Defining Objective Markers of Compliance for Dietary Therapies in IBS

Inclusion Criteria: 1. Patients with IBS ( including diarrhea, mixed or constipation type) and without unexplained alarm features (rectal bleeding, weight loss, nocturnal pain, nocturnal diarrhea). In presence of alarm symptoms, if they have had evaluation with colonoscopy or fecal calprotectin or serum C-reactive protein (CRP) since onset of alarm symptoms with normal results, they will be included. 2. Aged 18-65 years at the time of screening 3. IBS-SSS of at least 175 at baseline Exclusion Criteria: 1. Subjects adhering to a dietary treatment such as the low-fat diet, low FODMAP diet, or gluten-free diet, within the past 6 months. Those who are lactose intolerant will not be excluded from the study and will be allowed to limit lactose intake as previously. 2. Subjects who are predicted to make changes to their baseline IBS medication(s), over-the-counter (OTC) therapy, exercise, diet (beyond what is advised), or initiate/make changes to other complementary therapy that could affect IBS symptoms (e.g. yoga, acupuncture, etc.) during the four weeks study period. 3. Subjects with a known history of celiac disease, inflammatory bowel disease or microscopic colitis 4. Subjects with a history of an eating disorder requiring medical or behavioral treatment within the past 10 years. 5. BMI \< 18.5 6. Subjects with prior small bowel or colonic surgery (other than appendectomy or cholecystectomy). 7. History of appendectomy or cholecystectomy in the last 6 months. 8. Oral antibiotic use in the past 3 months 9. Any planned significant changes in dietary or exercise regimen within 30 days prior to Screening or during the study. 10. Currently pregnant or breastfeeding.