What's The Difference Between An Allergy, Sensitivity And Intolerance?

Food allergies and intolerances are defined by the time it takes for onset of symptoms. Read more here.

What's The Difference Between An Allergy, Sensitivity And Intolerance? photo

According to Allergy UK, up to 20% of the UK population experience adverse reactions to foods. These reactions range from a full-blown allergic response to milder sensitivities – but what exactly is the difference between an allergy, sensitivity, and intolerance, and why does it matter?

Food Allergies

A food allergy causes the immune system to mount an immediate and drastic response to protein molecules in a food. Immune cells called IgE antibodies detect the protein as an invader and trigger the release of large amounts of histamine and adrenaline.

The immediate symptoms of an allergic reaction include:

  • Difficulty breathing
  • Swollen lips and tongue
  • Hives
  • Rapid heartbeat
  • Abdominal pain
  • Vomiting
  • Diarrhoea

Common food allergies include cow’s milk, peanut, egg, soy, celery, shellfish, nuts, sesame seeds, and gluten.

Allergic reactions vary in severity. Anaphylaxis for example, is a life-threatening response that requires immediate emergency medical attention, whereas other reactions are milder.

Food Intolerance

The terms ‘intolerance’ and ’sensitivity’ are often used interchangeably to describe any reaction that isn’t an allergy. Food intolerance / sensitivity symptoms are wide ranging and can be unpleasant and life-limiting but are not life-threatening. Unlike allergies, these types of reactions don’t always involve the immune system. When an intolerance or sensitivity does stimulate the immune system, different kinds of antibodies are produced to those seen in food allergy.

Examples of intolerances that don’t involve the immune system include:

  • Lactose intolerance lactose is a type of sugar found naturally in dairy products. It is broken down in the small intestine by the enzyme lactase. Lactase production declines after infancy, and an estimated 65% of the global adult population has a reduced ability to digest lactose, with lactose intolerance most common in African and East Asian ethnicities. Symptoms include cramps, bloating, wind, and diarrhoea, and appear within 30 minutes - 2 hours of consuming dairy.
  • Histamine intolerance can occur when the body’s ability to breakdown and detoxify histamine is overwhelmed, leading to a build-up of histamine. Symptoms include hives, skin rashes, migraine, and digestive problems.

A key difference between allergy and intolerance is how quickly the reaction occurs. An allergic reaction usually happens within minutes, whereas food intolerance reactions may be delayed, with symptoms appearing several hours or even days later. This can make it tricky to know which food or foods are causing the issue.

Keeping a food diary for a few weeks can help identify food intolerances.

Elimination diets can be useful and are best carried out with personal guidance from a nutrition practitioner. Unlike allergies, food sensitivities are not always permanent, and problem foods can often be reintroduced gradually after a short break.

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Allergy UK, 2021. Statistics and Figures. [online]. Available at https://www.allergyuk.org/about-allergy/statistics-and-figures/

Medline Plus, 2020. Lactose intolerance. [online]. Available at https://medlineplus.gov/genetics/condition/lactose-intolerance/