Can probiotic supplements mitigate stress and its adverse health consequences?
A new study recently published in the journal, Neurobiology of Stress, attempts to answer that question.
Acute and chronic impact both mental and physical health. The hypothalamic pituitary adrenal (HPA) axis, which is the main stress response system, produces stress hormones, including cortisol, which can affect intestinal barrier integrity and immune signaling. This also affects the composition of the gut microbiome. We also know that the microbiome can influence how we respond to stress.
To test the hypothesis that an orally ingested probiotic might mitigate human stress and anxiety, Elaine Patterson, PhD, and her team at IFF (formerly DuPont Nutrition & Biosciences) in Kantvik, Finland, in collaboration with Juliane Hellhammer and her team at daacro contract research in Germany, randomly allocated 120 healthy adults, aged 18-45 years, to consume capsules containing either 1.75 x 1010 colony forming units of Lacticaseibacillus paracasei Lpc-37® or an identically matched placebo, every day for five weeks.
By helping to manage psychological responses to everyday stressors, friendly flora like Lpc-37 could be valuable allies for people facing heavy workloads, tight deadlines, and financial strain.
A total of 113 subjects completed the full 5-week intervention and fully complied with the protocol.
The primary outcome measure in this study was the effect of Lpc-37 on heart rate during the Trier Social Stress Test (TSST). The TSST combines multiple stress-inducing tasks–a simulated job interview and a mental arithmetic task. It has been the gold standard method of inducing stress in human research for nearly 30 years.
The investigators also looked at the effect of Lpc-37® on stress, anxiety and depression levels using a series of validated questionnaires and self-report scales and other physiological markers of stress including blood pressure, salivary alpha amylase and salivary cortisol.
Notable Impact
Lacticaseibacillus paracasei Lpc-37, formerly known as Lactobacillus paracasei, was chosen for this study because it had proven effective for preventing anxiety and depression-like behaviors in an anxious mouse model. Lpc-37 is very well characterized, and has been included in over 20 prior clinical studies investigating different endpoints. It is currently available for supplement formulation as a branded ingredient called HOWARU® Calm.
In this new study, Lpc-37 turned out to have a notable impact on several indicators of stress (Patterson E, et al. Neurobiol Stress. 2020)
Following the five-week intervention, there was a statistically significant reduction in perceived stress in those participants taking the probiotic compared to those taking the placebo (n=112, p=0.048).
Perceived stress scores decreased in the Lpc-37 group by 6.4% from baseline to the end of the study, but increased by 4.1% in the placebo group. The authors conclude that these findings indicate, “a significant effect of Lpc-37 toward reducing perceived stress over 5 weeks, compared to placebo.”
Complex Effects
While there was no significant difference between the probiotic and the placebo in terms of heart rate response to the TSST, a subgroup analysis based on baseline chronic stress levels did show some effect from the probiotic.
Among participants with low baseline stress levels, the heart rate increase induced by the TSST was significantly lower in the Lpc-37 group versus the placebo (n=56, p=0.014). However, among the subjects with high baseline stress levels, the heart rate elevations were significantly higher in those taking the probiotic (56, p=0.034).
“The effect of Lpc-37® on heart rate may be differentially dependent on chronic stress,” Patterson and colleagues note. “The autonomic nervous system is just one component of the microbiota-gut-brain axis and perhaps there is some mechanism mediated through the gut and influenced through probiotic intervention which beneficially influences the response to acute stress differently, dependent on underlying stress.”
The reasons for the seemingly divergent effects of Lpc-37® between low versus high chronic stress participants are not yet clear.
Perceived stress scores decreased in the Lpc-37 group by 6.4% from baseline to the end of the study, but increased by 4.1% in the placebo group. The authors conclude that these findings indicate, “a significant effect of Lpc-37 toward reducing perceived stress over 5 weeks, compared to placebo.”
What’s really interesting is that the Lpc-37 probiotic significantly decreased diastolic blood pressure in participants with high baseline stress, levels (n=56; p=0.047). In women, the probiotic significantly reduced the surge in systolic blood pressure in response to the TSST (n=57; p=0.031), compared to the placebo group. There seemed to be some gender specificity in terms of blood pressure response to the probiotic.
Quelling Anxiety
There’s some suggestion that the probiotic had an anxiety-lowering effect. Scores on the Beck Anxiety Inventory increased in the placebo group by 8.2%, but decreased in the Lpc-37 group by 13.8% from baseline to end of study, “indicating a marginally favorable effect of Lpc-37 toward reducing anxiety compared to placebo.”
There is also evidence that compared to the placebo, the probiotic normalized 8pm cortisol levels in participants with low baseline stress levels at the end of the study (n=54, p=0.036)
Dr. Patterson and her team conclude that, “intake of Lpc-37…tended to improve many other biomarkers related to stress in the general population and other significant beneficial effects were identified within the subgroups.”
In terms of safety, there were no adverse events associated with taking the probiotic, and no troublesome changes in any vital signs.
Stress is an inevitable part of life, and our stress responses are normal, natural, biological responses to situational threats. But when these states become prolonged and chronic, they become driving factors in a host of illnesses.
The emerging research on “psychobiotics”—targeting the microbiome for mental health benefits—suggests that this approach can help to mitigate stress to some degree.
By helping to manage psychological responses to everyday stressors, friendly flora like Lpc-37 could be valuable allies for people facing heavy workloads, tight deadlines, financial strain, work-at-home complexities, and the other challenges of our current lives.
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