Key Takeaways

  • Researchers identified various risk factors for PTSD including ethnicity, immigration status, socioeconomic status, and nutrition.
  • Eating fiber-rich foods can help to strengthen the gut and promote overall brain health.
  • Researchers urge that health and social services should work together more closely in developing mental health and PTSD treatment plans.

If more than 70% of us face a traumatic event in our lifetimes, then why do just a fraction—1% to 6%—develop post-traumatic stress disorder (PTSD)? A recent study highlights the role eating high-fiber foods may play in reducing that risk.

Researchers in Canada focused on identifying the relationships between four factors in mid-age and older adults: ethnicity, immigration status, PTSD, and nutrition.

In analyzing the data, factors that predicted PTSD included:

  • Being an immigrant from a minority group
  • Coming from a lower-income household
  • Daily consumption of high-sugar, low-fiber foods

“Sometimes people can face trauma, and they don’t necessarily realize how it can impact them, even years later,” lead study author Karen Davison, PhD, MSc, RD, director of the Nutrition Informatics Research Group, and health science program faculty member at Kwantlen Polytechnic University in Canada, tells Verywell. “Nutrition is an area that may be affected. It’s one piece of that puzzle.”

The gut can indeed play a direct role in mental health, Stefanie Malan-Müller, PhD, a postdoctoral fellow focusing on PTSD and the gut microbiome at the Complutense University in Madrid, Spain, tells Verywell. “If there is an imbalance in the gut bacteria, it could result in a leaky gut,” where the intestinal wall becomes damaged, allowing toxins and bacteria to leak into the bloodstream and even sometimes cross into the brain.

The February study was published in the journal Social Psychiatry and Psychiatric Epidemiology. Data was collected from the Canadian Longitudinal Study on Aging (CLSA), a national decades-long study of more than 50,000 individuals from 45 to 85 years of age. The current study is just a glimpse of the data being collected, which will conclude in 2033.

What This Means For You

Maintaining a healthy gut may also help you improve your mental health. Try adding more fiber-rich foods to your diet, like leafy greens. Generally, you should try limiting processed carbs that are high in sugar in your diet.

PTSD Risk Factors

More than 27,000 people ages 45 through 85, of whom 1,323 had PTSD, were included in the data collection.

To evaluate PTSD, researchers used the four-item Primary Care-PTSD tool, and defined ethnicity and immigration status into four categories: Canadian-born white, Canadian-born minority, immigrant white, and immigrant minority. They also collected information on social, economic, nutrition, and health-related variables.

They found that the prevalence of PTSD among immigrants to Canada from minority groups (7.5%) was more than double that of White immigrants (3.6%) and approximately 50% higher than the risk for White Canadian-born individuals (5.6%).

Other factors, too, predicted PTSD, including lower household income, the death of a spouse, divorce or separation, smoking, and chronic pain. Another key predictor had to do with nutrition, finding that daily consumption of pastries, pulses, nuts, or chocolate predicted PTSD.

It’s not so much that sweets or nuts are predictors of risk. These foods, instead, might be markers of a lower-fiber diet. Researchers also found that individuals 55 and older who consumed two to three fiber sources daily demonstrated a lower risk for PTSD.

Given the data, researchers recommended that clinicians and researchers consider ethnicity status, as well as immigration, socioeconomics, health, and nutrition in the treatment and prevention of PTSD.

The Nutritional Link

But what does fiber have to do with mental health? The broad mechanism, Davison says, looks something like this.

When ingesting foods high in fiber, “your enzymes can’t really break it down in the digestive system, so it passes through and gets to the colon. Then, the bacteria in the colon ferment it.” As byproducts, you get short-chain fatty acids, “which promote gut health and healthy gut bacteria to reduce inflammation. Other studies suggest that the short-chain fatty acids strengthen the blood-brain barrier, so less harmful substances pass across to the brain.” These fatty acids can also, Davison says, help with regulating neurotransmission and communication.

Malan-Müller, who gave a TEDxTalk on “the brain in your belly” in 2018, breaks down the connections even further.

“There are many interesting (direct and indirect) connections between the gut, its microbes, and the brain,” she says. “These bacteria produce, amongst many other things, two important hormones that play an improvement role in mood and mental health, namely serotonin (the feel-good hormone), and dopamine (the hormone involved in regulating reward and motivation). Another more direct link is the vagus nerve which directly sends signals between the gut and brain.”

These connections between the gut and brain mean, according to Malan-Müller, that an issue in one could lead to issues in another. At the same time, helping to cultivate a healthier gut could potentially alleviate mental health problems, namely through eating probiotic, prebiotic, and symbiotic foods. Still, this should not act as a replacement for other psychiatric therapies, but rather as a supplement to be discussed with a healthcare provider.

To maintain a healthy gut, Malan-Müller recommends a varied diet including many types of vegetables, like leafy greens, as well as fermented foods such as yogurt, kombucha, and kimchi. Generally, processed carbs that are high in sugar are not advised.

Integrating Health and Social Services

About 10 years ago, when Davison was a registered dietician, she discovered a lack of guidance on how to support mental health through nutrition.

“I was working with clients with mental health issues,” Davison says. “In terms of nutrition services, they were lacking, and there were not a lot of guidelines for health professionals to use when working with clients to support them nutrition-wise with their mental health.” So, she decided to go back to school and get a PhD focused on nutrition and mental health, specifically on mood disorders.

“Just from that research, I found links with specific nutrients and depression,” she says. Now, having worked as both a practitioner and researcher, Davison sees a need for a tighter connection between health and social services. “In Canada, for example, they’re under two separate umbrellas, and they’re not really integrated in the clinical setting, so if you need to get mental health support, it’s often that you be referred out to somewhere else, and it can be challenging to get those connections,” she says.

To Davison, it’s about “trying to be proactive,” or identifying and helping to reduce the impact of mental health issues on peoples’ lives. This could involve screening individuals for trauma history, as well as all the other factors identified in this study (like nutrition), and working with them to co-develop a plan to support their mental health and well-being.

Malan-Müller agrees. “A holistic approach that takes all the players into account that influence a patient’s mental health is imperative,” she says. “Other aspects that play an important role in PTSD and many other mental health disorders are traumatic life experiences, especially those that happened in childhood.”

“Some people may have experienced trauma, and they can be quite resilient to that, depending on other things that have gone on in their lives, whereas for others, it can have a huge impact,” Davison adds. For the most vulnerable, which this study helps identify, it’s about “looking at the person holistically and understanding, how has this impacted you, and how can we move forward?”