-based meals, seasonal fruits and vegetables, whole grains and healthy fats such as olive oil and nuts. Fish and lean meats are consumed in moderation, and red wine may be included occasionally. Fiber, which is abundant in fruits, vegetables and whole grains, is another essential component of the diet, requiring consistent intake to deliver its full benefits.
Identifying Protective Gut Bacteria
The team employed the generalized microbe-phenotype triangulation method to examine the link between PTSD symptoms and the gut microbiome signatures, aiming to identify putative PTSD protective species. They identified Eubacterium eligens as the top PTSD putative protective species. To test the consistency of this signature over time, the team found that the inverse association of E. eligens abundance with PTSD symptoms was highly consistent across all four time points.
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The researchers paid special attention to a particular bacteria species called Eubacterium eligens which stood out for its potentially protective role against PTSD symptoms; higher levels of E. eligens were associated with fewer PTSD symptoms. The bacteria species also showed a positive relationship with healthier eating patterns commonly found in the Mediterranean diet. For example, eating raw carrots seemed to raise levels of E. eligens. As Liu explained, the presence of E. eligens seemed to be favorable for both for gut health and for mental health. Thriving colonies of the species were more common in people who ate healthier foods and less common in those with more severe PTSD symptoms. “This was an observational study so we can only say that we see gut changes associated with PTSD symptoms. The findings are just a start, Liu added.
He further demonstrated that E. eligens was positively associated with the enriched components of the Mediterranean diet (such as vegetables, fruits, and fish).
“E. eligens might be a very strong candidate for a probiotic that works for PTSD prevention and arbitration,” he said.
Diet's Role in PTSD: A Closer Look
Around 4% of the world’s population has had PTSD in their lifetimes. The disorder develops in certain people who have experienced or witnessed traumatic events such as severe injuries, violence or deaths, but researchers are still uncovering why. "Many people get exposed to trauma, but only a small percentage go on to develop PTSD. It’s always been a bit of a mystery," said Christopher Lowry, an associate professor of integrative physiology at the University of Colorado, Boulder, who was not involved in the research.
Diet could be an important part of that explanation, he said. 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 several mental illnesses, including anxiety and depression. A study last year also found signs of intestinal inflammation in people with PTSD.
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PTSD, in particular, has been linked to dysregulation in brain circuits that manage stress and fear responses. Studies have shown, for instance, that people with PTSD have hyperactive amygdalae, which are a region of the brain that helps process emotions. According to Yang-Yu Liu, the study’s author, the gut microbiome - or the microorganisms, including bacteria, that live in the digestive tract - influences both the development and the response of the amygdala. "That could be the reason why the gut microbiome is important for PTSD," said Liu, an associate professor at Harvard Medical School and an associate scientist at Brigham and Women’s Hospital.
Several components of the Mediterranean diet - such as fiber and omega-3 fatty acids - are known to support gut health, which in turn can influence brain function.
The Impact of Saturated Fats on Stress Response
A new study published in the journal Brain, Behavior, and Immunity shows that adolescent rats who consume a diet high in saturated fats have a harder time coping with stress as adults. “The teen years are a very critical time for brain maturation, including how well (or not) we'll cope with stress as adults," said Dr. Johnny Figueroa, Assistant Professor, Division of Physiology, Department of Basic Sciences and Center for Health Disparities and Molecular Medicine, Loma Linda University School of Medicine.
The study, "Exposure to an obesogenic diet during adolescence leads to abnormal maturation of neural and behavioral substrates underpinning fear and anxiety," investigated the impact of an obesogenic Western-like high-saturated fat diet on the development of brain areas involved in responding to fear and stress. Study findings demonstrate that the consumption of an obesogenic diet during adolescence has a profound effect on phasic and sustained components of fear in the adult rat. Startle reflexes, which are studied in humans and lab animals, have a prominent role in anxiety and PTSD research.
In this study, consumption of an obesogenic diet during adolescence reduced the extinction of fear memories - a major impairment observed in people suffering from PTSD. In addition to not properly learning fear associations, the rats on the high-saturated fat diet incorrectly assessed the level of threat. Researchers reported that the animals in the high-saturated fat diet group exhibited alterations in the structure of brain regions associated with PTSD, including the amygdala and the prefrontal cortex. Notably, the group found that the left-brain hemisphere seems to be more vulnerable to the effects of high-saturated fat diet consumption and obesity-related metabolic alterations.
Figueroa said the study leaves other questions open for further investigation, such as replicability in human subjects and if the alterations seen in the brain structures are permanent or whether the effects can be reversed.
Key Nutrients and Dietary Strategies for PTSD Recovery
While nutrition for PTSD plays a crucial role in reducing inflammation, balancing neurotransmitters, and supporting the gut-brain connection, lifestyle choices are equally important for PTSD symptom relief.
Science confirms that targeted nutrition can reduce PTSD symptoms by improving brain chemistry, reducing inflammation, and supporting gut health. By making intentional dietary changes, you can support your mind and body in healing from PTSD. Small, intentional changes in your diet can have a profound impact on PTSD recovery.
Here's a breakdown of essential nutrients and dietary strategies:
- Omega-3 fatty acids: Play a crucial role in brain health, reducing inflammation, and improving emotional resilience. Looking for a high-quality, ultra-pure omega-3 supplement to support brain function, reduce inflammation, and promote heart health? Nordic Naturals ProOmega® 2000 delivers a powerful dose of EPA & DHA in triglyceride form, ensuring maximum absorption and effectiveness.
- Antioxidant-rich foods:
- Berries (blueberries, strawberries, blackberries) - Rich in flavonoids that protect the brain.
- Bell peppers, strawberries, citrus foods, broccoli - High in vitamin C reducing oxidative stress.
- Magnesium: A natural muscle relaxant that helps regulate the nervous system, improve sleep quality, and reduce stress. Research Insight: A randomized controlled trial in Medical Research Archives found that magnesium supplementation significantly improved sleep quality, suggesting potential benefits for PTSD recovery.
- Tryptophan: An essential amino acid required for serotonin production, which supports mood stabilization, emotional regulation, and sleep quality.
- Eggs, dairy products → Contain bioavailable tryptophan and other essential nutrients. Research Insight: A study in The American Journal of Clinical Nutrition found that high-carbohydrate meals significantly increased plasma tryptophan levels, which may support serotonin synthesis and mood regulation.
- Probiotics: Yogurt, kefir, sauerkraut, kimchi - Promote beneficial gut bacteria.
- Vitamin D-rich foods: Incorporate vitamin D-rich foods like fatty fish, egg yolks, and fortified dairy products. Vitamin D deficiency is common in individuals with PTSD and is linked to increased inflammation, fatigue, and mood imbalances.
Lifestyle Choices for PTSD Symptom Relief
- Walking in Nature (Green Therapy): Lowers stress hormones and improves mood. Even 20 minutes of movement a day can improve mood and resilience.
- Sleep Hygiene: PTSD and sleep disturbances go hand in hand.
- Create a bedtime routine → Set a consistent sleep-wake schedule to regulate circadian rhythms.
- Incorporate magnesium & tryptophan-rich foods → These nutrients naturally promote sleep.
- Stress Management Techniques: Chronic stress worsens inflammation, neurotransmitter imbalances, gut health, intensifying PTSD symptoms.
- Journaling & Expressive Writing → Helps process emotions and reframe negative thoughts.
- Aromatherapy (Lavender & Chamomile) → Proven to lower cortisol and promote relaxation.
The Broader Implications
The findings could help inform dietary recommendations for people who are vulnerable to PTSD, such as those serving in the military, said Carol Shively, a pathology professor at Wake Forest University School of Medicine who was not involved in the research.
Shively’s own research has shown that the Mediterranean diet protects against exaggerated stress responses in monkeys. “When you put that in the context of PTSD, what’s going to happen, I think, is that in response to overt stresses, if you’re consuming a Mediterranean diet, you won’t have these horrific stress responses that can be very damaging,” Shively said.
Reducing inflammation could be key to brain health. Lowry, however, said he is cautious about attributing any benefit to specific gut bacteria until additional studies replicate the results. He suspects that the Mediterranean diet may help alleviate or prevent PTSD systems largely by reducing inflammation. “The Mediterranean diet predominantly has an anti-inflammatory effect, and we have known for decades now that inflammation is a risk factor for depression," he said. "Now it’s become clear that it’s also a risk factor for PTSD.” Several studies have indeed suggested that elevated levels of inflammation may play a role in the development of PTSD. research on veterans has shown that anti-inflammatory probiotics have the potential to treat PTSD symptoms.
The Mediterranean diet cuts out processed foods with lots of sugar and saturated or trans fats, which can be highly inflammatory, Lowry said. The human gut is semi-permeable, and researchers suspect that processed foods can increase its leakiness, which allows gut bacteria to enter the bloodstream. That process drives inflammation that can travel from the blood to the central nervous system and have a wide influence on brain function. Shively said any diet that's high in fiber, fresh fruits, vegetables and plant-based fats and proteins should have the opposite effect. “There are so many reasons not to eat Western diet and so many reasons to eat a healthier diet,” she said.
Limitations and Future Directions
The team notes limitations to their study, including using a short screening scale for PTSD (instead of a formal clinical diagnosis of PTSD). “It’s exciting that our results imply that the Mediterranean diet may provide potential relief to individuals experiencing PTSD symptoms,” said Liu. “We are eager to learn more about the relationship between PTSD, diet, and the gut microbiome.
Liu added. It’s work that opens the door to future research on how diet directly influences the gut microbiome, and in turn the microbiome influences mental health.