Crohn’s disease (CD), a chronic, debilitating disease with no cure, affects more than 500,000 Americans. Current therapies are not completely effective and are associated with substantial risks of side effects. Dietary patterns are associated with incidence of CD, and diet is the most readily modifiable of the likely environmental triggers, thereby representing an ideal therapeutic strategy. However, further research is needed to define the optimal diet for patients with CD.
There has been increasing interest among patients and healthcare professionals in the specific carbohydrate diet (SCD) as a treatment for CD. The SCD restricts all but simple carbohydrates. Fresh fruits and vegetables are universally acceptable with the exception of potatoes and yams. No grains are permitted. Unprocessed meats are permitted without limitation. Certain lactose-free cheeses and lactose-free yogurt are permitted. Interest in the SCD has been driven by countless patient testimonials and at least four recent uncontrolled cohort studies of the SCD or slight modifications of this diet demonstrating clinical improvement and resolution of bowel inflammation in a large proportion of patients.
In contrast, the Mediterranean-style diet (MSD) is often recommended for the general population because of the strong evidence of its beneficial role in overall health. Furthermore, it is easier than the SCD to implement in routine life. It includes higher fiber and less red meat intake than a typical Western diet, which may be beneficial for patients with CD, and is consistent with recommendations from organizations such as the Crohn’s and Colitis Foundation of America (CCFA) to consume “a well-balanced, healthy diet” (http://www.ccfa.org/resources/diet-and-ibd.html).
The study will be open to 194 patients with active CD defined as having symptoms of CD as measured by a short Crohn’s Disease Activity Index (sCDAI) score >175 and documented active bowel inflammation. Eligible participants will be randomly assigned in a 1:1 ratio between the two diets. Participants will be provided with three meals and two snacks per day delivered directly to their home for six weeks. Participants will also be provided with instructions on how to follow the assigned diet on their own, including provision of the recipes used. The primary outcomes will be assessed at week 6 and are sCDAI < 150 (Aim 1) and fecal calprotectin <250 mcg/g and at least 50 percent reduction from baseline (Aim 2). Following week 6, participants will be able to pay out of pocket to purchase food and/or will attempt to follow the diet completely on their own. At week 12, we will assess clinical status using the same metrics, the proportion of patients who continue the study diets when prepared food is not provided without cost, and reasons for discontinuation of the diets.
This study will provide the strongest evidence to date as to whether the SCD, a commonly used restriction diet, is superior to a well-balanced MSD for patients with active CD.