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

Background & Aims. Polydextrose (PDX) (8-30g/day) has been reported to increase faecal bulk and consistency, leading to easier stool passage. However, studies on its effect on defaecation frequency and colonic transit time have provided mixed results, 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.Methods. We investigated the effects of PDX consumption by healthy subjects experiencing one or more symptoms of mild constipation on faecal bulk, defaecation 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 clinicaltrials.gov with the identifier" NCT05309837").Results. Consumption of PDX resulted in 120.7 g and 25.7 g higher faecal 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 the study was underpowered to detect a statistical 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).Conclusions. All in all, our study adds new evidence on how a moderate (18g) daily intake of PDX could increase faecal bulking and potentially shorten colonic transit time, making this ingredient a good candidate to be used to formulate, and reformulate, foods and beverages by replacing caloric carbohydrates with reduced caloric content, enriching food items easily consumed to enhance fibre intake and support bowel function.