Probiotics for Mental Health

By Kristie Reilly and Temma Ehrenfeld @temmaehrenfeld
January 11, 2024
Probiotics for Mental Health

Evidence backs the idea that the bacterial community in your gut plays a role in your mental health. Here's how to get beneficial bacteria from probiotics.

The beneficial bacteria in probiotics are increasingly the subject of intense study, called pyschprobotics. You can get probiotics if you take supplements, eat fermented foods like yogurt, and increase your fiber intake.

Evidence backs the idea that the bacterial community in your gut plays a role in your mental health. The question is how to turn that insight into medical advice, identifying the correct strains and diets that could help people with specific symptoms.


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In one example, a study of more than 700 young adults concluded that eating fermented foods — including   yogurt, kefir, tempeh, and kimchi — was linked to less social anxiety. The effect was especially strong among the volunteers who tended to be anxious in general.

Other research zeroed in on a specific bacterium that was more abundant in volunteers diagnosed with social anxiety and one they tended to lack. One day you might be able to take a supplement to address that problem — but it hasn’t happened yet.

Researchers are also analyzing bacteria linked to depression and the severity of symptoms. While the evidence is mixed, it appears that probiotics have a beneficial effect on depression, especially in combination with other treatment. The bacteria L. helveticus, L. rhamnosus, L. casei, B. longum, B. breve, and B. infantis may be the most effective at improving depressive symptoms.

It’s likely that probiotic treatment will have the greatest impact on depressed people who have digestive issues like irritable bowel syndrome (IBS) or other conditions associate with a gut problem, such as obesity and type 2 diabetes.

Doses matter. You may need more than 10 billion CFU (colony-forming units) a day for at least eight weeks.

You may be most curious about the impact on your gut if antidepressants haven’t helped you. In a small eight-week study in Japan, researchers concluded that 70 percent of a group of patients with treatment-resistant depression benefited from taking 60 mg a day of Clostridium butyricum alongside their medication.  

Another small study found that taking a large daily dose of Bacillus coagulans improved symptoms and lowered pain in depressed patients with IBS.

If you are curious about the research, you might check out this chart of bacterial strains and the early evidence of their benefits.

Researchers are still looking for the exact mechanisms by which your gut can affect your brain. Much of what they know comes from animal studies.

When mice are raised in sterile environments — and thus lack bacteria in their guts — they display irregularities in the function of the hypothalamic-pituitary-adrenal axis, a key driver of emotional regulation, along with other changes in the brain. They react more quickly and easily to stress than mice raised in normal environments and produce fewer important neurotransmitters.

The studies are promising, and they've generated an unusual amount of excitement in the scientific community for more than a decade.

It’s important to realize, however, that humans have been altering their gut bacteria via antibiotics, fermented foods and probiotic supplements for many years, and the effect on specific conditions isn’t clear.   

Don’t expect to ditch your medication if you eat yogurt every day, take a supplement, or adopt a radical diet. The best approach is to eat healthily.

Like everyone else, people fighting mental illness may benefit from increasing their fiber (which feeds healthy bacteria) and eating a wide variety of plant foods along with some fermented foods.

Consider keeping a food and symptom diary that may reveal which foods make you feel better or worse.

Antibiotics affect your gut, so it’s best to minimize them, and you might opt for organic meat from animals who haven’t been exposed to antibiotics.

If you're curious about your gut, consider donating a sample to the Microsetta Initiative, one of several projects gathering samples from the public. Researchers from the University of California in San Diego will analyze your microbiome, comparing it to others in its growing database.


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January 11, 2024

Reviewed By:  

Christopher Nystuen, MD, MBA and Janet O'Dell, RN