Vinegar beverage consumption improves defecation status in constipation-prone healthy adults: a randomized, double-blind, placebo-controlled trial

Abstract Constipation is a common gastrointestinal condition, and dietary modifications play a crucial role in its management. This randomized, double-blind, placebo-controlled trial evaluated the effects of a vinegar beverage on defecation status in healthy adults with mild constipation (defecation frequency of 3–5 times per week). A total of 44 participants were randomly assigned to the vinegar or placebo groups and consumed the test beverage daily at breakfast for 4 weeks; the sample size was determined based on feasibility considerations. The primary outcome, defecation frequency at Week 4, was significantly higher in the vinegar group than in the placebo group ( p = 0.042). Exploratory analyses of secondary outcomes without adjustment for multiplicity showed no consistent differences across all time points. However, at Week 1, we observed changes suggestive of potential improvements in defecation frequency ( p = 0.007), number of defecation days ( p = 0.021), and stool volume ( p = 0.043). No significant changes in fecal microbial diversity were observed following the intervention, and no adverse events related to the intervention occurred. In conclusion, these findings suggest that daily consumption of vinegar beverages may improve defecation status in healthy adults with mild constipation, supporting a potential dietary approach for maintaining bowel health.