Influence of Flax Seeds on the Gut Microbiota of Elderly Patients with Constipation

Purpose: This study was to explore the influence of flax seeds on the gut microbiota of elderly patients with functional constipation. Patients and Methods: Sixty elderly patients (68.68 [+ or -] 8.73 years) with functional constipation were recruited between January 2018 and March 2018. They received oral flax seeds (50 g/d) for one month. Bowel habits and adverse events were recorded before and after treatment. Fresh stool was collected before and after treatment and the amplification product of 16S rRNA V5 region was sequenced using the next-generation sequencing technique on the Ion Torrent PGM platform. The gut microbiota were analyzed before and after flax seeds treatment in the same subject. Results: Flax-seed treatment significantly increased the frequency of defecation and decreased abdominal distension in elderly patients with chronic constipation. The majority of gut bacteria belonged to the phyla of Firmicutes, Bacteroidetes, and Proteobacteria, accounting for 98.71%. After flax seeds treatment, the diversity of bacterial clusters significantly increased with increases of Roseburia_hominis, Pseudomonas_azotoformans, uncultured_Clostridiales_bacterium, Blautia_obeum, Ruminococcus_sp._16442, Pyramidobacter_piscolens, Acinetobacter_lwoffii, Prevotella_melaninogenica. The abundance of Blautia in patients with chronic constipation was significantly lower than healthy controls, while Blautia_obeum increased significantly after flax seed treatment. Blautia_obeum might be the predominant genus accounting for the therapeutic effect of flax seeds. Conclusion: Flax seeds may improve the defecation in elderly patients with chronic constipation and change intestinal microecological structure. Thus, flax seeds may serve as an effective diet supplement in the management of chronic constipation. Keywords: constipation, flax seeds, high-throughput sequencing, gut microbiota