 4. Visit 4 week 12: Participants will undergo usual assessment, treatment response will also be determined at this visit CGI-I score 2 as well as a 30 drop in YBOCS score. Participants will also complete the Quality of Life and Enjoyment Satisfaction Questionnaire. Patient diet will be assessed using the EPIC-Norfolk Food Frequency Questionnaire. At visit 3, participants will be provided with a collection kit and instructed on appropriate fecal sample collection as outlined above. The sample should be collected on the prior day to visit 4. Blood samples will be drawn again be drawn at a local lab to examine levels of IL-6, IL-1β, IL-10, IFNγ, TNF- α and CRP. Liquid Chromatography-Mass Spectrometry LC-MS will again be used for a kynureninetryptophan analysis. 