Review identifies patient-targeted dietary recommendations for IBD
The recent, rapid increase in the incidence and prevalence of ulcerative colitis and Crohn’s disease suggests an environmental trigger for inflammatory bowel disease, one of which could potentially be dietary, according to a recently published review.
Researchers reviewed the limited evidence behind patient-targeted dietary information for IBD from Internet searches and popular defined diets and summarized the data supporting the rationale for dietary intervention and the recommendations of poorly evidenced, popular diets.
Diet’s effect on gut inflammation
Mechanisms of dietary influence on gut inflammation may include direct dietary antigens, changes in gut microbiota and increased gastrointestinal permeability, the researchers wrote. Studies that support these disease mechanisms have shown:
- IBD development is consistently associated with dietary fatty acid and protein composition.
- Dietary fiber has been associated with lower risk for CD but not UC (HR=0.59; 95% CI, 0.39-0.9).
- Recurrence of CD “inflammation after ileal resection is dependent on exposure of the neoterminal ileum to the fecal contents.”
- High-fat diets may increase bowel permeability through changes in the gut microbiome.
- UC relapse is associated with greater consumption of meat (especially red and processed), eggs, protein and alcohol, and UC endoscopic activity is associated with sulfite consumption.
- Exclusive enteral nutrition induces mucosal healing and prolonged clinical remission of CD but not UC
- Exclusion diets have improved disease activity and prolonged time to relapse.
Patient-targeted diet recommendations
The review did not advocate any particular diet, but compiled the details and theories behind three defined diets commonly supported in lay literature: the specific carbohydrate diet (SCD), the fermentable oligosaccharides, disaccharides and monosaccharides (FODMAP) diet, and the Paleolithic diet.
The SCD is based on the theory that disaccharide and polysaccharide carbohydrates are poorly absorbed by the GI tract, causing overgrowth of bacteria and yeast that lead to excess mucus and small bowel injury. The diet restricts all but simple carbohydrates, or the monosaccharides glucose, fructose and galactose.
The FODMAP diet also is based on the notion that poorly absorbed carbohydrates cause bacterial overgrowth, but unlike the SCD, it restricts many fruits and vegetables.
The Paleolithic diet is based on the hypothesis that foods that were not present when human beings evolved can lead to modern diseases due to the GI tract’s inability to handle foods resulting from modern agriculture. This diet emphasizes lean game meats and noncereal plant-based foods.
There are no formal studies published about SCD or Paleo, but small pilot studies have tested FODMAP in patients with IBD, one that showed improved IBD symptoms (P<.02).
How to advise patients
“There is scientific evidence that dietary factors may influence both the risk of developing IBD and intestinal mucosal inflammation,” the researchers concluded. “However, there is a lack of large prospective controlled trials to provide the dietary recommendations patients desire. Taken together, studies of exclusive enteral nutrition, exclusion diets, and semivegetarian diets suggest that minimizing exposure of the intestinal lumen to selected food items may prolong the remission state of patients with IBD. Even less evidence exists for the efficacy of the SCD, FODMAP, or Paleo diets.”
Disclosure: James Lewis reports having served as a consultant for Nestec.