Myth 1: Food Intolerance Is a Mild Food Allergy
This is perhaps the most pervasive misunderstanding. A true food allergy involves the immune system — specifically, immunoglobulin E (IgE)-mediated hypersensitivity — and can produce anaphylaxis, urticaria, and angioedema within minutes of exposure. Food intolerance, by contrast, is a non-immune phenomenon. It arises from enzyme deficiencies (lactase in lactose intolerance), sensitivity to pharmacologically active food components (histamine, caffeine), or osmotic and fermentative effects of poorly absorbed carbohydrates (FODMAPs). The mechanisms, risks, and management strategies are entirely different.
Myth 2: IgG Food-Sensitivity Tests Identify Intolerances
Commercial IgG and IgG4 food-panel testing is marketed as a way to identify hidden intolerances. However, every major allergy and gastroenterology society — including the European Academy of Allergy and Clinical Immunology (EAACI) and the American Academy of Allergy, Asthma and Immunology (AAAAI) — has issued position statements against the use of food-specific IgG testing for diagnosing intolerance. IgG antibodies to food antigens are a normal physiological response to dietary exposure and reflect tolerance, not pathology. Elevated IgG to a food simply means you eat it regularly.
Myth 3: Strict Elimination Is Always Better
Many patients adopt increasingly restrictive diets in pursuit of symptom control. While structured elimination protocols — particularly the low-FODMAP diet — have robust evidence in IBS, they are designed as short-term diagnostic tools followed by systematic reintroduction. Prolonged, unsupervised restriction carries real risks: nutritional deficiency, disordered eating patterns, social isolation, reduced microbial diversity (because dietary fibre variety drives microbiome diversity), and paradoxically increased food sensitivity upon reintroduction.
Myth 4: Gluten Is Toxic to Everyone
Coeliac disease — an autoimmune condition triggered by gluten — affects roughly 1% of the population. Non-coeliac gluten sensitivity (NCGS) is a clinical entity under active investigation, with estimated prevalence of 0.5–6% depending on diagnostic criteria. For the vast majority of people, gluten is a well-tolerated protein. Much of what patients attribute to "gluten sensitivity" may actually reflect sensitivity to fructans — a FODMAP found in wheat — rather than the gluten protein itself. Controlled crossover trials have shown that many self-identified gluten-sensitive individuals respond identically to fructan-containing and gluten-containing challenges.
Myth 5: Food Intolerance Causes Inflammation
Food intolerances produce symptoms — bloating, gas, cramping, diarrhoea — but they do not produce the tissue-level inflammation seen in IBD, coeliac disease, or eosinophilic oesophagitis. The discomfort is real, but it is mediated by luminal distension, osmotic water shifts, and altered motility, not by immune-driven mucosal damage. This distinction matters because it shapes appropriate investigation and management: anti-inflammatory medications are ineffective for food intolerance, while dietary adjustment and enzyme supplementation often are.