Roughly 90 percent of the body’s mood-soothing serotonin is made in the gut, notes Vivian Asamoah, MD, a Houston-based integrative gastroenterologist. Other neurotransmitters, such as GABA, dopamine, and glutamate, are also synthesized by gut bacteria. That synthesis helps regulate mood, stress response, sleep, and cognitive functions like motivation and focus. (For more on GABA and mood, see “How Protein Affects Mental Health.”)
“When that process is altered by dysbiosis — whether from a postinfectious state, use of antibiotics, or diet — that will affect how those neurotransmitters are made, processed, metabolized, and passed along to the brain,” explains Vivian Asamoah, MD, a Houston-based integrative gastroenterologist.
The gut-brain connection is bidirectional, so brain signals also modify the gut.
“Emotions such as anxiety, loneliness, and depression can affect the gut microbiota as well,” she adds. An imbalanced gut microbiome may operate in a complex feedback loop with mental health challenges, each reinforcing the other.
Increasingly, functional practitioners are taking a multidisciplinary approach to untangling these loops. Asamoah often recommends that her patients work on diet and lifestyle changes to support the microbiome while partnering with a GI psychologist to help with stress reduction and emotional regulation.
Research shows that a type of bacteria known as psychobiotics can also be particularly supportive. “Certain strains of Bifidobacterium, Lactobacillus, and Akkermansia play key roles in gut-brain health,” she says. “We often see low levels of Akkermansia in patients with gut-brain axis issues, so we focus on restoring it, often by increasing polyphenols in the diet that help support its growth.”
Several studies indicate that Akkermansia supplementation can improve depression-like symptoms in mice. And a randomized controlled trial published in Translational Psychiatry in 2022 found that a short-term, high-dose, multistrain probiotic significantly reduced depression symptoms in people with major depressive disorder; the probiotic boosted levels of Lactobacillus in the gut and even changed patterns of brain activity. (Learn more at “Psychobiotics: Using Gut Bacteria to Treat Mental Illness.”)
The Mighty Microbiome
Your gut microbiome affects much more than digestion: It has an impact on your immune resilience, hormonal health, and more. Learn more at “9 Ways the Gut Microbiome Influences Health,” from which this article was excerpted.
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