Inclusion Criteria CD patients:  Participant understands the study procedures and signed an informed consent to participate in this study Previously diagnosed with CD; Montreal classification: L1 (Ileal) or L3 (ileocolonic). Low-mild disease activity (no clinically relevant symptoms and HBI<8 and CDAI <220) Evidence of mucosal inflammation (faecal calprotectin ≥100 μg/g) Able to attend to the outpatient clinic of the UMCG, Martini Hospital, MCL Leeuwarden or Isala Diaconessenhuis Meppel ≥18 years of age Able to use oral feeding and willing to undergo a dietary intervention (Follow a diet or use a vitamin B2/B3/C supplement or placebo)  Inclusion Criteria healthy volunteers:  Participant understands the study procedures and signed an informed consent to participate in this study Never been diagnosed with IBD or any other chronic inflammatory condition. Participant has no health conditions that would prevent him/her from fulfilling the study requirements as judged by the investigator on the basis of medical history and routine laboratory test results. Able to attend to the outpatient clinic of the UMCG, Martini Hospital, MCL Leeuwarden or Isala Diaconessenhuis Meppel ≥18 year of age Able to use oral feeding and willing to undergo a dietary intervention (Follow a diet or use a vitamin B2/B3/C supplement or placebo)  Exclusion Criteria CD patients:  Life expectancy <12 months Active Crohn's disease (HBI≥8 and CDAI>220), or expecting drug intervention within 3 months Colonoscopy and colon cleansing in the past 3 months; Use antibiotics, probiotics (eg Yakult, Vifit, Activia) or specific prebiotics supplements 3 weeks prior to the start of the intervention Use of vitamin/mineral supplements 1 week prior to the start of the intervention (except for vitamin D and/or calcium) Use Methotrexate drugs or chronic use of antacids, H2 or proton-pump inhibitors With a history of GI disorders that are likely to interfere with mode of action of the Colovit-capsule (for example ileocecal resection) Patients with a pouch or stoma Pregnant or breastfeeding (or foreseen pregnancy during dietary intervention period) Swallowing disorders, not able to tolerate oral food, or use of tube feeding (EEN) Previously proven anaphylactic reaction to foods included in the food boxes Previously diagnosed with Celiac Disease or following a gluten-free diet Following a vegetarian or vegan diet  Exclusion Criteria healthy subjects:  Life expectancy <12 months Previously diagnosed with IBD or any other chronic inflammatory condition Colonoscopy and colon cleansing in the past 3 months; Use antibiotics, probiotics (eg Yakult, Vifit, Activia) or specific prebiotics supplements 3 weeks prior to the start of the intervention Use of vitamin/mineral supplements 1 week prior to the start of the intervention (except for vitamin D and/or calcium) With a history of GI disorders or taken drugs that are likely to interfere with mode of action of interventions, such as chronic use of antacids or proton-pump inhibitors Abnormal clinical chemistry and haematology laboratory test results of clinical significance that in the judgment of the investigator would interfere with the participant's ability to comply with the study protocol (which might confound the interpretation of the study results), or put the participant at undue risk.  History of abdominal gastro-intestinal surgery:  Intestinal resection Presence of a pouch Presence of a stoma History or presence of cancer in the prior two years, except for non-melanoma skin cancer. Recent history of (within 12 months of screening visit) or strong potential for alcohol or substance abuse. Alcohol abuse is defined as >60g (men) / 40g (women) pure alcohol per day (1.5 l / 1 l beer resp. 0.75 l / 0.5 l wine). Pregnant or breastfeeding (or foreseen pregnancy during dietary intervention period) The method of contraception must be recorded in the source documentation. Swallowing disorders, not able to tolerate oral food, or use of tube feeding (EEN) Previously proven anaphylactic reaction to foods included in the food boxes Previously diagnosed with Celiac Disease or following a gluten-free diet Following a vegetarian or vegan diet