Tag Archives: anacardic acid

You’ve Got to be Nuts to Eat a Cashew Nut Shell

Last November we joined our next door neighbors on a lovely trip to Brazil.  We saw lots of interesting places, met lots of interesting people, ate lots of interesting foods.  One food in particular fascinated me, the cashew.  For most Americans the cashew is just a nut (like a walnut or almond) and we don’t think too much about where they come from or what they look like.  My grandparents used to always have a bowl of shelled nuts and a nutcracker that you had to use to break the shells, so I had a pretty good idea of what a walnut and almond looked like in their natural habitat.  Not so with cashews.  In Brazil cashews are primarily a fruit (usually consumed as a juice) and only sold as an afterthought to tourists on the beach as the roasted nut that we know in the States.

The fruits themselves are very unusual, so it was great to see them in the local market and understand how they grow.  First the nut part appears on the tree (see the cashew nut shaped object on each fruit below), then the fruit grows after it.  Very different than your regular apple, pear, or peach.

Fresh Cashews at the Market
Fresh Cashews at the Market

Our host family usually had cashew juice for breakfast every day which I enjoyed.  The flavor is a little difficult to describe, but think of combining a lime and orange and a mango together and you are getting close.  They even brought a cashew home from the market so I could try the fruit directly.  We brought it back to our apartment and it sat in the refrigerator for several days.

On the day before we were to leave Brazil, I decided to try and eat the fruit.  It tasted pretty much like the juice, with a slightly mushy pulp.  The juice of the cashew squeezes out of the pulp so you are just left with a flavorless glob of pulp that you spit out.  Not too bad.  Now I had this nice little cashew nut shaped shell in my hand, I wondered if there might be a nut inside.  There is only one way to find out.  First I tried using a knife from the kitchen, but as I worked at the leathery slippery skin I was worried that the knife would slip and I might cut myself.  So why not just bite it open?  Okay.

I stuck the nut in the corner of my mouth to get a good grip on it and bit down.  Hmmmm, that tastes very odd.  Wow that tastes really bad!  A bitter taste spreads through the side of my mouth.  My teeth and inside of my cheek become sticky.  The corner of my lips start burning.  I ran to get some water to try and stop the burning and it didn’t work.  Next stop, the Internet!

Thanks to Wikipedia I found out:

The seed is surrounded by a double shell containing an allergenic phenolic resin, anacardic acid, a potent skin irritant chemically related to the more well known allergenic oil urushiol which is also a toxin found in the related poison ivy. Some people are allergic to cashew nuts, but cashews are a less frequent allergen than nuts or peanuts.

GREAT!  So basically I’ve just been chewing on the equivalent of poison ivy or poison oak.   Time to break out the big guns and start treating this like a poison ivy infection.  First I brushed my teeth with toothpaste.  Sort of helped.  Next I literally washed my mouth out with soap.  Bar soap didn’t work so well, dishwashing soap was better.  More water and more spitting later seemed to resolve most of the pain.

Then back to the Internet to find out what you are supposed to do if this happens.  Interestingly, they don’t say very much about this.  Do I go to the hospital?  Am I going to have a major allergic reaction on our flight back from Brazil?  We called up our host family and they just laughed and said you aren’t supposed to do that, and started to tell all their friends about what the silly American did with the cashew fruit.

That night the corner of my mouth just stung, but it was bearable, the flight back to the U.S. was okay, but things went downhill from there.  First my belly started itching, then my butt, then my arms, legs and under my neck.  I never really broke out in the usual poison ivy type sores, but everything was itchy.  Seven days after the incident I woke up and couldn’t see out of my right eye.  Nothing itchy, but just all completely puffed up.  This went on for a few more days before things started getting back to normal and most of the itchiness was gone in about a month.

Day 7 After Biting Cashew Nut Shell
Day 7 After Biting Cashew Nut Shell

So it turns out the one reason you never see raw cashew nuts (in or out of the shell) anywhere is that the nuts are surrounded by a nice little poison.  The pickers of cashew fruit are often affected by this oil, but that’s usually about it.  All cashew nuts that are sold are actually roasted to deactivate the toxin in the shells which is why you never see true “raw” cashew nuts for sale.

So next time you are eating unusual fruits that you know the fruit is edible and the nut is edible, stop for a second and check the Internet to see if some other part of the fruit might be poisonous.  You have been warned.