 If deemed eligible, patients will provide a stool sample for microbiome profiling and a blood sample for the inflammatory marker analysis. They will return for their first visit where clinician and self-rated symptom severity scales will be completed and patients will begin their randomly assigned treatment condition to probiotic Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 or placebo. Contents of two sachets probiotic or placebo will be consumed daily with or just after breakfast. The participants will attend 3 additional study visits, once every 4 weeks and one phone visit at week 6. During these visits, the same clinician and self-reported questionnaires will be completed. At week 6, patients will be contacted by phone to complete the YBOCS and will also provide a midpoint stool sample. At the final visit week 12 patients will provide a third stool sample for microbiome profiling and a blood sample for inflammatory marker analysis. 