Raw cashews, or kaju as known in India, naturally contain a toxin known as urushiol. Fortunately, this concern is mitigated as manufacturers commonly roast cashews once or twice to render them safe for consumption. These delightful tree nuts are favored globally and are especially popular in cuisines across Australia, Japan, and Canada. Rich in nutritional value, cashews may provide a plethora of health benefits, including enhancing blood sugar regulation in individuals with type 2 diabetes and aiding in the reduction of total and LDL (bad) cholesterol levels.

Many people relish cashews either in their natural state, incorporated into creamy cashew nut butter, or blended into a velvety dairy-free cream that enhances soups, sauces, and even desserts like ice cream. However, it is crucial to highlight that certain forms of cashews can pose health risks due to the presence of urushiol, a potent toxin. This article delves into the factors that render certain cashew varieties unsafe and offers guidance on how to enjoy these nutritious tree nuts without the worry of toxicity.

Harvesting and Processing of Cashews

Cashews originate from the cashew tree (Anacardium occidentale), categorizing them as a unique variety of tree nut. These trees produce distinctive red or yellow pear-shaped fruits known as cashew apples, within which the cashew nuts are nestled inside gray shells at the fruit's end. Harvesting begins when the cashew apples start to drop from the tree, a clear indication of ripeness. Although these apples are edible and nutritious, they have a short shelf life, necessitating prompt collection.

The nuts, encased in their shells, are extracted from the fallen fruits. Depending on the manufacturer's practices, they may undergo sun drying. It's important to note that these freshly harvested cashews are classified as raw and are not commercially available because of potential urushiol exposure, a toxic oil. To eliminate any urushiol traces, the raw cashews are subjected to high-temperature roasting, achieved either through steaming in a large rotating drum or using vats of boiling oil. This crucial step occurs before the nuts are shelled, thoroughly dried, and peeled. At this juncture, these cashews may still be labeled as raw since they contain no added flavorings, preserving their natural state.

If intended for retail as roasted cashews, they may undergo a second roasting process to enhance flavor. This additional roasting also serves to further ensure that any lingering urushiol residue is eradicated before the nuts are packaged for sale. Once processed, commercial cashews undergo quality assessments, followed by packaging and distribution. It’s noteworthy that truly raw cashews remain within their shells and are inedible. Even those marketed as raw have been roasted at least once post-harvest and shelling to eliminate any hazardous oil residue.

What Toxins Are Present in Cashews?

Cashews (Kaju) naturally harbor a toxin known as urushiol, which is a significant concern for those who consume them. This compound is found in all members of the Anacardiaceae family, which includes not only cashews but also mangoes, poison ivy, poison oak, sumac, Peruvian peppers, and pistachios. Urushiol can be found throughout the plant, notably in the roots, stems, leaves, and particularly in the oil that exists between the cashew shell and the nut. When individuals come into contact with urushiol, it often leads to allergic contact dermatitis, a delayed skin rash that resembles the reaction one might have after being exposed to poison ivy.

The rash caused by urushiol typically manifests as itchy bumps or inflamed patches on the skin, which may ooze and could cause intense discomfort, including a burning sensation or localized swelling. A notable incident reported in 1982 by the Centers for Disease Control and Prevention revealed that 7,500 bags of cashews containing urushiol residue were sold in a fundraiser along the East Coast, leading to approximately 20% of the buyers developing a rash.

In an earlier study involving animals, cashew nutshell extract was administered to rats in different amounts, resulting in a variety of symptoms such as licking, scratching, tremors, heightened sensitivity to pain, mucus discharge, lethargy, and even fatal outcomes. The severity and type of reaction can vary based on the amount of urushiol one is exposed to, as well as whether it was ingested or if there was direct skin contact. It's crucial to note that raw cashews still in their shell contain urushiol, which can provoke a delayed allergic skin reaction akin to that of poison ivy. The intensity of these symptoms may fluctuate depending on the amount of exposure, the nature of contact, and individual bodily responses to allergens.

Are Store-Bought Cashews Safe to Eat?

When shelled cashews are roasted or steamed at high temperatures, any traces of urushiol that may have penetrated their shells are eliminated, rendering them safe for consumption. This crucial step is why cashews are rarely found in stores with their shells intact, and it also explains their common availability in roasted or heat-treated forms.

Even those cashews marketed as raw have undergone shelling and a heat treatment process—either roasting or steaming—to eradicate urushiol residue. The term 'raw' in this context signifies that no additional ingredients, such as salt or flavor enhancers, have been incorporated. Therefore, you can rest assured that the cashews you find in stores are safe for your diet, as they have been commercially processed to eliminate the naturally occurring urushiol. This careful preparation is consistent across all varieties, including those labeled as raw, ensuring that consumers can enjoy these delicious nuts without concern.

In summary, store-bought cashews are meticulously handled and processed to remove any potential urushiol residue before they are sold to the public, making them a safe and nutritious choice for snacking.

The Bottom Line

Cashews, known as Kaju in India, naturally contain a toxin called urushiol when they are in their raw, unprocessed state. This harmful compound is present around the cashew shell and may leach onto the nut's surface itself. If you were to handle or consume raw cashews, you might experience a reaction akin to that of poison ivy, resulting in an itchy, inflamed skin rash accompanied by a burning sensation. Fortunately, even cashews that are labeled as raw in stores have undergone shelling and heat treatment processes to eliminate any traces of urushiol residue, ensuring that consumers do not face such adverse reactions.