The goal of this pilot part of the study (Step 1) is to identify the optimal population of high and low anxiety and stress individuals who will differentially respond to a laboratory stress task as measured by changes in subjective stress response (affect), cognition, attention, and biological measures (autonomic and metabolite responses).

Based on experience with different study populations, the investigator's believe that a healthy, homogenous population (Caucasian, women, premenopausal) with higher levels of state anxiety and perceived stress, and with greater responsiveness to laboratory stress tasks (which can also be used in the probiotic intervention study in Step 2) will provide the highest likelihood of identifying the underlying central mechanisms of stress responsiveness in Step 1 and then for the probiotic intervention in Step 2.

For this pilot study, the investigator's will look at baseline measures to determine differences in responses to four subjective (affect/cognition/attention) stress tasks (primary endpoints) and biological (secondary endpoints) measures in a high stress group and a low stress group.

If for Step 1 of the study, the investigator's are able to verify the stratification of the participants into high and low stress groups based on questionnaire data and show differences between participants with high and low perceived stress in psychological characteristics, lab stress tasks and potentially in biological responses, this will help to determine the optimal cut off values, and the optimal stress tasks to be conducted in the planned probiotic intervention study of Step 2.

Inclusion Criteria:

• Caucasian
• Female
• 18-45 years of age
• For the high perceived stress group: a PSS score of 15 or higher and a STAI-S of 39 or higher
• For the low perceived stress group: a PSS score of 8 or lower and a STAI-S score of 24 or lower

Exclusion Criteria:

• Any ongoing major medical, psychological, or psychiatric conditions and recent changes (3mo) in the use of psychoactive medications or other medications that interfere with the measured outcomes.
• Medical conditions such as current neurological, cardiovascular, hepatic, renal, autoimmune diseases, diabetes, or cancer. This includes having a current or past within 1 year diagnosis of GI disorders, including but not limited to IBS, IBD, Celiac, or other nutritional deficiency/disease, current eating disorder, or past weight loss surgery.
• Psychological conditions such as anxiety and depression (I.e., without history of Diagnostic and Statistical Manual (DSM-4) psychiatric diagnosis.
• Prior/Concomitant Therapy (e.g., Recent changes in the use of psychoactive medications or other medications that interfere with the measured outcomes, as determined by the PI).
• Subject involved in any other clinical study within the preceding month or in the exclusion period after another clinical study.
• Positive test for COVID-19 infection in the past month or if presenting symptoms of COVID-19 infection in the past 2 weeks.

Diet:

• Participant who changes her dietary habits within the preceding 4 weeks.
• Participants on probiotics will be asked to wait 1 month before enrollment in the study.
• Participant with an eating disorder.
• Participant with special medicated diet (e.g., for obesity, anorexia, metabolic pathology).
• Participant under artificial nutrition in the last 1 month.
• Participant planning to modify her dietary habits during the course of the study.

Other Exclusions:

• Pregnant women or women planning to become pregnant during the study; breast-feeding women based on the interview at screen (Visit 1) and the urine test on day of stress test (Visit 2).
• Smoker with a moderate to high level of dependence to nicotine (e.g., more than 1/2 a pack of cigarettes a day).
• Participant consuming regularly more than 3 units of alcohol per day (1 unit = 10mL or 8g).
• Participants not able to answer questionnaires by writing, whatever the reason.
• Participant with loos of liberty, by administrative or judicial decision.
• Participant who is major but with a legal guardian.
• Participant on antibiotics will be asked to wait 3 months before enrollment in the study.

Medications not Authorized:

• Opiates/Narcotics
• Chronic/Daily use of analgesics
• Anti-seizure meds
• Antidepressants (5HT3's / Tricyclics etc.) are allowed as long as it's been a stable dose for 3 months
• Medications for ADD/ADHD (I.e., Adderall)
• Any medication for appetite suppression
• Chronic use of laxative/antidiarrheals/medications affecting GI motility
• Insulin
• Bile acid sequestrants
• Use of centrally acting medications that will interfere with CNS testing

At this time there is no plan to make the de-identified data available for sharing with other researchers

Participants will be blind to which stress/anxiety group they belong to. Researchers will not be blind to the group assignment as group assignment is part of the eligibility criteria for inclusion/enrollment in the study.