Bowel cleaning that uses two separate smaller dosages of polyethylene glycol electrolyte solution appears to introduce fewer alterations to the intestinal microbiota than a bowel cleanse with a single, larger dose of MoviPrep (Salix). The split-dose protocol has also been shown in previous studies to be effective for bowel cleansing before colonoscopy.

Jonna Jalanka, MSc, from the University of Helsinki in Finland, and colleagues published the results of their gut microbiome study online December 19 in Gut.

The investigators randomly assigned 23 healthy participants into two study groups. One group received two separate 1-L doses of MoviPrep, and the other group received a single, 2-L dose of MoviPrep. Fecal samples were collected at baseline, after bowel cleansing, and at 14 and 28 days after treatment.

In general, bowel cleaning resulted in a 31-fold decrease in microbial load. Approximately one quarter (22%) of participants experienced a marked alteration in the community composition of their microbiota after bowel cleansing. The shift in the microbial community was larger in the single-dose protocol than in the double-dose protocol.

Although the gut microbiome recovered to baseline after both protocols, the recovery was more rapid in the double-dose protocol than the single-dose protocol. Patients who received the larger, single dose of polyethylene glycol required as long as 1 month to recover their gut microbiome.

Connecting Bowel Cleansing to Irritable Bowel Syndrome

Bowel cleansing before colonoscopy is considered to be safe for healthy individuals. When the patient consumes polyethylene glycol, water is mobilized into the intestinal tract. Luminal content, including intestinal bacteria, is thus washed out in the stool. The investigators noted that some of the bacterial species that were enriched after bowel cleansing were similar to those associated with irritable bowel syndrome.

Moreover, patients with irritable bowel syndrome have elevated levels of fecal serine proteases, which are believed to increase intestinal permeability and possibly lead to visceral hypersensitivity.

The single-dose protocol correlated with a larger increase in fecal serine proteases than the double dose. This finding led the researchers to speculate it may reveal a clue to the microbial changes seen with irritable bowel syndrome and other diarrheal diseases.

This work was partly funded by the Finnish Funding Agency for Technology and Innovation and the Academy of Finland, as well as an educational grant from Norgine Pharmaceuticals. One coauthor received grant support for sample collection from Norgine; was an advisory board member of Almirall, Danone and Ironwood; and received lecturing fees from Abbott and Shire. The other authors have disclosed no relevant financial relationships.

Gut. Published online December 19, 2014. Abstract