Colonoscopies and colonic surgeries are known to require bowel cleansing prior to the procedure. To accomplish this, what are thought to be generally safe and effective products are used in order to cleanse the bowel. One commonly used cleanser is polyethylene glycol (PEG) supplemented with electrolytes. While the efficiency of this product has been tested, limited data has been collected on its effects on the microbiome of the colon.

A new study published on January 6th in the journal Gut tested the effects of bowel cleansing on the bacteria that colonize an individual’s gastrointestinal tract. 23 human subjects were put into two study groups, one group consuming the PEG electrolyte solution in a single dose of 2 L and the other group consuming the solution in two doses of 1 L.

They found that bowel cleansing had little long-term effect on an individual’s colonic microbiota though a substantial change was initially seen after consumption. In subjects who consumed the PEG electrolyte solution in two 1 L doses, the microbiota recovered to original composition after two weeks. In subjects who consumed the solution in a single 2 L dose, however, it took up to one month after treatment for the colonic microbiome composition to recover.

Due to these findings, the authors suggest that separating the dosage into two 1 L doses may benefit the microbiome of the patient and may be preferred in clinical practice. There are several new microbiome studies such as this one that could impact medical practice and it will be exciting to see how (and if) the outcomes outlined in these papers are adopted by clinicians into practice.