We plan to recruit 20 IBD patients, 10 with Ulcerative Colitis (UC) and 10 with Crohn's Disease (CD) with disease in remission for the active intervention arm and 20 IBD patients in remission for the control group. Remission for CD will be defined as Harvey-Bradshaw Index (HBI) <5 and C-reactive protein (CRP) <5. For UC it will be defined as partial Mayo score ≤2 and CRP <5. For both groups a faecal calprotectin (FC) of > 250ug/g will be regarded as indicating active disease and will exclude patients from the study. Patients will also be excluded if they are anaemic (Hb <14g/dL for males, 11.5g/dL for females). In the CD arm patients will be assessed for Vitamin B12 and Vitamin D status and excluded if B12 is less than 300 pmol/l or Vitamin D less than 30 ng/mL.