Do Probiotics Help with Anxiety?

We've all gone through it at some point: maybe it's a final exam or an interview for your dream job, or you're about to give a speech in front of a room full of people.

Then, you feel it. It could be a flutter. Or a gurgle. Or even full-on nausea.

Sometimes you might feel anxious for no clear reason. And on top of that anxiety is any number of GI troubles like cramping, bloating, and diarrhea.

If any of these sounds familiar, you're not alone. Anxiety disorders affect over 40 million Americans daily. Despite the wide range of drugs and self-help therapies meant to treat it, anxiety remains rampant in our society. What’s more: our digestive tracts are taking a hit. 

But as it turns out, the connection between anxiety and gut trouble is not a one-way street, but one that goes both ways. In other words, it's possible that when you support your gut health, you also help your mental health. Because of this gut-brain connection, experts are discovering a new strategy for anxiety relief: probiotics.

Probiotic capsules spilling out onto a light blue surface

What Are Probiotics?

We tend to think of bacteria in two different forms: the "bad" kind that makes us sick, and the "good" type, which keeps our bodies healthy. Probiotics are made from good bacteria, as well as yeast and other microorganisms that provide health benefits to our bodies, and they've got a well-deserved reputation for delivering gut health benefits. 

Probiotics are scientifically defined as live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. Some of the probiotics you find in dietary supplements and medical probiotic products are naturally occurring in the human body, and others are derived from plant sources. You can also find good bacteria in fermented foods. 

Studies show the possibility that probiotics benefit conditions such as inflammatory bowel disease, irritable bowel syndrome, and diarrhea. However, probiotics may give us more than a healthy gut. In fact, they can also benefit oral health, immune function, and skin conditions like eczema and psoriasis.

Probiotics may also benefit mental health, particularly stress disorders such as anxiety. Taking probiotics for anxiety might sound like a stretch, but there's growing evidence that gut health and mental health intertwine. This is where the gut-brain connection becomes important.

Anxiety & the Gut-Brain Connection

The gut-brain connection, or gut-brain axis (GBA) is a two-way connection between the brain and the gut. The GBA ties together the central nervous system (CNS) and the enteric nervous system (ENS).

While the CNS comprises the brain and the spinal cord, the ENS includes the digestive organs, including the gut. The effects of the GBA work both ways: just as your mental state affects your gut health, your gut health may directly affect your mental health and mood. 

What does this mean?

When we feel anxious or nervous, those feelings might accompany feelings of nausea, bloating, and gas. Likewise, it's possible that an imbalance between “good” and “bad” microbes in your gut microbiome has its own effect on mental health conditions - including anxiety.

The gut-brain connection

How the Gut-Brain Axis Works

Like any part of the body, the GBA is complex, but we can break it down into a few key players: the brain, gut bacteria, and the vagus nerve.

The Brain

The brain controls functions of the body like thought, memory, emotions, and sensory information. In order to perform such tasks, the brain uses neurotransmitters and hormones.

Neurotransmitters are unique chemicals produced by neurons and other endocrine cells, and their jobs are to communicate between neurons and target organs in order to control actions, feelings, and emotions. Hormones are chemical messengers of the endocrine system that also act on different organs. While there are numerous chemicals involving the brain, the three that are the most crucial for anxiety are the following:


Cortisol is a hormone that supports the stress response by raising blood-sugar levels, elevating heart rate, and repressing digestive functions. After the stress response is over, cortisol also helps to inhibit inflammatory responses.

Gamma-Aminobutyric Acid (GABA)

GABA is an organic acid existing in many foods that is also produced in the brain. GABA acts as an inhibitory neurotransmitter in our body to block the activation signals between neurons. GABA taps down hyperactivity in neurons linked to anxiety, stress, and fear to keep you calm, cool and collected. 


Serotonin is also a neurotransmitter participating in many functions of neurons. It contributes to feelings of happiness and regulates the internal clock. While its essential tasks occur in the brain, most serotonin is produced in the gut.

The Gut

Gut bacteria are made up of trillions of bacteria, yeasts, and other microorganisms living in the gut, and they play a major role in the interactions between the gut-brain axis. The gut microbiome actively produces and helps generate neurotransmitters and other neuroactive compounds, which impact brain functionality. The gut and the brain communicate and interact bidirectionally, particularly through neurons.

Neurons are cells that signal your body how to act, and there are a lot of them. In fact, there are about 86 billion neurons in the human brain and about 200-600 million in the gut.

If that wasn't already fascinating, these neurons work bidirectionally, meaning that they interact both ways with each other. Research has theorized that neurons in the brain communicate with neurons in the gut through their own superhighway: the vagus nerve.

The Vagus Nerve

The vagus nerve is a key pathway between the gut and the brain, and it works by sending signals both ways. 

One randomized controlled trial found that stimulation of the vagus nerve strengthened coupling between the stomach and the brain, which indicates a possible link in mechanisms between the two organs. Another study found that stimulating the vagus nerve provides antidepressant effects. This is possibly because the vagus nerve sends signals to regions in the brain that manage the stress response. These and other results indicate that the vagus nerve is critical in connecting the brain and gut.

The gut and anxiety

How Does the Gut Affect Anxiety?

Growing evidence indicates that anxiety affects both parts of the body.

Currently, the exact mechanism connecting gut health to neurological conditions like anxiety remains unknown. However, some of the most-researched possibilities include the following:

Inflammation & Leaky Gut

While inflammation impacts many parts of the body, it may have a massive influence on brain function – particularly anxiety. Inflammation happens for several reasons. Sometimes, your body's microbiome might undergo a negative change, whether from antibiotics, diet troubles, or stress affecting the body. 

When such changes occur, microbes in the gut can become imbalanced as opportunistic microbes take advantage of your gut microbiome. This imbalance is known as dysbiosis, and it triggers your immune system into action so that the body starts fighting off the harmful bacteria through the inflammatory response.

While inflammation is crucial in fighting diseases and pathogens, it can take a toll on the body over time. If gut inflammation continues, it may lead to additional issues like Parkinson's disease, leaky gut, and anxiety.

Excess inflammation in the gut affects whole body health. Abdominal discomfort can lead to bad mood and even anxiety symptoms via the gut-brain axis. For example, in one clinical trial, it was found that inflammation altered behaviors in the brain associated with serotonin production. 

Diarrhea, Constipation & Anxiety

Regarding anxiety and the gut-brain connection, p-cresol may also play a role. Produced by gut bacteria, p-cresol is a compound known for negatively affecting brain function. One preclinical study of autistic children with constipation showed higher levels of p-cresol in their urinary and fecal samples. 

The study was meant to observe the effects of gut motility on behavior in young autistic children with constipation. Researchers also looked for a correlation between p-cresol and anxiety levels. In the end, the study's findings indicated a strong link between constipation and anxiety-related behaviors. However, the exact mechanism behind this connection is still not fully understood.

Research has also indicated a link between improving mental health and helping with constipation and diarrhea. In one study, the effects of rifaximin, an antibiotic, on the mental state and digestive issues of patients with small intestinal bacterial overgrowth (SIBO) were studied. Throughout the study, patients were observed for anxiety and depression through mental health assessments and urine samples. The study showed an improvement in both mood and digestive ailments, strengthening the link between gut health and mood disorders like anxiety.

Poor Digestive Health

Good digestion is essential to our health. And disturbance of digestion, stress, pathogens, bad diet habits, etc., will impact the GBA. For example, it’s been indicated that those with chronic constipation tend to also have a stress or mood disorder. On top of that, one study on patients with IBS identified a microbial signature in the gut that’s associated with psychological distress.

Low Butyrate Levels

When we eat a diet rich in plant foods, our "good" gut bacteria produce a short-chain fatty acid (SCFA) known as butyrate. Butyrate provides energy for the cells that make up your gut lining, which helps strengthen the intestinal barrier. Additionally, butyrate can help prevent inflammation, which has been linked to depression and fatigue. When butyrate levels are low in the gut, this weakens the intestinal wall against inflammation, which can lead to problems like leaky gut.

You can promote butyrate levels in the gut by eating prebiotics like fruits, vegetables, nuts, legumes, and whole grains. Prebiotics are foods that provide direct sustenance to your gut bacteria, and among other beneficial SCFAs, prebiotics are transformed into butyrate.

For some ideas on a more prebiotic-rich diet, check out this article on 10 superfoods for your gut

Probiotics and test anxiety

Benefits of Probiotics for Anxiety

By supporting a healthy gut-brain connection, probiotics may help support mental health through gut balance. This, in turn, may help regulate brain chemistry.

At this point, the mechanism behind this connection hasn't been pinpointed, although there is research showing a causal relationship between probiotics-mediated gut health and anxiety. In one study, some students were given multi-strain probiotics for 28 days before an exam, while others were given a placebo. When cortisol levels were measured, it was found that those who were given the probiotics had lower levels than those in the placebo group. 

In a 2002 study, adults with stress or exhaustion were given the probiotic strains L acidophilus, B bifidum, and B longum. Post-intervention, it was found that the probiotic mixture improved subjects' general condition by 40.7% after six months.

Perhaps most interestingly, stress and depression can influence the gut microbiome’s composition through stress hormones and inflammation. Some bacterial species may even cause a surge in stress response, as well as encouraging dysregulated eating. There is still much to learn about how probiotics support those with anxiety. However, some probiotics have been shown to work in a multifaceted way. 

For instance, the probiotic L. plantarum PS128, or PS128 has been shown to not only manage inflammation, but also serotonin levels, which play a major role in key brain functions like memory, learning, and positive mood.

Choosing a probiotic for anxiety

Can You Take Probiotics for Anxiety?

While there’s still much to uncover about probiotics, the general consensus is that they’re worth trying for anxiety, especially since they hold minimal side effects. The question is: which probiotic is best?

Related article: Probiotics for Anxiety & Depression

Each one of us contains a unique blend of ~200 different species of gut microorganisms. As a result, the best probiotic for anxiety is likely to vary from person to person. That being said, some of the most promising updates have been on L. plantarum PS128, a strain recognized to relieve depression and anxiety in mice as well as people. At Bened Life, we call it Neuralli. Among all of the different products on the market, it's the only clinically studied medical probiotic for neurological conditions.

One of the qualities that distinguishes PS128 from other probiotics is the significant stress relief advantage.* In an 8-week clinical study on PS128’s effect on the stress levels of IT workers, noticeable improvements were made in stress and anxiety levels.*

In another clinical study, PS128 was studied alongside an SSRI, citalopram. The study consisted of 200 subjects: 100 received citalopram, while 100 received citalopram and PS128 capsules. By the end of the study, researchers found that anxiety symptoms in the PS128 group had decreased significantly more than in the group taking only the SSRI. 

While traditional drugs can override certain functions of the body and cause unwanted side effects, Neuralli works with your body to provide support.* Neuralli is here to help you take back your mind and restore your gut health.*

Go with your gut and bring your body back into balance. Learn more.


*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. 

Recommended reading:

Probiotics for Stress

What to Expect in Your First Month Taking Neuralli

Can You Use Probiotics for Sleep?


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