Taking probiotics—or friendly bacteria—might just be one of the simplest things you can do to help regulate your emotions.  Over the last few years, animal research and preliminary human clinical trials have shown promising results when it comes to how probiotics can influence mood.  As human trials continue to demonstrate the potential for psychological benefits, probiotic-based treatments are likely to follow in the coming years.  For now, how can you distinguish the hype from the potentially helpful?

The gut is often referred to as the “second brain” and for a good reason.  Gut bacteria produce and react to hundreds of the same neurochemicals that the brain uses for various psychological processes including mood regulation.  It is believed that having more beneficially bacteria—probiotics—can reduce inflammation and potentially protect against and even reverse mood disorders.  The recent term “psycho-biotics” refers to this potential.

Probiotics are amply found in fermented foods such as sauerkraut, pickles, kimchi, and yogurt.  They can also be taken in supplement form.  If you’re thinking about introducing more probiotics into your diet, talk to your health care provider.  In the meantime, there are a few things to keep in mind.

5 Things You Need to Know About Probiotics and Emotional Health   

1. The number of strains is more important than the number of bacteria

If you get a probiotic supplement that says it has billions of live bacteria cells, but only one strain, you might be missing out.  For example, some studies show that probiotics can help reduce symptoms of Obsessive-Compulsive Disorder (OCD).  But if you don’t look at specific strains, you might just end up with just a high concentration of one strain and no Lactobacillus rhamnosus, which is the strain that has been linked to reduced OCD symptoms.  (Be sure to check with your doctor before taking Lactobacillis rhamnosus as some studies have shown that it can increase the risk of developing a rare condition called endocarditis.)  Depending on what you’re looking for, more strains have you covered.

2. Stress can reduce the number of good bacteria in your gut

Trying to increase the number of helpful bacteria in your gut can be especially important during times of stress.  A 2016 study found that probiotics made people waiting for cancer surgery more resilient to stress.  Another study is investigating the probiotic strain Lactobacillus reuteri to see if it helps with symptoms of Posttraumatic Stress Disorder.

3. Probiotics can help reduce overthinking and depression

In a 2015 study, probiotics reduced rumination—overthinking and negative thinking—which is associated with depression.  Given the results, probiotics could potentially prevent depression.  Other studies demonstrate impressive findings when it comes to people who are diagnosed with depression.  For example, a well-designed 2016 study showed that after eights weeks of taking a probiotic supplement, participants had significantly lower scores on the Beck Depression Inventory.

4. Probiotics might be beneficial for anxiety

In a 2015 study on social anxiety and probiotics, researchers found that probiotics reduced social anxiety even among people who were at a greater risk for it due to high neuroticism.  Other studies on anxiety also seem promising.  For example, a well-designed 2018 study showed that the probiotic Lactobacillus plantarum reduced stress and anxiety while enhancing memory and cognition in adults.  And yet, other recent studies point to conflicting and inconsistent results when it comes to anxiety and probiotics.  So, it seems that the jury is still out.  They might be helpful when it comes to decreasing anxiety.  Fortunately, many would argue that the risk and cost of increasing your probiotic intake is relatively low as we wait for more research.

5. Probiotics can be beneficial for Bipolar Disorder

A 2018 study from Johns Hopkins University School of Medicine found that probiotics had a striking effect on the rates of rehospitalization among patients with Bipolar Disorder.  The study involved 66 patients who were diagnosed with Bipolar Disorder and were hospitalized for mania.  They administered a combination of probiotic strains to half of the patients for 6 months (along with their usual psychiatric medications) and then they compared the rates of rehospitalization.  While 50% of the patients required rehospitalization, the rate was three times lower in the probiotic group.  The participants in the probiotic group also had much shorter hospital stays (2.8 days compared to 8.3 days).  The effect was much more pronounced for people in the probiotic group who initially had the highest levels of inflammation.  This finding is consistent with inflammatory models of mental health as well as one of the proposed explanations for how probiotics work—by reducing inflammation.  Although this is the first clinical trial of Bipolar Disorder and probiotics, it is very promising.

It’s exciting to think that something as small yet abundant as probiotics could benefit our emotional well-being.  Yet, despite some of the exciting preliminary findings, we still need more data.  While animal research has been promising, the results aren’t always replicated in human trials.  Even when the results are replicated and human trails have significant findings, they often involve a small sample size.  In addition, when researchers do a meta-analysis of multiple previous studies, the findings are often inconsistent and further research is usually suggested.  Before any definitive treatment recommendations can be made about using probiotics to improve mood, we’ll have to see where science takes us.

And yet, we know that fermenting foods dates back to more than seven thousand years ago.  Traditional cultures have fermented their foods throughout history.  Although they might not have realized it, they enjoyed a diversity of gut microbes.  Perhaps they intuited something that we are just beginning to discover through science about health and healing.

(Always check with your doctor before starting a new diet or supplement.)