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Old 04-28-2004, 01:58 AM
oldfart oldfart is offline
Join Date: Apr 2004
Posts: 1
Are raw cashews poisonous?

I had a lady offer to sell me "raw cashews". She said that they are "healthier" than roasted ones. I told her they were poisonous. I lived in Central America for 5 years and cashews grew everywhere. The folks that harvested and sold them (roasted) told me that they were so poisonous when raw that they had to be roasted outdoors or the fumes would kill the people doing the roasting. Who's right Cecil?
Old 04-28-2004, 02:36 AM
SSgtBaloo SSgtBaloo is offline
Join Date: May 1999
Location: Sacred Tomato, CA
Posts: 1,657
In case you hadn't noticed, I'm not Cecil, but I had a friend who was stationed in Panama. He was present when an acquaintance of his (a new guy, just arrived from the states) took a handful of raw cashews, popped some in his mouth and bit down.


Then he started gagging and his jaw muscles started clenching and they ran him to the hospital and he had to be airlifted back to the states for more serious medical fun. I had forgotten what the toxins in cashews were, but a quick google led to the following: A Moment of Science.

I checked several other sites and they all seem to agree. Raw cashews (specifically the oils in the shell) contain toxins that are similar to those in poison sumac, poison ivy, or poison oak. I'm certain that even if the nut contains no toxins, the action of shelling them would certainly contaminate them. Properly roasting the nuts destroys the toxins, rendering them safe for consumption.

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Old 04-28-2004, 03:39 AM
Mangetout Mangetout is offline
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Location: England
Posts: 57,091
Yes; raw cashews are poisonous.

Cashews are really odd things; the nut grows at the bottom of a large pear-shaped fruit, which is edible raw (although most commonly processed into jam or juice, apparently) - I have heard anecdotal accounts of people eating the fruit and accidentally brushing the attached nut against their face, causing almost immediate blistering and exquisite pain.
Old 04-28-2004, 04:11 AM
KP KP is offline
Join Date: Sep 1999
Posts: 1,789
Urushiols are potent irritants to 80-90% of Americans (Poison ivy, poison oak, and poison sumac also owe their irritant properties to urushiols). Generally, they produce a contact dermatitis, similar to poison ivy. Smoke containing urushiol droplets (which is produced during the "burn-ff' stage of cashew harvesting) is well known to produce severe, occasionally life-threatening, reactions by irritating the lungs. (The same is sometimes seen when burning poison ivy)

In addition, it is estimated that 50-70% of Americans have developed allergies to urushiols, probably due to repeated contact. Urushiol allergies are quite different from urushiol irritation, and may cause a life-threatening anaphylaxis akin to bee sting or peanut allergies). The allergy may not occur with the first (or first few) contacts, but may arise later and/or worsen with subsequent contacts.

People who are allergic to cashew urushiols may also cross-react to mango skins, pistachio, and Japanese lacquer. However, boiling any of the above renders them nonallergenic for many otherwise susceptible people.

"Pore minimizers" containing 2% salicylic acid are said to be much better than over-the-counter antihistamines (e.g. Benadryl(tm), diphenhydramine) or topical steroids (e.g. hydrocortisone cream) for treatment of urushiol itching and burning on the skin. ORAL (or IV) steroids are even more effective. Surface creams don't work as well because the urushiols can pass through the epidermis to bind deeper layers of skin

CASHEW SHELL OIL should not be confused with CASHEW OIL or CASHEW OIL CAKE (which are excellent natural fuels in many parts of the world) or CASHEW SHELL NUT LIQUID (CNSL) which is used as a precursor for organic syntheses. However, people who react strongly to one cashew product may also react to others.
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Old 04-28-2004, 05:55 AM
cabdude cabdude is offline
Join Date: Feb 2004
Location: Fantasy Isthmus
Posts: 601
I think you need to differentiate between raw cashews and unprocessed cashews.

Unprocessed cashews (as stated above) have nasty blistering agents, etc. Nature's way of saying "don't get too close."

Roasted cashews are processed cashews, salted and roasted in a pan so they go crispy and brown and delicious to snack on.

Raw cashews, presumably the ones the lady offered to sell, are used primarily in cooking and are not poisonous. They are usually sold unsalted and for that reason would probably be healthier for you. You can snack on them, but I don't find them as tasty because they aren't as crunchy as roasted ones. But cooked with chicken strips, soy and oyster sauce and mushrooms and served on a bed of boiled rice they are fantastic.
Old 04-29-2004, 03:33 AM
Doobieous Doobieous is offline
Join Date: May 1999
Location: Marina, CA
Posts: 2,646
Actually, the "apple" of the cashew is a receptacle, a fleshy swelling of the stem (the "fruit" of strawberries is also a receptacle). The nut is actually the fruit plus the real nut. You CAN touch the fruit, but the seed shell does contain high amounts of urushiol. The whole outside roasting is to prevent toxic fumes from collecting which could cause serious reactions with lung tissue. In fact the common way to process these is to let the fruit and the nut fall, and then twist the fruit/seed off, and discard the apple (Usually left for livestock). These must be roasted to remove it.

The apple is sweet and astringent, and has high amounts of tannin. People usually chew the fibrous "fruit" and discard the pulp after the juice has been sucked out. There's a liquor made from it called "feni" and the juice is also served fresh (it spoils quickly).
Old 04-29-2004, 12:31 PM
minor7flat5 minor7flat5 is offline
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Join Date: Sep 2002
Location: Trenton, NJ
Posts: 4,525
More on the cashew nut/apple:

The nut is in a tough shell. I'm not sure exactly how tough, since the Brazilians I was with told me that the stuff between the shell and the nut was akin to battery acid mixed with arsenic (pretty much what has been described already here).

My point being: you can eat the "fruit" (apple) without danger of brushing against the nut since it's protected.

For whoever has never seen one, here's a picture.

They have an absolutely delicious aroma. My wife used to buy them and keep them in a fruit bowl in her house just to fill the place with their natural sweet scent.

As mentioned before, people do eat the "fruit," but, as with lemons, it is better to make juice from the "fruit" than eat it directly. I never knew what an "astringint" fruit was supposed to taste like, so one day I picked up the lushest, most inviting cashew apple and took a big bite. I didn't spit it out, but then again, I didn't finish it.

If you haven't tried the juice, it is delicious. In Jersey, we can often find cashew juice concentrate in the international section of our local huge supermarket -- it comes in clear glass bottles of yellow milky stuff. Buy one and mix up a batch. It is especially tasty on a hot summer afternoon.
Old 04-29-2004, 12:45 PM
DeVena DeVena is offline
Join Date: Jan 2003
Location: Montgomery AL
Posts: 4,383
From the Queensland Department of Primary Industries and Fisheries...

Can I shell cashews at home?
Yes, but this must be done with care as the caustic Cashew Nut Shell Liquid (CNSL) contained within the shell can cause skin irritation and severe burning in some people. It is critical to extract the kernel without contamination with CNSL.

You can deep-fry the nuts to remove the CNSL. Precondition the nuts before frying by putting them between layers of wet hessian bags for seven days. When you fry the nuts do so in a well ventilated area, wear protective clothing and use a respirator to avoid inhalation of dangerous fumes.

An alternative method is to freeze the nuts to solidify the CNSL. You must crack the nuts and remove the kernel before the nuts thaw.


Is the raw nut poisonous?
The shell of the raw nut contains a caustic liquid known as Cashew Nut Shell Liquid (CNSL). People sensitive to it can develop acute dermatitis on areas of the skin that contact it. The kernel itself is not poisonous and can be eaten raw or cooked.
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