Food Allergy

A food allergy occurs when the immune system mistakenly identifies a harmless food protein as a threat and mounts an inflammatory response against it, ranging from mild skin or digestive symptoms to a severe, potentially life-threatening whole-body reaction called anaphylaxis. Common allergenic foods include peanuts, tree nuts, milk, eggs, shellfish, fish, wheat, and soy, though any food can theoretically trigger an allergic reaction in a susceptible individual. Food allergies are distinct from food intolerances (such as lactose intolerance), which cause digestive discomfort but do not involve the immune system and are not life-threatening. Because even trace exposure can trigger a severe reaction in someone with a true food allergy, accurate diagnosis and, for severe allergies, an emergency action plan are essential.

Symptoms typically appear within minutes to two hours of eating the trigger food and can affect multiple body systems: • Skin: hives, itching, swelling (particularly of the lips, face, or eyes), or eczema flare • Digestive: nausea, vomiting, abdominal cramping, or diarrhoea • Respiratory: sneezing, nasal congestion, coughing, wheezing, or difficulty breathing • Cardiovascular: dizziness, fainting, or a drop in blood pressure Signs of anaphylaxis, a medical emergency: • Swelling of the throat or tongue, making breathing or swallowing difficult • Severe difficulty breathing or wheezing • A rapid drop in blood pressure, causing dizziness, fainting, or loss of consciousness • Rapid onset of widespread hives alongside any of the above

Food allergies occur when the immune system produces IgE antibodies against a specific food protein after initial exposure, so that on subsequent exposure, the immune system releases histamine and other chemicals that cause the allergic symptoms. Why some people develop this immune response and others do not is not fully understood, but genetic predisposition to allergic conditions (atopy), and possibly the timing and manner of early exposure to allergenic foods in infancy, both appear to play a role.

• Family history of allergic conditions: food allergy, eczema, asthma, or hay fever • Personal history of other allergic conditions (the "atopic" tendency) • Young age: many food allergies begin in early childhood, though some persist or first appear in adulthood • Existing food allergy: having one food allergy increases the likelihood of developing another

• Anaphylaxis, a life-threatening emergency requiring immediate treatment with adrenaline (epinephrine) • Significant lifestyle impact from the need for constant vigilance around food labels, cross-contamination, and eating outside the home • Nutritional gaps if multiple foods must be avoided, particularly in children, requiring careful dietary planning • Anxiety around eating, particularly in social or unfamiliar settings, for both the affected person and caregivers of allergic children

There is no way to prevent the development of a food allergy once the underlying predisposition exists, but reactions themselves are highly preventable: • Strict avoidance of the confirmed trigger food, including checking ingredient labels and asking about preparation when eating out • Anyone with a diagnosed severe food allergy should carry an epinephrine auto-injector at all times and ensure family, friends, and colleagues know how to recognise and respond to a reaction • Current guidance for infants at high risk of food allergy (such as those with severe eczema) supports early, supervised introduction of common allergenic foods rather than delayed introduction, which research has shown may actually reduce the risk of developing an allergy • Wear a medical alert bracelet if you have a severe, diagnosed food allergy