Visit 3: The subject will give the study coordinator their 3-day food diary, the daily and weekly IBS symptom diary, and any excess fiber product. The physician will review their IBS symptom diary and ensure there are no significant adverse events. The physician will do a physical exam and take their vitals (such as weight, waist circumference and blood pressure). The subject will then be asked to fill out a series of questionnaires relating to their IBS symptoms (IBS-Quality of Life questionnaire (IBS-QoL) and IBS Questionnaire by Whorwell and Francis), sleeping/circadian patterns (2 NIH sleep questionnaires, Munich Chronotype Questionnaire, Lark/Hummingbird/Owl questionnaire, food timing questionnaire), the Expectancy and Credibility Questionnaire, and the 34-item tool asking about their GI symptoms and severity. Next, they will have 2 tablespoons of blood drawn by a certified nurse or medical assistant. The following blood tests will be done: CBC, CMP and CRP. The subject will be reminded in advance to fast 12 hours prior to their research visit. A copy of their blood test results will be given to them at their next visit. Next, they will be given another 6-week supply of the fiber product, the 3-day food diary, a daily and weekly IBS symptom diary to fill out prior to Visit 4 and stool collection supplies. They are asked to collect stool as previously indicated and bring the stool to Visit 4; handling will be identical to previous visit. This visit will be about 2 hours in length. The next visit will be 6 weeks after their Visit 3.