How Your Gut Bacteria May Be Making You Feel Anxious

Probiotics may provide relief for anxiety when other remedies fail.

Summary:  Probiotics may be a possible treatment avenue to explore for patients with anxiety disorders who have intestinal issues along with their anxiety, taken antibiotics prior to the anxiety starting, or achieved very little relief from traditional treatments such as anti-anxiety medication, psychotherapy or behavioral therapy. 

Published: January 23, 2014

Updated: July 20, 2015

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Just getting through an average day in our modern world can feel very stressful.    Modern life is filled with anxiety provoking events:  taking a final exam; making a speech in public; a rash of burglaries in the neighborhood; the upcoming expiration date for unemployment benefits; a sick loved one and myriad other examples that you can come up with from your own life.  It is completely normal and healthy to feel stress when confronting life’s challenges.

A person experiencing anxiety can experience feelings of fear, nervousness, apprehension or worry.  But sometimes, for some people, the level of anxiety they feel starts to affect their ability to function and to lead happy and productive lives.  The feelings can be out of proportion to whatever is triggering the anxiety (the stressor) and can affect their ability to sleep, to function day-to-day and to be present and feel settled in  their lives.  If experienced for extended periods, anxiety can even create physical health problems for the sufferer.

There are many traditional therapies that can be very effective for certain people who are struggling with problematic anxiety.  But many do not enjoy the expected relief promised by these treatments.  Doctors and patients alike have long been frustrated by their inability to permanently cure patients of debilitating anxiety.   New medical research is now revealing an unexpected potential cause for anxiety disorders (gut bacterial imbalances) and a new approach for treating certain anxiety sufferers – promoting a healthy gut microbiome.

What is an Anxiety Disorder?

Anxiety disorders affect approximately 18% of American adults (about forty million people and about 8% of American teenagers.  The number of children affected is not known, but kids suffer from anxiety too.  Women are 60% more likely than men to be diagnosed with a disorder of anxiety, although this may be because they are more likely than men to seek out medical help for psychological symptoms than are men.  We all know a stoic guy who refuses to get that pesky symptom checked out by the doctor, no matter how bad it gets!

Types of Anxiety

When anxiety becomes excessive, bothersome and long-term for the person troubled by it, it can be classified as an anxiety disorder.  Anxiety disorders can take many forms:

• Generalized Anxiety Disorder (GAD) is a chronic condition characterized by excessive, uncontrollable, long-term, exaggerated anxiety and worry about nonspecific, daily life events, objects, and situations.  People who experience this disorder worry about the same sorts of things that we all do, but the level of anxiety that they feel about them is greater.  They may feel a general sense of unease, or worry that lasts throughout the day.  They may experience unpleasant physical symptoms like fatigue and sore muscles.  People with GAD may have a hard time sleeping and concentrating.
• Obsessive Compulsive Disorder (OCD) is an anxiety disorder characterized by recurrent and unwanted thoughts. People with it may have obsessions and compulsions.  To try to control the unwanted, intrusive and obsessive anxiety-provoking thoughts (the obsessions), a person suffering from OCD will feel an overwhelming urge to repeat certain time-consuming rituals or deliberate behaviors (the compulsions) to reduce the obsessive worry.  Examples of compulsions are: repeated hand washing, checking an rechecking the house locks, repeating day-to-day tasks multiple times to ensure they are perfect, excessive grooming (e.g. nail biting, hair pulling).  OCD sufferers often realize that their compulsions are unreasonable or irrational, but doing them helps to reduce the anxiety itself.
• Panic Disorder is a type of anxiety characterized by sudden, unexpected and repeated panic attacks of intense terror and apprehension that can lead to shaking, confusion, dizziness, nausea, and difficulty breathing and may even feel like a heart attack. Sufferers become very anxious about the thought of having future panic attacks and become fearful about bad things that might happen, such as dying, when they do have one.
• A Phobia Disorder is characterized by an irrational fear and or avoidance of a particular subject, activity or situation. Phobias are different from generalized anxiety disorders because the fear is always associated with a specific cause or trigger. Although the phobia may be acknowledged by the sufferer as irrational, the person is still unable to control the anxiety that results. Examples of phobias are an excessive fear of heights, snakes, germs, flying or even being with other people.
• Post-traumatic Stress Disorder (PTSD) is a condition triggered by experiencing a traumatic situation such as combat, rape, abuse, or a serious accident and causes the sufferer to feel fear even when they are no longer in any physical danger. PTSD often leads to flashbacks and avoidance of certain stimuli as well as ongoing feelings of tension, anxiety or anger.

Causes

Traditional Causes

The causes of anxiety disorders are currently only partially understood.  Doctors currently believe that anxiety disorders can be caused by a combination of factors that may influence each other within a person including genetics, environment, conditioning, trauma, diet and of course the individual psychology of the affected individual.

Gut Flora (Gut Bugs)

An exciting new medical frontier has been opening up recently with respect to how the mix of gut microflora (including bacteria, fungi and viruses) living in our guts can affect our mental health.  We each have about six pounds of these flora living in bodies.

Dr. Emeran Mayer, a professor of medicine and psychiatry at the University of California, Los Angeles believes that the microflora inhabiting a child’s gut actually influence the developing structures in his brain as the child grows up and that those brain structures can then influence that child’s feelings, thoughts emotions and mental health throughout his later life.  Dr. Mayer has taken MRI scans of the brains of thousands of volunteers, while collecting samples of their gut bacteria.  He has found that the connections formed between the regions in a person’s brain differ depending on what type of bacteria predominate in each individual’s gut.  It’s seems incredible that our gut bugs can affect our physical brain in such a profound way.  A conclusion that can be drawn from this research is that colonization by certain kinds of bacteria may led to particular brain structures or wiring that makes someone more susceptible to anxiety than might exist in another person whose gut was colonized by different bacteria.

Babies, who are bacteria-free in utero, get their first exposure to healthy bacteria from their mothers.  They first pick up helpful bacteria as they pass through the birth canal.  Later, beneficial (probiotic) bacteria are passed from mother to child through breast feeding.  The intestinal colonization of bacteria is normally stable by about two months. Factors related to the method of birth (C. Section vs. vaginal birth), early feeding (breast fed vs formula fed) and medical history (admittance to the Neonatal Intensive Care Unit (NICU) or treatment with antibiotics) can impact the mix of gut bacteria that a newborn is exposed to and which bacteria, fungi and molds eventually colonize themselves in a baby’s gut.

Once established in infants, the mix of bacteria in the gut tend to be relatively stable in that person throughout life, but can fluctuate based on things like antibiotic exposure, diet, stress and alcohol consumption.

The flora living in the gut, even if they are not causing active infection in the body, can also create psychological symptoms. A subset set of anxiety disorders are believed to be triggered by an imbalance or overgrowth of unhealthy microbes within the gut.  Dr. James Greenblatt, a Boston-area psychiatrist with an emphasis on psychopharmacology (the medications used to treat psychiatric conditions) believes that about twenty percent of his anxiety patients’ disease was triggered by an imbalance of microbes in or on a person (known as dysbiosis).

Dr. Stephen Collins of McMaster University’s research looked at differences in brain chemistry and behavior that may be driven by the gut flora in mice.  He transplanted the gut bacteria from anxious/ timid mice and put them into calm/bold mice and vice versa.  Following the transfer of gut microbes, the fearless mice then became timid and the timid mice became more gregarious and less anxious.  Dr. Collins later fed the aggressive mice probiotics and they calmed down.

We all have several hundred types of flora inhabiting our gut, including both good bugs (probiotics) and harmful bugs (pathogens).  Normally the pathogens are kept in check by competing for space with the probiotics that inhabit us.  Antibiotics are excellent at killing harmful bacteria, but they can also kill many of the good bacteria at the same time they are working their magic against disease causing pathogens.

The gut microbiome can be disrupted by taking a course of antibiotics, when both probiotics and pathogens are killed.  When the antibiotics kill off the good bacteria, there is then space within the intestines for antibiotic resistant bacteria or fungi such as yeast, which are resistant to antibiotics, to move in and reproduce within the intestines.  Oftentimes the bacteria that repopulate the gut following a course of antibiotics are a different mix of species than the original healthy gut bugs that were previously living in that person’s body – causing dysbiosis, a disturbance of the gut microbiome (mix of flora inhabiting a person’s gut) in the body.

Antibiotics, both in medications and also in anti-bacterial soaps and cleaning products, are not the only thing that can cause dysbiosis.  Diet can also contribute to the growth of unhealthy gut bacteria.  The modern diet which is heavy with highly refined foods, sugars and processed carbohydrates can feed the bad gut bugs. Yeast is a fungus that normally lives in the gut in small amounts, but can be problematic if it increases its numbers and it can thrive on sugars and easily digested simple carbohydrates, even causing people to crave starchy foods .  Chemical additives in our diets may alter bacterial function.  Psychological and physical stress, age and alcohol consumption can also impact the composition of bacteria in a person’s digestive system and can cause dysbiosis.

In dysbiosis, the bad gut bugs that establish themselves in greater numbers than before, are also able to communicate with the brain and may be able to increase feelings of anxiety, depending on which gut bugs they are.  Also, certain healthy gut bugs, like those transplanted in mice by Dr. McMasters above, promote calm feelings, and if their numbers are decreased in the intestines due to dysbiosis, anxiety may increase.  Dysbiosis can deliver a one two punch – more bad gut bugs that increase anxiety and fewer healthy gut bugs to reduce anxiety.

How Can Gut Bugs Communicate with the Brain?

There is a well-known connection between the brain and the gut. The trillions of bacteria living in a person’s gut (gut microbiome) can communicate directly with the brain via the Vagus Nerve that connects them.  Bacteria can also communicate with the brain via the enteric nervous system, the nervous system of the digestive track.  Believe it or not, there are actually more neurons wrapped around the gut than there are in the spinal cord.

We are starting to find out that gut bugs can communicate with the brain, scientists say, both by modulating the immune system and by actually producing neurochemicals.  Scientists have been aware for some time that about 50% of the neurochemicals in our bodies arise from the gut, but are now taking a close look at the role that microbes play in their production.  Some of the neurochemicals produced by our the microbes in our digestive tract are the same neurochemicals that are used by our neurons to communicate and affect mood including dopamine, serotonin and gamma-aminobutyric acid (GABA). Mark Lyte, a researcher at Texas Tech University Health Sciences Center who studies the effect that microbes can have on the endocrine systems (the body system of the endocrine glands and the hormones they produce) says, “I’m actually seeing new neurochemicals that have not been described before being produced by certain bacteria.  These bacteria are, in effect, mind-altering microorganisms.”  This special class of microbes is known are psychobiotics.

Through this communication from the gut to the brain, the gut bugs can affect behavior and mood.  Maybe those folks who coined the expression “gut feeling” were actually on to something! Recent research supports the theory that disturbances in the gut microbiome, or the combination of microbes living in a particular person’s gut, can play a role in some psychopathology such as anxiety, depression, schizophrenia and even autism.

Traditional Treatments for Anxiety

Medication

Unlike for an illness caused by bacteria or vitamin deficiency, both of which can be fixed by taking a pill, medicine cannot cure anxiety.  What it can do is help control the symptoms and ease suffering and improve quality of life for people who take it, while they are taking it.  It seems to work better for some patients than for others.  Unfortunately, it is not always easy to determine which, if any medications will help which person and what dose is necessary.

Medications must be selected through trial and error to find one that works.  To further complicate things, a treatment regimen that may have worked in the past may stop working suddenly and for no apparent reason.  Side effects may be an issue.  For children and adolescents, the issue of whether or not to give medication is complicated by concern about affecting their developing brains, causing many parents and doctors to resist prescribing them to youths.  All of these challenges aside, the medications can be an absolute godsend for the lucky person whose anxiety-related distress is eased with the right medication.

Therapy

Psychotherapy is a word used to describe the process of treating mental health problems by talking with a psychiatrist, psychologist, social worker or other trained professional.  As part of this kind of treatment, a patient learns more about her anxiety disorder and your feelings, thoughts and behaviors. Psychotherapy can provide the skills needed to learn how to function more effectively in everyday life and to take control of anxious feelings that cause distress.  It can teach skills on how to manage anxiety provoking situations with healthy coping skills.

One type of therapy known as Cognitive Behavioral Therapy (CBT) has been shown to be particularly effective for helping people with anxiety disorders.  With CBT, the patients learn to better understand the thoughts and feelings that are behind their behaviors.

Traditional treatments for anxiety can be effective at treating symptoms of anxiety and helping patients to better manage their anxious thoughts and feelings.

Probiotics as Treatment for Anxiety

For that subset of anxiety patients whose anxiety may be triggered or exacerbated by unhealthy gut bugs living in their intestines, there is a whole other possible course of treatment that is currently being studied by researchers now that may improve or eradicate their anxiety altogether.

Experiments that examine whether giving people probiotics can effectively treat anxiety disorders are in their infancy.  There have been some very exciting results coming out of those studies which have been completed and lots more are underway.

“Anyone who has a mental health disorder that coincides with a GI disorder is a good candidate for probiotics,” said Jane Foster, associate professor of neuroscience and behavioral science and part of the McMaster University & Brain-Body Institute, and who has found a link between anxiety like behavior and the intestinal microbiota.  Anxiety and mood disorders are often found in people who are also experiencing bowel disorder.

In a study by Amber Park and colleagues at McMaster University, the researchers have shown that anxiety like behavior often accompanies chronic colitis (inflammation of the intestine) in mice.  In their experiment, mice were randomly assigned into a group that was given a probiotic (B. longum) or a placebo. The mice with colitis given the probiotic showed reduced anxiety behaviors than did the control group. Conventional wisdom used to say that anxiety caused colitis, but it is now appearing to be a strong possibility that the colitis can impact the anxiety that appears to be associated with it or alternatively, both could be triggered by a common cause.

In a study published in the PNAS (Proceedings of the National Academy of Sciences of the United States of Americas), Dr. Javier Bravo and colleagues gave one group of mice the probiotic (L. Rhamnosis) and  gave the control group of mice only broth (i.e. no probiotic).  The researchers stimulated the poor mouse subjects in various ways to try to stress them out and found that the mice given the probiotic reacted to the provoking situations with reduced anxiety than the group that didn’t get it.  The probiotic treated group was found to have lower levels of stress hormone (corticosteroid) in their blood as compared to the control group.

Additionally, a subset of mice in both the control group and the group given probiotic had the vagus nerve that connects the brain and the gut cut.  The subset of mice who were given the probiotic and that also had their vagus nerve severed did not show the same chilled-out effect to stress as was shown by the cohort of mice that was given the probiotic and had their vagus nerve left intact – the former group of mice’s reaction to stress was the same as the control group.  This seems to show that the probiotic did not have the same anxiety-reducing effect when the gut could no longer communicate to their brain via the vagus nerve.  This is more support for the brain-gut connection.

Finally, the mice were then killed in the name of science and autopsied, poor little guys, and the researchers found that the mice who were given the probiotics had a greater number of anxiety-reducing receptors (GABA receptors) in their brains, which is fascinating.   This seems to show the potential power of the probiotics to not only reduce anxiety, but also to physically impact structures in our brains.

Dr. Mayer and his colleague have been studying the effects of giving fermented live-milk yoghurt with active cultures to healthy women with no psychological symptoms.  As published in the Journal of Gastroenterology, they have found that the areas of the brain associated with anxiety were less active in the women given the yoghurt than in the control group that was not given yoghurt.  This experiment suggests that probiotics might reduce anxiety even for those patients without an anxiety disorder.

Sarkis Mazmanian and colleagues gave Bacteroides fragilis (B. fragilis) to mice that who were showing unhealthy communication patterns and obsessive-like behaviors.  Those that were treated showed a reduction in the unhealthy behaviors.

Mark Lyte is currently planning to conduct fecal transplants (where fecal samples  are inserted into the large intestines of donor monkeys) to study how altering the mix of gut microbes and the neurochemicals they produce can affect the monkey’s neurodevelopment.

It may be that at some point, fecal transplants from psychologically healthy donors to depressed or anxious patients can offer them real hope of a relief from their debilitating symptoms.  However, this may not be in the near future.  Dr. Lyte has stated in a June 23, 2015 article on psychobiotics in the New York Times, “If you transfer the microbiota from one animal to another, you can transfer the behavior…What we’re trying to understand are the mechanisms by which the microbiota can influence the brain and development. If you believe that, are you now out on the precipice? The answer is yes. Do I think it’s the future? I think it’s a long way away.’’

Who Should Consider Probiotics

The results coming in from studies that examine the effect of probiotics on anxiety are really fascinating and exciting.

For those people who have digestive issues along with anxiety, probiotic supplemenation, both by taking specific probiotic supplements as well as by eating fermented food containing live cultures, may not only help with the digestive symptoms but also with the anxiety. Disruptions to our gut bugs can cause digestive problems and can trigger anxiety symptoms.  Anxiety symptoms are often seen in people who are also having digestive problems, such as colitis, diarrhea and leaky-gut. Adults with anxiety disorders who have recently taken antibiotics, have a poor diet, drink moderately to heavily or have other issues that may have caused dysbiosis (disruption in gut bugs) are also potential candidates for probiotics. Administering probiotics can assist in returning healthy gut bugs to the digestive system.  Giving probiotics has been shown to reduce anxiety both for anxious people and also for people without any known anxiety concerns.

In children, particularly those who might have had disruptions to the healthy colonization of their gut when they were babies, perhaps from taking antibiotics when very young, being admitted to the NICU, being born via Cesarean Section or not having been breastfed, giving them probiotics, with their pediatrician’s knowledge and agreement might help ease some anxiety symptoms that the child is experiencing.  Since many doctors and parents are reluctant to give prescription anti-anxiety medications to children, giving a probiotic could be an alternative treatment to consider that has fewer risks and side effects.  [Please do note that probiotics have not been shown to be helpful for treating children with PANDAS, an obsessive-compulsive like disorder that sometimes arises in children following a bacterial streptococcus infection.]

Probiotics may be a treatment avenue to explore for patients with anxiety disorders who have achieved very little relief from traditional treatments such as anti-anxiety medication, psychotherapy or behavioral therapy.

I will continue to follow this very interesting field of research and update the site when new studies come out. In the meantime please consider adding a comment below sharing your own story and experiences with anxiety and your microbes.

Further Resources:

Strains Probiotic Bacteria that Have Been Shown to be Anxiety Reducing

If you’ve read this far, you may already be inclined to try.  Which begs the question: what to try?  While it is still too early to say exactly, the following bacteria have been shown to reduce anxiety in scientific studies.  When considering a probiotic to treat anxiety, review the ingredients to see if any of the following are included:

• Bacteroides fragilis (B. fragilis)
• Bifidobacterium longum (B. longum)
• Lactobacillus bulgaricus (L. bulgaricus)
• Lactobacillus rhamnosis (L. rhamnosis)
• Bifidobacterium animalis (B. animalis)
• Lactococcus lactis (L. lactis)
• Streptococcus thermophiles (S. thermophiles)

Interesting Articles on Anxiety and Probiotics in the News

• Anxiety in Your Head could Come from Your Gut
  
• Do Probiotics Help Anxiety?
• Gut Bacteria May Guide the Workings of our Mind
• The Dirty on Good Bacteria
• PANDAS: Frequently Asked Questions about Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections
• Mental Health May Depend on the Creatures in the Gut

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