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Background Ileostomy output determines need for parenteral fluid support. Plant foods may contain chemicals that stimulate intestinal secretion eg. lactucins in lettuce and rhein in rhubarb. These may account for increases in ileostomy output but experimental demonstration of this is burdensome for patients. Objective Determine the effect of different foods on intestinal water content in healthy volunteers using Magnetic Resonance Imaging (MRI). Design Crossover trial of three isocaloric meals in healthy adults. Subjects underwent MRI scans fasting and hourly to 180min postprandial. Meals: 2 slices white bread with 10g butter; 300g rhubarb with 60mL lactose-free cream; 300g lettuce with 30mL mayonnaise. Visits one week apart. Primary outcome: small bowel water content (SBWC) using MRI. Secondary outcomes: ascending colon water content; T1 relaxation time of ascending colon (T1AC); gastric volume; visual analogue scales of bloating and satiety (0-100) scored half-hourly. Results 15 subjects completed the study. 9 female, 6 male, median age 21(IQR 20, 22). Bread induced a fall in SBWC compared to a rise after lettuce and greater rise after rhubarb, with significant differences in the area under the curve (0- 3 hours) of the change from baseline (P<0.01, paired t-test). Rhubarb increased T1AC but differences at 3 hours were not significant (P=0.06). Symptom scores were higher for lettuce >rhubarb >bread. Conclusion Lettuce and rhubarb meals increased intestinal water content, demonstrating how different foods can alter small bowel secretion. MRI can be used to evaluate the effects of diet, enteral feed and pharmaceuticals on intestinal content and function.

OBJECTIVES: The objective of this study was to investigate whether ingestion of fructose and fructans (such as inulin) can exacerbate irritable bowel syndrome (IBS) symptoms. The aim was to better understand the origin of these symptoms by magnetic resonance imaging (MRI) of the gut. METHODS: A total of 16 healthy volunteers participated in a four-way, randomized, single-blind, crossover study in which they consumed 500 ml of water containing 40 g of either glucose, fructose, inulin, or a 1:1 mixture of 40 g glucose and 40 g fructose. MRI scans were performed hourly for 5 h, assessing the volume of gastric contents, small bowel water content (SBWC), and colonic gas. Breath hydrogen (H 2) was measured and symptoms recorded after each scan. RESULTS: Data are reported as mean (s.d.) (95 % CI) when normally distributed and median (range) when not. Fructose increased area under the curve (AUC) from 0 – 5 h of SBWC to 71 (23) l / min, significantly greater than for glucose at 36 (11 – 132) l / min ( P < 0.001), whereas AUC SBWC after inulin, 33 (17 – 106) l / min, was no different from that after glucose. Adding glucose to fructose decreased AUC SBWC to 55 (28) l / min ( P = 0.08) vs. fructose. Inulin substantially increased AUC colonic gas to 33 (20) l / min, signifi cantly greater than glucose and glucose + fructose (both P < 0.05). Breath H 2 rose more with inulin than with fructose. Glucose when combined with fructose signifi cantly reduced breath H 2 by 7,700 (3,121 – 12,300) p.p.m. / min relative to fructose alone ( P < 0.01, n = 13). CONCLUSIONS: Fructose but not inulin distends the small bowel with water. Adding glucose to fructose reduces the effect of fructose on SBWC and breath hydrogen. Inulin distends the colon with gas more than fructose, but causes few symptoms in healthy volunteers.

Constipation is a common condition in which an individual suffers with hard stools which are infrequent and difficult to pass. It has an estimated prevalence of 15-20% however the pathophysiology of symptoms remains poorly understood and treatment is often unsatisfactory for patients. In approximately 60% of patients their constipation is associated with abdominal pain, whilst in the remaining this appears in absence of pain. This thesis is split into three sections, in the first I will review the background and current investigation and treatment strategies in constipation. The second will look at two healthy volunteer studies performed looking at the effect of different foods on gut function and how these could be relevant to treatment of constipation. In the third I will describe our patient study into the pathophysiology of constipation that take advantage of two new techniques. These are Magnetic Resonance Imaging (MRI), which allows us to see the contractions of the colon and High-Resolution Manometry (HRM) which measures the contraction using pressure sensing catheters placed into the bowel. Using these techniques, we will identify patterns of contractions in each patient and compare to healthy controls to determine whether these could be used to predict different treatment response