The effect of polydextrose on fecal bulk and bowel function in mildly constipated healthy adults: a double-blind, placebo controlled study


  • Davide Risso
  • Ieva Laurie
  • Essi Sarkkinen
  • Kavita Karnik



Background: Polydextrose (PDX) (8-30g/day) increases fecal bulk and consistency, helping to ease stool passage. However, the results of its effect on defecation frequency and colonic transit have been discordant, and most focused on either healthy or highly constipated adults, leaving the question on if and how PDX could also aid mildly constipated individuals partially unanswered.

Material and Methods: We investigated the effects of PDX consumption by healthy subjects experiencing one or more symptoms of mild constipation on fecal bulk, defecation frequency, stool consistency, ease of stool passage, and total colonic transit time to further characterize and generate additional evidence regarding the potential beneficial effects of this fibre. 51 subjects participated in a 4-week, two-center, randomized, double-blind, placebo-controlled, parallel study testing a control (CON) and a PDX treatment (18 g/d included in biscuits and drink mixtures) (registered on with the identifier" NCT05309837").

Results: Consumption of PDX resulted in 120.7 g and 25.7 g higher fecal wet and dry weight, respectively (p < 0.05). Colonic transit time was ~4 h shorter in the PDX group: although this difference did not reach significance (p > 0.05) as it was underpowered to detect a significant difference for this secondary outcome, this result still carries a physiological importance. Consumption of PDX was well-tolerated, with some PDX volunteers reporting more mild flatulence (p < 0.05).

Conclusion: All in all, our study adds new evidence on how a moderate (18g) daily intake of PDX could increase fecal bulking and potentially shorten colonic transit time, making this ingredient a good candidate to be used to reformulate packaged goods by replacing caloric carbohydrates with lower caloric content, enriching food items easily consumed to enhance fibre intake and support bowel function.

Keywords: polydextrose; PDX; constipation; bowel function; clinical trial gut health; fibre







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