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Do you know the difference between an allergy and intolerance?

Updated: May 31, 2023

Childhood food allergies and intolerances have become more common over the past couple of decades, with the number of children diagnosed with an allergy doubling between 2005 and 2015. Several factors are though to be behind the increase in allergies, including improved hygiene, antibiotic use, increased exposure to allergens in food and in medicinal creams, as well as delayed introduction of solid foods. Confusion around allergies and intolerances can often lead to unnecessary avoidance of foods, which can impact enjoyment of food, and may lead to nutrient deficiencies over time if the avoided foods are not appropriately compensated for.

What is a food allergy?

Food allergy is an adverse immune response to a substance that is usually harmless to the body - in this case, a specific food protein. Allergic reactions are usually fairly immediate and generally occur within an hour of contact with the food allergen, resulting in symptoms that range from mild (skin or gastrointestinal symptoms) to life-threatening (anaphylaxis).

What is a food intolerance?

Food intolerances are more difficult to diagnose than allergies as they don't involve the immune system and onset of symptoms is delayed, appearing anywhere from a few hours after eating the food, and up to 2 days afterwards. Although many symptoms are similar to those of allergies (particularly gastrointestinal symptoms), food intolerance reactions are not usually harmful or life-threatening.

Diagnosing allergies and intolerances

Blood and prick tests are often used to diagnose food allergies, however these can sometimes show a false result, so symptoms and dietary challenges are usually also taken into account when diagnosing an allergy.

Intolerances cannot be diagnosed by tests (with the exception of lactose intolerance), so are normally diagnosed based on a symptom history and by testing an elimination diet for improvement of symptoms. Elimination diets for allergies or intolerances should always be carried out under guidance of your doctor or a qualified nutrition professional to avoid misdiagnosis and unnecessary elimination of foods from your diet.

Management Options

Currently the only strategy for managing a food allergy is to avoid the allergen. You should only eliminate foods from your diet following proper diagnosis, and under guidance of a nutrition professional - again, this is to prevent unnecessary food restriction, and so you receive appropriate education on how to avoid nutrient deficiencies.

In the case of an intolerance you may not need to completely avoid the allergen, as intolerances are often dose responsive, meaning you may tolerate smaller amounts of the food. This is something you might need to experiment with to find your personal tolerance limit.

Preventing Food Allergies

Until fairly recently parents were advised to delay introduction of allergenic foods for infants at high risk of developing allergies. Several recent trials have found however that early introduction of allergenic foods may actually decrease the likelihood of developing food allergies. Most countries have now updated guidelines, recommending allergenic foods are introduced to infants before 12 months of age. A new study has also suggested that introducing small amounts of peanut, cow’s milk, wheat and egg (just dipping a fingertip in the food) from the age of three months could further reduce risk of developing allergy to these foods.

You can find out more about food allergies and intolerances here:


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