Food allergies and intolerances: what’s the difference?
While an intolerance to certain food can be unpleasant, a food allergy can be fatal
The main difference between food allergies and intolerances is how the body reacts. Food allergies occur when the immune system wrongly mistakes a type of food for a threat and tries to fight against it. The body undertakes extra and unnecessary work trying to fight off the allergen that it wrongly perceives as a threat. Severe allergies can lead to unconsciousness and become a risk to life.
Food intolerances on the other hand do not involve the immune system and are often a result of a lack of enzymes to break down food. Without these, the body is less active than it needs to be. Because the immune system is not alerted with food intolerances, the areas affected are more limited (gluten intolerance is the exception to this). Areas affected by a food intolerance are limited to the digestive tract.
Related: Five of the most uncommon allergies
While one in ten people are allergic to at least one food product, at least twice as many people have a food intolerance. Any amount of a food allergen can cause severe reactions in those who have an allergy – sometimes even being near the food is enough. However, those with intolerance can often consume different amounts of food before they show symptoms.
In addition, people with food allergies are a lot more likely to suffer a reaction quickly – often within seconds – and they will show symptoms within two hours. Symptoms from intolerances, on the other hand, can take up to two days to display.
Food allergies
Every cell in your body has antigens. These are proteins that identify the cell and brand it as friend or foe. Our bodies use these to decide which cells to ignore and which to attempt to destroy or flush out of our bodies. An example of those that are usually ignored by the immune system are the cells of food products. We need food to remain in our body to provide us with energy and nutrition. But for some people this isn’t always the case.
Related: How are calories counted?
If you are allergic to an item of food, it won’t take long to discover that your body doesn’t welcome it. Your immune system will often first react towards the apparent invader when the allergen touches your mouth, likely causing you to feel pain or discomfort.
Having wrongly identified a particular substance as a threat, proteins called antibodies are sent to locate the offender, attaching to it. When connected these antibodies act as a signal to other immune cells to show them where the danger is.
During this process, histamine is produced. Histamine is the chemical responsible for the persistent symptoms you experience during an allergic reaction. The result of this chemical depends on the location it is released into.
Just as the allergen can vary enormously, so can the body’s response. While some people’s allergies are an inconvenience, for others they are life-threatening. One aspect that can make reactions so deadly is that to most people, allergens are usually harmless. For example, to most of us peanuts are simply a food source.
White blood cells produce antibodies to target allergens Photo Credit: CHRISTOPH BURGSTEDT/SCIENCE PHOTO LIBRARY via Getty
They can be found in a wide variety of packaged foods, and many people would choose them at a supermarket. Because the threat is not a universal one, those who could be killed by being in close proximity to the nut have to have their wits about them at all times. Their allergy is always at the forefront of their mind, and through habit it becomes their first thought before they choose a snack.
Related: How do EpiPens work?
Some milder allergies produce similar symptoms to your average cold, including the common effects of a runny nose and puffy eyes, so how can you be sure that what you’re experiencing is an allergic reaction? One way to spot an allergy is to look for patterns in the appearance of your symptoms.
For instance, if you find that every time you go outside in the summer you begin to sneeze, this could be a seasonal hay fever allergy. Meanwhile, if you begin to feel itchy every time you play with your friend’s dog, you are likely to have an allergy to its dead skin, saliva or urine – not its fur.
Our understanding of the science behind allergies has improved through research, but our complex immune systems are unique to every one of us. Even as early as the first century BCE, Roman philosopher Lucretius is quoted as saying: “What is food to one man is bitter poison to others.”
Luckily for today’s allergy sufferers, there are ways to spot, diagnose and manage these anomalies in our bodies’ defences and ensure that our immune systems, designed to save our lives, are less likely to do the opposite.
This article is for informational purposes only and is not meant to offer medical or dietary advice.
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