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Study Finds Benefits of Probiotics for Depression

By Jillian Levy, CHHC


It’s well-known that probiotics, available from both fermented foods and supplements, support digestion and gut function. Can probiotics also improve mental health?

A new study suggests there are benefits of probiotics for people dealing with depression. How so? A little known fact is that certain gut bacteria are linked to depression, while others are associated with improved moods, neuron activity and cognitive function.

This makes sense, considering that probiotics in the gut can support neurotransmitter function. Neurotransmitters are the brain’s messengers that control one’s mood, energy, appetite and more.

Study Findings: Probiotics for Depression

A 2022 randomized, controlled trial published in the journal Translational Psychiatry found evidence that probiotics can function as a promising new treatment approach for major depressive disorder (MDD).

Probiotics are defined as “microorganisms introduced into the body for their beneficial qualities.” They’re known to have an effect on the microbiota-gut-brain (MGB) axis, also called the “gut-brain connection.” This gives probiotics the ability to impact physiological and behavioral functions that are associated with depression.

This particular study sought out to determine whether short-term, high-dose probiotic supplementation could reduce depressive symptoms by causing gut microbial and neural changes in depressed patients. Patients who were struggling with depressive episodes took either a multi-strain probiotic supplement or a placebo for one month (31 days) in addition to completing their usual treatments.

Participants completed an assessment of their symptoms before and after the probiotic intervention using the Hamilton Depression Rating Scale. Microbiome profiling and neuroimaging scans were also used to detect changes in the participants’ gut-brain axis.

Among those who took the probiotics, it was found that microbial diversity and abundance of the probiotic strain called Lactobacillus were both increased. These increases were associated with decreased depressive symptoms.

Another finding was that activation of certain neurons associated with depression was significantly decreased after the probiotic intervention.

In conclusion, data from the study indicate that probiotics taken in addition to other treatments can help decrease depressive symptoms due to changing gut microbiota and brain activities. Researchers involved in the study consider probiotic treatments to be an “accessible, pragmatic, and non-stigmatizing” approach to supporting mental health.

Other Probiotics Benefits

So what probiotic is good for depression?

The study mentioned above found that Lactobacillus seems to be supportive of mental health. Bacillus coagulans has been shown in other studies to improve depressive symptoms in patients with a combined diagnosis of MDD and irritable bowel syndrome.

On the other hand, increased abundance of Ruminococcus gauvreauii and decreased abundance of Bacteroides are thought to increase one’s risk for depression.

Can probiotics increase serotonin?

Some studies, and one systematic review, have found that certain probiotics present in the gastrointestinal tract may improve central nervous system symptoms associated with depression by increasing production of free tryptophan, which is then converted to serotonin. So yes, it’s possible that a healthy gut helps to boost serotonin production, which improves someone’s mood.

What other benefits do probiotics have?

In addition to supporting mental health, probiotics can help:

  • Support gut lining integrity, which is important for immune health and immune defenses.

  • Help with absorption of essential nutrients and synthesis of some vitamins and proteins.

  • Promote healthy digestion, including by limiting occasional diarrhea, gas and bloating.

  • Support a healthy body weight.

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