Food Allergy Explained


Food Safety Hazard


Undeclared allergenic ingredients in food products is a significant food safety hazard. Failure to control allergenic hazards results in 4,500 hospitalisations and 10 deaths every year in the UK1. There are also around 1,500 asthma deaths that may be triggered by an allergic reaction to food2. Many allergic reactions happen in restaurants (21-31%), followed by a school or work setting (13-23%)3. Things have improved with a recent study3 in 2017 reporting food allergy sufferers are more confident about eating out, but preventable incidents do still occur.


Problems can arise due to poor risk perception of allergenic hazards by food handlers, deliberate adulteration to increase profits, unintentional contamination and inaccurate information communicated to the customer about allergenic ingredients in food products.


What is a Food Allergy?


Food allergy in the UK affects around 8% of children under age of three and 2% of adults1. The condition is a two-stage immunological response where the body's immune system reacts unusually to food.


The first stage is sensitisation and happens when the body wrongly perceives protein in certain foods as a hazard. This results in the production of a specific antibody (IgE) to fight off the threat, which binds to a receptor on mast cells and basophils throughout the body. The immune system is now primed to deal with the unwelcome invader.


Immunoglobulin E (IgE) is the main antibody involved in defending our body against parasitic infections and produces the largest inflammatory response compared to other antibodies. Mast cells keep us healthy by fighting off parasites, viruses and pathogens. They are found in our skin, respiratory and digestive tracts, and circulatory and nervous systems4. Basophils are white blood cells found in our blood stream and help protect the body from disease.


The second stage (inflammatory response) is where mast cells and basophils release histamine and other chemicals when they come into contact with the protein that caused the sensitisation. These inflammatory chemicals can cause mild to severe skin, gastrointestinal and respiratory responses.



What are the Symptoms?


Allergic reactions can happen in minutes when food is consumed or in contact with the skin. Inhaling vapours from shellfish can also trigger an allergic response in the airways. Most cases are mild or moderate due to histamine and other chemicals being released locally into tissue, and will normally last no more than 24 hours. General symptoms include itching, swelling, vomiting and diarrhoea. Anaphylaxis on the other hand is an extreme and severe allergic reaction and occurs when histamine and other chemicals are released into the bloodstream. A severe allergic reaction can happen within minutes or in some cases can happen an hour or so later. Early symptoms may be mild, such as a runny nose, or skin rash which then develop into life threatening conditions that affect the respiratory system, heart rhythm or blood pressure. The risk of anaphylaxis may be increased due to factors such as body temperature, alcohol, exercise, cardiovascular disease, moderate to severe asthma, previous anaphylactic reaction and age5.



Common Allergenic Food


There are more than 170 foods known to cause allergic reactions. Although, it is believed eight foods cause the majority (90%) of reactions, including milk, eggs, fish, crustaceans, nuts, peanuts, wheat and soya6. Allergic reaction to celery and mustard are rare in the UK, but more prevalent in France and Switzerland. It is also possible to be allergic to more than one food due to cross reactivity, and occurs when the proteins in one food share characteristics with those in another food. People allergic to peanuts may also have a reaction to tree nuts. Allergenic foods that cause most cases of anaphylaxis include peanuts, tree nuts, milk, eggs, fish, sesame seeds and kiwi fruit7.Peanuts are implicated in most (55%) fatal reactions1.


Children often have allergic reactions to milk, eggs, peanut, nuts and fish. Milk is a common food allergy in infants under 3 years of age and Kiwi fruit is causing concern with a rapid rise in severe reactions reported. Many children will outgrow food allergies, but one in five children with a peanut allergy will continue to have reactions into adulthood. The most common food allergies among adults are fish, shellfish, peanuts and tree nuts. 



Why are Food Allergies on the Rise?


There is much discussion on the reasons for a rapid rise in food allergies throughout the world. Food allergies in the UK have risen year on year by 5%, especially in children.  Causal factors include better diagnosis, genetics, changes in our diet and the hygiene hypothesis.


Genetics can increase the likelihood of developing a food allergy. Children in the UK have a 20% chance of developing an allergy. This percentage doubles if one parent has an existing allergy and rises to 60% to 80% where both parents are sensitive. The hygiene hypothesis suggests reduced exposure to infections in early childhood may in fact increase the risk of developing a food allergy. We live in a very sanitised world where antibiotics and hygienic practices may weaken our immune system. There is evidence to suggest that populations in countries where hygiene is poor have much lower prevalence of food allergies.


We offer specialist in food awareness and management in catering. Visit our website or call us 01296 320247. These courses include Highfield Level 2 Award in Food Allergy Awareness and Control in Catering and Highfield Level 3 Award in Allergen Management for Caterers.




  1. Food Standards Agency (2016a). Allergy and intolerance. [Online]. Available at:  [Accessed on 25 January 2018]
  2. Food Standards Agency (2014). Allergy Training [Online]. Available at: [Accessed on 25 2019]
  3. Food standards Agency [2017] The preferences of those with food allergies and/or intolerances when eating out: Final Report [Online]. Available at: [accessed on 25 January 2018]
  4. Bolen,B. (2016).The Role of Mast Cells in Our Health [Online]. Available at [Accessed on 25 January 2018]
  5. Allergy UK (2015) ‘Food Allergy Vs. Food Intolerance’ [online]. Available at:  [accessed on 25 January 2018].
  6. Food and Drug Administration (2016). Food Allergies: What You Need to Know [Online]. Available at: [accessed on 25 January 2018]
  7. Anaphylaxis UK ( 2015) Anaphylaxis the Facts [Online]. Available at [Accessed on 25 January 2018]
  8. Bock SA, Muñoz-Furlong A, Sampson HA (2007). Further fatalities due to anaphylactic reactions to foods. In Journal of Allergy and Clinical Immunology. Vol 119, pp1016–8.


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