Overview of food intolerance

Conditions that can cause symptoms after food ingestion includeWaserman, 2018:

• immunoglobulin E (IgE)–mediated food allergy—can cause severe reactions including hives, asthma, facial swelling and anaphylaxis
• non–IgE-mediated allergy syndromes—eg coeliac disease
• mixed IgE- and non–IgE-mediated reactions—eg eosinophilic oesophagitis
• food intolerance—eg lactose intolerance, FODMAP intolerance, noncoeliac gluten sensitivity and food chemical sensitivity.

Some foods cause symptoms via a direct effect on the gastrointestinal tract; see Common triggers of food intolerance.

In general, food intolerance reflects increased sensitivity or reflexes of the gastrointestinal tract. Carbohydrate malabsorption is common in healthy individuals—symptoms are more likely to be seen in patients with underlying functional gastrointestinal disorders or following excessive intake of carbohydrates.

Food intolerance must be distinguished from food allergy. Food intolerance does not involve the immune system, does not cause severe allergic reactions (ie anaphylaxis) and is dose dependentBetterHealth Channel, 2017. In Australia and New Zealand, food allergy occurs in approximately 10% of infants, 4 to 8% of children and 2% of adultsAustralasian Society of Clinical Immunology and Allergy (ASCIA), 2021. For information about food allergy, see the Australasian Society for Clinical Immunology and Allergy website.

Food intolerance may mimic or mask a psychological condition; see Psychological considerations in patients with food intolerance.