Food allergy – how to identify food allergens and how to avoid them

Keeping a scrupulous food diary is the key to finding out what is causing your food allergy.

AlliApp Health Team May 5 · 4 mins read

A food allergy is caused when your body reacts to certain (otherwise harmless) foods, which it sees as potentially dangerous. When your immune system goes into gear to protect you from such outside threats, ironically it can itself be the cause of very debilitating symptoms, like sneezing, itching, skin rashes, a sore throat or a runny nose. Very rarely, life-threatening symptoms can be triggered by food allergies, in a ‘systemic’ (whole-body) reaction to certain foods.

What is a food allergy?

The antibody Immunoglobin E (igE) helps the immune system protect your body from harm by binding to potentially harmful substances like infectious bacteria. An allergy occurs when your immune system mistakenly reacts to an otherwise harmless exterior substance that it sees as a threat. Food allergy is triggered when igE binds to certain food molecules, thus causing the release of histamine. Histamine can produce typical allergy symptoms like runny nose, sneezing, itchy throat – which is why antihistamine tablets are often taken to offset allergic conditions like hay fever. The reaction is usually localised and though annoying and debilitating, it is not life-threatening.


Anaphylactic shock is a rare, potentially life-threatening allergic reaction which involves the whole immune system (a ‘systemic’ reaction) and which requires immediate medical attention. In susceptible individuals it can be brought on by common foodstuffs like peanuts (though it can also be brought on by other, non-dietary irritants like insect stings). It can be reversed by administering emergency adrenalin.

Who can develop a food allergy?

Anyone can develop a food allergy, though genetically disposed or ‘atopic’ families are more prone to allergic reactions, not just to food, but also to environmental factors like house dust or pollen. The majority of food allergies start during childhood. An allergy to dairy products like milk and eggs, for example, is more typical in children, as we often outgrow the condition as we get older. Adults can develop a food allergy later in life, often to a food that has formerly caused no problems.

What are the most common dietary causes of food allergy?

These 14 foods are the most common food allergy culprits:

  • Cereals containing gluten, eg wheat (including spelt and khorasan wheat), rye, barley, oats
  • Crustaceans  eg prawns, crabs, lobster, crayfish
  • Eggs
  • Fish
  • Peanuts
  • Soybeans
  • Milk (including lactose)
  • Nuts
  • Celery (including celeriac)
  • Mustard
  • Sesame
  • Sulphur dioxide/sulphites – a food preservative.
  • Lupin – lupin seeds and flour and can be found in certain bread, pastries and pasta (though the legume vegetable is more commonly eaten in the Mediterranean and Asian countries)
  • Molluscs eg mussels, whelks, oysters, snails and squid

What is the best way to protect yourself and your family against a food allergy?

Keeping a scrupulous food diary is the key to finding out what is causing your food allergy. As there are so many potential dietary triggers, with each meal likely to be made up of various ingredients, it is essential that you keep a meticulous record of everything you eat. Once you collate all allergic symptoms, together with all food eaten over a period of time, you can begin to build up a picture of likely food allergens. You must then avoid all foods which are likely to cause an allergic reaction. Though some allergic responses can be almost instantaneous, (like those to insect stings and bites, for example), others can take several hours to develop, especially those to food, which makes discovering the cause of your symptoms that much harder.

Adrenalin auto-injector

A rare, whole-body anaphylactic reaction to a food allergen, eg a prawn or a peanut, is the exception. These ‘systemic’  reactions ie involving the whole body, are instantaneous. Once any susceptibility to anaphylaxis has been established, it is essential that you carry an adrenalin auto-injector around with you, particularly if you are eating ready-prepared foods like restaurant meals, bought lunches and takeaways. Sometimes trigger foods like sesame or peanuts are not obviously visible in your sandwich or meal.

AlliApp – an easy and effective way to track your food allergens

A medically endorsed and trusted health-tracker app like AlliApp can be a crucial help in your quest to track down and identify the cause of yours, and of your family’s, food allergies. AlliApp is free to download to your phone so you can have a handy and effective way to record your food and your symptoms, every day. Premium AlliApp is an upgradewithmany valuable additional features, that makes your quest for good health that much easier. With Premium AlliApp, you can share your health data with health providers, as well as keep a record, not just of your foods, but also of your moods and air quality.