Probiotic bacteria found in yogurt, kefir may help improve mood

Evan Walker
Evan Walker TheMediTary.Com |
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Foods such as yogurt and kefir contain Lactobacillus bacteria. Claudia Totir/Getty Images
  • Researchers at the University of Virginia School of Medicine have discovered how Lactobacillus — a probiotic bacteria found in yogurt and kefir — assists the body in managing stress, potentially offering new avenues for combating mental health disorders like anxiety and depression.
  • The study distinguishes Lactobacillus from the broader microbiota, and sheds light on the role of gut bacteria in affecting mood disorders through immune system regulation
  • This breakthrough holds promise for innovative treatments across various diseases and conditions, ranging from mental health to physical health concerns, all while shedding light on the complex world of the human microbiome and probiotics.

In new research, published in Brain, Behaviour and Immunity, researchers have described the mechanism by which Lactobacillus — a type of bacteria commonly present in fermented foods and yogurt — assists the body in coping with stress.

The study stands out because it identifies the specific function of Lactobacillus, distinguishing it from the myriad of other microorganisms that naturally inhabit our bodies.

These microorganisms, collectively referred to as the microbiota, have gained increasing attention among scientists as potential targets for combating diseases and enhancing overall health.

This research could pave the way for the development of innovative treatments and potential cures for a broad spectrum of diseases, encompassing both mental and physical Health conditions.

Scientists have increasingly recognized the vital role played by these minute organisms and their intricate interactions in maintaining the Health of our immune systems, our mental well-being, and various other aspects of our overall Health.

Disruptions in the microbiota, whether due to illness, poor dietary choices, or other factors, are known to contribute to numerous diseases and can even facilitate the spread of cancer.

Consequently, researchers have become highly enthusiastic in recent years about the potential to combat diseases by targeting the microbiota.

To further their research on depression, the researchers utilized a collection of bacteria called Altered Schaedler Flora, comprising two strains of Lactobacillus and six other bacterial strains.

This unique bacterial community allowed them to create mice both with and without Lactobacillus, eliminating the need for antibiotics.

The researchers demonstrated how Lactobacilli influence behavior and how the absence of these bacteria can exacerbate depression and anxiety.

They found that Lactobacilli within the Lactobaccillacea family play a crucial role in maintaining the levels of an immune mediator known as interferon-gamma, which regulates the body’s response to stress and helps prevent depression.

Probiotic supplements for depression?

The researchers are now poised to develop novel approaches for the prevention and treatment of depression and other mental health conditions in which Lactobacillus plays a significant role.

For instance, individuals dealing with depression or at risk of developing it might eventually have access to specially formulated probiotic supplements designed to optimize their levels of beneficial Lactobacillus.

Two experts who were not involved in this research spoke to Medical News Today about this study.

Megan Hilbert, a registered dietitian specializing in gut health nutrition from Top Nutrition Coaching, said, “Research has shown a link in the past between the composition of the gut microbiome and stress but the exact link has been hard to elucidate in previous studies.”

“We’ve known that Lactobacillus concentrations are correlated with improved mental health, but there is mixed research on the effects that probiotics therapies have on mental wellbeing. This study shows that mice lacking Lactobacillus are more sensitive to environmental stressors due to changes in adaptive immunity, a system that plays an important role in mediating stress.”
— Megan Hilbert

“This research also confirms that it isn’t just disruptions in microbial communities that causes stress, but it’s specifically the lack of Lactobacillus that contributes to a lower stress tolerance seen in mice and the impacts the lack of Lactobacillus has on IFNy levels,” Hilbert explained.


Kelsey Costa, a registered dietitian and nutrition consultant for the National Coalition on Healthcare, said, “The gut-brain axis, a burgeoning area for psychological disorder research, underscores the intricate connection between gut microbiota and brain functions.”

“Dysbiosis — an imbalance in the microbial ecosystem — is frequently observed in individuals afflicted with stress or mood-related disorders, with Health">a marked reduction in the Lactobacillus family consistently reported across various studies,” Costa explained.

“In fact, Lactobacillus is considered a psychobiotic, a term that signifies its crucial role in mental health. The term ‘psychobiotic’ is generally used to describe live organisms that, when ingested in adequate amounts, produce a mental health benefit in patients.”
— Kelsey Costa

Costa highlighted that “these bacteria have demonstrated the capability to improve mental health through the gut-brain axis, enhancing stress resilience, reducing behavioral disorders in preclinical and clinical studies, and easing depressive and anxiety symptoms in humans.”

“The present research illustrates that the absence of Lactobacilli in mice from birth makes them more susceptible to stress, that stress may result in a reduction of Lactobacillus, and that transferring the microbiome from stressed animals to ‘germ-free’ animals could instigate anxiety and depression-like behaviors, while also suppressing an immune protein, IFNγ, important for stress resilience.”
— Kelsey Costa

Hilbert noted out that “these findings can help researchers and scientists better develop therapies and probiotics for mood disorders, something that has eluded the scientific community and has been hard to find successful therapies for.”

“These therapies may be able to better target lack of Lactobacillus and regulate the homeostasis of INFy,” Hilbert said.

Costa told MNT that this study “opens up new avenues to explore therapeutic strategies that target the gut microbiota for mitigating stress-related disorders, which may pave the way for developing specific probiotic solutions that could serve as adjunctive treatments.”

“Ultimately, this animal study adds value to the existing knowledge on how gut microbiota may influence neurological functions, particularly in areas of mood disorders such as anxiety and depression,” Costa said.

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