B. Lactis HN019 for Functional Constipation

This study will investigate the effects of 4-week probiotic supplementation on whole gut transit time and gastrointestinal symptoms in adults with functional constipation.

This prospective, double-blind, randomized, placebo-controlled clinical trial will investigate the effects of 4-week B. lactis HN019 supplementation on whole gut transit time and gastrointestinal symptoms in adults with functional constipation. Participants who meet all study entry criteria will enter a 2-week run-in period. Following successful completion of the run-in period, subjects will be randomized to 4-week supplementation with B. lactis HN019 (10 billion cfu), B. lactis HN019 (1 billion cfu), or placebo. The primary outcome of whole gut transit time will be evaluated with abdominal x-rays on days 0 and 28. Secondary outcomes include IBS-specific questionnaires (administered on days 0 and 28); abdominal pain severity, bowel movement frequency, stool consistency, and adverse events (evaluated daily throughout the study); and overall product satisfaction (evaluated at day 28). Physical activity questionnaires and 24-hour food recalls will be completed periodically during the trial.

Eligibility Criteria:
Inclusion Criteria:

* Age 18 to 70 years
* Body mass index between 18.5 and 34.9 kg/m2
* Self-reported unsatisfactory defecation due to infrequent stools and/or difficult stool passage, which includes at least one of the following: symptoms of straining, difficulty expelling stool, a sense of incomplete evacuation, hard or lumpy stools, prolonged time to stool, or a need for manual maneuvers to pass stool.
* Estimated stool consistency \< 4.0 on BSSF (self-reported at screening) within the past month prior to enrollment.
* Ability of the participant (in the investigator's opinion) to comprehend the full nature and purpose of the study including possible risks and side effects
* Consent to the study and willing to comply with study product and methods

Exclusion Criteria:

* Major gastrointestinal complication (e.g. Crohn's disease, ulcer)
* Prior abdominal surgery that, in the opinion of the investigator, may present a risk for the subject or confound study results
* Clinically significant underlying systemic illness that may preclude the subject's ability to complete the trial or that may confound the study outcomes (e.g. bowel cancer, prostate cancer, terminal illness)
* Daily consumption of probiotics, prebiotics, fermented milk, and/or yogurt within 2 weeks of screening and throughout the trial other than the provided study products
* Non-laxative constipation medication use within 2 weeks of screening, laxative use within 48 hours of screening (rescue medication allowed for intolerable symptoms during study)
* Daily use of anticholinergic agents, opioid analgesics, calcium supplements, calcium-channel blockers, and NSAIDs
* Anticipated major dietary or exercise changes during the study
* Systemic steroid use
* Eating disorder
* Contraindication to dairy products (e.g., intolerance to lactose or any substance in the study product)
* History of alcohol, drug, or medication abuse
* Pregnant or lactating female, or pregnancy planned during study period
* Participation in another study with any investigational product within 30 days of screening
* Investigator believes that the participant may be uncooperative and/or noncompliant and should therefore not participate in the study