Effects of Administration of SCFA in Rheumatoid Arthritis Inadequate Responders

This study is a pilot, proof of concept study to determine the effects of administering an oral short-chain fatty acid (SCFA) supplement to Rheumatoid Arthritis (RA) patients with inadequate response to methotrexate (MTX). The study will include up to 35 participants to obtain a sample size of at least 25 participants taking the oral supplement. The researchers hypothesize that oral SCFA will change the participants' gut microbiome and regulatory immune responses. Clinical data to assess for adverse events, stool, urine samples and peripheral blood will be collected at baseline, 1 month, and with an optional 2 month time-point. Fecal microbiome will be analyzed. Adaptive immune responses will be analyzed from participant blood samples.

Inclusion Criteria: 1. Diagnosis of RA meeting 2010 ACR/EULAR for RA and/or treating MD diagnosis 2. Inadequate response to MTX per treating MD at maximum tolerated dose. 3. Able and willing to provide written informed consent prior to any study specific procedures 4. Age 18 years and above at time of enrollment 5. Subjects not excluded based on race or ethnicity Exclusion Criteria: 1. Participants who are pregnant or are currently breastfeeding 2. History of sensitivity to study compound or any of their excipients 3. Previous intolerance to SCFA or related compounds 4. Current antibiotic treatment (within 3 months of screening) at discretion of PI 5. Current consumption of probiotics (within 3 months of screening) at discretion of PI 6. Severe hepatic impairment (eg, ascites and/or clinical signs of coagulopathy) 7. Renal failure (eGFR \