A Study to Assess the Safety and Efficacy of Probiotic to Modulate Psychological Stress

Inclusion Criteria: 1. Voluntary, written, informed consent to participate in the study 2. Currently enrolled in medical, dental or health science university/institute of technology course with intention to sit semester examination(s) 3. Male or female aged between 18-40 years (inclusive) 4. Body mass index (BMI) between 18.5 - 29.9 Kg/m2 5. Blood, urine and gastrointestinal safety parameters and blood pressure measurement at baseline indicate they are healthy in the opinion of the Principal Investigator 6. In good general health as estimated by the Principal Investigator, based on medical history (self-reported) 7. Ability of the participant (in the Principal Investigator's opinion) to comprehend the full nature and purpose of the study including possible risks and side effects 8. Ability of the participant (in the Principal Investigator's opinion) to fully comprehend and self-complete all participant reported outcomes (in UK English language) 9. Participant is willing to maintain habitual diet (including caffeine and alcohol), physical activity patterns and smoking habits throughout the intervention period 10. Agreement to comply with the protocol and study restrictions 11. Available for all study visits 12. Females of child-bearing potential required to provide a negative urine pregnancy test and be using effective contraception (e.g. surgically sterilized (tubal ligation or hysterectomy or partner is post-vasectomy, with sterility confirmed) or use an intrauterine device (IUD), a diaphragm or condom combined with contraceptive sponge, foam or jelly, or be using an oral contraceptive for at least 2 cycles before the screening visit (Visit 2). Women who are in same sex relationships or abstaining from sex are not required to take a pregnancy test or be using effective contraception 13. Male participants must agree to use a condom during sexual intercourse from Visit 3 onwards 14. Covered by health insurance system and / or in compliance with the recommendations of National Law in force relating to biomedical research Exclusion Criteria: 1. Suspected diagnosis of one or more DSM-IV axis 1 disorder(s), including but not limited to: current major depression, anxiety disorder, bipolar spectrum disorder or schizophrenia, as determined by MINI International Neuropsychiatric Interview (MINI) and/or currently diagnosed with one or more DSM-IV axis 1 disorder(s), per Diagnostic and Statistical Manual of Mental Disorders, 4th Edition. 2. Have a significant acute or chronic coexisting illness (cardiovascular, gastrointestinal (irritable bowel syndrome (IBS), inflammatory bowel disease (IBD)), immunological, metabolic (including diabetes and cardiovascular disease), neurodevelopmental or any condition which contraindicates, in the Principal Investigator's judgement, entry to the study 3. Currently taking (from Visit 1 onwards) or have previously taken (last 4 weeks prior to Visit 1) psychoactive medication (anxiolytics, sedatives, hypnotics, anti-psychotics, anti-depressants, anti-convulsants, centrally acting corticosteroids, opioid pain relievers) 4. Currently taking (from Visit 1 onwards) medication or dietary supplements that the Principal Investigator believes would interfere with the objectives of the study, pose a safety risk or confound the interpretation of the study results (e.g. melatonin, St. John's Wort, Rescue® products including Rescue Remedy®, Rescue® Energy, Rescue® Pastilles, Rescue® Pearls, Rescue Sleep® Rescue PlusTM, omega-3 dietary supplements (including fish oil), Cannabidiol (CBD), non-steroidal anti-inflammatory drugs (NSAIDS), over-the-counter sleep medication (not categorized as sedatives, hypnotics or anti-depressants), anti-coagulants, anti-cholinergic drugs or acetylcholinesterase inhibitors, proton pump inhibitors, anti-histamines that cause drowsiness, pseudoephedrine) 5. Recent (within last 4 weeks prior to Visit 1) or ongoing antibiotic therapy 6. Currently taking (from Visit 1 onwards) concentrated sources of probiotics and/or prebiotics other than the provided study products (e.g., probiotic/prebiotic tablets, capsules, drops or powders), including yoghurt / yoghurt drinks 7. Pregnant or lactating female, or pregnancy planned during the intervention period 8. Have self-reported dyslexia 9. History of or current alcohol, drug, or medication abuse (self-reported) 10. Self-declared illicit drug users (including cannabis and cocaine) in the past 1 month prior to Visit 1 11. Excessive alcohol consumption (consuming \> 8 units of alcohol for men and \> 6 units of alcohol for women in a single session) \> 3 times per week for 3 weeks prior to Visit 1 12. Significant change in tobacco, snuff, nicotine or e-cigarette usage habits in the past 1 month before Visit 1 or planned cessation of the use of these products during the intervention period 13. Contraindication to any substance in the investigational product 14. Participation in another study with any investigational product or drug within 60 days of Visit 1 15. Principal Investigator believes that the participant may be uncooperative and/or noncompliant and should therefore not participate in the study 16. Participant under administrative or legal supervision 17. Previous participation in the ChillEx study