Do you know the difference between a food allergy and a food intolerance? While they’re often confused, they’re very different in how they affect your body. From symptoms, to timing of a reaction, and testing – I’m here to give you the low down on the key differences between the two.
If you suspect you may have a food allergy or intolerance – please seek advise from a healthcare professional
What is a food allergy?
A food allergy occurs when an immune response is triggered by proteins in certain foods. This causes the creation of immunoglobulin E (IgE) in the body, which triggers allergic symptoms. Symptoms of allergies include hives/itching, vomitting, and, in severe cases, anaphaylaxis. Gut symptoms can also sometimes be experienced in food allergies. Symptoms of a food allergy typically occur quite quickly.
The most common food allergies are:
- Cow’s milk
- Hen’s egg
- Peanuts
- Tree nuts, such as hazelnuts, almonds, walnuts, brazil nuts, cashew, and pistachio
- Wheat
- Soya
- Fish
- Shellfish, especially prawns
- Sesame
If you are at risk of an anaphylaxis reaction and carry an epi-pen, it’s important that family and close friends are aware of how to use this for if you do have a reaction.
What is a food intolerance?
Food intolerances do not trigger an immune response like allergies do. Symptoms typically involve the digetive system, such as bloating, gas, diarrhoea, or nausea. Symptoms for a food intolerance are usually more delayed, which can make it difficult to identify which food(s) are causing symptoms.
Intolerances can sometimes occur for a short period of time and then be re-introduced. For example, it can be common to develop short term lactose intolerance after a bout of gastroenteritis (stomach bug). However, this is not always the case.
Intolerances also usually have a tolerance level. For example, some people with a lactose/dairy intolerance may be able to tolerate small amounts of dairy or lactose but not large amounts each day. Others may be more sensitive and have symptoms from even a small amount of the food they are intolerant to.
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Diagnosis and Testing
Allergies can be diagnosed via skin prick testing (SPT) or RAST blood tests. This is because they produce an immune response which is measureable in the blood. These 2 tests are the only evidence based test to diagnose an allergy.
There are no tests which can diagnose an intolerance – so please don’t waste your well earned money on hair/pee/blood test which will advise you to cut out half the foods in your diet. This can lead to extreme restriction in your diet and can result in weight loss, nutritional deficiencies, and you missing out on your favourite foods – which no one wants.
Intolerances are diagnosed via an elimination and re-introduction of the food product, which should be done with the support of a healthcare professional. The suspected food product should be eliminated, usually for 4-6 weeks, and then reintroduced. If symptoms resolve on elimination and reappear on reintroduction, this would likely warrant the diagnosis of an intolerance. Foods should be eliminated one at a time, so you are able to identify which food products are causing you symptoms. Eliminating multiple foods at a time can results in over-restriction of your diet putting you at higher risk of nutritional deficiencies.
Managing allergies and intolerances
If you’ve been diagnosed with an allergy or intolerance, and you’re struggling to manage your diet alongside this then please seek advice from a registered dietitian, who is equipped to help you manage this. Severe allergies should always be managed alongside an allergy team to support you.
Sometimes allergies can be grown out of, particularly in children. Allergens should only be reintroduced or rechallenged under the guidance of a medical professional. Severe allergies may be challenged in small amounts, which are gradually increased, in hospital if your medical team feel this is appropriate. There is emerging evidence for immunotherapy helping to improve allergen sensitivity. However, this is only available in some NHS trusts currently and only for some specific allergens such as peanut. This is where very small doses of the allergen are given to patients to help reduce sensitivity to the allergen.
When removing food items/groups from your diet, it is important to seek advice from a medical professional, such as a dietitian, to ensure you are still meeting all of your nutritional requirements. For example, when removing dairy from you or your child’s diet – it is important to ensure you are getting appropriate calcium and iodine alternatives to continue to meet your requirements for these minerals.
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Food Labelling
In the UK, it is the law that food businesses must inform you if they use any of the 14 allergens as ingredients in the food and drink they provide. These are usually in bold under the ingredients section of a food label so they are easily identifiable.
If you’re eating out and have a food allergy – it’s important to always inform the place you are eating of your allergen so they can ensure your food does not contains traces of this food product.