Effect of probiotics on gut microbiota after colonoscopy
Colonoscopy plays an important role in identifying intestinal diseases, including colon cancer. Prior to performing colonoscopy, the bowel is prepared with a cleanser, such as polyethylene glycol electrolyte, to facilitate diarrhea via permeability. However, this can disrupt the colonic environment by flushing out luminal bacteria, thereby introducing an aerobic environment to an otherwise anaerobic colonic system and depriving gut bacteria of essential nutrients. In particular, peaks in Proteobacteria and Clostridium are associated with elevated levels of fecal serine protease, which increase after a bowel prep. It takes approximately two weeks to recover the bacterial colonic environment after bowel cleansing. The human bowel has about 100 trillion microbial inhabitants, which include, at minimum, 1,000 different species. These gut microbes play a significant role in aiding angiogenesis, metabolism, digestion, and maturation of the immune system. Studies have linked the use of probiotics to the alleviation of abdominal discomfort and a significant reduction in duration of pain in various clinical gut conditions. These findings have led to interest in using probiotics as a therapeutic strategy to restore gut microbiota after bowel cleansing. However, large-scale research exploring the impact of probiotics in this capacity is lacking. The authors conducted a multicenter randomized controlled trial (RCT) to elucidate the impact of bowel prep and colonoscopy on gut microbiota and to determine if postcolonoscopy disruptions in gut microbiota homeostasis can be quickly reversed and gastrointestinal symptoms alleviated via probiotic interventions. For the study, 301 patients, all of whom had indications for colonoscopy, were randomly assigned to a probiotic or placebo group. The probiotic group received live combined Bacillus subtilis– and Enterococcus faecium-coated capsules (0.5 g three times a day for 28 days) postcolonoscopy. The placebo group received a placebo on a similar dosing schedule. Fecal microbiota samples were then collected from participants in the two groups and patient symptoms were recorded. The intestinal microbiota composition was assessed using 16S rRNA sequencing. The results showed a notable difference between alpha diversity and beta diversity among patients taking the placebo before and four weeks after colonoscopy. More specifically, bowel cleansing resulted in the proliferation of Pseudomonas and Klebsiella in the placebo group, while the probiotic group exhibited an abundance of protective bacteria, such as Lactobacillales. Of interest, the gastrointestinal symptom rating scale (GSRS) showed significant improvements in the probiotic group within the first week after colonoscopy (p=.005). The patients in the probiotic group also experienced fewer days of discomfort postcolonoscopy (p=.034) and had enhanced glucose metabolism (p=.040) and a notable increase in Lactobacillales (p=.009). Furthermore, even in the probiotic group, the alpha and beta diversities were significantly different in patients who did not demonstrate GSRS improvements. Bacteroides levels were also significantly elevated in patients without GSRS improvements (p=.004). This indicated that some symptoms were not relieved in symptomatic patients treated with probiotics. The authors also noted that Bacteroides, while generally beneficial, can become pathogenic in altered gut environments. While this study demonstrated that treatment with probiotics potentially can help reset the gut microbiota after colonoscopy, it had limitations, such as smaller sample sizes. Furthermore, the study involved only one type of probiotic, which was not targeted to individual differences in microbiota. The authors intend to do additional studies with larger sample sizes.
Wei H, Wang J, Xiao X, et al. Effect of probiotics on the gut microbiota after colonoscopy: A multicenter, randomized, placebo-controlled clinical study. J Gastroenterol Hepatol. 2025. doi.org/10.1111/jgh.70147
Correspondence: Dr. Suyu He at hesuyu2009@163.com or Dr. Qiang Zhang at 21011428@qq.com