No dairy or red meat is easy for me as I have been vegan for almost two years but most of what I eat (salads, grains, beans, nuts) I have read is not good for her while she has so much inflammation (and the doctor also recommended a low residue diet). We also just found out she is lactose intolerant so dairy is out anyway and she has GERD too so that limits what she can eat as well. I do believe that a whole foods, plant-based diet is the healthiest diet and I hope that she can get to remission and then be able to follow that type of diet.
I can relate to the situation, I was also diagnosed when I was 19 and had just started studying away from home in a different city.
You already got a lot of great answers above on medication and diet etc.
Here is my take on all this. First, unfortunately when you get the diagnosis how to manage Crohn's feels somehow overwhelming (or sometimes underwhelming so people ignore it...). This means, at least as far as I see it, that the first thing to do for pretty much everyone after diagnosis is to really read up lots and lots on the subject, including old threads on this forum, study results etc. That takes a while, days and weeks if done thoroughly.
Second, what people should understand is what Crohn's is and that any long term management of it only works through a combination of several things, a. short term medication dealing with immediate activity, b. Long term medication to be taken over years, c. an individualized diet, d. a change of the way of how one eats meals, e. no smoking of tobacco, f. reducing hard liquor consumption and eliminating binge drinking, g. (Debated by some but I believe it important) regular endurance sport, h. Stress relief and generally being in a calm and positive mood. Many people think they can manage Crohn's effectively with drugs alone while ignoring many other factors, while others think they can leave out drugs and concentrate on diet etc. I am not saying it can't work to stay in remission in the long term without any symptoms or problems at all without focusing on all these different factors, but I have made the experience that taking all these factors together has the greatest chance of success to doing well in the long run.
A few explanations on these different factors:
ad a. Short term meds are usually corticosteroids such prednisone or budesonide (entocort). Those should only be used in the short term as long term usage can lead to serious side effects. I understand she got entocort prescribed, it should be noted that this only works if the Crohn's is located in the lower part of the smaller intestine and upmost part of the colon.
Ad b. As explained by others above, the usually used 3 types of meds for Crohn's are pentasa (a variety of that is sulfalasine prescribed to her), immunosuppressive drugs and/or biologics. There are studies that Pentasa is little more effective, if at all, than a placebo when it comes to Crohn's as it primarily has a superficial effect on the inflammation and principally works in the colon and not in the smaller intestine where Crohn's is usually most active. In contrast, for UC patients who have the primarily affected area in the colon, pentasa is a very useful long term drug.
Having said that, the reason why modern medicine supports the view of using immunosuppressives and/or biologics pretty much for all patients diagnosed below the age of 30 with noticeable and ongoing inflammation is simply put to avoid scaring in the intestine from the inflammation and various other complications down the road.
Ad c. Very unfortunately, there is no clear diet specification for Crohn's patients. Very often some people tolerate things well that others can't tolerate at all. Usually a bland diet is recommended, or in other words everything that is "too" something isn't good, as in "too oily, too spicy, too fatty, too sweet, too salty, ...". Examples of pretty bad food for most people with active inflammation are popcorn, junk food burgers with lots of fatty sauce, oily fried foods, cheap microwave pizza etc." Or in other words everything people shouldn't really eat in the first place. Good foods are usually bland porridge, chicken noodle soup (not from a can...) etc. However, once inflammation is under control, usually most things can be tolerated well. I know you were asking about low residue diets, there is also SCD and no gluten diets etc., others can say how much they work, I have to admit these things never worked for me, I e.g. Need the fibre or I get into trouble.
I need to caution you about one thing you have said, being on a completely plant based vegan diet. Crohn's principle effect is inflammation in the intestine. This inflammation prevents nutritions being absorbed into the body, for instance protein but also quite a few other things such as vit D, B6, B12, minerals such as magnesium, calcium etc. A completely diary and meat free diet can even further worsen this malabsorption leading to all kinds of problems.
Ad d. How people eat. The usual advice is to eat smaller meals throughout the day instead of say just lunch and a huge dinner late at night. At least for me, the much more important factor is HOW I eat, that is a. The combination of things (e.g. Just soup for lunch might get me into trouble, while soup AND something solid works for me better) and b. whether I talk a lot while eating or eat rather fast or while having stress or in a rather hot environment etc. I know what I am saying is a but fuzzy, but that is how I have experienced things.
Ad e. And f., first medical marijuana helps (foremost because it calms people down, that is it contributes greatly to stress relief) but second, smoking is pretty bad for crohn's (and generally for anyone's health...). As to alcohol, your daughter is just 19 and at college, so she probably might be drinking quite some alcohol, all I can say is that generally it will get Crohn's patients into trouble. I don't have a problem with a beer or two or a glass of wine, but hard liquor and binge drinking is a big problem the next day for my crohn's activity.
Ad g. Sport. Some people on here might disagree, but at least for me that's the holy grail for keeping in remission long term. If I do endurance sport (where I actually sweat for a while...) 3-4 times a week, I do well with Crohn's as well. It's probably a combination of generally boosting health, stress relief and to some extent just shacking bowels up and down (as strange as that may sound). Anyway, when someone has active crohn's and active inflammation, sport is not recommended and usually doesn't work, but to keep in remission (that is, on e things are good) I recommend it.
Ad h. Lastly, stress relief. With "stress" what usually is bad is "bad stress" as in many things to worry about smashed over one's head in a short period of time. In contrast, at least for me, gold stress as in many things to do, but I like to do them, even if I need to work 16 hours a day, doesn't bother me much. Stress relief is a mental thing and for many people takes a long time to get to, some people try to augment stress relief through yoga, others through medical marijuana, others by just keeping calm generally or just lying down on a couch 20 minutes not thinking about anything. In my experience it is a key thing.
Anyway, this is now a rather long post. I hope it helps a bit.
P.S. If she is in California, my advice is that she has a good GI there. Especially at the beginning of having Crohn's she will be at a doctor's office quite often.
