Multi-Strain Probiotics Can Reduce Mental Health Symptoms, Breakthrough Study Finds

 A turning point in research offers promise for easing anxiety and depression through the gut microbiome.
The gut-brain connection. Inkoly/Shutterstock
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Researchers are beginning to learn more about how probiotics can be used to treat mental health issues, with a new study showing that a combination of 14 bacterial strains eased symptoms of anxiety and depression.

Probiotics are health-promoting live bacteria and yeast that live in the human body. We can also consume them through supplements and fermented foods.

Despite links between bacterial imbalances and depression, research hadn’t found that probiotic treatments are effective against depression before, though studies usually tested only a single strain of bacteria.

This pilot study, however, opens the door for larger studies exploring the use of multi-strain supplements for mental health. The combination included different strains of Bifidobacteria and Lactobacillus, in addition to Lactococcus lactis and Streptococcus thermophilus, taken in a proprietary blend.

All subjects were between 18 and 55, had major depressive disorder, and were taking an antidepressant that wasn’t fully resolving their symptoms. Patients received either the 14-strain probiotic or a placebo.

The probiotic group had greater improvement than the placebo group, and exhibited particular improvements in anxiety symptoms. Results were published in JAMA Psychiatry in June.
“Non- or partial response to antidepressants is a huge problem and this study is an important first step in exploring the therapeutic potential of probiotics as a treatment for depression,” James Stone, the study’s senior investigator, said in a statement. “We found that probiotics were an acceptable and tolerable supplement in people already taking antidepressant medications.”

Study Specifics

On average, those taking the probiotics—24 of 49 patients—experienced a reduction of one severity grade on two depression rating scales. Patients had even greater relief from anxiety, which is a comorbid condition in up to half of patients with depression. In fact, researchers hinted that a reduction in physical anxiety symptoms could be the driving factor for lessening depression.

The multi-strain probiotic contained 8 billion colony-forming units. Patients took either the probiotic or the placebo daily for eight weeks, in addition to regular antidepressant medication.

Patients tolerated the probiotic well, with no serious adverse reactions, and had a high adherence rate. The study authors said it had a better safety and acceptability profile than supplements in earlier studies.

Medication Doesn’t Work Well

If future studies find effective blends of probiotics to treat various mental health issues, millions of people could receive some much-needed help.
About 60 percent of people with major depressive disorder don’t respond to their initial treatment, and about one-third continue to experience symptoms even with further treatment, according to the American Journal of Psychiatry. Studies indicate vast challenges with treatment-resistant depression and its burden on society.
About 1 in 5 U.S. adults have mental illness, with about 1 in 20 having a serious mental illness, according to the National Alliance on Mental Health. Mood, psychiatric, and other mental disabilities account for 1 in 5 people receiving Social Security Disability Insurance benefits. In 2019, that was more than 2 million people.

However, hopes that probiotics could resolve depression may be inflated, according to Dr. James Greenblatt, a psychiatrist, author, and international lecturer on the role of nutrition in mental health.

“I don’t think everyone going out and taking probiotics is going to solve depression being the No. 1 cause of global disability worldwide,” Dr. Greenblatt said. “But the relationship between gut health and depression is real.”

Dr. Greenblatt told The Epoch Times that those in the field of functional psychiatry aren’t sure how exactly the microbiome—all the bacteria, fungi, and viruses living in and on humans—plays a role in brain function. However, both animal and human studies reveal an association.

Anyone interested in trying a probiotic for depression should ask a health care provider whether there’s research specific to what probiotic they are considering, Dr. Chris Palmer, a psychiatrist, told The Epoch Times.

“Generic claims, such as ‘probiotics are good for you,’ are unlikely to be helpful for a medical condition like major depression,” he added.

Possible Mechanism of Action

However, research needs to continue testing probiotics because more therapies for depression are desperately needed, according to the authors of a meta-analysis of probiotic studies for depression published earlier this year in the International Journal of Molecular Sciences.
This study points to the production of brain-derived neurotrophic factor (BDNF) as a possible explanation for how microbes in the gut can cause or cure depression. Dr. Palmer said this finding is consistent with research he did for his book “Brain Energy,” published in November 2022.

Although our gut microbes don’t directly produce BDNF, they do produce short-chain fatty acids (SCFA) that play a role in the production of BDNF.

Pinpointing this mechanism of action is meaningful progress that could help researchers determine which probiotics could be used to spur SCFA production.

The study pointed out that people suffering from depression have significantly lower levels of BDNF than healthy people. SCFAs are also associated with the integrity of the intestinal barrier, which protects the body from inflammation.

Some inflammation is good, as it’s how the body summons resources such as white blood cells to fend off pathogenic invasions, but chronic inflammation is associated with autoimmune diseases. A weakened intestinal barrier causes bacteria and antigens to escape into the body and trigger inflammation.

Microbiome and Oxidative Stress

Researchers have also established a link between oxidative stress and the types and numbers of microbes that form in the gut.

“Oxidative stress is related to various human diseases, which covers depression,” the International Journal of Molecular Sciences meta-analysis notes.

Oxidative stress arises when more reactive oxygen species are created than can be eliminated by protective mechanisms. These species play an important role in immune function but must be kept in check. Oxidative stress can indicate chronic inflammation, a marker of many disease states.
In their analysis, the researchers found studies that confirmed that probiotic therapy worked in depressed patients who had oxidative stress markers. This finding was only confirmed in the group of depressed patients with associated conditions, specifically irritable bowel syndrome, and myocardial infarction. At least a quarter of cardiac patients suffer from depression, which is also linked to an increased risk of heart disease, according to the National Institutes of Health.
It’s possible that the probiotics worked to tamp down inflammation of comorbid diseases, which alleviated depression.

Improving Gut Health Through Diet

Early studies showed that probiotics can be beneficial in certain people with psychosis, bipolar disorder, ADHD, and schizophrenia, Dr. Greenblatt said. He added that usually, increasing probiotics becomes part of a comprehensive lifestyle and treatment plan in a functional approach.

“Most cultures have wide ranges of fermented foods that seed your gut bacteria. The traditional American diet doesn’t have much fermented food,” he said.

Functional psychiatrists are likely to focus on sleep, hormone adjustments, environmental factors, and diet, Dr. Greenblatt said. The microbiome is associated with all of these, though the relationship isn’t particularly well understood.

“The most direct impact of bacteria in our gut is diet,“ he said. ”Dietary change will be important. Changing your diet will change your gut.”

Amy Denney
Author
Amy Denney is a health reporter for The Epoch Times. Amy has a master’s degree in public affairs reporting from the University of Illinois Springfield and has won several awards for investigative and health reporting. She covers the microbiome, new treatments, and integrative wellness.
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