The study included a total of 120 healthy adults who had a low fiber intake and a stool frequency of 3-6 times per week. Each participant took one of the three following treatments: 80 g/day of prunes (plus 300 ml/day of water); 120 g/day of prunes (plus 300 ml/day of water) or control (300 ml/day water) for 4 weeks. Stool weight was the primary outcome and determined by 7-day stool collection. Secondary outcomes as stool frequency and consistency were also measured, among others.
Results showed that both groups supplemented with prunes increased the stool weight and improved stool frequency when compared with the non-prunes consumer group (control). There was also a greater increase in Bifidobacteria across the prune-groups.
In conclusion, researchers found that prunes significantly improved gut transit in healthy individuals with infrequent stool habits and low fiber intake.
Lever, E., Scott, S. M., Louis, P., Emery, P. W., & Whelan, K. (2018). The effect of prunes on stool output, gut transit time and gastrointestinal microbiota: A randomised controlled trial. Clinical Nutrition, 30, 1e9.