At a young age I discovered that I am allergic to Pistachios. As a young adult training to be a Peace Corps Volunteer, I discovered that I am very allergic to Mangoes. What is the connection?
They are both plants in the Plant Family: Anacardiaceae. Interestingly enough so is the Cashew, yet I very rarely exhibit any reaction when eating cashews.
For medical and scientific reasons that are far beyond my comprehension, all possess the toxin known as urushiol.
For those of you that clicked on the link, you will also note that urushiol is also present in Poison Ivy, Poison Oak and Poison Sumac. All three of these plants are also a part of the Plant Family: Anacardiaceae.
In the Garden: Cashews, Mangos, Pistachios and Poison Ivy?!
Rhus glabra in its fall colors (Photo: Ellen Honeycutt)
These four plants actually have something in common. They’re all members of the Cashew Family, the Anacardiaceae. Some members of this family are a lot more people-friendly than others, however.
Among the tropical Anarcardiaceae, the familiar cashew (Anarcardium occidentale) is native to northeastern Brazil and widely cultivated in warmer regions. The cashew nut may readily be eaten by most of us, although 5 percent of the population is allergic.
The cashew shell is more problematic, containing a potent skin irritant related to urushiol, the nasty substance found in poison ivy and poison sumac. Roasting destroys the anacardic acid in cashew shells, but according to Wikipedia this must be done outdoors.
(I presume you might want to stand pretty far upwind from the smoke! And this is not the same thing as roasting raw cashew nuts at home. Here the shells have already been removed.
) Mangos are another tropical member of the cashew family; Mangifer indica is the species most commonly cultivated in warmer regions.
As for species from temperate regions, I had once championed the Chinese Pistache (Pistacia chinensis, a cousin to the edible pistachio) as a good landscape tree. Now I am having my doubts.
A small, drought-tolerant tree with brilliant fall color, it is reportedly becoming invasive further south and west. Plus, I have seen trees that appeared to be less than healthy, perhaps owing to clay soils and too much water.
Probably better to avoid this plant.
I hope everyone who spends any time outside is familiar with the ubiquitous Poison Ivy (Toxicodendron radicans, formerly Rhus radicans). “Leaves of three, quickly flee!” etc.
Much less well-known but actually more deadly is Poison Sumac (T .vernix or Rhus vernix).
A large shrub or small tree, fortunately for us it is generally uncommon in Virginia except in swamps.
Despite some bad players, several members of the Cashew family can work in your garden. The sumacs (Rhus), large shrubs or small trees, can provide outstanding fall color, attractive fruits, and bold form in the right situations.
Several of the sumacs are native to our area, so you might already have one on your property. The Smooth Sumac (Rhus glabra) and the Winged or Shining Sumac (R. copallina) are common across most of Virginia.
Both have large, compound leaves with many elongate leaflets; in the fall, the medium-to dark green foliage will turn crimson red on the former shrub, and to yellow, orange-red or purple on the latter. Greenish-yellow flowers appear in early summer on Smooth Sumac, late summer on Winged.
Fruits that follow in the fall are showy crimson-to-scarlet clusters measuring 4” to 8”. Neither of these sumacs are small in any sense of the word, with heights between 10 and 20 feet and with an equal spread.
In fact, their suckering nature means rapid spread may be their greatest virtue—if you want to cover a lot of ground—or their greatest vice.
Given their running nature, planting these sumacs around any other plant is not advisable. If you have a “wild” area on a large property, plant them where they have “plenty of room to romp,” as some of the plant catalogs phrase it.
On a smaller property, you might be able to contain them with a driveway or some other concrete barrier. Otherwise, plant your sumac in the middle of your lawn and mow around it to remove the suckers. Also, consider the texture of sumacs in any design scheme.
Fairly coarse even when in leaf, in winter the stout bare stems can look gaunt. Or perhaps “architectural” if you want to put a more positive spin on it.
Putting one in front of a wall would highlight the form; just make sure it’s not the wall of your house, or the suckering shoots might pop up in your living room.
Another species among the large sumacs offers an alternative to rampant spreading, at least in one variety. More common in the mountains and up north, Staghorn Sumac (R. typhina
Why Is a Mango Allergy Not Like Any Other Food Allergy?
Tom Grill / Getty Images
Food allergies are common and will affect nearly everyone at some point in their life. These include fruits, some of which have a high propensity for oral allergy syndrome (OAS), a cross-reaction between certain pollens and fruits that the body recognizes as being the same.
The one fruit that stands apart in its ability to cause an allergy is the mango (Mangifera indica). As the national fruit of India, Pakistan, and the Philippines, the mango is grown on a tree that belongs to the cashew family Anacardiaceae. This is the same family of plants which include poison oak, poison sumac, and poison ivy.
This distinction can not only make eating mango problematic for some people, but it can also sometimes be downright dangerous.
Oral allergy syndrome (OAS) is typically an uncomplicated allergy that occurs almost immediately after eating a piece of fresh fruit and usually resolves without treatment within minutes.
OAS occurs as a result of similarities in the proteins found in mangoes and pollens (most often birch pollen or mugwort pollen). Strangely enough, having a latex allergy can also cause OAS symptoms when eating mango, a condition referred to as latex-fruit syndrome.
The diagnosis of OAS is typically made with skin testing to confirm whether there is a cross-reaction between mango and commonly associated allergens.
OAS is usually not considered a serious condition as the saliva in a person’s mouth is usually able to break down the allergen quite quickly.
As such, any response is usually limited to the mouth and/or lips.
However, due to the relatively small risk of a more serious reaction, people with a mango allergy are advised to avoid all raw forms of the fruit. Cooked fruit rarely poses a problem.
Another type of reaction that can occur as a result of eating mango is something called contact dermatitis, This is due specifically to a substance found in plants of the Anacardiaceae family called urushiol.
Urushiol is the substance that causes rashes from poison ivy, poison oak, and poison sumac.
In mango, urushiol is found in high concentrations in the peel and the fruit just beneath the peel. In most people, contact with urushiol will induce an allergic skin response. With mango, the allergy may not be as common as, say, poison oak or poison ivy but, in some cases, it can be just as profound.
This reaction, which resembles a poison oak rash, most often occurs on the face within hours of eating the fruit and can last for several days. The rash will appear as small, itchy blisters that can sometimes ooze.
While this type of mango allergy isn’t especially dangerous or life-threatening, it can be uncomfortable and annoying. Treatment, when needed, will involve a topical or oral corticosteroid, depending on the severity of symptoms.
What Do Cashews, Mangoes and Poison Ivy Have in Common?
Avid listeners of this podcast may recall my past revelations that I have a super power. When I encounter poison ivy or poison oak, even in the tiniest amount, my body’s immune system explodes in a systemic reaction, creating a situation that requires fast treatment. It’s itchy, uncomfortable, and I’ve spent many sleepless weeks on steroids trying to keep the rash at bay.
Well, stop rolling around in poison ivy, you might be thinking. I wish! Unfortunately, for me, it’s usually my dog that frolicks in the plant. Dogs do not react to the plant’s oils, so she carries on none the wiser but brings the oils to me.
In one instance, however, I broke out in a poison ivy-type rash after visiting a friend in downtown Los Angeles and my dog was nowhere in sight. This was a bit much, even for me.
I think I saw one tree the entire time, and it certainly wasn’t hosting a nefarious vine.
So, how was that possible? It was then that I learned—the hard way—that poison ivy is just one member of a family of trees, the anacardiaceae family, that can carry an oily irritant that causes a rash.
You see, my friend had cooked for me a popular meal from her homeland of Trinidad, which was full of delicious, fresh mango. Mango, it turns out, is also a member of the anacardiaceae family.
What is the difference between poison ivy, poison sumac, and poison oak?
The anacardiaceae family of trees, sometimes called the cashew family, includes mango, poison ivy, poison oak, sumac, Peruvian pepper, pistachio, and you guessed it, cashews.
They all contain urushiol, the sneaky oil that causes the skin to erupt in rashes for some people and is the bane of my existence, but to varying degrees.
The oil is found in all parts of the plant, including the leaves, stems, and even the roots.
Urushiol is the reason cashews are never sold in the shell and are typically roasted.
The oil is found on the outer shell (similar to mangos, where it’s found on the skin) and roasting the cashews at high temperatures can kill any remaining oil that makes its way through to the nut.
The Center for Disease Control published a report in 1982 about a batch of >7500 bags of shell-contaminated cashews being sold in Pennsylvania and Maryland, mostly as part of a Little League fundraiser. Around 20 percent of the unlucky cashew-eaters developed a rash.
Also in the family is Toxicodendron vernicifluum, or the Japanese lacquer tree. This tree produces the sap used in painting those beautiful lacquered boxes. There have been cases of rashes developing in reaction to contact with lacquerware because the oil remains in the paint.
»Continue reading “What Do Cashews, Mangos, and Poison Ivy Have in Common?” on QuickAndDirtyTips.com
“Shiny leaves of three, let them be.” Remember that? It's a helpful rhyme to recall when hiking to avoid brushing up against poison ivy. Don't heed this warning, you just may break out in an itchy rash the next day.
Many are aware of the uncomfortable result of tangling with poison oak, ivy and sumac, especially if they've already gotten that rash before. However, many don’t know that mangoes, cashews and ginkgo biloba can cause a similar skin reaction.
Indeed, if you are highly allergic to poison oak, ivy and sumac, you should avoid these three things, as well.
Poison ivy and its cousins poison oak and poison sumac are members of the Anacardiaceae plant family. This family is comprised of fruit trees, woody trees, shrubs and vines that contain the rash-inducing oil called urushiol.
Urushiol is the culprit behind those wicked rashes that ravage allergic individuals. The oil can be found year-round in all parts of the plant, including the roots, stems, flowers and leaves.
Poison oak can grow as a dense shrub in sunlight or a vine in the shade. The three leaflets have scalloped edges resembling the leaves of a true oak and can change color depending on the season. The plant can produce greenish-white or tan berries.
Poison sumac has compound leaves with seven to 13 leaflets, and the veins from which the leaflets grow are always red. The plant grows as a shrub and produces fruit that is a small white or gray berry.
Read more: 6 Natural Remedies for Springtime Allergies
What's Going to Happen to Me?
In those who are allergic to urushiol, contact with the resin causes an itchy rash, often configured in lines or streaks. Other features include blistering and swelling: It is not uncommon to see eyelids swollen shut. The eruption starts 12 to 72 hours after the first touch, and it may not come out all at one time, meaning new patches develop each day.
The rash itself is not contagious to others, and animals cannot get the rash, but they frequently transmit the oil to their owners. Garden tools, athletic equipment, balls retrieved from a neighbor’s yard, etc., can also be stealth sources of exposure. Lastly, don’t think that clothing is always an effective barrier; the resilient resin can leach right through.
How to Treat the Rash
If you think you have been exposed, wash off the oil immediately. When the rash is in full swing apply cool compresses or take colloidal oatmeal baths or prescribed topical or oral steroids from a health care provider for relief.
Read more: 8 Natural and Soothing Sunburn Remedies
The Connection Between Urushiol and Food
It turns out that the mango tree and cashew nut tree are also members of the Anacardiaceae family. Urushiol is found in mango peels in small amounts. Once you’ve had a bad case of poison oak or ivy, however, your immune system becomes sensitized.
The more poison oak or ivy reactions you have, the more sensitized your immune system becomes, so your reactions actually get worse each time your infected. Some immune systems become so sensitive from multiple poison oak or ivy exposures that they become susceptible to getting a rash from mango peels or cashew shells.
The rash from mango peels is similar to poison oak in that it is itchy and blistery. It can be localized, such as around the mouth if eating the fruit off the peel, or systematized, meaning all over the skin. Generally, if the peel is off, chances of a problem are slim to none because the pulp does not contain urushiol.
In cashew shells, the rash-inducing oils have usually been removed from store-bought unsalted, salted, roasted or raw cashews. But there are certainly reported cases of unintentional contamination that have resulted in systemic, all-over reactions as described above with mangoes.
If you are highly allergic to poison oak or ivy, it is best to avoid cashews unless you are absolutely certain that the shell oil has been fully extracted.
The Cross Reactors
Although ginkgo biloba comes from a different plant family than poison oak and poison ivy, the nuts harvested from the female tree contain urushiol. These nuts are harvested and made into supplements because they improve neurological health and aid in the prevention of Alzheimer’s.
If your immune system is sensitized by repeated poison oak or poison ivy reactions, you may be more susceptible to an allergic reaction to ginkgo biloba.
Read more: Allergic Reactions to Ginkgo Biloba
What Do YOU Think?
Are you severely allergic to poison oak, ivy or sumac? If so, have you also had bad reactions with mangoes, cashews or ginkgo biloba? Tell us about your experiences in the comments below 2!
The Wrap Up
SCIENCE EXPLAINS THE CASHEW AND MANGO DILEMMA
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.
Cashew (Anacardium occidentalis)
The Anacardiaceae, commonly known as the cashew family or sumac family, are a family of flowering plants, including about 83 genera with about 860 known species. Members of the Anacardiaceae bear fruits that are drupes and in some cases produce urushiol, an irritant. The Anacardiaceae include numerous genera, several of which are economically important, notably cashew (in the type genus Anacardium), mango, poison ivy, sumac, smoke tree, marula, yellow mombin, Peruvian pepper and cuachalalate. The genus Pistacia (which includes the pistachio and mastic tree) is now included, but was previously placed in its own family, the Pistaciaceae.
Lannea grandis in Banten, Indonesia
Trees or shrubs, each has inconspicuous flowers and resinous or milky sap that may be highly poisonous, as in black poisonwood and sometimes foul-smelling.
Resin canals located in the inner fibrous bark of the fibrovascular system found in the plant's stems, roots, and leaves are characteristic of all members of this family; resin canals located in the pith are characteristic of many of the cashew family species and several species have them located in the primary cortex or the regular bark. Tannin sacs are also widespread among the family.
The wood of the Anacardiaceae has the frequent occurrence of simple small holes in the vessels, occasionally in some species side by side with scalariform holes (in Campnosperma, Micronychia, and Heeria argentea (Anaphrenium argenteum). The simple pits are located along the vessel wall and in contact with the parenchyma.
Leaves are deciduous or evergreen, usually alternate (rarely opposite), estipulate (without stipule) and imparipinnate (rarely paripinnate or bipinnate), usually with opposite leaflats (rarely alternate), while others are trifoliolate or simple or unifoliolate (very rarely simple leaves are palmate). Leaf architecture is very diverse. Primary venation is pinnate (rarely palmate). Secondary venation is eucamptodromous, brochidodromous, craspedodromous or cladodromous (rarely reticulodromous) Cladodromous venation, if present is considered diagnostic for Anacardiaceae.
Flowers grow at the end of a branch or stem or at an angle from where the leaf joins the stem and have bracts.
Often with this family, bisexual and male flowers occur on some plants, and bisexual and female flowers are on others, or flowers have both stamens and pistils (perfect).
A calyx with three to seven cleft sepals and the same number of petals, occasionally no petals, overlap each other in the bud. Stamens are twice as many or equal to the number of petals, inserted at the base of the fleshy ring or cup-shaped disk, and inserted below the pistil(s).
Stamen stalks are separate, and anthers are able to move.
Flowers have the ovary free, but the petals and stamen are borne on the calyx.
In the stamenate flowers, ovaries are single-celled. In the pistillate flowers, ovaries are single or sometimes quadri- or quinticelled.
One to three styles and one ovule occur in each cavity.
Fruits rarely open at maturity
and are most often drupes.