The Effect of Dietary Supplementation on Intestinal Barrier Function in IBS-D

Inclusion criteria

• Participant has provided written informed consent before participating in the study after being given a full description of the study and prior to any study-specific procedures being performed.
• Participant has irritable bowel syndrome with diarrhoea (IBS-D), as defined by the Rome IV criteria, confirmed by bowel diary.
• Participant has an IBS-SSS score of >175
• LPS at screening >0.21 ng/ml.
• Participant is a male or non-pregnant female and is 18-70 years of age
• If WOCBP participant is willing to adhere to one of the following methods of contraception i) Hormonal contraception e.g. the 'pill' or an implant ii) Intrauterine device (IUD) iii) Intrauterine hormone-releasing system (IUS) iv) Hysterectomy v) Vasectomised partner vi) Sexual abstinence (if it is in line with your preferred and usual lifestyle).
• Participant can communicate well with the Investigator and to comply with the requirements for the entire study.
• Participant has capacity to understand written English.
• Participant has a body mass index (BMI) of 18.5 - 39.9kg/m2 (bounds included).
• Participant agrees to follow all pre-test preparation before L/M testing.

Exclusion criteria

• Prior abdominal surgery other than appendectomy, tubal ligation, hysterectomy or cholecystectomy.
• Participated in a trial of an investigational medical product or medical device in the last 28 days.
• Females who report to be pregnant or lactating
• Unwilling to maintain stable doses of permitted concomitant medication.
• Unwilling to maintain a stable diet for the duration of the trial.
• Being in the opinion of the investigator unsuitable
• Insufficient knowledge of English to complete the daily bowel diary and food diary.
• Hypersensitivity to any component of the supplement
• Hypersensitivity or known allergy to lactulose or mannitol.
• Consumption of oral antibiotics in the last 2 weeks.
• NSAIDs for 2 weeks prior to and during the entire 21 day study period. Participant should not be a chronic NSAID user (>1 day/week).
• Participants who have received bowel preparation for investigative procedures in the 4 weeks prior to the study.
• Diabetes mellitus (type 1).
• Participants with known hepatic disease.
• Inflammatory bowel disease (Crohn's/Colitis) or coeliac disease.
• Gastrointestinal infection in the past 4 weeks.
• Any other condition, deemed by the investigator, that may be causing their symptoms.
• Participant is involved in this study as an Investigator, sub-Investigator, study coordinator, other study staff, or Sponsor member.
• Participant is unable to adhere to withholding in endurance exercise, such as >45 minutes of high intensity running, cycling, rowing etc, from the screening phone call to the end of study visit.