Comparison of gluten-free and low-FODMAP diets in patients with IBS with apparent wheat intolerance
| Gluten-free diet | Low FODMAP diet | |
|---|---|---|
| Putative pathogenic mechanisms targeted | ▸ Epithelial injury, alteration of intestinal permeability ▸ Stimulation of innate immune mechanisms | Mechanoreceptor stimulation via luminal distension in small and large intestine |
| Likelihood of efficacy | 24% of 920 patients with IBS36 | Efficacy in 68–76%22 |
| Time for response | Not reported | Within 7 days65 |
| Predictors of response | ▸ Increase intraepithelial density in duodenum53 ▸ Positive double-blind placebo-controlled re-challenge or confocal laser endomicrosopic lesions in response to exposure 17 ▸ Latent coeliac disease | Nil reported |
| Durability of response | Durable over 1 year (n=13) 17 | 72% (n=90) satisfied with mean follow-up 15.7 months72 |
| Ease of introduction | ▸ Large amount of high-quality literature available on the GFD ▸ Dietitians trained in GFD widely in some but not other countries ▸ No information regarding patients’ perspective | ▸ High quality information readily available ▸ Paucity of dietitians trained in this diet in many countries ▸ 61% patients find it easy to follow, 44% easily incorporated into lifestyle in prospective study (n=90)72 |
| Adherence | Not reported in this patient group | Adherence 76% in prospective (n=90) observational study72 |
| Advantages | ▸ Diet directed to underlying pathogenic mechanism ▸ Widely understood and packaged/processed foods available in many countries ▸ Restriction only in one food group | ▸ High chance of response ▸ In the long term, need only reduce the level of FODMAP intake sufficiently to achieve symptomatic benefit. Alternatives available across all four food groups |
| Disadvantages | ▸ Low chance of symptomatic response ▸ Gluten-free packaged/processed food: – More expensive – Often high fat, high sugar – Issues of food texture (breads, pasta, cakes, biscuits) ▸ Exclusion diet=requirement for total abstinence from gluten ▸ Difficult in countries where food labelling inadequate | ▸ Symptomatic therapy only ▸ Restrictions across a four food groups ▸ International food database of FODMAP content limited ▸ Limited availability of branded low FODMAP packaged and/or processed foods |
| Specific risks: nutritional adequacy | ▸ Restrictions on the intake of many breads and cereals may lead to deficient intake of folate, thiamine, fibre ▸ Calcium, iron and zinc intake less than population ▸ Many gluten-free foods not nutritionally balanced | ▸ If not exchanged for low FODMAP alternatives: – Restriction of lactose-containing dairy products may lead to deficient intake of calcium, vitamin D – Restriction of legumes, grains and cereals may lead to deficient intake of folate, thiamine, fibre ▸ Natural prebiotic intake reduced65 |
| Specific risks: other | ▸ Risks of precipitating an eating disorder ▸ Impaired ability to exclude coeliac disease if diet commenced prior to investigation | ▸ Risks of precipitating an eating disorder ▸ Alteration of gut microbiota when on strict FODMAP restriction67 has unknown implications for long term |
FODMAP, fermentable oligo-di-monosaccharides and polyols; GFD, gluten-free diet.