Food Allergy vs Intolerance

The world over has seen a dramatic rise in food allergies – almost a doubling effect in the last decade for certain allergens in many parts of the world! Younger children have a much higher incidence of food allergies, some of which they may potentially outgrow in later years. Adverse reactions to food are pretty common but the majority are food intolerances rather than a true allergy. Does it really matter how we classify a food reaction? The answer is YES because Food allergies are serious and can be fatal if not properly diagnosed and treated.

A food allergy occurs when the body’s immune system over-reacts to an otherwise harmless food protein (also known as an allergen). The most common food allergens are peanuts, egg, milk, fish, shellfish, wheat, soy and tree nuts.  The body makes special antibodies called IgE which flags the food allergen every time a person is exposed to it. Certain chemicals, of which the main one is histamine, are released and affect different systems of the body. A person may present with a mild skin reaction with hives, swelling and itching or vomiting, diarrhoea and tummy pain. This can, in some cases, very quickly progress to more life-threatening symptoms with difficulty breathing and swallowing, feeling faint due to a drop in blood pressure and a sense of impending doom.

A food Intolerance is not mediated by the immune system. It occurs when your body cannot properly digest a food and results in irritation to the digestive system. Patients present with bloating, tummy cramps, heartburn, headaches and irritability. It may mimic a food allergy due to the shared
symptoms of diarrhoea, vomiting and tummy pain. The most common form is Lactose Intolerance where a person cannot digest the sugar found in milk due to a deficiency of the enzyme, Lactase. Some patients may have a sensitivity to certain chemicals in foods like tyramine in cheeses or
caffeine. Preservatives like sulphites (often found in wine or dried fruit) and MSG are
common triggers for some people.

Listed below are certain clues that may help you figure out if a food reaction is an intolerance or an allergy.

Allergy Intolerance
sudden onset minutes to 2 hrs Usually gradual onset
occurs every time you eat the food may only occur with cumulative exposure
small amounts trigger a reaction may only occur when a lot is ingested
can be life threatening is not life threatening

A doctor or allergy specialist will be able to confirm a food allergy by either doing an oral food challenge, skin prick test or blood IgE testing. The correct diagnosis is key and may have life changing effects to a person’s quality of life!