Bifidobacterium longum subsp. longum Reduces Perceived Psychological Stress in Healthy Adults: An Exploratory Clinical Trial.

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• There is mounting evidence to suggest that nutritional interventions can influence our stress responses. One of the routes by which nutrition can influence physiological and psychological stress responses involves the microbiota– gut–brain-axis.
• This exploratory trial suggests that supplementation with Bifidobacterium longum (BL) strain NCC3001 leads to a beneficial effect on stress relief and improves subjective sleep quality in a healthy adult population reporting moderate levels of psychological stress.

Introduction

A randomised, placebo-controlled, two-arm, parallel, double-blind exploratory clinical trial was conducted to investigate the effect Bifidobacterium longum (BL) strain NCC3001 on stress-related psychological and physiological parameters and acute stress in healthy adults who typically experience mild-to-moderate-levels of stress.

Method

47 Participants between the ages of 25-65 years old with mild-to-moderate psychological stress received 1x1010 CFU of Bifidobacterium longum (BL) strain NCC3001 daily or a placebo for 6 weeks.

Participants completed the Perceived Stress Scale (PSS), the Hospital Anxiety and Depression Scales (HAD-A and HADS-D), the Gastrointestinal Symptom Rating Scale (GSRA), the Pittsburgh Sleep Quality Index (PSQI) questionnaire, the Positive and Negative Affect Schedule (PANAS), the State Trait Anxiety Inventory (STAI-6), the Maastricht Acute Stress Test (MAST) and the Visual Analog Scales (VAS, which measures pain intensity) during the clinical study. The Depression, Anxiety and Stress Scale (DASS-42) questionnaire was also used to depict the progression of the participants through the study.

Faecal samples were taken at baseline and 6 weeks and awakening saliva samples were taken at baseline, 2, 4, 6 and 8 weeks. At the endpoint, 45/49 (91%) of the subjects completed the study. One participant reported an adverse event and the other withdrew without an explanation. Two participants were excluded from the full analysis.

Results

The primary outcomes were:

• After 6-week of the probiotic intervention, there was a significant decrease in perceived stress in the probiotic group (21.4%) compared to the placebo group (-10.2%), p = 0.017.
• There was a significant improvement in subjective sleep in the probiotic group compared to the placebo group (p = 0.037).
• There was a significant decrease in the positive PANAS change score from the pre-stressor stage in the probiotic group compared to the placebo group (p = 0.01).
• There were lower pain values (VAS) scores from pre-stressor to post-stressor in the probiotic group compared to the placebo group (p = 0.05).
• There was no significant difference between groups in anxiety (HADS-A) and Depression (HADS_D) scores.

Conclusion

Oral supplementation with BL NCC3001 may have beneficial effects on stress relief and improves subjective sleep quality in a healthy adult population reporting moderate levels of psychological stress.

• While the mechanism underlying the correlation between the microbiota and the gut-brain-axis is not fully understood, it is thought to play a critical role in the links between the microbiota, mood, stress, and brain health.
• This exploratory trial additionally supports the potential of specific probiotics being used to reduce perceived stress and improve subjective sleep quality in healthy adults.

• Larger, powered clinical trials are needed to provide further insights into the mechanisms underlying the stress-relieving and sleep-improving effect of Bifidobacterium longum.
• Furthermore, the dosage and duration of the probiotics need further investigation in a larger healthy population.
• Comparative research is needed to help investigate the effect of different probiotic strains on stress relief and sleep quality.