Combination of Diet and Oral Budesonide for Ulcerative Colitis

Inclusion Criteria: * Informed consent * Established diagnosis of UC with mild to moderate active disease, 5 ≤ SCCAI ≤ 10 * Age: 17-65 years (inclusive) * Extent E1-E3 by the Montreal classification * Active colitis in the rectum or sigmoid colon on sigmoidoscopy * Stable medication use of oral 5ASA for at least 8 weeks, thiopurines, vedolizumabs, Ustekinumab or tofacitinib for at least 12 weeks Exclusion Criteria: * Severe colitis (SCCAI\>10) hospitalization for acute severe colitis (ASC) in the previous 6 months * Use of steroids in the previous 3 months * Patients treated with Anti-TNF currently or in patients who had previously failed or lost response to anti TNF * Vegans (vegetarians may enroll) * Pregnancy * Inability use of budesonide due to severe adverse events * Extraintestinal manifestations such as arthritis, spondyloarthropathy or uveitis * Presence of baseline hypoalbuminemia * Fever \>38°C * Evidence for Clostridioides difficile infection * Renal failure * Hepatitis or PSC (Primary Sclerosing Cholangitis) * Active malignancy (excluding skin BCC).