The Effect of Psyllium Husk on Intestinal Microbiota in Constipated Patients and Healthy ControlsOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This study examined how psyllium husk, a widely used fiber-based treatment for constipation, affects the composition of faecal microbiota. Psyllium works by trapping water in the intestine, which increases stool water content, eases defaecation, and alters the colonic environment. The researchers ran two randomised, placebo-controlled, double-blinded trials, comparing seven days of psyllium against a placebo (maltodextrin). Alongside microbiota composition, they measured gastrointestinal transit, faecal water content, and short-chain fatty acid (SCFA) levels.
Who was studied?
The study included two separate cohorts: 8 healthy volunteers and 16 constipated patients. Both groups underwent the same seven-day psyllium versus placebo comparison in a randomised, double-blinded design. This dual-cohort setup allowed the researchers to compare psyllium's effects in people without bowel symptoms against those with constipation.
What were the most important findings?
In healthy adults, psyllium had a small but significant effect on microbial composition, increasing Veillonella and decreasing Subdoligranulum. In constipated patients, the effects were greater, with increases in Lachnospira, Faecalibacterium, Phascolarctobacterium, Veillonella, and Sutterella, and decreases in uncultured Coriobacteria and Christensenella, alongside changes in acetate and propionate levels. Several taxa were associated with altered GI transit, SCFA levels, and faecal water content in the constipated patients. Notably, three genera known to produce butyrate, including Lachnospira and Roseburia, increased significantly.
What are the greatest implications of this study?
The findings suggest that psyllium's benefit for constipation may work partly through reshaping the gut microbiota toward more butyrate-producing taxa, not just through its water-trapping mechanical effect. The stronger microbial response seen in constipated patients compared to healthy controls indicates that psyllium's impact may depend on the pre-existing gut environment or dysbiosis. These results support further research into fiber-driven microbiota changes and SCFA production as a mechanism underlying relief of constipation symptoms.