Effects of Probiotic Supplementation on Stress and Anxiety in Students (PROfoS)

The Efficacy of Probiotic Supplementation in Reducing Stress and Anxiety: A Randomized, Placebo-Controlled Study in Healthy Students During the Examination Period

This randomized, double-blind, placebo-controlled study evaluates the efficacy and safety of an 8-week probiotic supplementation (Lactobacillus plantarum LP140 and Bifidobacterium breve BB010 in total daily dose 1 × 10¹⁰ CFU or matching placebo) in reducing perceived stress and anxiety, and improvement related psychological parameters in healthy university students during the examination period. The primary outcome is the change in Perceived Stress Scale (PSS-10) score at week 5 and week 8 of interevention compared to placebo. The secondary outcomes are the changes in DASS-21 subscales (Stress, Anxiety, Depression), State-Trait Anxiety Inventory - State version scale (STAI-S), Sense of Coherence Scale (SOC-29), Pittsburgh Sleep Quality Index (PSQI), self-reported gastrointestinal symptoms (Likert scale) and incidence of adverse events during the 8-week lasting interventional study.

Study Overview

• Status: Not yet recruiting
• Conditions: Stress; Sleep; Anxiety; Gastro-intestinal Symptoms in Healthy Subjects
• Intervention / Treatment: Other: Placebo; Dietary supplement: Probiotics

Detailed Description

The gut-brain axis enables bidirectional communication between the gastrointestinal tract and the central nervous system. Emerging evidence suggests that selected probiotic strains (psychobiotics) may modulate stress responses and emotional regulation. University examination periods constitute a predictable model of transient psychological stress in otherwise healthy individuals.

This study investigates whether daily supplementation with a probiotic combination of Lactobacillus plantarum LP140 and Bifidobacterium breve BB010 reduces perceived stress and improves related psychological parameters in healthy students exposed to exam-related stress. Two hundred male and female students aged 18-40 years with at least moderate stress and mild anxiety, but without clinical depression, will be enrolled at the Medical University of Lublin, Poland. After providing written informed consent and confirming eligibility criteria, participants will be randomized in a 1:1 ratio to receive either a probiotic formulation containing Lactobacillus plantarum LP140 and Bifidobacterium breve BB010 (total daily dose of 1 × 10¹⁰ colony-forming units) or a matching placebo.

The investigational product and placebo will be identical in appearance and administered orally once daily (two capsules) for 8 weeks. Randomization will be computer-generated, and both participants and investigators will remain blinded to treatment allocation throughout the study. The intervention will begin approximately six weeks before the first scheduled academic examination. Study assessments will be conducted at baseline, at week 5 (approximately one week before the first examination), and at week 8 (±3 days before a subsequent examination). Psychological and functional parameters will be collected using validated self-report instruments administered electronically, with selected assessments performed during on-site visits. Participants will be asked to maintain their usual diet, physical activity, and caffeine intake during the study period. Safety and tolerability will be monitored throughout the intervention, and adverse events will be recorded using an electronic reporting system with daily reminders.

The study is powered to detect clinically meaningful differences between groups in perceived stress levels and will be analyzed using appropriate covariance-based statistical models adjusted for baseline values and relevant covariates. All participant data will be coded to ensure confidentiality and handled in accordance with applicable data protection regulations.

• Study Type: Interventional
• Enrollment (Estimated): 200
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Emilia Majsiak, Professor of University, PhD; Phone Number: +48667633263; Email: Emilia.Majsiak@umlub.edu.pl
• Study Contact Backup: Name: Bożena Cukrowska, Prof., MD, PhD; Phone Number: 609447892; Email: bc@nordicbiotic.com

Study Locations

• Poland
  • Lublin, Poland
    • University of Lublin, Faculty of Health Sciences
    • Contact: Emilia Majsiak, Prof. PhD; Phone Number: +48 667633263; Email: Emilia.Majsiak@umlub.edu.pl
    • Principal Investigator: Emilia Majsiak, Prof., PhD
    • Sub-Investigator: Renata Markiewicz, PhD
    • Sub-Investigator: Mariusz Wysokiński, Prof., PhD
    • Sub-Investigator: Wiesław Fidecki, Prof. PhD
    • Sub-Investigator: Kinga Zdunek, PhD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Male or female students aged 18-40 years
• At least moderate stress (DASS-21 Stress score ≥10)
• Mild anxiety (DASS-21 Anxiety score 6-13)
• No clinical depression (DASS-21 Depression score ≤9)
• Willingness to maintain usual diet, physical activity, and intake of caffeinated beverages during the study
• Written informed consent

Exclusion Criteria:

• Irritable bowel syndrome (Rome IV criteria) or any chronic intestinal disease (including celiac disease)
• Known food allergies, immunodeficiency disorders, or immunosuppressive treatment
• Antibiotic use within 4 weeks prior to screening
• Any psychiatric illness within the past 5 years
• Any malignant disease or autoimmune or allergic diseases (e.g., atopic dermatitis, asthma)
• Use of systemic psychotropic medications or steroids; use of topical corticosteroid creams within 4 weeks prior to screening
• Pregnancy, breastfeeding, or plans to become pregnant during the study
• Probiotic or prebiotic consumption or planned dietary changes within 4 weeks prior to screening
• Heavy caffeine consumption (>4 cups of 300 mL coffee per day)
• Drug or alcohol addiction or regular use of recreational drugs
• Smoking more than 10 cigarettes per day

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Probiotic; Two capsules containing Lactobacillus plantarum LP140 and Bifidobacterium breve BB010 will be administered orally once daily (total daily dose of 1 × 10¹⁰ colony-forming units) for 8 weeks.	Dietary supplement: Probiotics; Lactobacillus plantarum LP140 and Bifidobacterium breve BB010
Placebo Comparator: Placebo; Maltodextrin will be used as a placebo. The placebo capsules will be identical in appearance to the probiotic capsules and will be administered orally once daily (two capsules) for 8 weeks.	Other: Placebo; Maltodextrin

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in perceived stress score	Perceived stress will be assessed using the 10-Item Perceived Stress Scale (PSS-10), a validated questionnaire measuring the degree to which situations in one's life are appraised as stressful. The total score ranges from 0 to 40, with higher scores indicating higher perceived stress levels (worse outcome). Changes in the total score from baseline will be analyzed to evaluate the effect of probiotic supplementation.	Change in total perceived stress score from baseline to week 5 and to week 8 (±3 days) compared to placebo

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in stress, anxiety and depression scores	Stress, anxiety, and depression will be assessed using the Depression Anxiety Stress Scales - 21 Items (DASS-21). The DASS-21 consists of three subscales (Depression, Anxiety, and Stress), each including 7 items. Scores for each subscale range from 0 to 42 after standard score multiplication, with higher scores indicating greater symptom severity (worse outcome). Changes in the Stress, Anxiety, and Depression subscale scores from baseline will be analyzed to evaluate the effect of probiotic supplementation.	Change in DASS-21 Stress, Anxiety, and Depression subscale scores from baseline to week 5 and week 8 (±3 days) compared to placebo.
Change in sleep quality score	Sleep quality will be assessed using the Pittsburgh Sleep Quality Index (PSQI), a validated questionnaire measuring sleep quality over the previous month. The global PSQI score ranges from 0 to 21, with higher scores indicating poorer sleep quality (worse outcome). Changes in the PSQI global score from baseline will be analyzed to evaluate the effect of probiotic supplementation.	Change in Pittsburgh Sleep Quality Index (PSQI) global score from baseline to week 5 and week 8 (±3 days) compared to placebo.
Change in sense of coherence score	Sense of coherence will be assessed using the Sense of Coherence Scale - 29 Items (SOC-29), a validated questionnaire measuring psychological resilience and the ability to cope with stress. The total score ranges from 29 to 203, with higher scores indicating a stronger sense of coherence (better outcome). Changes in the SOC-29 total score from baseline will be analyzed to evaluate the effect of probiotic supplementation.	Change in Sense of Coherence Scale - 29 Items (SOC-29) total score from baseline to week 5 and week 8 (±3 days) compared to placebo.
Change in state anxiety score	State anxiety will be assessed using the State-Trait Anxiety Inventory - State version (STAI-S), a validated questionnaire measuring the current level of anxiety. The STAI-S total score ranges from 20 to 80, with higher scores indicating higher levels of anxiety (worse outcome). Changes in the STAI-S total score from baseline will be analyzed to evaluate the effect of probiotic supplementation.	Change in State-Trait Anxiety Inventory - State version (STAI-S) total score from baseline to week 8 compared to placebo.
Change in severity of gastro-intestinal symptoms	The severitty of gastro-intestinal symptoms will be assessed with the use of 4-point Likert scale (0 - no symptom, 1 - weak, 2 - moderate, 4 - severe). The following symptoms will be assessed: abdominal pain, flatulence, nausea.	Change from baseline in gastro-intestinal severity score at Week 5 and Week 8 compared to placebo
Incidence of treatment-emergent adverse events (Safety and Tolerability)	Safety and tolerability will be assessed by monitoring the incidence of adverse events throughout the study. Adverse events will be self-reported by participants using an electronic reporting platform, which provides daily reminders for study product intake and allows participants to record any symptoms or adverse events experienced during the study period.	From baseline through the 8-week intervention period.

Collaborators and Investigators

• Sponsor: Nordic Biotic Sp. z o.o.
• Collaborators: Wörwag Pharma GmbH & Co. KG
• Investigators: Principal Investigator: Emilia Majsiak, Prof. PhD, Medical University of Lublin

Study record dates

Study Major Dates

• Study Start (Estimated): April 20, 2026
• Primary Completion (Estimated): July 15, 2026
• Study Completion (Estimated): August 15, 2026

Study Registration Dates

• First Submitted: March 10, 2026
• First Submitted That Met QC Criteria: March 10, 2026
• First Posted (Actual): March 13, 2026

Study Record Updates

• Last Update Posted (Actual): March 17, 2026
• Last Update Submitted That Met QC Criteria: March 13, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Anxiety; Stress; Probiotics; Gut-brain axis
• Additional Relevant MeSH Terms: Mental Disorders; Anxiety Disorders; Dietary Supplements; Food; Diet, Food, and Nutrition; Physiological Phenomena; Food and Beverages; Probiotics
• Other Study ID Numbers: CT/NB/180/2025/PR-MS

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No