Exploring nutritional deficiencies in obesity and after bariatric surgery: from gastrointestinal physiology to compliance

In the past decades, obesity has become an international public health issue. A paradoxical challenge is the co-existence of overnutrition alongside undernutrition known as the 'double burden of malnutrition' (e.g., obesity and nutritional deficiencies). While there has been some progress to eliminate malnutrition, the prevalence of obesity continues to grow and is outweighing the efforts taken to prevent a further rise. Consequently, obesity treatment remains pivotal and explains the increased popularity of bariatric surgery. The anatomical changes contribute to the favorable aspects of bariatric surgery, but can also result in a diversity of complications. Among all, nutritional deficiencies are one of the most common repercussions of bariatric surgery. An inadequate diet, altered gastrointestinal tract, and a patient's medical history may predispose patients with obesity and after bariatric surgery to develop nutritional deficiencies, but their contribution is not yet fully understood as described in chapter 1. As micronutrients are essential, nutritional deficiencies can have severe hematological, musculoskeletal, or neurological consequences, especially after bariatric surgery. Available prophylactic and therapeutic strategies for nutritional deficiencies are largely eminence-based rather than evidence-based medicine as the pathological onset of nutritional deficiencies is not yet fully understood. To improve the nutritional care of patients with obesity and patients that underwent bariatric surgery, we have taken different steps to narrow current knowledge gaps related to gastrointestinal physiology and supplement intake as described in chapter 2. Chapter 3 provides a literature overview of information related to gastrointestinal physiology in obesity that was available at the start of the PhD project. Few studies reported lower or similar gastric pH in people with obesity compared to people with normal weight. Interestingly, information was absent for small intestinal and colonic pH. Extensive research addressed gastric emptying without a clear answer, while small intestinal and colonic motility was largely unexplored in people with obesity. Clinical studies revealed higher fasting bile acids serum levels and blunted post-prandial increases in bile acids in people with obesity. In general, the review indicated that important research questions remained unanswered for people with obesity related to gastrointestinal pH and motility. Consequently, we assessed gastrointestinal pH and motility in fasted and fed states using a wireless motility capsule in people with obesity and people with normal weight as described in chapter 4. In the stomach, we observed a higher motility index after capsule administration in fed state in people with obesity. No differences were observed in gastric emptying between people with normal weight and obesity in either condition. In the small intestine, our results revealed a shorter small intestinal transit in people with obesity. This can be explained by a higher contractility as observed in people with obesity in fasted and fed state. Beyond motility, a lower pH was observed in the small intestine in people with obesity in both fasted and fed state. No differences were observed in gastric pH, colonic pH or colonic motility between people with normal weight and obesity. Altogether, these findings indicate important changes in gastrointestinal physiology in people with obesity. Chapter 5 provides a literature overview of information related to gastrointestinal physiology after sleeve gastrectomy and Roux-en-Y gastric bypass that was available at the start of the PhD project. For gastrointestinal pH, a virtual absence of acid secretion and therefore, neutral pH was observed in the gastric pouch after Roux-en-Y gastric bypass. Nonetheless, small intestinal and colonic pH remained unclear after Roux-en-Y gastric bypass. For sleeve gastrectomy, gastrointestinal pH remained to be elucidated. For gastrointestinal motility, various studies observed faster gastric emptying after Roux-en-Y gastric bypass and sleeve gastrectomy, but intestinal transit remained largely controversial. For gastrointestinal secretions, clinical studies indicate higher bile acids serum levels after both Roux-en-Y gastric bypass and sleeve gastrectomy, but intestinal findings were lacking. In general, the review indicated that important research questions remained unanswered for sleeve gastrectomy and Roux-en-Y gastric bypass related to gastrointestinal pH, motility, and intestinal bile acid concentrations. Consequently, we assessed gastrointestinal pH, motility and intestinal bile acid concentration using a wireless motility capsule, through gastric emptying scintigraphy and gastrointestinal fluid aspiration in people with obesity, in people after sleeve gastrectomy and people after Roux-en-Y gastric bypass as described in chapter 6. Regarding gastric emptying, immediate emptying of the gastric pouch and faster gastric sleeve emptying were observed when compared to obesity. Moreover, we observed a trend for a shorter orocecal transit in both bariatric groups. Regarding gastrointestinal pH, there was no abrupt increase in pH when travelling from the gastric pouch through the alimentary limb in participants with Roux-en-Y gastric bypass. This indicates that the gastric pouch mimics the more neutral environment of the alimentary limb after Roux-en-Y gastric bypass. This is confirmed by the higher 25th percentile pH and trend for higher median pH in the orocecal segment of participants with Roux-en-Y gastric bypass compared to participants with obesity. For sleeve gastrectomy, a drop in gastric pH was observed after capsule ingestion in all but one patient. Nonetheless, a significantly higher 75th percentile pH was observed in the sleeve of participants that underwent sleeve gastrectomy compared to participants with obesity. The former suggests that gastric pH does decrease to acidic values after sleeve gastrectomy, but not to the same extent as in participants with obesity. No differences were observed in colonic pH values. For intestinal bile acid concentration, our results revealed that total bile acid concentration from jejunal samples was at least 3.0-fold higher in participants after sleeve gastrectomy and at least 6.5-fold higher in participants after Roux-en-Y gastric bypass compared to total bile acid concentration in jejunal samples from participants with obesity in fasted and fed state. Altogether, these findings indicate important changes in gastrointestinal physiology in people after sleeve gastrectomy and Roux-en-Y gastric bypass, which is the (in)direct result of the anatomical alterations of the gastrointestinal tract. In chapter 7, we explored supplement intake, compliance and patients' perspectives towards nutritional supplementation in Belgian patients that underwent bariatric surgery. Our findings indicate that one out of five patients does not consume nutritional supplements after bariatric surgery. Among the remaining supplement users, the majority follow the recommendations of consuming a multivitamin and mineral supplement on daily basis and in the form of bariatric specialized supplements. To identify patients with low compliance, we found that age and medicine intake were positive predictors. Moreover, the experience of any barrier after supplement intake was a strong negative predictor. Consequently, we observed that the top five barriers for non-compliance consisted of patient-related (e.g., forgetfulness), financial-related (e.g., price of nutritional supplements) and therapy-related issues (e.g., unpleasant taste, the presence of side effects and swallowing difficulties). In line with these issues, the top five facilitators were a supplement reminder tool to overcome forgetfulness, a price reduction or reimbursement, a better taste, fewer side effects, and fewer tablets. Importantly, a small group of respondents indicated that they perceive supplement intake as unnecessary especially when eating healthy or feeling good. Altogether, these findings provide a better understanding of the real-life nutritional supplementation regimen of post-bariatric surgery patients living in Belgium. Overall, the PhD project contributed to elucidating important knowledge gaps related to gastrointestinal physiology in obesity and bariatric surgery and related to nutritional supplementation after bariatric surgery. In chapter 8, we reflect on a number of methodological aspects of our studies, address the practical implications of the current findings, and give directions for future research. Overall, our findings will contribute to the evidence-based prevention and treatment of nutritional deficiencies in people with obesity and after bariatric surgery. Evidently, further research is needed for a better evidence base.

Jaar van publicatie:2022

Toegankelijkheid:Closed