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Title: Effect of bariatric surgery on small bowel physiological changes pertaining to absorption of nutrients & bile acid metabolism
Author: Vincent, Royce Priyanth
ISNI:       0000 0004 2728 3127
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2012
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Background: The dogma that persisted for many years was that malabsorption plays a significant role in contributing to the weight loss following bariatric surgery. The aim was to assess for evidence of malabsorption after bariatric procedures; adjustable gastric banding (AGB), Roux-en-Y gastric bypass (RYGB) and biliopancreatic diversion-duodenal switch (BPD-DS). Methods: This cross sectional study recruited participants into four groups: obese controls (n=7), AGB (n=6), RYGB (n=7) and BPD-DS (n=5). Biochemical tests were used to assess; (i) entire gut: sulphasalazine test for oro-caecal transit time (OCTT) & plasma citrulline for functional enterocyte mass. (ii) foregut: faecal elastase-1 (FE1) for exocrine pancreatic function. (iii) mid-gut: Lactulose:rhamnose (L:R) ratio for gut permeability, faecal calprotectin (FCp) for gut inflammation & plasma and urine bile acids (BAs) for BA metabolism. (iv) hindgut: Faecal fat (Ffat) excretion for fat malabsorption. Results: (i) entire gut: There was no difference in OCTT (p=0.935) or functional enterocyte mass (p=0.819). (ii) foregut: FE1 was lower in the RYGB vs. the control group (p=0.002), with no difference between other groups (all p>0.05). (iii) mid-gut: L:R ratio was higher in the BPD-DS vs. the control (p=0.012), AGB (p=0.016) and RYGB (p=0.012), with no difference between other groups. FCp was higher in the RYGB vs. the control (p=0.016), with no difference between other groups. The fasting plasma and urine BAs were elevated in BPD-DS vs. the control, ABG and RYGB (all p<0.05). (iv) hindgut: The BPD-DS had higher Ffat excretion vs. the control (p=0.038), AGB (p=0.046) and RYGB (p=0.024). The RYGB had higher Ffat excretion vs. the control (p=0.033). There was no difference between the RYGB and AGB (p=0.808). Conclusion: There was no evidence to support the notion that RYGB causes severe malabsorption of fats or sugars. However, BPD-DS does cause fat malabsorption.
Supervisor: LeRoux, Carel Sponsor: Not available
Qualification Name: Thesis (M.D.) Qualification Level: Doctoral