One of the most common questions that patients with inflammatory bowel disease (IBD) ask is: what should I eat?
It is obvious that in addition to genetic factors, certain environmental factors, including diet, can trigger the excessive immune activity leading to intestinal inflammation in IBD, which includes both Crohn’s disease and ulcerative colitis (UC). However, the limited number of studies and the wide variety of studies have made it difficult to confidently advise patients on which specific foods can be harmful and which are safe or actually provide a protective benefit.
New IBD diet guidelines
To help patients and providers navigate these nutritional issues, the International Organization of IBD (IOIBD) recently reviewed the best current evidence to develop expert recommendations on dietary measures that can help control and prevent relapse of IBD. In particular, the group focused on the dietary components and supplements that they considered to be the most important to consider because they make up a large portion of the diets that IBD patients can follow.
The IOIBD guidelines include the following recommendations:
| Food | If you have Crohn’s disease | If you have ulcerative colitis |
| Fruits | increase intake | insufficient evidence |
| vegetables | increase intake | insufficient evidence |
| Red / processed meat | insufficient evidence | decrease intake |
| Unpasteurized dairy products | best to avoid | best to avoid |
| Dietary fat | decrease intake of saturated fats and avoid trans fats | decrease consumption of myristic acid (palm, coconut, dairy fat), avoid trans fats, and increase intake of omega-3 (from marine fish but not dietary supplements) |
| Food additives | decrease intake of maltodextrin-containing foods | decrease intake of maltodextrin-containing foods |
| thickeners | decrease intake of carboxymethyl cellulose | decrease intake of carboxymethyl cellulose |
| Carrageenan (a thickener extracted from seaweed) | decrease intake | decrease intake |
| Titanium dioxide (a food colorant and preservative) | decrease intake | decrease intake |
| Sulfites (flavor enhancer and preservative) | decrease intake | decrease intake |
The group also identified areas where there was insufficient evidence to reach a conclusion and highlighted the critical need for further studies. Foods for which there was insufficient evidence to generate a recommendation for both UC and Crohn’s disease included refined sugars and carbohydrates, wheat / gluten, poultry, pasteurized dairy products and alcoholic beverages.
How would following these guidelines help?
The recommendations were developed to reduce symptoms and inflammation. The ways to change the intake of some foods can trigger or reduce inflammation are quite different, and the mechanisms are better understood for some foods than others.
For example, fruits and vegetables are generally higher in fiber, which is fermented by bacterial enzymes in the large intestine. This fermentation produces short-chain fatty acids (SCFA) which provide beneficial effects for the cells covering the large intestine. Patients with active IBD have been observed to have reduced SCFA, so increasing the intake of plant-based fiber may partially work by increasing the production of SCFA.
However, it is important to note disease-specific considerations that may be relevant to your particular situation. For example, about one-third of patients in Crohn’s disease will develop an area of bowel obstruction, called a stricture, within the first ten years of diagnosis. Insoluble fiber can aggravate the symptoms and in some cases lead to bowel obstruction if there is a stricture. So while increased fruit and vegetable consumption is generally beneficial for Crohn’s disease, patients with strictures should limit their intake of insoluble fiber.
Specific Diets for IBD?
A number of specific diets have been investigated for IBD, including the Mediterranean diet, specific carbohydrate diet, Crohn’s disease exclusion diet, autoimmune protocols and a diet with low fermentable oligo-, di-, monosaccharides and polyols (FODMAP).
Although the IOIBD group initially began evaluating some of these diets, they did not find enough high-quality studies that specifically studied them. Therefore, they limited their recommendations to individual dietary components. Stronger recommendations may be possible when further studies of these dietary patterns have become available. Currently, we generally encourage our patients to monitor for correlations of specific foods to their symptoms. In some cases, patients can explore some of these specific diets to see if they help.
New guidelines are a good place to start
All patients with IBD should work with their physician or a nutritionist, who will conduct a nutritional assessment to check for malnutrition and advise on correcting deficiencies if they are present.
However, the latest guidelines are an excellent starting point for discussions between patients and their physicians about specific dietary changes that may be helpful in reducing the symptoms and risk of relapse of IBD.
source: Harvard Medical School
