Crohn’s disease dietary strategies and scientific support

Crohn’s disease exclusion diet (CDED)

What is it?

The Crohn’s Disease Exclusion Diet (CDED) looks to avoid products which may have a pro-inflammatory effect on the intestinal mucosa, as well as those which may have a negative impact on gut bacteria.

There are three phases with dietary restrictions becoming progressively less strict as you progress through each stage. Exclusions include red and processed meats, preservatives, emulsifiers and some fibres.

What’s the evidence?

This has largely been studied in children, although it is now beginning to be replicated in adults with some promising effects.

Often this diet will be used in combination with a partial-liquid diet to help induce remission in mild-moderate Crohns, with a view of slowly reducing the liquid nutrition and returning to a whole foods diet in the long-term which helps to support gut health.

Exclusive enteral nutrition (EEN)

What is it?

This is a specially formulated, fully liquid diet which has been shown to help reduce inflammation and induce remission in Crohn’s disease. The diet is followed for 2-8 weeks and should be done with the guidance of a gut-health dietitian or doctor.

This can also be useful to follow in the build-up to surgery with Crohns disease, as an adjunctive to medicine or as an independent treatment option to induce remission. This diet isn’t suitable for everyone and should always be discussed with your gut health dietitian and doctor.

What’s the evidence?

There is some good evidence behind the use of short-term EEN, to promote tissue healing and remission.

Crohn’s disease treatment with eating (CD-TREAT) diet

What is it?

This diet was designed to have a similar composition to exclusive enteral nutrition (a specially formulated liquid diet), but in food form with the goal of improving tolerance to the diet (a liquid diet can be difficult to stick to!).

The diet excludes gluten, lactose, complex carbohydrates and alcohol and matches the macronutrients as well as vitamins and minerals and low fibre seen in EEN.

This is used as a diet for treatment, not remission and should only be temporary.

What’s the evidence?

Most of the evidence for the CD-TREAT diet is for children, however there are a few adult studies being produced which are also showing promising results.

Specific carbohydrate diet (SCD)

What is it?

This diet was developed by a gut specialist doctor in 1951. It modifies the types of carbohydrates within the diet, removing most starches and allowing only short-chain carbohydrates such as fruits. The original recommendations are to follow the diet for at least a year before liberalising, for which there is a low level of guidance.

What’s the evidence?

Evidence for the SCD diet is from observational studies and case studies. Evidence is limited and low quality. Further to this, the diet is very restrictive, and the suggested restrictive phase is long (1 year).

Mediterranean diet

What is it?

This is a diet high in olive oil, oily fish, fibre and plant-based products. This diet is much more flexible than some of the alternatives recommended for Crohn’s disease and can be easier to follow in the long-term.

What’s the evidence?

There are a number of studies looking at the Mediterranean diet in Crohn’s disease. The Mediterranean diet can be helpful to improve diversity of gut bacteria and is thought to be protective in the long-term. There are studies showing it can potentially help to regulate inflammation within the body. Due to it’s high fibre content, it can be unsuitable for some people in a flare of IBD.

Low residue diet

What is it?

This diet limits foods which enter the large intestine (fibres) and which can stimulate bowel activity (high fat foods).

What’s the evidence?

This has some good evidence behind it’s use to help manage symptoms of IBD whilst in a flare and waiting for medical treatment to take effect. It alone cannot reduce inflammation and it should not be followed long term as it is restrictive and low fibre, starving gut bacteria.

High fibre diet

What is it?

A diet high in plant-based products including wholegrains, beans/pulses, nuts/seeds, fruits and veggies.

What’s the evidence?

Studies show that those who have a higher fibre intake, may have fewer flares than those with a low fibre intake. It can be temping after a flare to remain low fibre, but evidence and experience shows us that a slow and gradual re-introduction of fibres, beginning with soluble fibres can be very helpful. This is a diet to look at when in remission, if there is no stricturing (intestinal narrowing).

Low FODMAP diet

What is it?

This is a diet used to treat IBS (not IBD!). It can help improve gut symptoms such as bloating or loose stools if there is no underlying cause. It does not help reduce inflammation and can have a negative impact on gut bacteria.

What’s the evidence?

This has good evidence for use in improving gut symptoms for those with IBS. Sometimes those with Crohn’s disease have ongoing gut symptoms whilst in remission, which could be due to IBS. In this case, the low FODMAP diet can be helpful for some. It should always be dietitian guided and to treat symptoms which are not due to a flare.

The autoimmune protocol (AIP) diet:

What is it?

This diet is based upon the palaeolithic diet, with some extensions. A usual paleolithic diet is an eating pattern which mimics what people were thought to be eating during the paleolithic era, including fruits, vegetables, meats, fish, eggs, nuts and seeds. The AIP diet has an initial exclusion phase which eliminates grains, legumes, nightshades, dairy, eggs, coffee, alcohol, nuts/seeds, refined sugars, oils and food additives.

What’s the evidence?

There is one small study showing potential improvements in IBD, however the study is small (15 participants) and there was no control arm so it is of poor quality.