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Probiotics for Depression?

Results from a recent study give new hope

By Austin Perlmutter, MD



  1. Study Overview: Conducted from 2019 to 2022, this research explored the effectiveness of probiotics as an adjunctive treatment for major depressive disorder (MDD). Participants, aged 18 to 55 and already on antidepressants, were administered a multistrain probiotic or placebo for 8 weeks in a double-blind, placebo-controlled trial.

  2. Promising Results: Among the 50 participants, 49 completed the study, predominantly female, with no serious side effects. The probiotic group demonstrated notable improvements in depressive symptoms and anxiety (based on one questionnaire) compared to the placebo group.

  3. Clinical Implications: The study's findings suggest probiotics as a safe, well-tolerated adjunct therapy for MDD, indicating a potential role for gut health in managing mood disorders. However, these preliminary results call for cautious optimism and need further validation in larger trials.

  4. Future Directions and Holistic Health: Acknowledging the limitations of current depression treatments, the study emphasizes exploring diverse interventions, including the gut-brain connection. It advocates for holistic gut health care, including a diverse plant-based diet, minimal antibiotic use, and consumption of fermented foods, while acknowledging that probiotic supplements might not be universally suitable.


As someone who’s spent years studying the biology of depression, it seems very clear that there are a few incredibly important themes in the current research. First, mental health disorders are rampant (especially depression and anxiety). Second, our current treatments are simply not good enough to turn the tide. This is why the breakthrough science of the gut-brain connection is so important and interesting. Now, a recent study shows the potential benefit of a gut-brain intervention for depression.



This study, carried out from September 2019 to May 2022, aimed to assess the acceptability, tolerability, and potential effectiveness of probiotics in patients with major depressive disotder (MDD). The participants in the study were adults aged 18 to 55 years and were already on antidepressant medication but had not achieved a full response. It was a single-center, double-blind, placebo-controlled pilot randomized clinical trial.


What did they actually do in the study?

The intervention involved administering a multistrain probiotic (14 different types of bacteria at a dose of 8 billion. The other group received a placebo. Both groups also continued to take their antidepressant medication, and the study lasted for 8 weeks.



Out of 50 participants, 49 completed the trial, with a notable majority being female. No serious side effects were noted. The results were promising. The probiotic group showed greater improvements in depressive symptoms compared to the placebo group. Anxiety symptoms also improved more significantly in the probiotic group based on one questionnaire.

Clinical Implications and Future Directions

The results of this study are significant for several reasons. First, they indicate that probiotics can be a safe and well-tolerated adjunctive treatment for MDD. Second, the improvement in clinical symptoms suggests a potential role for gut health in managing mood disorders. With this said, it's important to approach these findings with cautious optimism. While the results are encouraging, they are preliminary and require further exploration in larger, more definitive trials.


What Should We Do Now?

Returning to the theme at the start, it’s very clear that current mood disorder treatment (especially depression) is lacking. This is why it’s so important that study more than just conventional therapy as potential options for managing and preventing these conditions. From psychedelics to anti-inflammatory medications and lifestyle changes, there’s lots to be excited about, and the gut-brain connection may represent a key thoroughfare for so many of these potential anti-depressant interventions. It’s still early in the game, and researchers aren’t sure whether probiotics strains in supplement form are necessarily right for everyone. With this said, generally caring for the gut is a good call for general health. Some basic ways to do that include eating a diversity of plant-based foods rich in fiber and polyphenols, avoiding unnecessary antibiotics and considering consumption of fermented foods like kimchi, sauerkraut. For more on the gut-brain connection, check out this article.

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