Food Intolerance – A Clinical Approach to Non-Immunologic Adverse Reactions to Food

Abstract There is often confusion between food intolerances that are mediated by non-immune reactions and food allergies that are mediated by immune reactions, which collectively constitute adverse food reactions, as their distinct pathogenic mechanisms are often misunderstood. Managing and understanding food intolerances, which affect up to 20% of the population, is a complex process due to varying mechanisms and presentations. This review provides an update on common intolerances, such as FODMAP (fermentable oligo-, di-, and mono-saccharides and polyols) sensitivity, which is well-supported by evidence showing increased osmotic activity and fermentation, leading to symptom presentation. However, there is a lack of sufficient research on many other intolerances, making diagnosis and management challenging. Enzyme deficiencies, like low amine oxidase activity and sucrose–isomaltase deficiency, are implicated in some sensitivities. The absence of reliable diagnostic biomarkers necessitates an iterative strategy where presumed foods are temporarily eliminated and then reinstated in the diet to evaluate the body’s response. Incorrectly identifying food intolerances can result in employing inappropriate diets, potentially leading to severe nutritional deficiencies. Future research should focus on identifying biomarkers to guide dietary management.