The primary objective of the current study is to investigate the effect of two probiotic formulations on task-switching following acute stress in healthy, adult action video gamers. It is hypothesized that the participants that consume the probiotic formulations will have improved task-switching performance following acute stress compared to those who consume a placebo.

Participants who are action gamers will be recruited to participate in this randomized, placebo-controlled, 2-arm, parallel trial. Eligible participants will be enrolled in this study for 8 weeks.

The study will consist of 2 laboratory visits: Baseline Visit and Post-Treatment Visit.

Inclusion Criteria:

1. Male and female adults aged 19 to 35 years-old.
2. Have played action video games (i.e., first- and third-person shooter and action role playing games) for a minimum of 5 hours per week over the course of the previous year as assessed by self-report (as per [1])
3. Willingness to continue the same amount of video game playing throughout the duration of the study.
4. Willingness to maintain eating habits throughout the duration of the study.
5. Willingness to discontinue consumption of probiotic supplements and probiotic- fortified products, as well as fiber supplement consumption (e.g., Metamucil, Benefiber, etc.), throughout the duration of the study.
6. Willingness to maintain current physical activity levels throughout the duration of the study.
7. Willing and able to consume a probiotic or placebo supplement for 8 weeks.
8. Willingness to complete questionnaires, records, and diaries associated with the study and to complete all study visits.
9. Able to provide informed consent.

Exclusion Criteria:

1. Use of antidepressants, anti-anxiolytic medication, and/or medication that improves attention, including amphetamines, methylphenidates, dexmethylphenidates, and atomoxetine hydrochloride.
2. Disordered gaming, as per a score above 32 on the Internet Gaming Disorder Scale Short Form (IGDS9-SF; [2]).
3. Head trauma that was diagnosed by a medical professional as a concussion or was associated with a loss of consciousness within the past two years.
4. Currently diagnosed with alcohol use disorder and/or substance use disorder.
5. Diabetes (type I and II), blood/bleeding disorders, liver and/or kidney disorders, unstable cardiovascular diseases, neurological diseases (e.g., Alzheimer's disease, Parkinson's disease, epilepsy), gastrointestinal diseases (e.g., gastric ulcers, Crohn's disease, ulcerative colitis).
6. Presence of unrelated sleep disorders, diagnosis of a mental disorder within the previous year, history of diagnosis of attention-deficit/hyperactivity disorder or attention-deficit disorder
7. Immunodeficiency (immune-compromised and immune-suppressed participants; e.g., AIDS, lymphoma, participants undergoing long-term corticosteroid treatment, chemotherapy and allograft participants).
8. Arthritis pain or other chronic pain.
9. Currently suffering from periodontitis.
10. Pregnancy (as per urine pregnancy test at screening), planning to be pregnant or currently breastfeeding.
11. Females of childbearing potential not using a medically approved method of birth control (e.g. hormonal contraception, intrauterine devices, vasectomy/tubal ligation, barrier methods, double-barrier method) or true abstinence.
12. Milk, soy, and/or yeast allergy.
13. Lactose intolerance.
14. Use of any antibiotic drug within 4 weeks of randomization. Volunteer could be eligible to participate after a 2-week washout period.
15. Current use of probiotics. Volunteer can be eligible after a four (4)-week washout period.
16. Currently enrolled in another clinical trial.

After publications of the results, de-identified data will be shared with qualified researchers and scientists upon reasonable request to the sponsor including a detailed proposal of the intended use of the data, as per the Lallemand Health Solutions Inc. Policy on Clinical Trial Transparency and Data Sharing (available upon request).