Working in the hospital I see a lot of cases of flares or inflammatory bowel disease (which includes both ulcerative colitis and crohn’s disease). Often the patients are seen by a gastroenterologist and placed on a low residue diet to “rest the colon.” During a flare there is profuse diarrhea and sometimes bleeding and the low fiber diet or even holding off on any food makes clear sense to me. However, I was surprised to hear that some of these patients were being told to continue this diet all the time. Even at major university centers with famous inflammatory bowel disease specialists they were being told to rest their colon with low residue diets (the term for a low fiber diet). Knowing that fiber is good for intestinal health this sounded counter intuitive to me so I went to see if there was literature backing this up. I was surprised at what I found.
A 1999 Journal of Gastroenterology study of 105 patients randomized them to plantago ovata seeds (a good fiber source) vs mesalamine (the most widely used ulcerative colitis medication). The patients in the fiber group did just as well as far as staying in remission as the mesalamine group at 1 year follow-up. So clearly fiber does not do harm and may be as effective as current medications. In 2003 in Japan another study was done using germinated barley as a fiber source and again showed significant benefit to giving fiber to ulcerative colitis patients.
So how about Crohn’s disease? Well in 1985 a study by Dr. Levenstein et al showed that a regular unrestricted diet was no worse than a low residue diet. In 1979 Dr. Heaton et al. did a study where they instructed Crohn’s patients to eat more fiber and unrefined carbohydrates and compared them to patients who received no dietary instruction. The high fiber diet patients did MUCH better than those not given instruction.
So from what research we have it looks like the low residue diet recommendation may actually be detrimental. The data that is out there is old and sparse but what we have points in the direction of a huge benefit of fiber for ulcerative colitis and crohn’s patients. Given the immense importance of diet in these diseases (which predominantly affect the gastrointestinal tract) there is no excuse as to why we don’t already know through extensive research what diet is best for these patients. This should have been done decades ago, but it is never too late. We need to do a study looking at high fiber vs low fiber vs uninstructed/unrestricted as soon as possible.