Abstract
Background and aim: Prunes (dried plums) are perceived to maintain healthy bowel function, however their effects on gastrointestinal (GI) function are poorly researched and potential mechanisms of action are not clear. We aimed to investigate the effect of prunes on stool output, whole gut transit time (WGTT), gut microbiota and short-chain fatty acids (SCFA) in healthy adults.
Methods: We conducted a parallel group, randomised controlled trial with three treatment arms in 120 healthy adults with low fibre intakes and stool frequency of 3-6 stools/wk. Subjects were randomised to 80 g/d prunes (plus 300 ml/d water); 120 g/d prunes (plus 300 ml/d water) or control (300 ml/d water) for 4 weeks. Stool weight was the primary outcome and determined by 7-day stool collection. Secondary outcomes included stool frequency and consistency (stool diary), WGTT (radio-opaque markers), GI symptoms (diary), microbiota (quantitative PCR) and SCFA (gas liquid chromatography). Group assignment was concealed from the outcome assessors.
Results: There were significantly greater increases in stool weight in both the 80 g/d (mean +22.2 g/d, 95% CI -1–45.3) and 120 g/d (+32.8 g/d, 95% CI 13.9–51.7) prune groups compared with control (-0.8 g/d, 95% CI -17.2–15.6, P=0.026). Stool frequency was significantly greater following 80 g/d (mean 6.8 bowel movements/wk, SD 3.8) and 120 g/d (5.6, SD 1.9) prune consumption compared with control (5.4, SD 2.1) (P=0.023), but WGTT was unchanged. The incidence of flatulence was significantly higher after prune consumption. There were no significant differences in any of the bacteria measured, except for a greater increase in Bifidobacteria across the groups (P=0.046). Prunes had no effect on SCFA or stool pH.
Conclusions: In healthy individuals with infrequent stool habits and low fibre intake, prunes significantly increased stool weight and frequency and were well tolerated. Prunes may have health benefits in populations with low stool weight.
Methods: We conducted a parallel group, randomised controlled trial with three treatment arms in 120 healthy adults with low fibre intakes and stool frequency of 3-6 stools/wk. Subjects were randomised to 80 g/d prunes (plus 300 ml/d water); 120 g/d prunes (plus 300 ml/d water) or control (300 ml/d water) for 4 weeks. Stool weight was the primary outcome and determined by 7-day stool collection. Secondary outcomes included stool frequency and consistency (stool diary), WGTT (radio-opaque markers), GI symptoms (diary), microbiota (quantitative PCR) and SCFA (gas liquid chromatography). Group assignment was concealed from the outcome assessors.
Results: There were significantly greater increases in stool weight in both the 80 g/d (mean +22.2 g/d, 95% CI -1–45.3) and 120 g/d (+32.8 g/d, 95% CI 13.9–51.7) prune groups compared with control (-0.8 g/d, 95% CI -17.2–15.6, P=0.026). Stool frequency was significantly greater following 80 g/d (mean 6.8 bowel movements/wk, SD 3.8) and 120 g/d (5.6, SD 1.9) prune consumption compared with control (5.4, SD 2.1) (P=0.023), but WGTT was unchanged. The incidence of flatulence was significantly higher after prune consumption. There were no significant differences in any of the bacteria measured, except for a greater increase in Bifidobacteria across the groups (P=0.046). Prunes had no effect on SCFA or stool pH.
Conclusions: In healthy individuals with infrequent stool habits and low fibre intake, prunes significantly increased stool weight and frequency and were well tolerated. Prunes may have health benefits in populations with low stool weight.
| Original language | English |
|---|---|
| Pages (from-to) | 165-173 |
| Number of pages | 9 |
| Journal | Clinical Nutrition |
| Volume | 38 |
| Issue number | 1 |
| Early online date | 15 Feb 2018 |
| DOIs | |
| Publication status | Published - Feb 2019 |
Bibliographical note
Sources of supportThis trial formed part of a California Dried Plum Board PhD studentship. The funders had no role in trial design, data collection, analysis or interpretation, report writing or submission of the paper for publication. PL received support from the Scottish Government Rural and Environment Science and Analytical Services Division.
Acknowledgements
The authors thank the trial participants, and the Research Assistants Miranda Blake, Jayne Cole, Dr Emma Copeland, Adele Hug, Edita Juseviciute, Laura King for their role in recruiting participants and undertaking data collection.
Keywords
- prunes
- dried plums
- fibre
- stool weight
- transit time
- stool frequency
- microbiota
- Transit time
- Prunes
- Microbiota
- Stool weight
- Fibre
- Dried plums