Bariatric surgery Studies on gastrointestinal consequences

Bariatric surgery is a commonly performed treatment for morbid obesity, changing the gastrointestinal anatomy, with various consequences, which are studied in this thesis. After surgery, patients report an increase in multiple abdominal complaints and numerous food intolerances. One of these reported intolerances are dairy products. However, lactose itself was not found to cause complaints. Bariatric surgery influences bowel habits, as the consistency moves away from the normal range towards firmer and looser stools. Also, flatulence increases, including the incontinence for this. Levels of several faecal biomarkers are altered after Roux-en-Y gastric bypass, like elastase. Furthermore, the majority of patients have elevated faecal calprotectin and lactoferrin levels, biomarkers that can indicate gastrointestinal inflammation. Yet, no relation with gastrointestinal complaints was found. Faecal calgranulin C, a more specific protein for inflammation with neutrophilic involvement, was not found to be elevated after surgery. Moreover, biopsies of the gastric remnant and bypassed duodenum did not show inflammation with neutrophils in this part of the gastrointestinal tract. The origin of the elevated inflammatory proteins remains unknown, as well as the clinical significance of this finding. Another notorious consequence of bariatric surgery is the development of gallstones, with unknown exact pathogenesis. Differences were found between patients with and without gallstones after surgery in microbiota, conjugated plasma bile acids and expression of genes in subcutaneous adipose tissue, which are involved in cholesterol synthesis and inflammation pathways.