Effects of black bean vinegar on functional constipation: a randomised, double-blind, placebo-controlled study

Introduction: Functional constipation is a widespread gastrointestinal ailment associated with infrequent defecation, unfavorably affecting quality of life. However, it has not been well studied worldwide. This study aimed to investigate the effects of black bean vinegar (black bean and black bean yeast) consumption in alleviating functional constipation. Methods: A randomised, double-blind, placebo-controlled, parallel group study involving 70 adults with functional constipation was conducted in Peninsular Malaysia from May till July 2016. Subjects aged 18-60 years diagnosed with a score of more than 15 based on the Constipation Scoring System were included. A third-party-controller assigned black bean vinegar and placebo drinks to two groups with 1:1 ratio using randomisation software. Participants received once-daily doses of black bean vinegar (20 ml daily) or fruit-flavored squash placebo (20 ml daily) which contained vitamins, minerals, trace elements and carbohydrates, without black bean and black bean yeast, for four weeks. Analysis was conducted on an on-treatment basis (i.e., all randomised participants conformed to the study protocol by consuming 20 ml of drinks daily, with less than 10% leftover drinks at post-intervention assessment). Data were analysed using SPSS version 22. Results: Administration of black bean vinegar did not demonstrate statistically significant differences in any of the outcomes when compared with a placebo drink at ?=5% level. However, black bean vinegar consumption significantly improved overall score at postintervention assessment compared to placebo group (p