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New research indicates the gut microbiome is related to stress, which begs a question: When you’re trying to do a better job with stress management, should you use your head or go with your gut?

Using your head, of course, means thinking things through and relying on facts to make sensible decisions. Going with your gut involves trusting your instincts, even when the available evidence might contradict what those instincts are telling you.

For the most part, people use these simple head-gut metaphors to express more complex thoughts. But could they actually allude to a surprising truth about how our bodies actually work?

Recently published research suggests this could very well be the case.

According to a June 2024 study from UCLA, the ability to handle stress may rely on how well the brain communicates with the gut microbiome.

What Is the Gut Microbiome?

As explained by the Cleveland Clinic, a biome is “a distinct ecosystem characterized by its environment and its inhabitants.”

In the case of the gut microbiome, the environment is the human digestive tract, mostly the large intestine. And the inhabitants are thousands of bacteria, viruses, fungi, and other microorganisms.

Given its location, it makes sense that the gut microbiome is involved in the digestive process. Bacteria in your gut produce enzymes that break down certain complex carbohydrates and fibers that your body can’t naturally process. Other enzymes handle digestion-related functions such as producing fatty acids, absorbing vitamins, and recycling bile from the liver.

But breaking down food is not its only function. Researchers discovered it also interacts with the immune, nervous, and endocrine systems.

Over the past few years, studies revealed that the gut microbiome can play an important role in a mental well-being, as well.

For example, a July 2023 review in the journal Nutrients found links between the gut microbiome and several mental health disorders, including:

In addition to more accurately identifying individual risk for these conditions, the study authors also noted that research on the gut microbiome could one day lead to customized treatments:

“Due to the potential significant differences in the composition of the gut microbiome among individuals, it is crucial to accurately identify the changes of featured microbes that occur in each individual with mental disorders, which is important for personalized treatment of mental disorders through targeting gut microbiota.”

How Does the Gut Microbiome Affect Mental Health?

Neurotransmitters are chemicals that deliver messages throughout the central nervous system (CNS). They are essential for virtually every important bodily function, including heartbeat, respiration, digestion, muscle movement, and concentration.

Certain neurotransmitters can also influence mood and affect other aspects of mental health.

Though people often refer to neurotransmitters as brain chemicals, this is a misnomer. They’re created, stored, and used in various parts of the body – including the gut microbiome.

Research indicates that cells in the intestine produce about 95 percent of the body’s supply of serotonin, a neurotransmitter that can influence mood, sex drive, and the sleep/wake cycle. Experts link abnormal serotonin levels with mental health disorders such as anxiety, depression, PTSD, and obsessive-compulsive disorder (OCD).

Organisms in the gut also produce neurotransmitters that can affect mental health, such as:

Dopamine:

Involved with pleasure, satisfaction, memory, learning, and motivation. The negative effects of abnormal dopamine levels can include depression, schizophrenia, and ADHD. About 50% of the body’s dopamine supply originates in the gut microbiome.

Glutamate:

This excitatory neurotransmitter stimulates activity in the CNS. Its functions include learning and memory. Glutamate imbalances may be a risk factor for anxiety, depression, and psychosis.

Gamma-aminobutyric acid (GABA):

GABA is an inhibitory neurotransmitter and has a calming effect on the CNS. Experts have linked insufficient GABA with generalized anxiety disorder (GAD), autism spectrum disorder, major depressive disorder, and schizophrenia.

In addition to interacting with these neurotransmitters, microbiota – miniscule organisms in the gut – also communicate with other parts of the body through a system called the gut-brain axis. As described by Jeremy Appleton, MD, the quality of this communication can affect a person’s thoughts and feelings:

“Research continues to elucidate mechanisms of action to explain the effects of microbiota, both directly and indirectly, on emotional and cognitive centers of the brain, and has demonstrated that fluctuations of the microbiota are linked to changes within these systems of communication.”

The Gut Microbiome and Stress Management

Changes in how a person thinks and feels can increase or diminish resilience, which refers to the capacity for making healthy adaptations in response to stress. The UCLA study we mention above explored the role of the gut microbiome in resiliency.

Published by the journal Nature Mental Health, the UCLA study involved 116 participants – 45 men and 71 women – none of whom had any mental health disorders or major medical conditions. Methods included:

  • Resilience metric: Researchers administered the Connor–Davidson Resilience Scale (CD-RISC).
    • Participants with scores of 83.1 or higher joined the high resilience (HR) group
    • Participants with scores lower than 83.1 joined the low resilience (LR) group.
The mean CD-RISC score among the general public in the U.S. is 80.7.
  • Participants completed additional tests on a wide range of physical, psychological, and behavioral topics.
  • Participants also underwent multimodal magnetic resonance imaging (MRI) and submitted stool samples.
    • MRIs assessed brain function and structure
    • Stool samples provided DNA
    • Stool samples provided material to analyze contents of the gut microbiome.

The UCLA team used machine learning to analyze the data they collected. Here’s what they found:

The High Resiliency group:

  • Scored lower than the LR group on tests to determine depression, anxiety, perceived stress and neuroticism. For these tests, lower scores indicated fewer or less intense symptoms.
  • Scored higher on tests that assessed mindfulness, empathy, the ability to express emotions with words, and being nonjudgmental.
  • Showed a higher number of characteristics previous researchers have linked to robust cognition and effective emotional regulation.
  • Showed distinct markers in the brain-gut microbiome compared to the LR group.
  • More likely to show lower levels of inflammation in their gut microbiome
  • More likely to show better gut barrier integrity, or the ability to absorb nutrients while resisting pathogens.

In an NPR article about the study, lead author Arpana Church explained that the brain interprets inflammation and poor barrier integrity in the gut as stress signals.

Resilience against stress, Church and her colleagues determined, may be the result of:

  • Fewer stress signals from the gut microbiome to the brain
  • Greater activity in brain areas that regulate emotions

The UCLA team summarized their efforts:

“Our findings suggest resilient individuals, particularly those demonstrating tenacity and perceived ability to control life outcomes, possess a microbiome that supports gut-barrier integrity and eubiosis [a healthy balance of microbiota] and a cortical signature that reflects adaptive emotional and cognitive regulation.”

How to Strengthen Your Gut Microbiome to Improve Stress Management

Stress management tips often focus on behavioral changes such as practicing mindfulness, finding healthy ways to process your emotions, and developing more effective conflict resolution skills.

These and similar steps remain valid and can lead to substantial improvements in mood and mindset.

But what happens when imbalances in the gut microbiome cause problems with stress management?

The good news is that there are many ways to improve your health in this vital area, such as:

  • Increasing your intake of leafy green vegetables: Spinach, artichokes, broccoli, and other foods in this category contain high levels of fiber, which your body cannot process naturally. Consuming these foods promotes the growth of healthy bacteria within your gut microbiome.
  • Decreasing your reliance on sugar and processed foods: Your body digests these types of foods quite rapidly, before the microorganisms in your gut have the chance to get to work on them. When these microorganisms don’t have enough to eat, they can begin to attack the intestine itself, which can cause inflammations and send distress signals to your brain.
  • Limiting your consumption of red meat: Studies show that vegetarians have a greater number of healthy bacteria in their gut microbiome and a smaller amount of disease-causing bacteria.
  • Staying active: Physical activity promotes a healthier and more diverse gut microbiome. You don’t have to hit the gym hard every day to reap the benefits of exercise. Low-impact options such as walking, yoga, and working in your garden can make a substantial positive difference.

Finally, don’t neglect the importance of good sleep hygiene. Multiple studies show the amount and quality of sleep can have a powerful impact on the health of the gut microbiome.