Nutrition therapy in Crohn’s disease
What is the role of nutrition therapy in CD?
- Enteral nutrition (EN) is effective in the treatment of the acute phase of the disease and is considered the first line therapy in children.
- In adults, however, treatment with corticosteroids is more effective. However other investigators have reported EN to be equally efficacious.
- Elemental or polymeric diets are appropriate adjunctive therapy to other medical treatments
Discuss the indications of EN in Crohn’s disease?
EN should be considered in adult patients with:
- Active Crohn’s disease requiring hospitalisation for treatment
- CD refractory to other medical treatment like steroids, immunosuppressive or biologics
- Side effects/intolerance to medical treatments
- To maintain remission when other treatments have failed to maintain remission
- Patient choice
What are the chances of success with nutrition therapy?
- The localisation of CD has no prognostic value for the response to EN. Approximately 50-70% of all patients reach remission within 4-6 weeks.
- The length of remission and subsequent relapse rate after remission induced by EN are comparable to that after treatment with corticosteroids in children and adults.
- One-year relapse rates of active CD by EN are comparable to steroid therapy. About 60-70% will relapse within 12 months of resuming a normal diet.
What is the mechanism of action of nutrition therapy?
The mechanism of action is not known. The following mechanisms have been proposed:
- Bowel rest (elemental diets). An elemental diet is thought to provide distal bowel rest by eliminating intra luminal contents in the distal bowel.
- providing nourishment to the bowel,
- reducing antigenic load,
- decreasing permeability changes and protein loss from the inflamed bowel &
- Decreasing colonic faecal bile salt load.
One of the newer theories regarding the benefit of EN suggests that an anti-inflammatory effect on the GI mucosa may be related to specific fatty acids in diet or to the potential of defined enteral regimens to alter gut flora. There is now stronger evidence supporting the concept that enteral diet therapy for CD will result in histologic healing of the mucosa and down-regulation of mucosal pro inflammatory cytokines.
What is the role of elemental or polymeric formula to be used?
The optimal enteral formula is unknown. Initially elemental formulas were thought to be most likely to induce remission. Current evidence shows polymeric formulas are equally effective. Most trials investigating the role of the nitrogen source have confirmed that whole protein polymeric diets are equally as effective as elemental diets.
Findings from studies of fat composition have suggested that formulas with high concentrations of medium-chain triglycerides and low concentrations of long-chain triglycerides (LCTs) are associated with beneficial outcomes.
Discuss the role of nutrition therapy in maintaining remission?
- In longstanding (more than 1 year) clinical remission and in the absence of nutritional deficits, a benefit of EN has not been demonstrated.
- 2 different approaches with enteral feeding have been used to prevent relapses in the first year after remission induction with EN:
- Use of daily elemental/polymeric nutritional supplements (supplying around one third of their usual energy intake in one study) after induction of remission by elemental diet
- 3 months of normal eating followed by 1 month of exclusive enteral feeding
- There are fewer (and smaller) studies of nutritional treatment in maintenance of remission compared to remission induction. The available studies show a beneficial effect with either intermittent exclusive supplementation or continuous partial supplementation.
Is TPN better than EN in the treatment of active Crohn’s disease?
TPN is no better than EN in the therapy of active CD and should therefore be used only in patients with a contraindication to or intolerance of EN
Although the faecal stream is likely to play a role in the pathogenesis of CD, there is no evidence that bowel rest combined with parenteral nutrition may be beneficial in refractory CD.
Discuss the reasons for the limited use of EN in the treatment of adult Crohn’s disease?
Limiting corticosteroid exposure, correcting the underlying malnutrition, and facilitating normal growth in the paediatric population are major advantages regarding EN. This does not hold true in adults. Other reasons for its limited use are:
- Poor compliance (compliance rates of 21%)
- Poor palatability. Hence use of nutrition therapy necessitates use of overnight tube feeding (NG tube or PEG) in most patients. Palatability is less of a problem with polymeric diets.
- Inconveniences of exclusive feeding of formulated food
- Lack of demonstrated long term benefits with short-term use
