Long live bacteria!

You’ve surely heard of probiotics, which can help maintain a healthy gut for better digestion, nutrient absorption and immune support.

But a budding class of probiotics called “psychobiotics” is being touted for mental health benefits, too, with promises of improving mood, cognition and anxiety — without medication.

On TikTok and Instagram, dozens of content creators hawk different “natural” brands, raving that the supplements have helped them with everything from mood swings to depression to panic attacks.

“[They] helped me get over crying spells, anxiousness, rage and become more resilient to my daily challenges,” said one.

“I didn’t want to feel angry anymore. I didn’t want to be irritated when my daughter would cry … I made a simple shift in my wellness routine that started working the first week I used it,” wrote another.

But do they really work on stress and depression? The Post spoke with several experts about the latest nutritional craze and if it’s worth joining this cultured club.

What are psychobiotics?

Researchers John Cryan and Ted Dinan introduced the term in 2013, describing them as live organisms that, “when ingested in adequate amounts, [produce] a health benefit in patients suffering from psychiatric illness.” 

The definition was later broadened to classify them not only as probiotics but also as prebiotics, which support the growth of good gut bacteria.

Examples of psychobiotics include certain strains of Lactobacillus plantarum, which research suggests may help ease stress, anxiety, depression and insomnia. Certain strains of Bifidobacterium longum, too, have been shown to improve mood, in part by lowering the stress hormone cortisol and modulating brain activity.

The number of probiotic strains with solid evidence of mental health benefits has increased “remarkably” in the last five years, neuroscientist Dr. Jane Foster, PhD, a professor at UT Southwestern Medical School’s Department of Psychiatry, told The Post. 

How do psychobiotics work?

While it’s not 100% clear how they improve mental health, we know that they “act through the gut bacteria to influence the brain,” said Foster, who studies the link between the microbiome and mental illness.

By positively affecting the gut-brain axis, psychobiotics can reduce inflammation and regulate the release of stress hormones.

These probiotics can also help produce “feel-good” neurotransmitters including dopamine, serotonin and GABA through the gut-brain axis. The nuts and bolts of these mechanisms are still being explored.

What does the science say?

“It’s so attractive to say, ‘Oh, the serotonin from your gut is released by [the] gut microbiome and influences our brain,” gastroenterologist Dr. David Levinthal, director of UPMC’s Neurogastroenterology & Motility Center, told The Post. “And rather than taking Prozac, you have to just tweak your gut microbiome.”

But, he added, “I don’t think it’s that simple.”

People might report feeling better after taking these supplements, but those observations are difficult to confirm in clinical trials.

Though the studies are small, emerging research has found that psychobiotics may alleviate stress, anxiety and depression.

And certain strains stand out. Taken together, Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 have shown mixed, but some positive, results for depression symptoms. 

Depression and anxiety improved after just two weeks in mildly or moderately depressed people who took a combo of Lactiplantibacillus plantarum HEAL9 and the compound SAMe. 

Additional L. plantarum strains (like DR7 and P8) seemed to lower anxiety and stress. Bifidobacterium breve CCFM1025 shows promise for depression and Bifidobacterium longum 1714 for stress.

Before you head to the pharmacy, you should consult with your doctor.

Many questions remain unanswered, like: What are the most effective psychobiotic strains? Who should take them, and how much should they take?

“[Doctors] have to be incredibly cautious about recommending this for patients because the evidence is still being worked out,” Levinthal said.

Can you mimic the effects of psychobiotics in food?

If your goal is to find food with the exact strains that you’d get in pill form, that’s going to be a hard task, Levinthal said.

Still, adopting a “psychobiotic diet” could help your mental health. One study had a small group of healthy adult volunteers eat prebiotic and fermented foods “known to benefit the microbiota composition” for four weeks.

These foods include whole grains, legumes, fermented fare like kefir, kombucha and yogurt, plus fruits and vegetables high in prebiotic fiber. The “psychobiotic dieters” reported lower stress the more they followed the diet. 

Changing what you consume, whether you call it a “psychobiotic diet” or not, could be worth a shot.

Dr. Drew Ramsey, a nutritional psychiatrist, suggests eating probiotic- and prebiotic-rich food such as sauerkraut, fermented veggies, sourdough, kefir, miso and leafy greens. 

“Until science proves otherwise, that probiotic pills are superior to fermented foods, I think it’s a safer, more sustainable, more economical recommendation to encourage people to increase their plant intake and to explore more fermented foods in their diet,” Ramsey, author of “Eat to Beat Depression and Anxiety,” told The Post. 

Research also indicates that following a Mediterranean diet can significantly reduce depressive symptoms.

What should I know before I try psychobiotics?

Though probiotics are generally pretty low risk, supplements don’t face the same rigorous standards as medicines. 

“The regulation of supplements [or lack thereof] is a completely different ballgame than FDA-approved,” Levinthal noted. “You can make a lot of claims and don’t have to substantiate them.”

So, if you’re struggling with your mental health, don’t confuse the promising benefits of psychobiotics with FDA-approved SSRIs, for example.

If you’re on antidepressants, you shouldn’t quit them cold turkey for psychobiotics. But you may want to talk with your doctor about adding them to your treatment plan, as studies suggest that probiotics can complement antidepressants. 

Interested in trying a probiotic for mental health? Foster suggests looking at the Alliance for Education on Probiotics’ guide, which evaluates on-the-market supplements backed by research. 

Potency matters too. Levinthal suggests looking for dosing info on the bottle around 1 × 10⁹ colony-forming units — and check for the CFU count listed for the end of the product’s shelf life, as live probiotics can die over time. 

“Some people want a very natural approach [to mental health], and I think that’s reasonable,” Levinthal said. Psychobiotics as a concept is intriguing, he admitted. “It’s just that we need more data. If we have this interview five years from now, I might say something different.”