Dr. Michael Ruscio, DC is a clinician, Naturopathic Practitioner, clinical researcher, author, and adjunct professor at the University of Bridgeport. His work has been published in peer-reviewed medical journals and he speaks at conferences around the globe.
Research suggests that probiotics are likely helpful for anxiety, but more research is needed.
If you’re one of the 19% of Americans who experience anxiety disorders, you may want to consider
trying probiotics for relief. It may
seem counterintuitive, but anxiety and other mental
illnesses may have a lot to do with what’s happening in your gut.
emerged as a potential anti-anxiety treatment with minimal side effects.
Let’s take a look at what is known.
and the Gut-Brain Axis
Research tells us that the gut and brain share a very close
connection. Through multiple lines of communication, your central nervous system (which includes the brain)
talks to your endocrine and digestive systems. 
Inflammation in the intestines is known to cause digestive
and immune system symptoms and also
inflammation in the brain. This may look like brain fog, irritability, and yes,
anxiety. Changes in the gut microbiota
can produce many different types of symptoms, including mental health symptoms like anxiety and depression, and loss of
cognitive function. 
Having sleep problems, such as difficulty falling or
staying asleep, restlessness, or unsatisfying sleep
Another type of anxiety is panic disorders. Symptoms include:
palpitations, a pounding heartbeat, or an accelerated heart rate
of shortness of breath, smothering, or choking
of impending doom
of being out of control
Other types of anxiety include phobias (fear of particular
things or actions, like heights) and social anxiety.
Data from multiple meta-analyses (the highest quality science) suggest that probiotics are likely helpful for anxiety, but more research is needed.
Summary: Probiotics and Anxiety
Four meta-analyses all determine that there may be some
anti-anxiety effect from probiotics,
but that the current available data isn’t conclusive.
One meta-analysis determined that the available data wasn’t clear, and more high-quality human clinical trials were needed. 
A second meta-analysis identified possible anti-anxiety effects from probiotics, but found the total sample sizes too small to make widespread claims. 
A third meta-analysis found a clear anti-anxiety effect in animal studies, but not enough data in human clinical trials. 
A fourth meta-analysis determined a likely positive benefit of using probiotics for anxiety and depression. 
Even more interesting, a significant number of people
experience relief from mental health
symptoms when they rebalance their gut.
In a systematic review
of randomized control trials, 56% of participants experienced improved anxiety
with the use of probiotics and a low
FODMAP diet. 
Anxiety May Start in the Gut
It’s no secret that people with gut health problems often feel anxious or depressed. But which
comes first, the mental health challenge
or the gut symptoms?
A 2016 study of 1,900 people found that two-thirds of
them experienced irritable bowel syndrome (IBS)
before mental health symptoms, implying
that for many people, the gut disturbance was the source of their anxiety. 
Another way to think about this connection is by considering the role of a leaky gut. Gut inflammation can make the gut lining permeable, which allows bacterial toxins to enter the bloodstream. These toxins have been shown to contribute to anxiety and depression symptoms. 
A systematic review
found that people with underlying autoimmune thyroiditis or hypothyroidism are
likely to experience anxiety and depression. 
But hypothyroidism is also closely linked with gut dysbiosis, especially Small
Intestinal Bacterial Overgrowth (SIBO). 
I often find restoring my patients’ gut function resolves their thyroid
symptoms, and this includes their related anxiety symptoms.
Many people advocate for choosing probiotics based on your health condition. Usually this is
because particular probiotic strains,
such as B.
infantis, or B. longum,
were used in one or more studies. For anxiety or depression, this may
include recommendations to include “psychobiotics”,
or probiotics that have shown promise
for psychiatric conditions. For example, a recent
study on rats showed that Lactobacillus helveticus reduced their
anxiety scores. 
And so the thinking goes, “If that probiotic helped anxious rats, maybe it will help me.”
supplementation doesn’t work like a medication (and animal studies
aren’t necessarily a good way to assess how a therapy will benefit you).
Instead, the benefits of probiotics are general. They repair function and restore your gut environment. Though there may be hundreds of probiotics, almost all of them fall into one of three categories.
The best approach is to choose one high-quality probiotic supplement from each category and use regularly. The specific brand or strains aren’t as important as making sure you are using one probiotic from each type:
Use all three probiotics
daily for about a month, and see how you feel. If you notice positive effects, you can continue, or reduce
your dose to the smallest effective dose. Common effects
of probiotics include:
Many sources also recommend using fermented foods to reset your gut
microbiota because they contain good
bacteria. Though fermented foods,
like kimchi or sauerkraut, are healthy,
they generally don’t have enough colony-forming units (CFUs) to provide a clinical benefit.
which feed your beneficial bacteria,
aren’t necessary to supplement, as long as you’re eating a diet rich in fiber
from fruits, vegetables, and nuts and seeds. I recommend using caution with prebiotics, as they can flare digestive
Do Probiotics Work Better with the Right Diet?
In one study that compared probiotic use with a low FODMAP diet, many participants experienced significant relief of anxiety from trying the low FODMAP diet. The low FODMAP diet alone has been shown to restore a healthy gut microbiome, and decrease symptoms related to IBS, like bloating and stool changes.  It works by decreasing the food supply for bad bacteria in your gut. Improving your diet reduces gut inflammation, which helps improve many types of symptoms, including anxiety.
The Bottom Line
Though there isn’t yet iron-clad evidence that probiotics improve anxiety, the research
suggests that they may help. Following a low FODMAP diet along with probiotics may be even more effective. Because probiotics are typically safe and don’t cause negative side effects, a trial of probiotic therapy makes sense if you suffer
Ohland CL, Kish L, Bell H, et al. Effects of Lactobacillus helveticus on murine behavior are dependent on diet and genotype and correlate with alterations in the gut microbiome. Psychoneuroendocrinology. 2013;38(9):1738–1747. doi:10.1016/j.psyneuen.2013.02.008
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