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Can Probiotics Help Reduce Stress?

Probiotic Strain L. paracasei Lpc-37® Reduced Stress in Healthy Adults

Scientists have been searching for “psychobiotics,” probiotics that can modify the gut-brain axis,1 and now a recent publication using a robust clinical trial design demonstrated a probiotic strain that improved the stress response.

Previous preclinical studies demonstrated that Lacticaseibacillus paracasei Lpc-37 (Lpc-37), formerly known as Lactobacillus paracasei Lpc-37 prevented the development of certain behaviors associated with chronic stress.2 This “psychobiotic” candidate was selected from other probiotic strains for clinical effects on perceived stress in a randomized clinical trial.3

Randomized, placebo-controlled, double-blind trial3

A total of 120 healthy adults between the ages of 18 and 45 were randomized to consume the probiotic Lpc-37 or a placebo for five weeks and were administered the Trier Social Stress Test (TSST) before and after the intervention. The TSST is a protocol for stimulating an acute and psychological stress response, including an introduction, preparation, and interview followed by mental arithmetic, which increased both systolic and diastolic blood pressure in both groups (p<0.001). While multiple measurements of stress response were evaluated in this study, highlights are as follows:

  • Perceived Stress Scale
  • Blood pressure
  • Heart rate
  • Saliva samples (for cortisol)

Overall results

Participants consuming Lpc-37 self-reported significantly lower perceived stress compared to the placebo group after five weeks (p=0.048).

Additional research highlights

At baseline, the participants were asked how many stressful events they experienced in the last three months. Based on whether they scored above or below the age-related median for the number of prior stressful events in three months, they were classified into a “low chronic stress” or “high chronic stress” group.

Two of the main benefits Lpc-37 consumption provided for the low-stress group included a statistically significant reduction in heart rate in response to the TSST (p=0.014) and normalization of evening (8 PM) cortisol.

For those in the high-stress group, taking Lpc-37 resulted in benefits including a statistically significant increase in heart rate in response to the TSST (p=0.034), an improvement in sleep-related recovery throughout the study period (p=0.006), and an increase in perceived health throughout the study period (p=0.012).

Why is this clinically relevant?

  • Chronic stress predisposes individuals to develop diseases such as psychiatric illnesses or depression, gastrointestinal damage such as ulcers, diabetes, and dysregulation of the immune system
  • Benefits of the probiotic strain Lpc-37 may depend on the individual’s baseline level of stress
  • In a healthy population of adults, L. paracasei Lpc-37 significantly reduced perceived stress relative to placebo

View the Article 



  1. Foster JA et al. Stress & the gut-brain axis: Regulation by the microbiome. Neurobiol Stress. 2017;7:124-136.
  2. Stenman LK et al. Strain specific stress-modulating effects of candidate probiotics: A systematic screening in a mouse model of chronic restraint stress. Behav Brain Res. 2020;379:112376.
  3. Patterson E, et al. Lacticaseibacillus paracasei Lpc-37® improves psychological and physiological markers of stress and anxiety in healthy adults: a randomized, double-blind, placebo-controlled and parallel clinical trial (the Sisu study). Neurobiol Stress. 2020;13:100277.



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