SCIENCE EXPLAINS THE CASHEW AND MANGO DILEMMA
Posted by Zel Allen's nutgourmet on January 22, 2012
Within a few hours after I posted my family’s experience with allergic rashes from consuming mangoes and cashews, I received the comment below. It’s so well explained in scientific terms I thought it important to share in a post rather than a comment.
The information comes from Sandra J. Baker, author of The Poison Oak & Poison Ivy Survival Guide.
Thank you so much Sandra. Your information explains the science behind my husband’s and two sons’ itchy rashes after eating mangoes and cashews. Hopefully, this post and the previous one will benefit others who suffer the misery of itchy skin rashes and haven’t discovered the cause.
I can add to your quest for information. Mango, cashew and poison oak, ivy and sumac are all in the family Anacardiaceae. Then poison oak, ivy and sumac join the genus Toxicodendron which contains the allergenic oil urushiol in its resin. But, mango and cashew also have allergenic oils. Mango has resorcinol, and cashew has anacardiol and cardol. All of these allergenic oils have enough similarity that if you are allergic to one, you are probably allergic to the others.
Mangos’ allergenic oil is mostly in the resin canals in the skin (always peel first before eating), and is thought to be somewhat weaker than poison oak/ivys’ oil. Some people are extremely allergic to it, but a mango grower said his workers usually don’t get much of a rash at the beginning of working with the plants. After a while, the sensitivity usually goes away. The oil can migrate from the skin into the flesh, so it is a good idea to stay away from all mango products, even juice if you know you are allergic.
All cashews imported into the US (even those labeled raw) are shelled and cooked a bit beforehand, because that will destroy the allergenic potential of the cashew nut shell oil that is between the honeycombed layers of the shell. (the oil of the cashew itself is harmless). (Poison oak/ivy and sumac oil is highly resistant to heat by the way.
Very seldom, cashews are accidentally imported without being cooked, and may have been contaminated from the shell cracking procedure, Rashes have been documented. This is a much smaller problem than that of mango rashes.