Food intolerances are reactions in which a food or food component repeatedly causes symptoms, usually without the immediate IgE-mediated immune reaction seen in many food allergies. They can still be disruptive, but they are generally managed differently from allergy.
The distinction matters because food allergy can cause anaphylaxis, while intolerance more often causes digestive symptoms such as bloating, abdominal pain, diarrhoea or constipation. Some symptoms overlap, so a careful history is needed before removing major food groups.
Common Types
Common examples include lactose intolerance, reactions to some fermentable carbohydrates, sensitivity to certain food additives, and symptoms linked to naturally occurring substances such as caffeine or histamine in some people.
Gluten-related symptoms need careful assessment because coeliac disease is an autoimmune condition, wheat allergy is an allergy, and non-coeliac gluten sensitivity is a separate diagnosis of exclusion.
Symptoms
Symptoms vary by person and trigger. Digestive symptoms can include bloating, cramps, abdominal pain, wind, diarrhoea, constipation and nausea. Some people also report headaches, flushing, tiredness, skin flares, rhinitis-like symptoms or palpitations.
Symptoms may depend on dose. A person might tolerate a small amount of a food but develop symptoms after a larger portion or repeated exposure.
Diagnosis
Diagnosis usually starts with a medical history, symptom timing, diet pattern and other possible causes. A food and symptom diary can be useful, especially when symptoms are intermittent.
For many intolerances there is no single definitive test. A supervised elimination and reintroduction plan may be used to check whether symptoms reliably improve and return. Coeliac disease and true food allergy should be considered before gluten, wheat, milk or other major foods are removed for long periods.
Commercial tests should be treated cautiously unless they are recommended by an appropriate clinician. Poorly supported testing can lead to unnecessary restriction and missed diagnoses.
Management
Management focuses on identifying triggers, reducing symptoms and keeping the diet balanced. Some people can avoid a trigger completely, while others can tolerate small amounts.
Dietitian input can be useful where several foods are suspected, where a child is affected, where weight loss or nutritional deficiency is a concern, or where a restricted diet is being considered.
Examples include using lactose-free dairy or lactase enzyme for lactose intolerance, adjusting fibre and fermentable carbohydrate intake for some bowel symptoms, or avoiding specific additives only when they are clearly linked to symptoms.
Difference from Food Allergy
Food allergy can cause rapid symptoms such as hives, swelling, wheeze, vomiting, collapse or anaphylaxis after exposure to a trigger. Food intolerance usually has a slower pattern and is often dose-related.
Someone with breathing difficulty, throat swelling, collapse, or rapidly worsening symptoms after eating should be treated as a possible emergency allergic reaction rather than a routine intolerance episode.
See Also
References
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