Low‐fat/high‐fibre diet prehabilitation improves anastomotic healing via the microbiome: an experimental model

Background Both obesity and the presence of collagenolytic bacterial strains ( Enterococcus faecalis ) can increase the risk of anastomotic leak. The aim of this study was to determine whether mice chronically fed a high‐fat Western‐type diet (WD) develop anastomotic leak in association with altered microbiota, and whether this can be mitigated by a short course of standard chow diet (SD; low fat/high fibre) before surgery. Methods Male C57BL/6 mice were assigned to either SD or an obesogenic WD for 6 weeks followed by preoperative antibiotics and colonic anastomosis. Microbiota were analysed longitudinally after operation and correlated with healing using an established anastomotic healing score. In reiterative experiments, mice fed a WD for 6 weeks were exposed to a SD for 2, 4 and 6 days before colonic surgery, and anastomotic healing and colonic microbiota analysed. Results Compared with SD‐fed mice, WD‐fed mice demonstrated an increased risk of anastomotic leak, with a bloom in the abundance of Enterococcus in lumen and expelled stool (65–90 per cent for WD versus 4–15 per cent for SD; P  = 0·010 for lumen, P  = 0·013 for stool). Microbiota of SD‐fed mice, but not those fed WD, were restored to their preoperative composition after surgery. Anastomotic healing was significantly improved when WD‐fed mice were exposed to a SD diet for 2 days before antibiotics and surgery ( P  < 0·001). Conclusion The adverse effects of chronic feeding of a WD on the microbiota and anastomotic healing can be prevented by a short course of SD in mice. Surgical relevance Worldwide, enhanced recovery programmes have developed into standards of care that reduce major complications after surgery, such as surgical‐site infections and anastomotic leak. A complementary effort termed prehabilitation includes preoperative approaches such as smoking cessation, exercise and dietary modification. This study investigated whether a short course of dietary prehabilitation in the form of a low‐fat/high‐fibre composition can reverse the adverse effect of a high‐fat Western‐type diet on anastomotic healing in mice. Intake of a Western‐type diet had a major adverse effect on both the intestinal microbiome and anastomotic healing following colonic anastomosis in mice. This could be reversed when mice received a low‐fat/high‐fibre diet before operation. Taken together, these data suggest that dietary modifications before major surgery can improve surgical outcomes via their effects on the intestinal microbiome.