Common triggers of food intolerance

A number of ingredients or foods directly or indirectly stimulate or irritate the gastrointestinal tract and can produce gastrointestinal symptoms. These foods do not need to be avoided completely; they can be consumed as tolerated. Patients should be managed with reassurance and education.

Common food triggers include:

• lactose—see Lactose intolerance
• fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs)—see FODMAP intolerance
• gluten—see Noncoeliac gluten sensitivity
• food chemicals—see Food chemical sensitivity
• caffeine—can irritate the gut, causing diarrhoea, nausea and reflux
• fats—can delay gastric emptying and stimulate colonic activity, causing nausea, bloating and diarrhoea
• fibre—insoluble or highly fermented soluble fibres (see Types of fibre and their role in irritable bowel syndrome) can be poorly tolerated, causing bloating, pain and flatulence
• chilli or spicy food—can stimulate the gut, causing reflux, dyspepsia and diarrhoea
• alcohol—direct gut irritant; may alter peristalsis and relax the lower oesophageal sphincter, causing reflux, nausea, bloating and diarrhoea.