General Paediatrics, Asthma and Allergy

Dr John Chapman   FRCPCH
  Consultant Paediatrician (NHS & Private)

Making sick children better.

Pollen Fruit Syndrome

Pollen fruit syndrome is also known as Oral Allergy Syndrome. Both names explain something about the disease; the former explains the cause and the latter the symptoms.


PFS/OAS used to be a disease of people in their twenties, then we started to find it in teenagers and now we are seeing signs of it in younger children. I recently diagnosed it in a child of 7 years old.


It all starts with pollen allergy most often to Birch tree (part of the Early tree pollen group) but also to grass pollen. There are in fact many varieties of PFS triggered by different pollens (see image below) and is is perfectly possible that you can have more than one type.

Male birch tree (the nice silver ones with catkins - very cheap, fast growing and all over modern developments) shed huge amounts of pollen. The pollen blows around looking for a female tree. The pollen has defence proteins on its surface to protect it from fungi etc and it is these proteins that we become allergic to. Birch pollen has a plant defence protein called PR10 on its surface. This is the bit of the pollen that your body recognises as foreign and mounts a response (allergy) to it.


But PR10 is quite a useful gadget. So other plants use the same protein on the surface of their fruits to keep away moulds and fungi. So, if your body is all wound up fighting the PR10s in birch pollen, it will also react to the PR10s in the skins of the fresh fruit

Now PR10s are actually quite delicate things. They are destroyed by cooking and by digestive enzymes so the body no longer recognises them as PR10s and doesn't react to them.


The term Oral Allergy Syndrome comes from the fact that, as the protein is broken down quickly, it doesn't, get very far into your body before it is destroyed so it usually only gives symptoms in your mouth (tingling) or at worst in you stomach (nausea).


Some people, one of my own children included, react to many different fresh fruits and vegetables. However these fruits can usually be eaten if they are cooked or juiced. Sometimes peeling the fruit can remove enough of the allergen to prevent the reaction.


If you eat the fruit outside of the pollen season then the reaction is likely to be reduced or not happen at all. This variability of reaction to different forms of the same fruit at different times of the year can lead to confusion about the diagnosis. Many parents just think that their teenagers are being stroppy or fussy about eating healthy fruit!

How can you diagnose PFS/OAS?


Firstly you need to find knowledgable doctor who can take an allergy focussed history. Then you need to have appropriate testing.


Skin prick testing against pollens and prick-prick testing with fresh fruit is a good way of diagnosing what type of PFS you have.


If you want a more detailed answer then you could have component testing. This is blood testing which looks for the antibodies that your body produces again the specific proteins involved in PFS such as PR10s or Profilins. This will give you a specific and personified map of your allergies and can give some indication of their severity.


How can you treat PFS/OAS?


Treatment would be the same as for hay fever. Antihistamines, nasal steroids and/or sodium cromoglycate or a course of grass pollen desensitisation.