Effect of Probiotic Supplement on Intestinal and Psychological Symptoms in Subjects with Irritable Bowel Syndrome (IBS)


This is a placebo controlled study that will evaluate the effects of 6 weeks of using a daily probiotic supplement on intestinal and psychological symptoms of IBS. The trial will last about 14 weeks including screening, 6 weeks of treatment and 4 weeks of follow-up after treatment. You have a 50% chance of receiving the active probiotic and 50% chance of receiving a non-active placebo in this trial.
There are 4 in-person, weekday visits at the Research Clinic and 1 phone visit mid-way through the treatment period. You will answer questionnaires asking about physical and mental health, have vitals measured and blood drawn at visits and collect urine, stool and saliva samples as part of the study.
During the study, there are medications and supplements that you will not be allowed to use and you will need to maintain a stable diet.
The probiotic used in this study has been shown to be very safe and participating in this study is considered low risk. Parking at the Foothills Campus will be covered for all in person appointments and participants will receive $50 gift cards as a thank you for attending each in person visit.


Currently recruiting participants: Yes

Eligible gender: Male, Female, Transgender, Other

Eligible ages: 18 to 70

Inclusion criteria:

1. Between 18 and 70 years of age.
2. Willing and able to sign written informed consent form prior to study entry.
3. Able to comply with all study procedures, in the opinion of the study investigator.
4. Prior diagnosis of IBS (any sub-type) with active symptoms as assessed by questionnaire at Screening Visit.
5. Experiencing mild to moderate symptoms of anxiety or anxiety as assessed by questionnaire at Screening Visit.

Exclusion criteria:

1. Concurrent formal diagnosis of mood or anxiety disorder by a psychiatric specialist.
2. Experiencing substantial symptoms of anxiety or depression requiring treatment.
3. Experiencing no symptoms of depression or anxiety as assessed by questionnaire.
4. Concurrent disease or laboratory tests that could interfere with study data collection or interpretation.
5. Concurrent gastrointestinal disease except for reflux disease, gastritis, asymptomatic gallbladder disease, benign polyps, diverticulosis, hemorrhoids.
6.History of attempted suicide in the past 5 years.
7.Previous abdominal surgery except for hernia repair, appendectomy, caesarian section, tubal ligation, hysterectomy. Cholecystectomy with no impact on symptoms in past 2 years is allowed.
8. History of celiac disease.
9. Pregnant or currently nursing.
10. Medically diagnosed lactose intolerance without continuing lactose free diet.
11. Currently taking probiotic supplements, and unwilling to stop 2 weeks prior to randomization and withhold during study duration.
12. Additional criteria that will be reviewed by study personnel with prospective participants.


Fill out the following form if you want to participate in this research

Method of contact

Additional information

Contact information

Lynn Wilsack or Yekta Eslambolchi

Principal investigator:

Christopher Andrews

Clinical trial: