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Probiotics: Could good gut bacteria help tackle depression?

A recent study published in Translational Psychiatry has found that probiotics may be a helpful supplemental treatment for people with depression.

The study adds to current evidence demonstrating a link between gut health and mental health.

Current treatment for depression

According to the NIMH, a major depressive episode is defined as:

“A period of at least two weeks when a person experienced a depressed mood or loss of interest or pleasure in daily activities, and had a majority of specified symptoms, such as problems with sleep, eating, energy, concentration, or self-worth.”

Treatment for depression is often different for each person because the symptoms and severity are different for everyone. Treatment may include a combination of the following:

  • Support from groups, friends, and family members

  • Cognitive behavioral therapy, which involves learning to change thought patterns and actions to help manage symptoms

  • Medications such as the use of antidepressants

Improving other areas of health and supporting overall well-being can also help treat depression. For example, utilizing relaxation techniques and exercise can benefit people with depression.

However, researchers are still working to understand how to best help people with depression, including using supplemental treatments.

Probiotics to complement treatment

The study in question was a randomized controlled trial that delved deeper into the relationship between the natural bacteria in the gut and its connection to the brain. The study authors note that previous research has shown that among people with depression, there are also changes to the composition of the bacteria in the gut.

Participants included in the study were adults who currently had depression. Researchers used the Hamilton Depression Rating Scale to evaluate participants’ depression.

The participants were in one of two groups: one group received probiotics over four weeks while the other received a placebo.

Probiotics, as per the National Institutes of Health, are “live microorganisms (such as bacteria and yeasts) that provide health benefits when you consume them.” They can have an impact on the bacteria in the gut and people can get them through supplements or certain types of food.

The researchers found that the participants who received the probiotic had a higher reduction in their depressive symptoms. They also saw an increase in a group of bacteria called Lactobacillus among the gut flora of the participants who received the probiotic.

Dr. André Schmidt, study author and neuroscientist, noted that among the highlights of the study were the supportive effect probiotics had on antidepressants in patients with major depressive disorder.

“A 4-week intervention period further facilitated clinical decision-making, i.e., to decide whether the combination of antidepressants and probiotics worked or not. The amelioration of depressive symptoms went along with an increased abundance of Lactobacillus,”

Dr. Schmidt said that these findings could help develop better, more efficient, and individually-tailored probiotics for treating depression.

Study limitations and next steps

The study provides valuable data and indicates that the use of probiotics may be helpful in the treatment of depression. However, the study also had several limitations.

First of all, the study included a limited number of participants. The authors also note that participant compliance in taking the probiotic or placebo wasn’t perfect, which may have impacted the results. Further research can include longer follow up and more participants.

In addition, the results may be impacted by numerous probiotic strains and their interaction with the body, so investigating the specifics will be important in future research. Another area researchers can work to understand is the distinct interaction between antidepressants and probiotics.

Dr. Graham Rook, emeritus professor of medical microbiology with the University College London, who was not involved in the study, found the study’s results encouraging.

“There was modest evidence for reduced symptoms of depression at least in a high-compliance subgroup (remission rate of 55%) compared to a 40% remission rate in the placebo group,” he pointed out.

Dr. Rook noted that researchers could work toward understanding why these particular results happened.

''It seems probable that probiotics can be of benefit in depression, but there are many candidate mechanisms. Perhaps, if we could pinpoint the mechanism, we would be able to enhance the effect to a more useful level.” — Dr. Graham Rook


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