This is a simplified description of chitinase 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 chitinase proteins?
Many plant and animal tissues contain chitinase proteins. Lots of insects, fungus and bacteria contain chitin cells, so a plant will produce chitinase to use in defence against damage and infection.
They are often grouped together in classes, called Chitinase I, Chitinase II up to Chitinase VI. Different classes of chitinase are different in their structure, but the same in their general function. They are thought to have evolved separately in different plants, bacteria, insects and animals which accounts for their different structures.
Chitinase proteins are considered to be panallergens, are less commonly associated with allergy than Lipid Transfer Protein
and seed storage proteins
, but have become more studied in recent years due to the possibility of cross reactivity.
These proteins vary from species to species in how the allergenicity is changed due to heat, but most studies show many are heat resistant and will still elicit an allergic reaction after cooking or processing.
Which foods contain chitinase proteins?
The World Health Organization (WHO) recognises 14 chitinase allergens, 8 of these are categorised as food allergens where chitinase have been identified as causing allergic reactions after consumption of food.
Fruits and vegetables containing these proteins are kiwi
, corn (maize)
There are additional studies showing that chitinase has been identified in tamarind
, cashew nuts
Which animals have chitinase proteins?
There are 3 animals associated with chitinase proteins including certain species of cockroaches and dust mites
What is the link between chitinase proteins and latex?
The plant involved in latex allergy Hevea brasiliensis
, the rubber tree plant, has an allergen called Hev b 11 which is a chitinase protein. Those very sensitised to latex may have a contact allergic reaction from foods, plants or insects containing similarly shaped proteins. This gives this protein an important role in Latex Food Syndrome
What is the link between chitinase proteins and pollen food allergy syndrome?
In Pollen Food Allergy Syndrome
the most common sensitising pollen is Bet v 1
, which is an allergen from birch tree pollen. It is also sometimes referred to as a PR-10 protein (where PR means pathogenesis related).
In Latex Food Syndrome
the sensitising allergen is the chitinase protein from the rubber tree plant.
The symptoms associated with this syndrome are often referred to as OAS (Oral Allergy Syndrome) as it mostly affects people who already suffer from pollen allergies and seasonal rhinitis, but also includes a lot of oral symptoms like an itchy mouth, lips, tongue and throat.
What symptoms do they cause?
Allergy to foods containing chitinase proteins have a wide range of symptoms and severity including urticaria (hives or welts), angioedema (swelling under the skin), nausea, abdominal pain, vomiting or breathlessness and anaphylactic shock.
What is the importance of knowing whether a reaction is to chitinase 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
Let me know if you found any of these interesting or useful.
If you spot an article or research that you think is interesting you can message me or tag me on Facebook or Twitter - links at the bottom of the page.