Gut Health and Mental Health | 5 Conditions Linked to an Unhealthy Gut

What Is the Gut-Brain Connection?

In simple terms, the gut-brain axis is the communication system between the gut and the brain. These two areas of the body are connected through:

• The vagus nerve. Like a telephone line or walkie-talkie system, the vagus nerve (part of the parasympathetic nervous system) serves as a communication pathway between the digestive system and the brain.
• Neurotransmitters. The brain is known to produce chemicals such as serotonin and dopamine, but the gut also plays a role in these key neurotransmitters. In fact, about 90 percent of serotonin, which influences mood and anxiety, is produced in the gut.
• The enteric nervous system. This autonomous network of more than 100 million neurons lining the gut walls stretches from the esophagus to the rectum and hosts trillions of microorganisms. These microorganisms, collectively known as the gut microbiome, influence motility, immunity, and brain function by producing neurotransmitters, metabolites, and interacting with nerves embedded in the gut wall. Often called the “second brain,” the enteric nervous system helps regulate key digestive processes, local blood flow, and mood.

These areas engage in bidirectional communication, from the brain to the gut, and from the gut to the brain. It’s no surprise that researchers are increasingly finding that the gut microbiome health and mental health are closely linked.

A diverse, balanced gut microbiome supports emotional resilience and reduces inflammation. But disruptions, which can be caused by poor diet, stress, antibiotics, or illness, can negatively impact mood, sleep, and focus, leading to emotional and cognitive challenges.

Related: Gut Health and Mental Stability

How Your Gut Microbiome Affects Your Mental Well-Being

With the gut constantly “talking” to your brain, maintaining a healthy gut is critical for healthy brain function and a sound mind. For optimal health, the gut needs an abundance of healthy bacteria. Specifically, the gut needs roughly 85 percent beneficial bacteria, with harmful bacteria making up no more than about 15 percent in order to maintain good health overall. For years, research has noted the strong link between microbiota, mood, and mental health.

The Role of Neurotransmitters

Your brain relies on an intricate system of chemical messengers that affect everything from mood to memory: neurotransmitters.

Neurotransmitters play a key role in both gut and mental health. Interestingly, your gut microflora have a key part in synthesizing neurotransmitters and influencing critical hormones. For example, certain beneficial gut bacteria produce calming neurotransmitters, such as GABA, while others influence cortisol levels and the body’s stress response.

Neurotransmitters may serve several roles, including ones tied to your mental health. For example, serotonin (often called the “feel-good” neurotransmitter) influences mood, digestion, sleep, and cardiovascular function. Higher serotonin levels are linked to happiness and emotional well-being.

Meanwhile, the neurotransmitter dopamine is involved in about 65 percent of the brain’s decision-making process, thanks to its important role in motivation and achieving goals. This neurochemical helps control behavior, cognition, and emotion, specifically regarding pleasure and reward.

The Gut Microbiome Explained

What is the gut microbiome? The term describes the ecosystem of bacteria, fungi, and other microorganisms that live in the digestive tract. Gut microbiome health is dependent on bacterial diversity, while imbalances in the gut’s bacteria are associated with a variety of physical and mental health symptoms.

Inflammation and Mental Health

When there’s a microbiome imbalance, it can set off a host of problems. Chronic gut inflammation can contribute to physical health issues such as leaky gut syndrome and toxins entering the bloodstream. But it can also impact cognitive function, leading to:

• Brain fog
• Memory problems
• Difficulty concentrating, which can affect learning

Gut inflammation is linked to chronic stress and several mental health conditions, including anxiety, depression, major depressive disorder, bipolar disorder, and obsessive-compulsive disorder (OCD), along with neurodevelopmental disorders such as ADHD and autism.

What Are the Signs of an Unhealthy Gut?

If you have an unhealthy gut, a variety of symptoms may affect both your physical and mental health.

How to Tell if Your Gut Health Is Affecting Your Mental Health

The following warning signs may point to gut health issues:

• Digestive issues (irritable bowel syndrome, bloating, constipation, diarrhea)
• Mood disorders (anxiety, depression)
• Brain fog and cognitive difficulties
• Sleep disturbances
• Frequent illness (signaling a weakened immune system)
• Food intolerances
• Skin problems
• Autoimmune conditions

Persistent and/or severe symptoms, especially if they are affecting your quality of life, are clear indicators that you need to consult a medical doctor.

What Mental Health Conditions Are Linked to Gut Health?

Thanks to the gut-brain axis, gut health issues are often connected to brain health (and therefore mental health) and vice versa.

The Connection Between Gut Problems and Mental Health Disorders

Research from 2023 noted that disruption of the gut’s microbiota (known as dysbiosis) is associated with schizophrenia, depression, and other psychiatric disorders. Because gut microbiota are involved in modulating neurotransmitters like dopamine, GABA, and glutamate, they have implications for both neuropsychological disorders and GI conditions.

Additional research published in 2023 pointed to significant evidence linking anxiety and depression disorders to gastrointestinal microbes. Stress-related conditions can also affect gut health, while GI conditions such as irritable bowel syndrome (IBS) carry their own stigma and social impact. Any of these issues can diminish an individual’s quality of life.

Here are five psychiatric conditions that have been linked to the microbiome:

1. Anxiety

A growing body of evidence suggests that symptoms of anxiety are related to gut dysbiosis. A 2025 review determined that individuals with anxiety disorders often exhibit alterations in gut microbiota. These include reduced microbial diversity and fewer short-chain fatty acid-producing bacteria.

2. Depression

A study published in 2022 analyzed microbiome diversity and depressive symptoms in more than 1,000 subjects. Findings suggested that gut microbiome composition may play a key role in the development of depression.

3. ADHD

Increasingly, science points to a link between attention deficit hyperactivity disorder (ADHD), also called attention deficit disorder (ADD), and gut dysbiosis. A 2025 review established that differences important to key gut-brain axis pathways may contribute to the inflammation, brain functioning differences, and symptoms associated with ADHD.

4. Schizophrenia

A growing number of researchers are finding that the microbes that live in our gastrointestinal tract may play a role in schizophrenia. A 2022 review noted that studies have found significant differences in the gut microbiome of schizophrenic subjects compared to healthy controls. An altered microbiome is believed to contribute to the development, symptom severity, and prognosis of psychosis.

5. Alzheimer’s Disease

Problems in the gut are also linked to memory loss and Alzheimer’s disease, the most common form of dementia. Several studies have explored the links between gut health, the microbiome, and Alzheimer’s.

Related: Fermented Foods: Nature’s Mental Health Booster

How Can You Improve Gut Health for Better Mental Health?

With so much research connecting mental health to the gut microbiome, experts are calling for more investigation into how the gut can offer a pathway to more effective treatment options.

Science-Backed Ways to Support Your Gut-Brain Connection

Here are some ways to promote gut health in support of your mental well-being.

1. Optimize Your Diet

Following these recommendations may help to improve your gut health:

• Increase dietary fiber through whole grains, vegetables, and fruits
• Choose whole grains over refined grains (such as quinoa vs. white rice)
• Eat probiotic-rich foods (such as yogurt, kefir, sauerkraut, and kimchi)
• Consume prebiotic foods (including garlic, onions, bananas, and asparagus) in your diet
• Reduce or eliminate sugar and processed foods
• Incorporate specific foods for gut health (such as eating kiwi for constipation)
• Consider a Mediterranean diet or intermittent fasting

Of course, before making any changes to your diet, it is best to consult your primary care physician.

2. Exercise Regularly

Movement improves digestion and encourages beneficial gut bacteria production. Any type of exercise helps, from walking and yoga to strength training and cycling. Exercise helps create a positive cycle between the gut and the rest of the body while boosting brain and mental health.

3. Manage Stress Effectively

If you’ve ever felt an “upset stomach” as a result of stress, you have experienced firsthand the stress-gut connection. Research shows that stress can have short- and long-term effects on the functions of the gastrointestinal tract and alter the gut-brain axis.

To prevent the damaging effects of severe or chronic stress, implement stress management techniques such as:

• Meditation and mindfulness
• Breathing exercises
• Yoga
• Adequate sleep
• Self-care practices, such as journaling or therapy

4. Consider Probiotics (With Caution)

Probiotic and prebiotic foods and supplements help restore the balance of healthy gut bacteria.

For example, fermented foods, such as sauerkraut, kimchi, unsweetened yogurt, kefir, kombucha tea, and miso soup, contain live bacteria. You can also get a quality probiotic supplement. However, keep in mind that more research is needed to understand the impact of probiotic supplements on gut and mental health, and the FDA does not regulate dietary supplements.

Prebiotics are fiber-rich, non-digestible carbohydrates that fuel beneficial gut bacteria. Some key sources include onions, garlic, leeks, asparagus, apples, bananas (slightly unripe are even better), oats, flaxseeds, chicory root, dandelion greens, and Jerusalem artichokes. If you choose to take a prebiotic supplement, it should target Bifidobacterium and Lactobacillus strains of bacteria.

Be sure to choose reputable sources for probiotic or prebiotic supplements. Consult a healthcare provider to find the best options for you.

5. Stay Hydrated

Water plays a significant role in digestion as well as brain health. Even mild dehydration can have numerous effects on your well-being, including:

• Lowering mood, causing you to feel depressed, anxious, tense, or irritable
• Depleting your energy
• Increasing pain levels
• Compromising your ability to concentrate

Your recommended daily water intake varies depending on your age, physical activity level, and even the weather. As a general rule, aim for eight to ten 8-ounce glasses of water per day.

6. Limit Antibiotics When Possible

Antibiotics can disrupt your balance of gut bacteria. A 2022 study established that antibiotic-induced changes in microbial composition can have negative impacts.

These effects include reduced microbial diversity, changes in functional attributes of the microbiota, and the formation of antibiotic-resistant strains, which increases susceptibility to infection. Follow medical advice regarding antibiotic use to minimize risk.

7. Avoid What Harms Your Gut Health

Reduce or eliminate factors that can detract from your gut health, including:

• Alcohol
• Artificial sweeteners
• Smoking
• Medications such as antibiotics (including antibiotics in meat and poultry)
• Drug use
• Environmental toxins
• Dysbiosis (imbalance of the gut’s microflora, caused by diet, stress, and other factors)

What Is the Role of Healthcare Professionals in Maintaining Gut Health?

When you notice gut-health symptoms, especially if they are interfering with your daily life, it’s important to pay attention.

When to See a Gastroenterologist or Mental Health Professional

Having regular digestive health screenings, such as receiving a regular colonoscopy starting at age 45, is a great way to protect against colorectal cancer and other digestive health issues. Early-onset colorectal cancer is rising dramatically among people under 50, believed to be driven by diet and lifestyle.

You may need to work with specialists, such as a gastrointestinal doctor, a nutritional psychiatrist, or a brain health nutritional coach, to optimize gut health.

A whole-body approach, like the one practiced at Amen Clinics, offers precision medicine with targeted, personalized care for your specific gut and mental health symptoms. Our clinicians practice holistic psychiatry, using natural ways to treat mental health conditions and digestive issues, and medication only when necessary.

What Are the Signs of a Healthy Gut?

An absence of gut health problems is your best indicator that your gut is healthy. But there are other signs too.

What Does Good Gut Health Look Like?

Here are some markers of good gut health:

• Regular bowel movements
• Minimal digestive discomfort
• Good energy levels
• Stable mood
• Strong immune function

When it comes to gut health, no news is good news. In other words, not thinking about your gut constantly, because it isn’t causing you significant issues, is a positive sign!

How Can I Optimize the Gut-Brain Connection?

The gut-brain axis is a highly complex, intricate system allowing for constant communication between your brain and your gut. That’s why a whole-body approach is so important, as all systems and parts of the body work together and affect the others.

Taking action to promote gut health now, rather than waiting for mental or physical symptoms or conditions to arise, is easy. Start with one small change. Whether it’s adding more fiber and water to your diet or introducing a new stress-relieving practice, you can take steps to promote better health of the gut, mind, and entire body.

And, if needed, consult a healthcare professional to investigate persistent gut or mental health issues. Clinicians at Amen Clinics are trained in offering holistic support that will promote optimal gut-brain health, reducing the chance of GI or mental health issues interfering with your everyday life.

FAQ About Gut Health and Mental Health

How does gut health impact mental health?

The gut-brain axis describes the constant communication that takes place between the gut and the brain. When the gut’s microbiome (the vast collection of microorganisms in the digestive tract) is out of balance, it directly impacts brain chemistry. This can lead to emotional and cognitive challenges.

How can I improve my gut health?

Diet, exercise, stress-relieving practices, probiotics, prebiotics, and staying hydrated are some easy steps you can take every day to boost gut health. Also be aware of outside influences that can disrupt the gut microbiome, such as antibiotics or alcohol, and monitor their effects.

When should I seek professional help for gut health issues?

If you have persistent or severe gastrointestinal symptoms, seek help from a medical doctor as soon as possible. Likewise, seek help for mental health symptoms such as mood changes, depression, and anxiety, especially if they are impacting your daily life. Amen Clinics offers a whole-body approach and is staffed with qualified medical professionals to help with both digestive health and mental health issues.