My nephew is under treatment for ulcerative colitis & taking 'Ramicaid' through IV.Food restriction for him?

My 15 yrs old nephew is under treatment for ulcerative colitis & taking 'Ramicaid' through IV,Doctor is not much specific about his food and drink intake.What kind of food and drink he should not eat?Tomatoe or other vegetable soup are good for him?Anyone have really a good suggestion for him?Thanks in advance.

Self-care
Sometimes you may feel helpless when facing ulcerative colitis. But changes in your diet and lifestyle may help control your symptoms and lengthen the time between flare-ups.
Diet
There's no firm evidence that what you eat causes inflammatory bowel disease. But certain foods and beverages can aggravate your symptoms, especially during a flare-up in your condition. It's a good idea to try eliminating from your diet anything that seems to make your signs and symptoms worse. Here are some suggestions that may help:
* Limit dairy products. Like many people with inflammatory bowel disease, you may find that problems, such as diarrhea, abdominal pain and gas, improve when you limit or eliminate dairy products. You may be lactose intolerant 鈥?that is, your body can't digest the milk sugar (lactose) in dairy foods. If so, try substituting yogurt or low-lactose cheeses, such as Swiss and cheddar, for milk. Or use an enzyme product, such as Lactaid, to help break down lactose.
In some cases, you may need to eliminate dairy foods completely. If you need help, a registered dietitian can help you design a healthy diet that's low in lactose. Keep in mind that with limiting your dairy intake, you'll need to find other sources of calcium, such as supplements.
* Experiment with fiber. For most people, high-fiber foods, such as fresh fruits and vegetables and whole grains, are the foundation of a healthy diet. But if you have inflammatory bowel disease, fiber may make diarrhea, pain and gas worse. If raw fruits and vegetables bother you, try steaming, baking or stewing them.
You may also find that you can tolerate some fruits and vegetables, but not others. In general, you may have more problems with foods in the cabbage family, such as broccoli and cauliflower, and with very crunchy foods such as raw apples and carrots.
* Avoid problem foods. Eliminate any other foods that seem to make your symptoms worse. These may include "gassy" foods such as beans, cabbage and broccoli, raw fruit juices and fruits 鈥?especially citrus fruits 鈥?spicy food, popcorn, alcohol, caffeine, and foods and drinks that contain caffeine, such as chocolate and soda.