FODMAPs and functional dyspepsia: emerging evidence but unanswered questions

Functional dyspepsia (FD) is a common disorder of gut-brain interaction (DGBI) characterised by symptoms of epigastric pain or burning, referred to as epigastric pain syndrome, and bothersome postprandial fullness or early satiation, referred to as postprandial distress syndrome (PDS).1 Colloquially, of course, such symptoms are described by patients as ‘indigestion’ and, given their meal-related nature, it is perhaps unsurprising that symptoms are often attributed to food. Indeed, patients with dyspepsia often prioritise identifying dietary triggers for their symptoms. Advice to avoid alcohol, as well as spicy or fatty foods, for example, is common. However, this is based on little evidence, and there are few studies of exclusion diets in FD. Conversely, in irritable bowel syndrome (IBS), another DGBI that frequently overlaps with FD, a diet low in fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs) is widely used.2 FODMAPs are short-chain carbohydrates that are poorly digested or absorbed in the small intestine, leading to osmotic effects. FODMAPs also undergo fermentation by colonic bacteria. Hence, restricting FODMAP intake can improve abdominal pain, diarrhoea and bloating in IBS. In Gut , Van den Houte et al have evaluated a low FODMAP diet (LFD) for treating patients with FD, including assessing symptom recurrence using blinded reintroduction of FODMAPs administered as powders.3 Given the mechanisms of action described above for IBS related to the small intestine and colon, an LFD might not be an obvious choice for …