Evidence-Based Dietary Guidance for IBD Patients
Inflammatory bowel disease (IBD), which includes Crohn's disease (CD) and ulcerative colitis (UC), affects an estimated 1.4 million Americans1 and an estimated 2.2 million Europeans.2
The incidence of IBD has been rising, although the reasons for this increase are unclear. Several environmental factors may be responsible, although smoking is the only established environmental risk factor.3
Both epidemiological and interventional studies suggest an association between diet and the pathogenesis of IBD.3 However, there is no "convincing evidence from interventional studies to implicate any specific foodstuffs."3
Clinicians might therefore "reasonably conclude that evidence is insufficient to allow any dietary recommendations to be given to patients other than to have a 'well-balanced diet' that ensures adequate nutrition."
A review article by Richman and Rhodes3 addresses this assumption on the part of clinicians by offering the "best evidence-based dietary advice" for their patients. In particular, the authors seek to provide education regarding inappropriately restrictive diets that are not evidence-based.
Evidence From Interventional Studies
Enteral nutrition: The authors conclude that "enteral nutrition as sole feed can induce clinical remission and mucosal healing" in CD—especially in cases in which the small intestine is involved. Enteral nutrition, given as 50 percent of caloric intake, is also effective in maintaining remission.
In active UC, there is no evidence that bowel rest by either enteral nutrition or intravenous feeding is effective, although nutritional support is "appropriate" if the patient is malnourished.
Dietary supplementation with omega-3 fatty acids: Despite "theoretical evidence" that omega-3 fatty acids might be beneficial in CD and UC, current evidence is "weak."
Dietary supplementation with curcumin: Curcumin, a natural phenol found in turmeric, "shows promise" as adjunctive therapy for UC maintenance, but data are currently "inconclusive."
Dietary component modification: Interventional studies do not support avoidance of sugar or increased intake of fiber (nonstarch polysaccharide) in the treatment of CD. Moreover, insoluble fiber might cause obstruction at CD strictures.
Dietary exclusion of nanoparticles—ie, man-made, submicron-sized particles derived from food additives and excipients—may show promise, but larger-scale trials are necessary to support this intervention. The authors regard the evidence for removal of milk, dairy products, and other items to be inconclusive. They state that "strict lactose exclusion, even though widely practiced, is not usually necessary."
Vitamin and mineral supplementation: Vitamin D deficiency may contribute to the pathogenesis and progression of IBD-CD. Low-dose vitamin D supplementation seems "reasonable" for all patients with CD.
Prebiotics: A growing "impressive" body of research points to an association between IBD and an alteration in gut microbiota. However, there is insufficient evidence to recommend dietary supplementation with prebiotics in patients with IBD.