Study under review: Clinical and Fecal Microbial Changes with Diet Therapy in Active Inflammatory Bowel Disease
Inflammatory bowel disease (IBD) refers to a group of chronic inflammatory conditions that affect the gastrointestinal tract. The two most common types of IBD are Crohn’s disease, which can impact any portion of the digestive system from mouth to anus, and ulcerative colitis, which is restricted to the colon and rectum. Up to 0.5% of the Western world is estimated to suffer from IBD and associated medical costs may exceed $6 billion annually.
There is no known medical cure for IBD, with the most common treatment option being surgery to remove affected areas of the intestinal tract. Individualized drug therapies, including immunosuppressant drugs and steroids, are also used to help control symptoms and reduce inflammation. But side effects can be substantial from some of these medications.
One reason for the lack of a full-blown cure is the complicated etiology of IBD. For instance, there is a clear genetic predisposition for developing IBD that shares similarities to type 1 diabetes and other autoimmune conditions. In addition, IBD is associated with a reduced diversity of bacteria in the gut microbiome, including a reduction of bacteria with anti-inflammatory properties and an increase in bacteria with pro-inflammatory properties. It is likely that IBD arises from an interaction between environmental and genetic factors that ultimately leads to an inappropriate immune response against the gastrointestinal tract.
The role of the microbiome in the pathology of IBD has spurred an interest in dietary strategies to manage IBD. Enteral nutrition (tube feeding) is currently the first line therapy in children with IBD and in adults who do not tolerate treatment with steroids. However, a major problem of enteral feeding as primary therapy for IBD is the high relapse rate when patients return to a normal diet: approximately 50% within six months. Moreover, the low palatability of feeds, going for long periods without solid food, the cost of the enteral formulas, and the social inconvenience make staying on enteral therapy difficult over the long term.
Aside from enteral therapy, there are several diets promoted in the lay literature for managing IBD. One of the most commonly recommended is the specific carbohydrate diet (SCD), which postulates that disaccharides and starch are poorly absorbed in the intestinal tract, causing an overgrowth of bacteria that exacerbate mucosal damage. Accordingly, the SCD excludes several types of food (shown in Figure 1), including all grains and sugars except for honey, processed foods, and lactose-containing dairy products.
Reference: Gottschall, E. Breaking the vicious cycle: intestinal health through diet. Kirkton, Ont Kirkton Press, 1994.
To date, there is limited evidence supporting the use of the SCD in managing IBD. Three case studies, two retrospective analyses, an online survey, and a single small-scale clinical study have documented clinical and symptomatic improvements, including mucosal healing of the intestinal tract, in patients with IBD following the SCD. The study under review sought to add to the currently available literature by examining the effect of the SCD on clinical disease activity, markers of inflammation, and microbiome composition in patients with IBD.
Inflammatory bowel disease (IBD), including Crohn’s disease and ulcerative colitis, is a chronic inflammatory condition of the gastrointestinal tract with no known medical cure. Current treatment options include surgery, steroids, and tube feeding, none of which are popular. The specific carbohydrate diet (SCD) is a common recommendation in the public domain for managing IBD, but it lacks scientific rigor to support its efficacy. The study under review sought to evaluate the effect of the SCD on clinical disease activity, markers of inflammation, and microbiome composition in patients with IBD.
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Interview: Dana Ellis Hunnes, PhD, MPH, RD
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