GOS to Reduce Symptom Severity in IBS

Inclusion Criteria:

1. Patients who have been diagnosed with IBS by a medically trained person/Health CareProfessional (HCP).

2. IBS diagnosis to be confirmed according to the Rome-IV criteria by a primary orsecondary care clinician, including a gastroenterologist, at study entry

3. An IBS Symptom Severity Scale score of ≥125 points at baseline

4. Male or female between 18 and 64 years of age (age ranges included)

5. Possession of a smartphone

6. Willing and eligible to provide consent and comply with protocol and product intake.

Exclusion Criteria:

1. Unclassifiable IBS (IBS-U) as determined by Investigator

2. Use of products marketed as prebiotics, probiotics or synbiotics within 4 weeksprior to study entry (e.g. Yakult, Actimel, Activia, VSL#3, Kefir). o Regular cheese or yogurt containing lactic acid bacteria are not an exclusioncriterion.

3. Systemic antibiotic or antimycotic treatment within 4 weeks prior to study entry

4. Use of laxatives or antidiarrheal medication within 1 week prior to study entry

5. An unstable antidepressant/antipsychotic treatment regimen within 3 months prior tostudy entry (i.e. treatment should be stable for at least 3 months prior to studyentry).

6. Confirmed lactose intolerance, defined as patients who report response to dietaryelimination of lactose/dairy products. Confirmation is patient-reported and not donewithin the scope of this study.

7. Confirmed food allergy, with reported confirmation based on OFC, IgE, or skin pricktest. Confirmation is patient-reported and not done within the scope of this study.

8. Galactosemia (galactose metabolism disorder)

9. Following diets likely to affect study outcomes, including: o low FODMAP, KETO/high-fat, gluten free/coeliac, paleo, weight loss, caloricrestriction, low-carb, 5:2/whole day energy restriction, Atkins/high-protein,sugar-free, single-food, juicing/any day of juicing, any other restriction diet (e.g. very low calory), or vegan diets (GOS is derived from cow's milk).

10. Severe illness(es) or medical condition(s), including gastrointestinal pathologies: o GI ulcers, coeliac disease, inflammatory bowel disease, bowel cancer, bowelresection, , bariatric surgery, acute or chronic diarrhoea secondary to confirmedinfectious gastroenteritis, or enteral or parenteral nutrition.

11. Subjects suffering from auto-immune disorders (e.g. Rheumatoid Arthritis, Systemiclupus erythematosus, Multiple Sclerosis, Graves' Disease) that require treatmentwith an immune modulator treatment or anti-inflammatory medication

12. Surgical operations to the mouth or gastrointestinal tract within 4 weeks prior tostudy entry, or planned during the study o Appendectomy within 6 months prior to study entry

13. Recent unintended weight loss: o >5% of total body weight within 6 months prior to study entry

14. Excessive alcohol consumption (>14 units per week) and/or drug abuse

15. Pregnancy and lactation, or plan to become pregnant during the study period

16. Participation in other studies involving investigational or marketed productsconcomitantly or within 3 months prior to study entry

17. Changes in diet, supplement or medication use likely to affect study outcomes (i.e.medication that influences GI function) within 4 weeks prior to study entry orplanned during the study (at the discretion of the Investigator). For example, thefollowing medications will influence GI function and changes must be avoided:opioids, prokinetics (domperidone, metoclopramide, prucalopride), antispasmodics (peppermint oil, buscopan), and acid suppressants (PPI, H2 blockers). Of note: theintake of fibres (e.g. psyllium husk) may be used provided that the participant hasbeen using this as a supplement for more than 4 weeks prior to study participationand intake does not change during the course of participation.