Overview
Crohn’s Disease (CD) is with Ulcerative Colitis (UC) the most common forms of Inflammatory Bowel Disease (IBD). It is a chronic inflammatory disorder that causes inflammation and tissue damage in the gastrointestinal (GI) tract1,2. CD can occur at any age and patients often experience recurrent exacerbations alternating with periods of remission. CD affects quality of life of patients and caregivers and represents important psychological, social as well as economic burdens3-5. Genetics, immune system, intestinal microbiota and the environment can all play a role in the physiopathology of CD. The global burden of IBD has been increasing overtime, generally correlating with industrialisation and western life style. The estimated age standardised prevalence rate of 84.3 per 100,000 people5. Dietary habits and nutritional changes can help manage and improve the condition. Indeed, nutritional therapy with exclusive enteral nutrition (EEN) for induction of remission was shown to be highly effective and is broadly recommended as first line therapy either as monotherapy or co-therapy combined with biologics for paediatric CD by many institutions and expert groups ECCO/ESPGHAN6, the Porto IBD group of ESPGHAN7, ESPEN8, NICE9, and JSPGHAN10. However, in adult patients, standard of care is to use corticosteroids11. Even though, clinical practice is evolving and new guidelines, including those from ECCO11, do recognise the use of enteral nutrition as an adjunctive therapy in adult patients. In the recent years more attention was paid for hole-food dietary strategies, such as Crohn’s Disease Exclusion Diet that are now being recommended as primary or adjunctive therapy for individuals with active Crohn’s disease (CD) and offer an alternative diet therapy to EEN for both paediatric and adults patients12,13,14.
Symptoms
CD typically appears as patches of inflammation in any region of the gastrointestinal tract and usually affects all layers of the intestinal wall1,2. However, it can also have extraintestinal manifestations in areas such as the skin, eyes, joints, the musculoskeletal system, and the hepatobiliary system1. Typical symptoms may include diarrhoea, steatorrhea, abdominal pain, rectal bleeding, loss of appetite, nausea, vomiting, malabsorption, weight loss, and constipation15-19. Patients with CD experience periods of remission and relapse, with 50% of patients relapsing in the first year after diagnosis and 10% having a chronic relapsing course. Patients also experience number of complications that often require surgical treatment and/or hospitalisation2,20,21. The inflammation of the intestinal wall in CD can lead to the formation of strictures which can cause intestinal blockages2,22. Furthermore, the penetrating nature of the disease can also result in the formation of abscesses, fistulas, or perforations in the intestinal wall2,22,23. Paediatric-onset CD is often more severe than adult-onset CD22, manifesting with more extensive inflammation24, and higher disease activity25. Paediatric CD is associated with impaired growth, delayed puberty, and undernutrition26,27.
Diagnosis
The cause of CD is not completely understood but current evidence suggests an interaction between genetics, the immune system, the intestinal microbiota, and environmental factors1,28-30. The correlation between increase in incidence and industrialisation has implicated the “westernisation” of diets and environment as a key factor; however, the specific elements of these lifestyle changes that are responsible are still being elucidated28,30,31. The diagnosis of CD is typically based on a combination of history, physical and laboratory examination, and endoscopy15,11. Most often, disease activity with a CD activity index (CDAI) or paediatric equivalent (PCDAI)32 as well as fecal calprotectin and CRP levels are assessed as composite measure of CD stage. The symptoms of CD vary between individuals and may be classified as mild, moderate, or severe. They also tend to present as recurrent exacerbations with periods of remission but may change and become worse over time due to the formation of strictures, fistulas, and abscesses2,22,25.
Intervention
CD cannot be cured, therefore current treatments aim at the induction and maintenance of clinical remission, improvement of symptoms and reduction of inflammation. Beyond history, physical and laboratory examination, and endoscopy11,15 as well as determination of disease activity index (CDAI) or paediatric equivalent (PCDAI)32, mucosal healing, as assessed with endoscopy, and fecal calprotectin levels as proxy biomarker is increasingly recognised as a key treatment goal by ECCO and ESPGHAN guidelines6. Nutritional therapy with exclusive enteral nutrition (EEN) for induction of remission was shown to be highly effective and is broadly recommended as first line therapy either as monotherapy or co-therapy combined with biologics for paediatric CD by ECCO/ESPGHAN6, the Porto IBD group of ESPGHAN7, the ESPEN8, NICE9 , and JSPGHAN10. However, for paediatric patients with severe disease, and those who cannot tolerate EEN, drug treatments including biologics agents, such as, anti-tumour necrosis factor (anti-TNF) therapy, are recommended6. Same, in adult patients, standard recommendation is to use corticosteroids and/or other drugs11. Nevertheless, even when used intensively the drugs impact on remission may still be moderate with relatively high rate of loss of response and nutritional issues remain not addressed33. Along those lines, clinical practice is evolving and some adult guidelines, including those from ECCO11, do recognise the use of enteral nutrition as an adjunctive therapy in adult patients. Moreover, increasing evidence further support the use of nutrition in clinical practice. In the recent years more attention was paid for hole-food dietary strategies, such as Crohn’s Disease Exclusion Diet (CDED) complemented with partial enteral nutrition (PEN) that are now recommended as primary or adjunctive therapy for individuals with active Crohn’s disease (CD) offering an alternative diet therapy to EEN for both paediatric and adults patients12-14, 34.
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