This is a simplified description of Bet v 1 proteins – there are more resources available at the bottom of the page for further reading for those who are interested in knowing more.
What are Bet v 1 proteins?
The scientific name for birch tree is Betula verrucosa
. Bet v 1 is the name of the most common allergen found in birch tree pollen
(Learn more about how allergy proteins are named
). It is important and well studied as it is the sensitising allergen which can go on to cause allergies to multiple pollens and foods.
Proteins of a similar shape are referred to as "Bet v 1-like proteins" and are also known as PR-10 proteins (pathogenesis related) as they are used by plants as a defence against disease and predators.
These proteins are considered to be secondary allergens as they only cause allergic reactions as a result of cross reactivity between similarly shaped proteins.
These proteins vary from species to species in how the allergenicity is changed due to heat. Most studies show Bet v 1 proteins are generally not heat resistant and will be broken down after cooking, processing or removal of fruit skin/rind.
Which foods contain Bet v 1 proteins?
The World Health Organization (WHO) recognises 25 Bet v 1 allergens, 16 of these are categorised as food allergens where Bet v 1 proteins have been identified as causing allergic reactions after consumption of food.
In the top 14 foods, soyabeans
all contain Bet v 1 proteins.
Fruits and vegetables containing these proteins are mung beans
This list is not exhaustive, please visit the Food Allergy Index
to see a list of foods, each page will show whether studies have linked them to Bet v 1 allergies.
Which pollens contain Bet v 1 proteins?
There are 9 pollen allergens associated with Bet v 1 proteins including holly, oak, hornbeam, beech
and of course, birch trees
What symptoms do they cause?
Allergic reactions as a result of exposure to Bet v 1 are generally less severe than a classic IgE allergic reaction. There is a wide range of symptoms, often described as Oral Allergy Syndrome
, these include itchy mouth and tongue and sore throat. More severe reaction to Bet v 1 proteins may include urticaria (hives or welts), angioedema (swelling under the skin), nausea, abdominal pain, vomiting or breathlessness and in rare cases, anaphylactic shock.
Pollen Food Allergy Syndrome
If you are allergic to multiple plant pollens and have OAS type symptoms to at least 3 foods containing Bet v 1 proteins you may be suffering from Pollen Food Allergy Syndrome
What is the importance of knowing whether a reaction is to Bet v 1 or other allergens?
Multiple allergies are becoming more common and this often leads people to impose a strict restrictive diet on themselves. This can lead to a poor diet lacking in essential nutrients and frustration over a lack of eating options. Knowing which foods are the most likely to be causing your reactions can bring more options back into your diet.
This is why food diaries continue to be an important tool in diagnosis of your allergies – noting the times reactions took place and what medications were taken are a necessary starting point for a proper diagnosis.
There is more information on food diaries HERE
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