Research Summary

Chicory Inulin Improves Stool Frequency, Quality of Life in Adults With Functional Constipation

Edited by:
Kate Young

Key Highlights:

  • Inulin increased stool frequency by 0.53 bowel movements per week versus placebo.
  • Significant improvements were observed in PAC-QOL total score and PAC-SYM total score.
  • Inulin intake was associated with higher relative abundances of butyrate-producing genera, including Anaerostipes and Coprococcus.
  • Apparent carry-over effects were linked to baseline microbiota composition and sustained microbial shifts after wash-out.

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In a randomized, double-blind, placebo-controlled cross-over trial published in BMC Gastroenterology, researchers evaluated whether daily supplementation with 12 g of native chicory inulin improves bowel habits, constipation-related quality of life, and fecal microbiota composition in adults meeting Rome III criteria for functional constipation.

The study enrolled 39 adults aged 18 to 75 years in Cork, Ireland. Participants were randomized to receive either 12 g/day of inulin or maltodextrin placebo for 4 weeks, followed by a 4-week wash-out and crossover to the alternate intervention. The primary endpoint was change in weekly stool frequency from baseline. Secondary outcomes included stool consistency (Bristol Stool Form Scale), Patient Assessment of Constipation–Quality of Life (PAC-QOL), Patient Assessment of Constipation–Symptoms (PAC-SYM), physical activity (IPAQ), and fecal microbiota composition assessed by 16S rRNA gene sequencing.

Study Findings

In cross-over analysis, stool frequency increased by 1.43 bowel movements per week with inulin compared with 0.90 with placebo, yielding a statistically significant between-group difference of 0.53 (95% CI, 0.02–1.04; P = .046). Mean post-intervention stool frequency reached 3.44 per week with inulin versus 3.15 with placebo. Stool consistency improved modestly in both groups without a significant between-group difference.

Inulin significantly improved patient-reported outcomes. The PAC-QOL total score decreased by −0.61 with inulin versus −0.21 with placebo (difference −0.41; P = .007), exceeding the minimum important difference threshold. Improvements were most pronounced in psychosocial discomfort and worries/concerns subscores. Similarly, PAC-SYM total score decreased by −0.61 with inulin versus −0.27 with placebo (difference −0.35; P = .022), driven primarily by reductions in abdominal symptoms.

Microbiota analyses showed no significant difference in overall beta-diversity between interventions. However, relative abundances of putative butyrate-producing genera, including Anaerostipes spp. (1.75-fold higher) and Coprococcus 1 spp. (1.59-fold higher), were increased after inulin intake. Bifidobacterium spp. also increased during inulin intake, consistent with its established bifidogenic effect.

Apparent carry-over effects were detected, particularly among participants receiving inulin first. In these individuals, improvements in stool frequency and patient-reported outcomes persisted beyond the four-week wash-out. Baseline microbiota differences—including higher relative abundances of Faecalibacterium and Roseburia and lower Bifidobacterium—were associated with stronger microbial and clinical responses to inulin.

Clinical Implications

The authors report that 12 g/day of chicory inulin improved stool frequency, abdominal symptoms, and constipation-related quality of life in adults with functional constipation. The observed microbial shifts toward butyrate-producing taxa may contribute to these clinical benefits. However, the presence of carry-over effects in this cross-over design highlights the need for careful consideration of wash-out duration and trial structure in microbiota-targeted interventions

Limitations include the predominantly female study population, incomplete fecal sampling during wash-out, lack of metabolite measurements, and potential limitations of cross-over design in disorders of gut-brain interaction

Expert Commentary

“Our cross-over study confirmed that inulin is a promising non-pharmacological treatment alternative. It improved constipation-related quality of life, social-emotional well-being as well as abdominal symptoms, and promoted gut health by increasing stool frequency and modifying the fecal microbiota in functional constipation,” the researchers concluded.

Reference
Puhlmann ML, Wegh CAM, van der Zalm SCC, et al. Inulin-induced improvements on bowel habit and gut microbiota in adults with functional constipation: findings of a randomized, double-blind, placebo-controlled study. BMC Gastroenterol. 2025;25(1):806. Published 2025 Nov 13. doi:10.1186/s12876-025-04409-6.