NUTRITION MANAGEMENT
THE LOW-FODMAP DIET FOR CROHN’S DISEASE This article will look into current research in the area of the low-FODMAP diet and its effect on functional gut symptoms. Priya Tew Freelance Dietitian and Specialist in Eating Disorders Priya runs Dietitian UK, a freelance dietetic service that specialises in social media and media work, consultancy for food companies, eating disorder support, IBS and chronic fatigue. She works with NHS services, The Priory Hospital Group and private clinics, as well as providing Skype support to clients nationwide.
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Crohn’s disease is an autoimmune condition that can affect anywhere along the gastrointestinal tract, with ulceration and an unpredictable relapsing remitting course. Symptoms commonly include abdominal pain, bloody diarrhoea, fatigue, loss of appetite and weight loss. FODMAPs are short-chain carbohydrates that are poorly absorbed in the small intestine, then passed to the colon; the process of fermentation by the colonic microflora leads to an osmotic effect. This draws fluid into the lumen and causes an increase in gas production, resulting in abdominal pain, bloating, flatulence and diarrhoea in some individuals. There is strong evidence for the use of the low-FODMAP diet for IBS management and, now, it also appears to decrease functional gut symptoms in IBD. People with IBD are three times more likely to have IBS-style symptoms than the normal population.1 A small scale study on 52 patients with Crohn’s and 20 with ulcerative colitis found that one in two patients responded well to a low-FODMAP diet (improvement of at least 5/10 in symptoms) for abdominal pain, bloating, wind and diarrhoea.2 A UK study on 180 patients with IBS or IBD given low-FODMAP advice via a dietetic/nutrition-led clinic, found normal stools improved by 66% in the IBD group. A higher adherence was associated with a longer duration of symptom improvement. Foods most often not reintroduced were wheat and onion (fructans) and dairy.3 It was concluded that the low-FODMAP diet seems to decrease functional gut symptoms in IBD. Another study on 88 people looked at symptoms and stool, finding a
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significant improvement on the lowFODMAP diet in symptoms and stool consistency.4 IS ONE FODMAP OF MORE CONCERN THAN ANOTHER?
A series of three-day fermentable carbohydrate challenges of fructans, galacto-oligosaccharides (GOS) and sorbitol were compared to glucose placebo on 32 patients with quiescent IBD. 12 of the patients had Crohn’s disease. Although a small scale study with limitations, it was found that fructans at high doses exacerbated symptoms.5 Another study6 shows that patients with active Crohn’s disease consume lower quantities of fructans and oligofructose than their inactive counterparts and healthy controls. This case control study used a food frequency questionnaire comparing 98 people with active Crohn’s disease, 99 with inactive Crohn’s disease and 106 healthy controls. A lower fructan intake was found in those with active Crohn’s disease compared to the other two groups. More research is needed to look into the impact of lower intakes of prebiotic fructans on gut microbiota. ACTIVE VS INACTIVE CROHN’S
Crohn’s disease can be intermittent with periods of remission and activity. Even in remission there can be some functional gut symptoms that persist. These symptoms can be similar to IBS symptoms and up to 40% of those with Crohn’s can suffer.7 A very small study on eight people in Australia suggested that the lowFODMAP diet may be more useful in periods when the disease is inactive. Patients were fed either a low-FODMAP
This material is for healthcare professionals only.
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NUTRITION MANAGEMENT Table 1: Prebiotic foods FODMAP foods that are prebiotics
Low-FODMAP foods that are prebiotics – (portion sizes where indicated limit the foods to low FODMAP)
Wheat/rye breads, couscous, wheat pasta, barley and gnocchi
Chicory leaves (<1 cup), fennel bulb ( ½ cup), green section of leeks and spring onions, beetroot (2 slices or 20g), sweetcorn ( ½ cob), canned lentils ( ½ cup), red cabbage (1 cup)
Jerusalem artichokes, garlic, onion, leeks, asparagus, beetroot, peas, snow peas, and sweetcorn
Banana, rhubarb, kiwifruit, dried cranberries (1 tbsp), pomegranate (½ small or ¼ cup seeds).
Nectarines, peaches, watermelon, persimmons, grapefruit, pomegranate, dried fruit
Oats
Cashews and pistachios Foods containing inulin
diet or a typical Australian diet for three weeks, followed by a three-week washout period before the diets were switched over. The native diet had a prebiotic effect, likely due to the levels of oligosaccharides and polyols. Symptoms of abdominal pain, bloating and flatulence almost doubled on the low-FODMAP diet. This was suggested to be due to the patients being in active Crohn’s.8 Comparing this to a Danish non-blinded RCT, where the 89 people studied had IBS in remission, or IBD with functional gut symptoms, a low-FODMAP diet decreased the functional gut symptoms and increased the quality of life in the IBD group.7 This has been backed up by a study on 127 people, 56 with IBS, 30 with IBD and 41 with coeliac disease. Abdominal symptoms improved after one and three months on the low-FODMAP diet in all subjects and it was suggested that this diet was a valid option in non-active IBD to improve quality of life and social occasions.9 NUTRITIONAL ADEQUACY OF THE FODMAP DIET
Some of the evidence on this topic is unclear and weak, but it can still highlight limitations of using the low-FODMAP diet with this population group. Caution is needed when using a restrictive diet with people who may already be nutritionally compromised. They could be malabsorbing, or consuming foods that they already know need to be avoided.10 The low-FODMAP diet can be a good treatment option if careful attention is paid to the nutritional adequacy of the patient’s diet.11 If it is needed for a long-term approach, then dietary supplements will be required to avoid deficiencies.12 In active states, vitamin B12, folate, B6 and vitamin D can be low.13 34
MICROBIOME
The low-FODMAP diet restricts the intake of many foods that are high in probiotics, therefore, this is not a diet to be on long term as it can impact on the microbiome. These prebiotic food, however, are good for gut health, helping with the growth of beneficial bacteria (see Table 1). This is not limited to Crohn’s, as decreased levels of Bifidobacteria and faecalibacterium prausnitzii have been found in IBS patients on the lowFOMDAP diet, so this is likely to occur in anyone on this diet.7 Encouraging people to consume more prebiotics that are low in FODMAPs may be helpful, as well as keeping the elimination phase to weeks and not months. CONCLUSION
The low-FODMAP diet does appear to have a place in the treatment of Crohn’s disease. It may be more helpful for inactive stages of the disease, but there are limitations to consider. The lowFODMAP diet can impact on the microbiome in the short term, plus there is concern about the nutritional adequacy of this population group, so it can be concluded that the low-FODMAP diet should be used in the short term only. This is exactly how the diet was designed to be used, but many people stay on the restrictive, exclusive phase of the diet. This can be due to fear of their symptoms reappearing, or a lack of support and education from their nutrition team. Encouraging and empowering people to the reintroduction stage is vital for their long-term health. If, for some reason, a patient does need to follow the exclusion stage long term, then supplements are likely to be needed to help the microbiome and to correct nutritional deficiencies.
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