Effects of fruit products on gastrointestinal function and motility in constipation

Student thesis: Doctoral ThesisDoctor of Philosophy


Dried fruits, often suggested as a remedy for constipation, are high in dietary fibre, which is known for its laxative properties, as well as other compounds, such as sorbitol and (poly)phenols. Despite their promising nutritional composition, evidence regarding the efficacy and potential mechanisms of action of dried fruit on gut function is scarce.

The aim of this thesis is to investigate the effects of a dietary intervention, specifically fruit products of various nutritional compositions, on gastrointestinal function and motility in healthy people with functional constipation. Results from a systematic review and meta-analysis on the effects of diets, foods, drinks, herbs and spices on constipation are additionally demonstrated. Fruits led to higher bowel movement frequency and consistency, compared to psyllium, rye bread resulted in more weekly bowel movements and shorter gastrointestinal transit time compared to white bread and mineral water led to a better treatment response and more frequent bowel movements compared to plain water. Furthermore, this thesis presents results of a 3-arm, parallel, randomized, placebo-controlled trial investigating the effects of 3 daily servings of dried fruits (prunes, raisins and dried apricots), an intervention rich in fibre and sorbitol, compared to those of 3 servings of fruit juices of the same fruits, a high-sorbitol but fibre-free intervention, and to 3 servings of a control fruitflavoured cordial, containing no fibre and no sorbitol, for 4 weeks in healthy people with functional constipation. The primary outcome was change in faecal weight, with secondary outcomes including bowel movement frequency, stool consistency, faecal moisture, whole and regional gut transit time, pH and contractibility, gastrointestinal symptom severity and incidence, and quality of life.
Date of Award1 Jul 2023
Original languageEnglish
Awarding Institution
  • King's College London
SupervisorAna Maria Rodriguez Mateos (Supervisor) & Eirini Dimidi (Supervisor)

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