The surprising link between your microbiome and mental health
Your gut has its own ecosystem of microbes that play a big part in how you feel. Learn how your microbiome influences your brain and how you can help keep both in balance.
If you’re hearing more about the gut-brain connection these days, there’s a good reason: It turns out that the health of your gastrointestinal (GI) tract — also known as your gut microbiome — can directly affect your brain chemistry and mood.
It might seem odd that your gut would hold such power over your mental state, but anyone who’s felt butterflies before a speech or had a nervous stomach after a sudden shock knows there is a connection.
For several decades, researchers have been exploring the mind-gut relationship, and they’ve discovered several connections. People with GI disorders, for example, have an increased risk of depression and anxiety. Even if you don’t have digestive issues, an unhealthy gut can lower your mood.
Here’s what’s going on between your gut and brain and how to get things in balance so you feel better — physically and emotionally.
How the gut-brain connection works
Your gut is home to a microbial environment called the microbiome. “It’s an entire ecosystem of bacteria, viruses and other microorganisms that we rely on for survival,” says Andrea Nazarenko, PhD. She’s a psychologist in Lexington, South Carolina, and the author of When Food Hurts. “These bacteria play a major role in almost all aspects of human physiology, mental processes included.”
In simple terms, the gut bacteria communicate with the brain and vice versa. The gut is so important to bodily processes that it’s considered the “second brain” and functions somewhat independently of the brain itself, Nazarenko says.
The gut microbiome is command central for several essential roles:
- It defends against infections.
- It digests nutrients that are otherwise indigestible.
- It regulates the creation of new blood vessels.
How does all this interplay affect your mental health? The gut makes neurotransmitters. Neurotransmitters are chemical messengers that are sent and received by a type of brain cell (neurons). And they help regulate all sorts of things, from movement to motivation to emotions.
“Many people think of depression and anxiety as a chemical imbalance in the brain. But these chemicals are created in the gut, not the brain,” Nazarenko says. In fact, more than 30 different neurotransmitters and nearly 90% of the body’s serotonin, the feel-good hormone, come from your gut.
Bottom line? “The imbalance of neurotransmitters may not be in your brain but in your gut,” Dr. Nazarenko says.
Mental health conditions linked to the gut microbiome
An imbalance of bacteria in the microbiome can have serious consequences when it comes to GI health and mental health. In fact, researchers have discovered that people with certain digestive disorders have a higher risk of depression and anxiety.
“People with digestive disorders such as inflammatory bowel disease (IBD) — Crohn’s disease and ulcerative colitis — are at a greater risk of mental health conditions,” says Nazarenko. “These comorbidities [conditions that exist at the same time] of depression and anxiety aren’t just secondary to the diagnosis of IBD. They can actually be independent predictors of the severity of the digestive symptoms, meaning they can make matters worse.”
- Alzheimer’s disease
- Attention-deficit/hyperactivity disorder
- Bipolar disorder
- Obsessive-compulsive disorder
- Post-traumatic stress disorder
Researchers are still figuring out the nature of the relationship between the microbiome and each of these mental health conditions, as well as what else might be involved, such as genetics or environmental factors.
Simple strategies to improve your microbiome and your mental health
If you think you’re suffering from a mental health condition, the first step is to talk to your provider and seek help from a therapist. (If you’re struggling with anxiety or depression, you can make a virtual appointment with one of Optum’s licensed therapists. Learn more.)
But you can also work on getting your gut microbiome healthier. “Healing the gut can address the root causes of the mental disorder,” she says. The 2 main ways to do this: through dietary changes and with probiotic supplements.
Although medication is required to control or suppress symptoms of certain conditions, easy lifestyle strategies can potentially improve a condition or help prevent mental health issues in the future.
3 food-mood strategies
Every meal or snack offers a chance to support your mental health. Here are 3 ways to use food to boost your mood.
1. Tap the power of plants and the Mediterranean diet
One of the best plant-based diets to follow: the Mediterranean diet. It has the most evidence for promoting a healthy gut and playing a role in mental health, Nazarenko says.
Focus on adding fruits and vegetables, whole grains, and nuts and seeds to your diet. You can even take it a step further by concentrating on plant foods that promote GABA, the neurotransmitter that many anxiety medications work on, she adds. (Check out these sneaky signs of anxiety.) These foods include:
- Brown rice
- Green tea
- Whole grains
2. Eat foods that contain probiotics
Probiotics are live microorganisms that benefit your gut, and they’re found in fermented foods such as:
3. Eat foods that contain prebiotics
Prebiotics are plant fibers that serve as food to grow good bacteria in your gut, says Jyothi Rao, MD. She’s the medical director at the Shakthi Health and Wellness Center in Mount Airy and Elkridge, Maryland. She’s also the coauthor of Body on Fire. Prebiotic foods include:
- Jerusalem artichokes
Probiotic supplements for mental health
While the goal is to get probiotics mostly through your diet, supplements are also useful, says Dr. Rao. There are hundreds of probiotic supplements on store shelves, with all sorts of different strains in them. “While many of the probiotics are for general health, they can also be targeted to a specific condition,” says Dr. Rao.
For instance, a strain called L. rhamnosus has been shown to possibly reduce anxiety, Dr. Nazarenko says. And a small study in the journal Nutrition found that 3 probiotic strains — Lactobacillus acidophilus, Lactobacillus casei and Bifidobacterium bifidum — helped reduce symptoms of depression. Other research has linked several strains, including lactobacillus and bifidobacterium, to improvements in mental health.
Dr. Rao doesn’t think taking probiotic supplements substitutes for eating a diverse, plant-based diet. But if you do use them regularly, she recommends changing the probiotic supplement every 3 months to promote diversity in the bacteria colonies in your gut.
While diet and supplements provide a good foundation for improving gut health, that’s not all you can do. Nazarenko works with clients virtually in a guided self-help program about following a gut-healthy lifestyle. That lifestyle includes exercise, nurturing positive relationships, working on maintaining a positive mindset and learning healthy ways to manage stress.
Gut-brain basics: Annals of Gastroenterology (2015). “The Gut-Brain Axis: Interactions Between Enteric Microbiota, Central and Enteric Nervous Systems”
Gut health and ADHD: Nutrients (2021). “Current Evidence on the Role of the Gut Microbiome in ADHD Pathophysiology and Therapeutic Implications”
Gut health and mood disorders: Frontiers in Psychiatry (2018). “Gut-Brain Axis and Mood Disorder”
Gut health and mental illness: Brain, Behavior and Immunity (2017). “The microbiome, immunity, and schizophrenia and bipolar disorder”
Gut health and Alzheimer’s disease: Journal of Alzheimer’s Disease (2017). “The Gut Microbiota and Alzheimer's Disease”
Gut health and OCD: Acta psychiatrica Scandinavica (2020). “The Gut Microbiome and Inflammation in Obsessive-Compulsive Disorder Patients Compared to Age- and Sex-Matched Controls: A Pilot Study”
Probiotics and depression: Nutrition (2016). “Clinical and Metabolic Response to Probiotic Administration in Patients With Major Depressive Disorder: A Randomized, Double-Blind, Placebo-Controlled Trial”
Annals of General Psychiatry (2017). “The Effects of Probiotics on Depressive Symptoms in Humans: A Systematic Review”
L. rhamnosus and anxiety: PLoS One (2018). “The Anxiolytic Effect of Probiotics: A Systematic Review and Meta-Analysis of the Clinical and Preclinical Literature”