Are you really allergic to certain foods or just being a paranoid dinner guest? Knowing your status could save your life, so read on and be enlightened.
Tragedies involving food allergies have been in the news these past few years.
In 2012, a 20-year-old Canadian woman died allegedly after being kissed by her boyfriend, who had eaten a peanut butter sandwich nine hours earlier. She went into immediate anaphylactic shock; even though the paramedics arrived soon after, they were unable to resuscitate her. In another case, an undergrad passed away reportedly after consuming a smoothie on campus. Then there’s the seven-year-old who died of anaphylaxis and cardiac arrest after she ate a peanut offered by a friend.
Instances of food allergies in Singapore have not reached the epidemic proportions they seem to have reached in the West. But allergies, including food allergies, are the most common non-communicable disease among children here, according to a 2014 report in the Singapore Medical Journal.
Given that food allergies can lead to dire consequences, it bodes well to understand what they are and who is most susceptible to them.
How food allergies work
When the body views a particular food as harmful, it forms immunoglobulin E (IgE), a typo of antibody, to fight against it.
For an allergic reaction to occur, a person predisposed to forming IgE in response to specific foods first has to be exposed to those foods.
When he or she eats them, the food allergens – parts of the food responsible for an allergic reaction – interact with specific IgE on the surface of the mast cells and trigger the cells to release chemicals such as histamine. The IgE attaches itself to the survace of mast cells, which are present in all body tissues. They are especially common in the nose, throat, lungs, skin and gastrointestinal tract – common sites of allergic reactions. Depending on where they are released, these chemicals will cause various food allergy symptoms.
These chemicals are usually resistant to cooking heat, stomach acids and digestive enzymes. After surviving those harsh environments, they cross the gastrointestinal lining, enter the bloodstream, and go to target organs, causing allergic reactions throughout the body.
The timing and location of an allergic reaction is tied to the digestive process, which begins in the mouth.
- Mouth: Those allergic to a particular food may experience itching here as they start to eat the food.
- Nose & Throat: If the chemicals are released here, you may get itching in the throat and have trouble breathing or swallowing.
- Gastrointestinal Tract: If the affected mast cells are here, abdominal pain, vomiting or diarrhoea could occur. After digestion in the stomach, abdominal symptoms such as vomiting, diarrhoea or pain may begin.
- Bloodstream: When the allergens enter and travel through the bloodstream, a drop in blood pressure can occur.
- Skin: The chemicals released by skin mast cells can cause hives or eczema.
- Lungs: Once here, they may cause bronchospasm, which is wheezing or constriction of the lungs. All of this takes place within a few minutes to an hour.
Who is at risk?
The tendency to form IgE against food is an inherited presidsposition. It predominates in those who come from families where allergies are common. These do not necessarily need to be food allergies – hay fever, asthma or hives could be triggers. Someone with two allergic parents is more likely to develop food allergies than someone with one allergic parent.
There are also non-IgE -mediated reactions. These, however, are less common.
Allergy vs Intolerance
Food intolerance is often mistaken food allergy. What’s the key difference between the two?
- Food allergy is triggered by the immune system every time you consume the offending food; even a tiny amount can set you off. The consequences are more severe and can even be life-threatening.
- Food intolerance may not always present with symptoms; in fact, you may need to have a lot of the food or eat it often before a reaction is induced. Consequences are not typically severe.
