Yes. Though in some IBD patients, insoluble fiber (wheat bran, whole grains, cereals, seeds, vegetable with peels, etc.) may irritate the digestive tract--for instance, during a flare, when the mucosa is already inflamed--in a study of people with ulcerative colitis (a type of IBD), psyllium seeds were as effective as the prescription drug mesalamine in reducing recurrences of the disease. In addition, a physicians often recommend the use of fiber as a bulking agent for mild to moderate cases of diarrhea from either ulcerative colitis or Crohn's disease.

Fiber supplements may reduce or delay the absorption of certain medications. For this reason, it is best to refrain from taking fiber supplements at the same time as  medications. Instead, medications should be taken at least one hour before, or between two and four hours after, taking fiber.

Fiber supplements should always be taken with a full 8 oz glass of water. Taking fiber supplements without adequate liquids may cause it to swell and, in extreme cases, cause choking.  In any case, when increasing fiber in your diet, do so gradually, and drink at least 6 to 8 full glasses of water throughout the day or constipation may develop. People with esophageal strictures (narrowing of the esophagus) or any other narrowing or obstruction of the gastrointestinal tract should not take fiber supplements.