Urushiol and Mangoes

Now there is a difficult name, urushiol. Never heard of it. Not surprising but we are sure that you will have heard of where it’s found the most and how it causes the most contact allergies: in poison ivy and poison oak.

Urushiol is a very potent allergen and is the most common allergy type in the USA. Even the smallest concentration will cause a reaction, which includes a severe inflamed rash with itching and oozing. Reactions also include swelling, and blisters.

The good news is that as it is an allergy, the rash and the blisters themselves are not contagious: you cannot get the rash by touching a person’s rash unless you’ve touched urushiol that’s still on that person or his or her clothing. BUT, urushiol, which is an oily resin, sticks to everything it gets into contact with. Until clothing, or anything else it got in contact with, has been washed, it is possible to get a reaction to urushiol without being aware that the material was contaminated. Another “good” thing about urushiol is that as it causes an allergic reaction, the person being in contact with it, must have been sensitised against it which according to research is the case in 50 to 70 % of the US American population.

But what you might ask yourself, does this have to do with mango? And why we write about an allergy which we rarely find in Switzerland, since poison ivy and poison oak are only found the North America and Asia.

It is because this contact dermatitis and the reaction to urushiol can also be caused by other plants, such as mango, pistachio, sumac and cashews. The urushiol oil is found in the skin of mango and the shells of pistachios and cashews. Sumac, which is probably the least familiar one, is a plant and its fruit are used in Middle Eastern cuisine and are one ingredient in the spice mixture za’atar. They all belong to the same plant family, the Anacardiaceae family.

With the reaction to urushiol being such a massive and unpleasant one, the rash typically goes away only after two to three weeks, treatment is divided into two phases: an immediate management started within minutes to stop the skin reaction and a later phase managing pain and itching of the formed blisters.

According to the Mayo Clinic, the first phase requires rigorous washing with water and soap and rubbing the very sticky oil off the skin. If you have a skin reaction one or two days after consuming mango, and a feeling of itchiness, swelling or a rash after touching mango, pistachios or cashews, you might want to consider a reaction to urushiol. Should you experience such a reaction again next time, wash your mouth and face immediately as much as you can.

Looking for some good news in all this dilemma: next time, have someone else touch and peel the mango: mango pulp does not contain urushiol and you should be fine to eat the fruit (but do be careful because peeling mango and avoiding oil from the mango skin infusing into the mango pulp might be tricky). And if you are a cashew lover, most cashews that we buy are shelled and cooked before being packaged and therefore contain no urushiol. As for pistachios, they usually come in their shell which makes avoiding contact nearly impossible. As it is not sure whether roasting can guarantee the destruction of the urushiol oil, you simply have to try whether you can still enjoy them.

Posted on March 09, 2016 by Luitgard Holzleg

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