Right. High quality studies have shown partial EN is not effective, they have consistently been ignored in the media favor of "CDED+PEN" studies that are of much lower quality. Pediatrics in general seem somewhat biased towards low quality studies that show adherence isn't necesarry, and ignore studies that show quite strict adherence is necessary (Anthony Segal only allowed patients to drink some tea).
It is likely the exclusive nature of EEN, rather than the addition of EN, that explains its method of action. The only noteworthy similarity between all these different types of EN, that all seem to induce remission, is that it's a liquid and that it's proximally absorbed, there's otherwise nothing really noteworthy about EN.
In some people crohn's disease disappears, but it's quire rare, and yes it happens after long term induced remission like Colombel said. EN studies are generally somewhere between 4 and 8 weeks, until calprotectin is in the normal range and a colonoscopy shows mucosal healing. But inflammation just comes back in these patients rather quickly after reintroduction of a regular diet. But it is not uncommon to use EN exclusively for much longer. There are several EN studies that used EEN as a form of nurtitional support from the 80s and 90s that used EN for much longer, Anthony Goody used EEN in crohn's disease patients for 360 days in 1976.
I got introduced to EN because I was extremely underweight, extremely anorexic, I simply stopped eating when I had crohn's disease, until my parents and school forced me to see a nutritionist. So I was put on IV feeding for a week, and then EN, I have been on EN for years. Eventually you get used to it, the desire to eat whole foods disappears, it gets much easier after a few months. I don't know what would happen if I reintroduced whole foods, I assume inflammatoin would come back, but I remain on EN because I don't want to go through all this again and I know reintroduction of whole foods would make it harder to adhere to EN (studies with partial EN actually seem to have lower rates of compliance than those using EEN, which shouldn't be surprising, these studies keep reintroducing whole foods so the desire for a regular diet doesn't go away).
