What is the most reliable food intolerance test?

Food intolerance describes difficulty digesting or reacting to a food without the same immune mechanism seen in a classic food allergy. Symptoms may include bloating, abdominal discomfort, or diarrhoea, and several digestive conditions can look similar. A clinician asks what you ate, how much you ate, how soon symptoms began, and whether they recur. Breath testing may be useful for selected problems such as lactose or fructose malabsorption. Blood tests have a role in particular diagnoses, but broad commercial food panels can produce results that do not match your symptoms.

Keep a short food and symptom diary, including portions, timing, bowel changes, medicines, and recent illness. Do not remove many foods for a long period before advice, because this can make the diet nutritionally narrow and obscure the pattern. A clinician may suggest a limited elimination followed by planned reintroduction; improvement during avoidance is more meaningful when symptoms return on reintroduction. A dietitian can help protect nutritional variety while testing a suspected trigger.

Arrange medical assessment for persistent diarrhoea, repeated vomiting, blood in the stool, unexplained weight loss, fever, or symptoms that wake you at night. Seek urgent help for swelling of the lips or tongue, breathing difficulty, faintness, or a rapidly spreading itchy rash after eating, because these features may indicate a food allergy rather than intolerance.

Ask which diagnosis fits your timing and symptoms, whether a breath test is appropriate, how long any elimination should last, and how foods should be reintroduced safely. Ask whether a dietitian referral would help you avoid unnecessary restrictions.