Effects of FODMAPs on Small Bowel Water Content: an MRI Study
Condition: Healthy
Study type: Interventional

Summary: 
      Some carbohydrates, particularly fructose, the sugar found in fruit and bread may cause
      bloating, pain and erratic bowel habits (diarrhoea and constipation) particularly in patients
      suffering from the irritable bowel syndrome (IBS). This may be because they are not well
      absorbed in the small intestine and cause water to be trapped in the bowel causing
      distension. Studies have shown that reducing the amount of these sugars in the diet can
      relieve these symptoms. There is some evidence that combining fructose and glucose can reduce
      the symptoms caused by fructose but just why is unclear. In this study, the investigators
      will use a non invasive medical imaging technique called "magnetic resonance imaging" (or
      MRI) to look at the behaviour of drinks containing these sugars in the bowels of healthy
      human volunteers.

      The investigators will give four different drinks: one beverage consisting of a very well
      absorbed sugar, glucose, another consisting of the less well absorbed sugar fructose, a third
      which is a mixture of glucose and fructose, and a fourth consisting of several fructose
      subunits joined together (called fructan). The investigators will take MRI images of the
      stomach and intestines at intervals for 5 hours and compare these with the feelings of
      distension and bloating in our volunteers. The results will act as control for subsequent
      studies in IBS patients and these may help design diets to reduce symptoms in IBS.
    

Detailed description: 
      Title: Effects of FODMAPs (Fermentable Oligo-, Di-, and Mono-saccharides, And Polyols) on
      small bowel water content: an MRI study

        1. Background. FODMAPs consist of fructose, lactose, fructo- and galacto-oligosaccharides
           such as fructans and galactans, and polyols such as sorbitol and mannitol. These
           carbohydrates are poorly absorbed in the small intestine and have been shown to trigger
           symptoms of irritable bowel syndrome (IBS). Previous studies have shown that fructose
           malabsorption results in an increased osmotic load in the small bowel, which can have a
           laxative effect. Physical proof of this has only been obtained using an ileostomy model
           on patients. This study indicated increased small bowel water content (SBWC) but this
           has never been established in intact humans .). We have been using noninvasive magnetic
           resonance imaging (MRI) to provide novel insights on the fate of food materials within
           the gastro-intestinal tract (GIT) of humans for the last decade.

        2. Aims (to include hypothesis to be tested) This study aims to investigate whether
           fructose alone will increase SBWC compared to an equivalent mass of glucose, and if
           adding glucose to fructose will reduce its effect on the SBWC. The study also aims to
           determine if fructans alter colonic transit.The main hypothesis is that fructose will
           increase small bowel water while fructans will mainly affect colonic transit..

        3. Experimental protocol and methods. A single-centre, randomized, cross-over design study
           consisting of a screening visit and four test days, which will be approximately 1 week
           apart The subjects (18 healthy volunteers for main study plus 4 for pilot studies) will
           receive (according to a randomization schedule) each test day one out of four test
           products: 1) glucose (control) 2) fructose, 3) glucose with fructose and 4) fructans. On
           each test day, volunteers will have a baseline scan in a 1.5T scanner, consume one of
           the products instead of breakfast at 09:00 and will be imaged in the scanner at
           intervals for 5 hours using a range of MRI sequences.

      All the tested ingredients are food grade, have a history of safe use at intended usage
      levels, and are regarded as safe.

      Four test products will be evaluated:

        1. 500 mL of glucose (40g of glucose dissolved in water with pure lime juice as flavorant)

        2. 500 mL fructose (40g fructose dissolved in water with pure lime juice as flavorant)

        3. 500 mL of glucose with fructose (40g glucose and 40g fructose dissolved in water with
           pure lime juice as flavorant, 40 or 80 gm)

        4. 500 mL fructan (40g of 100% fructan (inulin) dissolved in water with pure lime juice as
           flavorant)

      4. Measurable end points/statistical power of the study. Primary endpoint: small bowel water
      content area under the curve (AUC) -45 - 315 minutes. Secondary endpoint: gastric emptying
      T50, colonic volume as characterised by AUC -45 - 315 minutes of ascending colon, colonic
      motility, symptoms questionnaires, small bowel transit time, breath hydrogen concentrations
      and tryptase faecal content.

      Previous work using mannitol and glucose indicates that mean (SD) SBWC at 40 minutes
      postprandial after ingesting 300ml glucose was 47 (SD 15) and using n=12 the investigators
      calculate the investigators can detect an increase of 20 ml in excess of this with 90% power
      which is very much less than the investigators are predicting. The investigators plan to use
      18 to ensure the investigators can assess our secondary endpoints for which there is no data
      with which to perform a power calculation.
    

Intervention name(s): Glucose; Fructose; Fructan; Fructose and glucose
Intervention type(s): Dietary Supplement; Dietary Supplement; Dietary Supplement; Dietary Supplement
Intervention description(s): 500 ml water drink containing 40g glucose; 500 ml water drink containing 40g fructose; 500 ml water drink containing 40g fructan; 500 ml water drink containing 40g fructose and 40g glucose
Intervention MeSH terms: Levan
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Single (Participant)
Primary purpose: Basic Science
Keywords: Gastrointestinal physiology; Gastrointestinal response to sugars; MRI; gastrointestinal; stomach; small bowel; colon; glucose; fructose; fructan; FODMAP