When my son was diagnosed, he was treated with one week of flagyl through IV (he was inpatient at the time) and was commenced on exclusive enteral nutrition (EEN) for six weeks and he had great success with it.
In certain situations, EEN has a comparable success rate at inducing remission as steroids. I believe the success rate may not be as high in adults as in children (having said that, my son was almost 17, 140 lbs before getting sick and 5'10" - so not a small/young child) and EEN works better at alleviating inflammation in the small bowel/terminal ileum areas (although, again, my son's response was a bit different - EEN cleared inflammation in his duodenum and colon but left some inflammation in his terminal ileum).
EEN has no side effects but does provide nutrition, is anti-inflammatory, provides bowel rest, is very easily digested and has shown to aid in mucosal healing. My son had been sick, off and on, for 3 months, ending up in the hospital. Within 2 weeks of beginning EEN (including the week on flagyl), he was back at school, doing a couple of hours of phys.ed. classes per day and playing on his hockey teams (although, a bit weaker than before getting sick). It is a challenging treatment - EEN means NO food for six weeks (sometimes longer), your nutrition comes completely from nutritional formulas. The formula can be ingested orally through shakes (modulen, peptamen, etc.) or through naso-gastric tube (as my son did). The 'best' formulas (in the sense that they are most broken down, most easily digested, etc.) are the elemental for semi-elemental formulas, however, the more 'elemental', the worse they taste. My son inserted an NG tube each night and ingested an elemental formula overnight so taste was not an issue.
If you have any questions, please let me know. There is also a section on EEN in the Treatment subforum.
Good luck!