The Roux-en-Y gastric bypass (RYGB) remains the most effective treatment for morbidly obese patients to lower body weight and improve glycemic control. There is recent evidence that the mycobiome (fungal microbiome) can aggravate disease severity in a number of diseases including inflammatory bowel disease (IBD), irritable bowel syndrome (IBS) and hepatitis; moreover, a dysbiotic fungal microbiota has been reported in the obese. We characterized fungal and bacterial microbial composition in fecal samples of 16 morbidly obese patients before and three months after RYGB surgery and compared with nine healthy controls. We found that RYGB surgery induced a clear alteration in structure and composition of the gut fungal and bacterial microbiota. Beta diversity analysis revealed significant differences in bacterial microbiota between obese patients before surgery and healthy controls (P < 0.005) and a significant, unidirectional shift in RYGB patients after surgery (P < 0.001 vs. before surgery). In contrast, there was no significant difference in fungal microbiota between groups but individually specific changes after RYGB surgery. Interestingly, RYGB surgery induced a significant reduction in fungal alpha diversity namely Chao1, Sobs, and Shannon diversity index (P<0.05, respectively) which contrasts the trend for uniform changes in bacteria towards increased richness and diversity post-surgery. We did not observe any inter-kingdom relations in RYGB patients but in the healthy control cohort and there were several correlations between fungi and bacteria and clinical parameters (P<0.05, respectively) that warrant further research. Our study identifies changes in intestinal fungal communities in RYGB patients that are distinct to changes in the bacterial microbiota.

Background Fasting during Ramadan is one of the five pillars of the Muslim faith. Despite the positive effects of fasting on health, there are no guidelines or clear recommendations regarding fasting after metabolic/bariatric surgery (MBS). The current study reports the result of a modified Delphi consensus among expert metabolic/bariatric surgeons with experience in managing patients who fast after MBS. Methods A committee of 61 well-known metabolic and bariatric surgeons from 24 countries was created to participate in the Delphi consensus. The committee voted on 45 statements regarding recommendations and controversies around fasting after MBS. An agreement/disagreement ≥ of 70.0% was regarded as consensus. ResultsThe experts reached a consensus on 40 out of 45 statements after two rounds of voting. One hundred percent of the experts believed that fasting needs special nutritional support in patients who underwent MBS. The decision regarding fasting must be coordinated among the surgeon, the nutritionist and the patient. At any time after MBS, 96.7% advised stopping fasting in the presence of persistent symptoms of intolerance. Seventy percent of the experts recommended delaying fasting after MBS for 6 to 12 months after combined and malabsorptive procedures according to the patient's situation and surgeon's experience, and 90.1% felt that proton pump inhibitors should be continued in patients who start fasting less than 6 months after MBS. There was consensus that fasting may help in weight loss, improvement/remission of non-alcoholic fatty liver disease, dyslipidemia, hypertension and type 2 diabetes mellitus among 88.5%, 90.2%, 88.5%, 85.2% and 85.2% of experts, respectively. Conclusion Experts voted and reached a consensus on 40 statements covering various aspects of fasting after MBS.

No abstract

Conflict of interest: RES is employed by DSM Nutritional Products. MB reports personal fees from Johnson & Johnson and Medtronic, outside the submitted work. The Resource 2.0+Fibre nutritional products were provided free of charge by Nestlé Suisse S.A.