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A food allergy is an adverse immune response to a food protein. Allergies are distinct from other adverse responses to food, such as food poisoning.
In extreme cases a food allergy can lead to rapid incapacitation and even death.
The Allergic Response
These kinds of allergic reactions occur when the body's immune system mistakenly identifies a protein as harmful. Some proteins or fragments of proteins are resistant to digestion and those that are not broken down in the digestive process are tagged by the Immunoglobulin E (IgE). These tags fool the immune system into thinking that the protein is harmful. The immune system, thinking the individual is under attack, triggers an allergic reaction. These reactions can range from mild to severe. Allergic responses include dermatitis, gastrointestinal and respiratory distress, including life-threatening anaphylactic responses that require immediate emergency intervention.
Classic IgE-mediated allergic reactions have an acute onset (from seconds to one hour) and may include:
- Hives (a rash with pronounced raised bumps);
- Itching of mouth, lips, tongue, throat, eyes, skin, or other areas;
- Swelling (angioedema) of lips, tongue, eyelids, or the whole face;
- Difficulty swallowing:
- Runny or congested nose;
- Hoarse voice
- Wheezing and/or shortness of breath
- Abdominal pain and/or stomach cramps
Note that some symptoms are similar to those of food poisoning.
Symptoms of allergies vary from person to person. The amount of food needed to trigger a reaction also varies from person to person. Most extreme cases an allergic reaction occur as a result of ingestion. However, an allergic reaction may occur if a person comes into contact with the only the minutest of traces of a substance, for example if their food has been prepared on a surface that has previously been used to prepare a food that they are allergic to.
Food Types Associated with Allergic Reaction
Many foods can trigger an allergic reaction; this may occur upon the first known ingestion.
Common triggering foods vary around the world depending on the diet.
Ingestion of, or exposure to, the following foods may cause a reaction:
- Tree nuts (pecans, pistachios, pine nuts, and walnuts),
- Milk (dairy products generally from cows, goats, or sheep),
- Seeds (sesame and poppy) and oils derived from them,
- Eggs (the white rather than the yolk), and
- Food additives (including colouring).
Serious danger regarding allergies can begin when the respiratory tract or blood circulation is affected. This can be indicated through wheezing and a blue tinge to the skin caused by lack of oxygen. Poor blood circulation leads to a weak pulse, pale skin, and fainting.
When symptoms include impaired breathing and affect circulation, the person is said to be in "anaphylactic shock". Anaphylaxis occurs because no nutrients are circulated throughout the body, causing the widening of blood vessels (Vasodilation). This vasodilation causes blood pressure to decrease, which leads to the loss of consciousness. Those with asthma or an allergy to peanuts, tree nuts, or seafood are at greater risk of anaphylaxis.
Note that an anaphylactic shock can also be triggered by venom from insect bites or stings (especially bee and wasp stings) and as a reaction to medication (including certain anti-biotics, aspirin, and morphine.
Epinephrine, also known as adrenaline, is a common medication used to treat allergic reactions. Epinephrine reverses the allergic reaction by improving blood circulation. This is done by tightening blood vessels in order to increase the heart beat and circulation to bodily organs.
People diagnosed with a food allergy may carry an injectable form of epinephrine such as an EpiPen (portable epinephrine-dispensing devices), or wear some form of medical alert jewelry, or develop an emergency action plan, in accordance with their doctor. The affected individual may recognise the onset of anaphylaxis and be able to brief other crew members on the correct response. They may administer the EpiPen themselves or they may need help from another crew member.
It is possible that a second dose of epinephrine may be required for severe reactions.
- CAP 757: Occupational Health and Safety on-board Aircraft - Guidance on Good Practice, 2012.