Dietary measures for adults with Crohn disease

Malnutrition is common in patients with Crohn disease. Diet has an important role in restoring and maintaining nutritional status. A normal diet is recommended for most patients; the addition of polymeric oral nutrition supplements may be required. Parenteral nutrition is indicated if the gastrointestinal tract is not functional, or if oral or enteral nutrition is not tolerated. For more information on the diagnosis and management of malnutrition and nutrition support, see Malnutrition in adults.

Correct micronutrient deficiencies with appropriate supplements—see Fat-soluble vitamin deficiencies, Water-soluble vitamin deficiencies and Mineral and trace element deficiencies. Micronutrients particularly at risk of deficiency include vitamin D, vitamin B₁₂, folic acid, iron, zinc, calcium and magnesium.

During an exacerbation of Crohn disease, short-term implementation of a diet low in insoluble fibre may help to control diarrhoea and pain related to food intake. This may also be useful in patients with strictures, stenosis or symptoms of low-grade intestinal obstruction. The purpose of this diet is to reduce the amount of residue in the bowel by limiting the amount of fibre consumed (ie restricting foods such as wholegrain cereals and bread, seeds, nuts, legumes and many vegetables and fruit). Nutritional adequacy may be compromised, so encourage use of a multivitamin and mineral supplement, and monitor the patient’s caloric intake and weight. Referral to an accredited practising dietitian is recommended, especially if the diet is followed medium to long term.

Any foods that repeatedly exacerbate symptoms of Crohn disease should be avoided. Lactose intolerance may occur in patients with diffuse disease in the small intestine, but should resolve when remission is achieved.

Exclusive enteral nutrition (using a polymeric formula) has been shown to effectively induce remission of Crohn disease in adults and children. There is emerging evidence that certain diets, including the Crohn disease exclusion diet (CDED), can be effective for maintaining remission in paediatric and adult Crohn diseaseSigall Boneh, 2017. These diets should be implemented under the supervision of an accredited practising dietitian.

Small studies of probiotics in Crohn disease have shown positive results for a strain of Escherichia coli (Nissle 1917). However, at the time of writing there is insufficient evidence to recommend the use of probiotics in Crohn diseaseCoqueiro, 2019Limketkai, 2020.