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To the unsuspecting, a handful of a beautiful three leafed vine will give an unwelcome surprise; an exclusive ticket to enter Scratch City. But quite unbelievable is the fact that Poison Ivy and Cashews share an itchy chemical.
So many of us have experienced the pain and itch of Poison Ivy that even non-gardeners tend to keep a watchful eye for Poison Ivy, Poison Oak and other itchy or poisonous plants. For the most part, no one would ever consider eating any of these plants.
But most of us have enjoyed a cashew or two or two hundred and twenty two. Cashews are a favorite for many people, including my mother. Most Americans are accustomed to the roasted, toasted and salted cashews sold in the grocery stores. Health food stores sell cashews marketed as "raw". These are a light, off-white color and taste almost sweet. The majority of these "raw" cashews are not truly "raw". These cashews are processed to remove the chemical resin urushiol, which is also the chemical that is found in poison ivy and mangos. The cashew is also related to poison sumac and to pistachios.
According to Wikipedia, 32 countries of the world produce a total of 3.1 million tons of cashews a year. Also interesting is that Cashews have been used against tooth abscesses and other bacteria.1
The Cashew tree can spread as wide as a basketball court. Its botanical name is Anarcardium occidentale, and it is a subtropical (or tropical) evergreen tree that produces a false fruit. This fruit looks like a slim red or yellow basic "green pepper" like we find in the American grocery stores. This edible false fruit is called the Cashew Apple. My sister has eaten the fruit after it has been cut in strips and grilled or sautéed. She says that it tastes simply okay, like Prickly Pear Cactus leaves. Some people rave about the fruit and a juice made from it but others practically spit as they recall the taste as being "unbelievably horrible". Dave's Garden critterologist said that the fruit juice concentrate was "...absolutely foul...it tasted about the way that ginkgo fruit smells".
Special thanks to artcons from Dave'sGarden for the use of the picture on the left; a Cashew Tree/maturing false fruit and the cashews (shells). See the footnotes for a link to interesting plant files information.
The item on the right is a rendering of a mature false fruit and cashew shell.
Hanging like a worm emerging from the bottom end of an apple or like a Lima Bean hot glued to the apple, is a shell; the true fruit of the Cashew Tree. This is shaped like a very large lima or kidney bean. Inside this interesting double shell is not only the chemical urushiol but also, encased in a thin brown wrapper, is the seed: the prized and expensive cashew nut. The nut is found in the upper part of this shell (the part near the false fruit), while the lower part contains the resin. Once harvested, cashews are typically either steamed or roasted; less frequently, the cashew nuts are extracted without roasting.
The leaves of the Cashew Tree also contain urushiol according to an internet site called wisegeek. This website also notes that processed urushiol is used in other products, including in finishes, coatings and brake linings.2 Who knows; maybe urushiol contains a potent cancer fighter, too!
Although anyone could be allergic to any substance, true raw cashews may cause severe, fatal allergic reactions.Of course, there are many other plants that can cause skin problems. According to Dermnetnz on-line, even Marigolds, Onions, Figs and Kiwifruit can irritate skin.3 Also, the unbelievable stinky Ginkgo biloba tree fruit produces a substance called Ginkgolic acid that irritates skin. For example, Dave's Garden member critterologist D-mailed me this comment on the article: "I had an outbreak of poison ivy rash one spring at U Chicago and was lamenting to my doc at student health how unfair it was when I hadn't even managed to 'really' get outside except to sit next to Botany Pond. A passing intern overheard and asked if I'd been sitting under the old ginkgo tree... when I said yes, she told me that decades of the fruit falling around the pond has actually built up a level of chemical in the soil there, and I'd been sitting around in shorts...
See the foot-notes for a link to a list of many irritating plants.
So, the next time that you enjoy some cashews, you can amaze your friends with your vast wisdom. But beware; I have received a few of the "crazy looks" when I mention this strange paradox between Cashews and Poison Ivy.
The moral of the story is: If you eat a truly raw cashew, it might be the last cashew you ever eat.
Writer, Speaker, Accountant, Gardener, Teacher, Sign Language Interpreter, Friend, Inactive Real Estate Agent. I love plants but don't grow as many as I wish. The garden in my head is better than the one in my yard. However, I plant at least one tree every year and have left every home with a little more green than it had before. I hope you enjoy reading these articles as much as I enjoy writing them.
Posted by Catamarca (from El Paso, TX) on August 10, 2008 at 01:01 PM:
Years ago in Panama I stood downwind from cashews being roasted, and in a day every part of my body that was not covered by clothes (and remember Panama is a tropical place) was covered with a hideous rash. I ended up in the emergency room. Earlier I had learned that mango juice would cause a poison-ivy-like rash on my skin when I cut up mangoes. Only after the cashew episode did I learn they were all in the same family. Eating mangoes did not cause any problem.
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Posted by Aunt_A (from Tulsa, OK) on August 10, 2008 at 11:13 PM:
Catamarca,
Thanks for stopping by. It is very interesting; I wonder why eating mangoes does not seem to cause problems. I'm thinking that once it was a mango that would not come off the pit. (The pit was large and light brown, almost like strips of wood) I started to chew the fruit off the pit but it seemed itchy. I wonder if there is somthing in the pit as well.
Thanks again.
April
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Subject: Cashew allergies
Posted by pattybotanic (from Lansdale, PA) on August 04, 2008 at 09:35 AM:
A few years ago I tried a high protein diet and ate a lot of nuts. I mail ordered several pounds of cashews from an on line supplier and ate lots of them. I had a severe reaction INSIDE and in a rather delicate area opening to the outside. The discomfort (putting it mildly) lasted for months.
It took much internet research for me to track down the cause being as my doctor was no help at all in diagnosing the cause of the problem. I'm highly allergic to poison ivy (My first case as a child caused me to make my First Communion wrapped head to toe in bandages) so once I saw what cashews were related to I knew what was happening to me.
Now that I have read this article I figure the cashews I got such a good price on via the internets probably weren't treated properly - if at all - to remove the offending oil. But even if I was sure they had been treated I don't think I would take the chance and eat them again, EVER.
So even though this was an embarrassing reaction I think I ought to pass it on so readers know that cashews can cause internal problems as well as external.
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Posted by Loligo (from Murphysboro, IL) on August 04, 2008 at 12:15 PM:
Yes, my mom has had the same reaction, and that was from regular old name-brand cashews, so I think you're very wise to avoid them entirely! She's had head-to-toe allergic reactions to poison ivy before, so she's definitely one of those people who is hyper-sensitive to that chemical.
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Posted by Aunt_A (from Tulsa, OK) on August 04, 2008 at 06:38 PM:
pattybotanic and Loligo,
Thanks for stopping by, reading and commenting.
I'm sure many people have had the same problems and never knew. I was allergic to NCR (the carbonless chemical) paper; it about drove me crazy. I handled it every day (almost every minute) at work. Couldn't make my hands heal up until I changed departments.
Thanks again for sharing your experiences; you may have really helped someone by sharing. Who would have thought?
April
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Posted by Catamarca (from El Paso, TX) on August 10, 2008 at 01:20 PM:
Years ago in Panama I stood downwind from roasting cashews (a rather nasty thick smoke) and the next day was covered with a thick rash everywhere that the smoke had touched. Ended up in the emergency room. Cutting up mangoes leaves a rash like that of poison ivy as well - but I've had no problems eating them. It's worth checking out the entire family if you have a severe reaction to one member.
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Posted by Aunt_A (from Tulsa, OK) on August 10, 2008 at 11:08 PM:
Catamarca,
Thanks for reading and writing. I have read of this happening w/ the smoke; very interesting. Glad you are better now and you are so correct!
April
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Subject: Wonderful
Posted by MitchF (from Lindsay, OK) on August 02, 2008 at 09:04 PM:
Love it - just love your style too... Mitch
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Posted by Aunt_A (from Tulsa, OK) on August 03, 2008 at 09:38 PM:
Thanks, Mitch. I love your style, too! Can't wait to see you all! Great to see M &N!
Blessings and Love,
Aunt April
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Subject: Allergic to poison ivy?
Posted by joegee (from Bucyrus, OH) on August 02, 2008 at 01:04 PM:
I discovered, the hard way, that my allergy to poison ivy also means I have a mild allergy to cashews. I dearly love cashews, to the point where I can eat large containers of them. Unfortunately when I do I get a severe rash on my hands and feet due to the residual urushiol content in the cashews.
Today I limit myself to only a handful of these delicious nuts at a time, over a period of weeks.
Gluttony has its price. :)
-Joe
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Posted by marsue (from Cabot, AR) on August 02, 2008 at 01:45 PM:
Thanks for this article. That is very interesting about the cashew/poison ivy relationship. I love cashews and have never had any trouble with eating them. However, I do currently have a bad case of contact dermatitis so it could be that I need to be careful about eating too many cashews in the future since I am allergic to the ingredient that cashews have in common with certain plants. At any rate, the only thing I have in my flower beds that might cause contact dermatitis is a type of mint. The morning of the day that I came down with the rash I had been cutting back a prolific mint that a DGer had given me in the spring. I looked it up on Plant Files in DG and found that mint can cause a skin rash. Then I read your article and went to the DermNet NZ web site. There was a photo there of the type of mint that I have. The mystery is solved as to the culprit that caused my rash but the itching hasn't stopped! I have been to the doctor twice in the past two weeks, have taken a 10-day round of prednisone and I am now using an ointment which he prescribed. This is miserable stuff! All you folks who don't have this type of allergy consider yourselves fortunate and be careful around mint! My DH will have to rid my flower beds of the nasty stuff. Too bad, because I like the way it looks and smells.
Thanks again for the article and the links to the other information.
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Posted by ecrane3 (from Dublin, CA) on August 03, 2008 at 12:48 AM:
I'm allergic to poison ivy but have never had a problem with eating cashews or mangoes which are also in that family and have some urushiol in the skin (although I always peel my mangoes before I eat them).
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Posted by Aunt_A (from Tulsa, OK) on August 03, 2008 at 09:37 PM:
joegee,
I bought a large container of cashews to snap the pic w/ the cashews in the blue bowls. Hubby and I have eaten quite a few of them. They are so delicious; it is a shame that anyone is allergic to them.
marsue,
Wow; what a story and a sadness. Good thing you decided what was causing your problems. I had horrible contact dermatitis on my hands about 10 years ago; the drs tried everything including steroids (yuck!). I've found that wet aspirin rubbed into my hands works better than those steriods every did. Has something to do with the acid in aspirin and with it calming my nerves so I don't itch the skin off. Dr decided maybe I was allergic to the NCR (carbonless chemical carbon) paper that I handled constantly at work. Maybe some gardener in the area would like to come to your house and dig it all up for you so it can have a new home. You are so welcome. Thanks for reading and commenting!
ecrane3,
So true about Mangos. I had no idea once and ended up with quite a rash. Thanks for reading and for your comment.
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Posted by marsue (from Cabot, AR) on August 04, 2008 at 09:14 AM:
Aunt A: Yesterday afternoon, my DH rid my flower beds of every single bit of mint that was in there! He is not allergic to poison ivy and other plants as I am but to be cautious, he put his hand down inside a plastic bag and pulled up the plants and immediately put them inside a trash bag and bagged it up for the garbage man. Although I do love the way the mint looks and smells, I didn't want to take a chance on giving it to anyone else who might not know that they have an allergy to it. So all my mint has gone bye-bye. Of course, I will be on the look-out for any that might spring back up from roots and/or runners that DH might have overlooked. Mint can be very aggressive so it is probably just as well that it has been eliminated from my flower bed. Afterwards, as another precaution, DH washed his hands and arms really good and changed his clothes.
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Posted by Aunt_A (from Tulsa, OK) on August 04, 2008 at 06:33 PM:
marsue,
You are correct. Mint can just take over. It is a good thing he washed up really well for your sake also.
My DH is totally allergic to poison ivy; seems like he can look at it and break out. I wanted to plant some mint but I might wait and see if my DH is allergic to mom's plants before transplanting any. Wow.
Thanks again,
April
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Subject: growing cashews
Posted by katiebear (from mulege, Mexico) on August 02, 2008 at 11:55 AM:
Perfect article for me. I have five small cashew nut trees that I started from seed. They are growing well in their pots during our hot summer. I look forward to doing my own taste testing on my cashew apples. I suspect the flavor does vary from tree to tree (like apple apples).
Thanks,
katiebear
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Posted by Aunt_A (from Tulsa, OK) on August 03, 2008 at 09:29 PM:
katiebear,
Thanks for reading and for your nice comment. Those trees can, in the right conditions, grow pretty big.
Enjoy...
April
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Subject: cashew apple
Posted by jjacques (from LE TAMPON, Reunion (French)) on August 02, 2008 at 03:41 AM:
Funny how it goes for taste...we have a few cashew trees on Reunion and I really enjoy the true fruit, a very refreshing one especially as it comes in full summer (december here), either bright yellow or red, most people disregard it though.
JJ
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Posted by Aunt_A (from Tulsa, OK) on August 02, 2008 at 03:45 AM:
JJ
Thanks for stopping in, reading and commenting.
You are right, it is funny. Cashews have slightly different flavors depending on where they grow. I wonder if the fruit is the same?
Of course, some people love black olives and others hate them. Maybe the difference is each one of us. LOL.
Have a great day!
April
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Posted by jjacques (from LE TAMPON, Reunion (French)) on August 02, 2008 at 01:27 PM:
Well I only tasted fruits from the same location but I guess they are quite variable depending on the variety, soils, watering and so on.
I love olives with bread and cheese!
JJ
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Posted by Aunt_A (from Tulsa, OK) on August 03, 2008 at 09:27 PM:
JJ,
Sounds wonderful. What kind of olives, bread and cheese? How about a nice unusual olive (not the American canned store bought) with real Rye bread (or let's go with that bread with rosemary cooked in it) and Feta cheese. MMMMMMMMMMMMMMMMMMMM good!
April
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Posted by jjacques (from LE TAMPON, Reunion (French)) on August 04, 2008 at 09:57 AM:
April
As I am at the moment in Southen France we can get about twenty different olives on street markets, regular black or green ones, soaked in spices, hot pepper, stone broken, you name it! As for cheese France is supposed to have as many different ones as we have days in a year so choice is rather large but I like the hard ones, not too keen on Camembert. Yes, feta is erfect with olives and cheese. We also get here what is called 'tapenade', olive puree with anchovies, goes well with a glass of cool rosé wine.
Time for a nap after all this food!
JJ
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Posted by Aunt_A (from Tulsa, OK) on August 04, 2008 at 06:30 PM:
Okay,
Did you say you lived in Heaven??? LOL Yum!
April
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Posted by jjacques (from LE TAMPON, Reunion (French)) on August 05, 2008 at 08:11 AM:
