Irritable bowel syndrome (IBS) is a common gastrointestinal (GI) disorder, in global terms affecting more than every tenth person. Grains are a staple food and an integral part of daily diets all around the world. The FODMAPs (Fermentable Oligo-, Di-, Monosaccharides And Polyols), gluten and amylase trypsin inhibitors (ATIs), which are present in wheat, barley and rye, might be at least part of the reason why gluten-containing grains are often considered as triggers of functional gastrointestinal symptoms. However, the relative contributions and comparative importance of these substances in symptom aggravation remain unclear. The main purpose of this thesis was to determine whether a reduction in the levels of FODMAPs and ATIs in grain products would improve gastrointestinal tolerability of rye and wheat in IBS and non-coeliac gluten sensitivity (NCGS). The intervention grain products used in the studies were produced by sourdough baking method which resulted in a reduced FODMAP and ATI content in the test breads. Four different randomised studies were performed among a female dominant adult population suffering from IBS. In study I, subjects with IBS (n=87) consumed either low FODMAP rye bread or regular rye bread for 4 weeks. This cross-over trial revealed that the low FODMAP rye bread reduced colonic gas formation and alleviated some IBS symptoms (flatulence, abdominal pain, cramps and borgorygmi) but that there was no difference between the breads in overall symptom control or quality of life. In the second study, 26 IBS subjects with poor subjective tolerance for wheat were randomised to either wheat bread with yeast as a leavening agent or wheat bread made by a sourdough baking method which was free of additives and had a lower content of ATIs and FODMAPs. No difference was detected in the gastrointestinal tolerance of these two breads during the observation period of seven days. In study III, the effects of low FODMAP rye bread and regular rye bread on intestinal events were evaluated with a wireless motility capsule (SmartPill®, Given Imaging ltd, Israel) in seven subjects with IBS. It was found that a low FODMAP content reduced colonic fermentation as measured by breath hydrogen excretion but there were no differences between the bread periods in intestinal pH, transit time, pressure or contractions. However, the overall symptom severity and the total score of symptoms were associated with colonic pressure during the period when the subjects consumed the regular bread. Study IV was performed as a sub-study of study I by examining microbial changes in feces being analysed in 50 subjects. The low FODMAP rye bread reduced the abundance of the genus Klebsiella in fecal samples in comparison to regular rye bread but no other statistically significant changes in fecal microbiota were found between the periods when the test subjects ate the regular and low-FODMAP rye breads. The results emerging from this thesis demonstrated that the rye bread with the low FODMAP content reduced colonic fermentation and therefore there was less gas formation when compared to the consumption of regular bread. It can be speculated that low FODMAP breads may represent a means of improving tolerability of breads among subjects with IBS but switching from regular to a low FODMAP version of bread is likely to exert only modest effects on objectively measured transit times, intestinal pH, intraluminal pressure and faecal microbiota. Low FODMAP breads can be used as a part of a holistic low FODMAP diet for individuals with IBS.
|Tilldelningsdatum||14 sep 2018|
|Status||Publicerad - 2018|
|MoE-publikationstyp||G5 Doktorsavhandling (artikel)|
Bibliografisk informationM1 - 114 s. + liitteet
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