Food Allergy

Food Allergy occurs when one’s immune system react unusually to a particular food. The body defence mechanism has mistaken certain protein in certain food as a threat, hence producing an abnormal immune response towards the food. This can affect both adults and children.

The incidence of food allergies has increased tremendously over the past few decades. The actual reason remains elucidated, but it is postulated that there are evolutionary changes in a typical child’s diet over the past 30-40 years. Another belief involves the ‘hygiene hypothesis’. In our new generation, children are increasingly growing up in a ‘germ-free’ environment. This leads to the body immune system not developing well, as it is not exposed to germs in their early stages of life. When the person is introduced to a certain food in their later life, allergy occurs.

What are the Types of Food Allergies?

IgE-mediated food allergy
The most common type. A specific food triggers the body’s immune system to produce an antibody known as immunoglobulin E (IgE). A patient can develop allergic symptoms a few seconds or minutes after consuming the food. There is a greater risk of anaphylaxis in this type of food allergy.

None-IgE-mediated food allergy
This is less common. This type of food allergy is not caused by immunoglobulin E, but other cells of the immune system.  The allergy reaction takes longer (up to hours and days) to develop after eating the culprit food.

Oral allergy syndrome (pollen-food syndrome)
This occurs in people developing allergy reaction such as itch, swelling over their mouth and throat, directly after eating fresh vegetables and fruits. The body’s immune system produces allergy antibodies against certain proteins in fresh fruits, vegetable, and mistaken them for pollen. Anaphylaxis can occur. The symptoms of oral allergy syndrome can resolve by cooking fruits and vegetables.

Exercise-induced food allergy
Interestingly, food allergy can be triggered in certain people after eating a particular food and then exercising. In severe cases, anaphylaxis can occur, and this is termed food-dependent exercise-induced anaphylaxis. Avoiding certain food or avoid eating a few hours before exercising can prevent this type of allergy.

What are the Symptoms of Food Allergy?

Often food allergic reactions are mild, though they can present with life-threatening symptoms that one should be aware of.

IgE-mediated food allergy causes symptoms within few seconds to minutes after eating a certain food. Common symptoms include:

  • Itchiness and flushing over the mouth, throat, or ears
  • Itchy raised red bumpy rashes over the body
  • Swelling affecting the face, eyes, lips, tongue
  • Abdominal cramps
  • Diarrhoea
  • Nausea or Vomiting
  • Hay fever-like symptoms such as itchy eyes, sneezing

Anaphylaxis is a serious allergy condition, that any delay in treatment can result in fatality. Having said that, it is completely reversible if managed promptly.
Call 995, if you think yourself or anyone has symptoms of anaphylaxis such as:

  • Breathing difficulty
  • Wheezing
  • Tongue swelling
  • Swallowing or speaking difficulty
  • Feeling lightheaded or dizzy
  • Collapse

None-IgE-mediated food allergy causes allergic reaction much slower after ingesting the food. This can sometimes take up to hours or even days after ingesting the food. Symptoms include:

  • Itchy red bumpy rashes
  • Dry itchy cracked eczematous skin
  • Nausea or vomiting
  • Abdominal cramps
  • Diarrhoea
  • Constipation

Is Food Intolerance same as Food Allergy?

No, they are different.

  • Food intolerance happens due to difficulty of the body to digest certain food such as lactose, gluten, food additives or other food components.
  • A person with food intolerance presents with symptoms such as abdominal cramps, bloating, and diarrhoea. The symptoms of food intolerance usually occur a few hours after ingesting the food. 
  • A person with food intolerance usually needs to eat a huge amount of that particular food to trigger response, whereas, in food allergy, a person only needs a small amount of the culprit food for allergic reaction. 
  • Intolerance to food is not life-threatening as there is no allergic reaction occurring. 

What are the foods that commonly cause Food Allergies?

Almost any food can cause allergic reaction, however common food that can cause an allergic reaction include:

  • Eggs
  • Peanuts
  • Tree nuts
  • Milk
  • Soybeans
  • Fish
  • Shellfish
  • Wheat
  • Fruit and vegetable

What do I expect when I consult my doctor on Food allergy?

Your doctor will enquire further on your symptoms of allergy and history of exposure to the food. Your doctor may offer you skin-prick testing, blood test, or even place you on a food elimination diet. 

Skin-prick test
This test allows a possible allergen to come into contact with the cells of your immune system through the skin. This is performed by a drop of a standardized extract of the food on the forearm. The skin over the tested area is pierced by a small lancet. The test is nearly painless, though you may feel mild discomfort. Any itching, redness and swelling may indicate a positive reaction.

There is a small theoretical risk of anaphylaxis in a skin-prick test. Your doctor will weigh out the risks and benefits of the procedure before offering to you. The test is usually performed in a controlled setting such as an allergy clinic, GP clinic or hospital.

IgE blood test
This is an alternative to skin-prick test, to measure the amount of allergic antibodies present in a person’s blood.

Food elimination diet
Your doctor will advise you to avoid consuming the possible food that causes allergy for 2-6 weeks. The food is later then reintroduced. A positive test suggesting food allergy or intolerance is when the symptoms resolved with food avoidance and recur with food re-introduction.

Depending on individual cases, your doctor may refer you to an Allergist for further evaluation.

What are the Treatment Options for Food Allergies?

The key is to identify the food allergy and avoid the culprit food altogether.
You may be asked to work together with your doctor for a food diary and management plan:

  • Identify the possible triggering food
  • Avoid the possible triggering food
  • Aware and able to manage the early stages of allergic reaction with antihistamine
  • To be aware of the symptoms of severe allergic reaction and reach out for help
  • Alternative diet replacement to ensure sufficient nutritious diet

Injectable Epinephrine
In cases of anaphylaxis, your doctor will prescribe you an epinephrine pen (Epi-pen). Your doctor will teach you how to self-administer the medication in the event of anaphylaxis allergic reaction. This is a life-saving medication that acts quickly to improve breathing, and swelling over face and lips within seconds. You can repeat inject the medication every 5-15 minutes as needed. You must then go immediately to the Emergency Department for further acute care.

Living with Food Allergy

While food allergy has no cure, here are some measures to deal with it:

  • Know your food allergens, avoid them. 
  • Be watchful for food ingredients labelling. If food labelling is not available, ask before consuming. 
  • Carry standby emergency epinephrine pen. 
  • Babies are recommended for breastfeeding in the first 4 months. Consider hydrolyzed baby formula if exclusive breastfeeding is not possible. 
  • Introduce solid to babies after 4 months of age.
  • Avoid restricting diet during pregnancy or breastfeeding.

Take care, eat well.

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