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.

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

A substantial number of protocol violations occurred for the primary end-point. Only 39 out of 224 subjects consumed sufficent radio-opaque markers for baseline and post-intervention transit time.Therefore, the study failed to yield evaluable data.