IBD diets

Formula only, for six to eight weeks — no food at all, then a structured reintroduction. It is the most demanding approach here and the best evidenced, and those two facts are not in tension: it works, and it is very hard to do.

What the evidence shows

The paediatric guideline is unambiguous: exclusive enteral nutrition is recommended as first-line therapy to induce remission in children with active luminal Crohn’s disease, at the highest evidence level, with 96% panel agreement. It is favoured over corticosteroids in children because it also promotes mucosal healing, restores bone mineral density and improves growth. The trial evidence is overwhelmingly in children; this is not an approach with the same standing in adults.

Guideline: ECCO/ESPGHAN recommend EEN as first-line induction therapy for children with active luminal Crohn’s disease.

There is no food list, because for its duration there is no food.

Sources

• EEN is recommended as first-line therapy to induce remission in children with active luminal Crohn’s disease [EL1], 96% agreement.

  Ruemmele FM, et al. Consensus guidelines of ECCO/ESPGHAN on the medical management of pediatric Crohn’s disease. Journal of Crohn’s and Colitis, 2014;8(10):1179–1207

A defined list of allowed and excluded foods, in phases, alongside formula for part of your calories (partial enteral nutrition). It was designed to get much of what EEN achieves while still letting you eat.

What the evidence shows

In 74 children with mild-to-moderate Crohn’s disease, CDED plus partial enteral nutrition and exclusive enteral nutrition both induced corticosteroid-free remission at week 6 (75% vs 59%). By week 12 more of the CDED group had sustained it (75.6% vs 45.1%). The difference people actually feel is tolerability: 97.5% of children stayed on CDED, against 73.6% on EEN. The trial was in children, and mild-to-moderate disease.

Sources

• Corticosteroid-free remission at week 6: 75% (30/40) CDED+PEN vs 59% (20/34) EEN. At week 12: 75.6% (28/37) vs 45.1% (14/31). Tolerated by 97.5% vs 73.6% (P=.002).

  Levine A, Wine E, Assa A, et al. Crohn’s Disease Exclusion Diet Plus Partial Enteral Nutrition Induces Sustained Remission in a Randomized Controlled Trial. Gastroenterology, 2019;157(2):440–450.e8

A short, structured reduction of fermentable carbohydrates, followed by reintroduction to find your own tolerances. It is aimed at the gut symptoms that persist when your disease is otherwise quiet — it is not a treatment for inflammation.

What the evidence shows

In 52 people with quiescent IBD and ongoing gut symptoms, 52% on a low-FODMAP diet reported adequate symptom relief at 4 weeks against 16% on the control diet. The symptom-severity score did not separate significantly, and — the point that matters most — markers of inflammation did not change. It can make you feel better while doing nothing to the disease underneath, which is exactly why it is not a substitute for treatment.

We don’t label foods as high or low FODMAP — that data was measured and is owned by Monash University, who created the diet. For a food-by-food answer, use their app: Monash FODMAP.

Sources

• Adequate relief of gut symptoms at 4 weeks: 52% (14/27) low-FODMAP vs 16% (4/25) control, P=.007. IBS-SSS reduction 67 vs 34, P=.075 (not significant). Microbiome diversity and markers of inflammation did not differ significantly between groups.

  Cox SR, Lindsay JO, Fromentin S, et al. Effects of Low FODMAP Diet on Symptoms, Fecal Microbiome, and Markers of Inflammation in Patients With Quiescent Inflammatory Bowel Disease in a Randomized Trial. Gastroenterology, 2020;158(1):176–188.e7

A pattern rather than an exclusion list: mostly vegetables, fruit, legumes, whole grains, fish and olive oil, with less red and processed meat. Nothing is forbidden, which is why it has no food verdicts — there is no such thing as a food that is "not allowed".

What the evidence shows

In 191 adults with mild-to-moderate Crohn’s disease, 43.5% reached symptomatic remission at week 6 on the Mediterranean diet, against 46.5% on the Specific Carbohydrate Diet — a difference that was not significant. Neither diet moved C-reactive protein much. The trial’s authors concluded that, given the similar results and how much easier it is to live with, the Mediterranean diet may be preferred for most patients with mild-to-moderate symptoms. That is a comparison against one other diet, not proof against no diet at all.

This is a dietary pattern, not an exclusion list — there is no such thing as a food that is “not allowed” on it.

Sources

• Symptomatic remission at week 6: 43.5% Mediterranean vs 46.5% SCD, P=.77. The authors concluded the Mediterranean diet may be preferred for most patients given its greater ease and other health benefits.

  Lewis JD, Sandler RS, Brotherton C, et al. A Randomized Trial Comparing the Specific Carbohydrate Diet to a Mediterranean Diet in Adults With Crohn’s Disease. Gastroenterology, 2021;161(3):837–852

An explicit legal/illegal food list: no grains, no refined sugar, no most dairy, no processed foods. It is a long-standing approach with a devoted following, popularised by the book "Breaking the Vicious Cycle" decades before it was trialled.

What the evidence shows

The trial that finally tested it did not find what its advocates expected. In 191 adults with mild-to-moderate Crohn’s disease, SCD achieved symptomatic remission at week 6 in 46.5% against 43.5% on a Mediterranean diet — not superior. Faecal calprotectin response (34.8% vs 30.8%) and CRP response were no better either, and CRP response was uncommon on both. SCD is a great deal more restrictive than the diet it failed to beat.

Sources

• SCD was not superior to the Mediterranean diet for symptomatic remission at week 6 (46.5% vs 43.5%, P=.77), faecal calprotectin response (34.8% vs 30.8%, P=.83), or CRP response.

  Lewis JD, Sandler RS, Brotherton C, et al. A Randomized Trial Comparing the Specific Carbohydrate Diet to a Mediterranean Diet in Adults With Crohn’s Disease. Gastroenterology, 2021;161(3):837–852