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What is allergy?

Wat is allergie

Everyone is, one way or another, familiar with the condition ‘allergy’. But not everyone knows the answer to questions such as: what happens in the body when allergy occurs? How often does allergy occur? What is causing allergy? And what is the impact of an allergic disease on daily life?

In the medical dictionary allergy is defined as:

“A specific response of the body’s immune system to normally harmless substances”

The ‘foreign substances’ some people react to are called allergens. Examples of allergens are tree pollen, grass pollen, house dust mites, animal dander, insect venom and food. People who are sensitive to these allergens react with allergic symptoms such as hives, eczema, stuffiness, a runny nose, sneezing, and/or watery eyes after being in contact with this/these particular allergen(s). The particular allergens can enter the body through the nose, mouth and/or contact with the skin.

The allergic reaction

The allergic reaction is an adverse reaction involving the immune system, caused by inhaling, swallowing, or touching an allergen to which a person is sensitized. The most common type of allergy is the type I reaction in which IgE antibodies are involved.

The first time the body gets in contact with an allergen, IgE antibodies are produced but at this stage there are no physical symptoms of an allergy yet. This process is called sensitization. An allergy can’t develop itself without the process of sensitization. The second time the same allergen gets in contact with the body, the IgE antibodies directly become active. IgE antibodies bind to mast cells which will then release histamine, causing the typical allergic symptoms in the skin, respiratory tract, the gastrointestinal tract and/or eyes. This process is shown In the figure below:


How often does allergy occur?

The last 30 years, the number of people suffering from allergic diseases increased enormously, therefore allergy is becoming a serious health problem worldwide. In The Netherlands 1 out of 4 people suffer from a (chronic) allergy. A grass pollen allergy (hay fever) is most common, followed by a house dust mite allergy and a tree pollen allergy in third place.

What is causing allergy?

There is still a lot unknown about the causes of allergy. However we do know that hygiene plays an important role. Our lifestyle has become more and more hygienic over the years and it seems that the chances of developing an allergy thereby increased. The immune system is less triggered than before and is therefore more vulnerable to (harmless) invaders such as bacteria, viruses but also allergens.

It is also known that eating fresh and unprocessed food reduces the chance of developing an allergy as opposed to eating a lot of processed foods.

Finally, heredity plays an important role in the development of an allergy. An allergy itself is not hereditary but the predisposition to develop an allergy is. This is called atopy. The table below shows an overview of the risk of developing an allergy within a family:


The impact of an allergy on daily life

The influence and impact of allergy on daily life is regularly underestimated. “A runny nose is not that bad, is it? Watery eyes … is that all? ”

People who are allergic indeed experience serious limitations in daily life. Research has shown that the quality of life is affected by an allergy. In addition to physical symptoms, an allergy has a negative effect on sleep and concentration. Therefore an allergic disease has serious impact on daily functioning in school, at work, at home and in social life.

The effects of allergies are not only noticeable to the person who is suffering from an allergic disease. Socially, an allergic disease has also noticeable consequences. These include medical, economic and social consequences as a result of regular doctor visits, the (chronic) use of medication, a decreased productivity and absenteeism.