The classification of the cashew often sparks confusion, existing at the intersection of botanical science and culinary practice. Many items labeled as “nuts” are not true nuts in the strict scientific sense, and the cashew is a prime example. This article clarifies the discrepancy between the plant’s true identity and its commercial categorization, explaining why this seed is universally treated like a nut. This practical grouping is driven by flavor, processing, and public health concerns.
Defining the Cashew Botanically
Botanically, the cashew is not a true nut; it is the edible seed of a fruit. A true nut is defined as a dry fruit with a hard shell that contains a single seed and does not naturally open to release it. Examples of true nuts include chestnuts and hazelnuts. The cashew develops from the tropical evergreen tree known scientifically as Anacardium occidentale.
The edible portion is the seed contained within a specific type of fruit called a drupe. A drupe is a fleshy fruit that encases a hard shell, or pit, which contains the seed. Familiar drupes include peaches, olives, and mangoes. Unlike these fruits, where the fleshy exterior is eaten, the internal seed of the cashew is consumed, creating the classification difference.
How the Cashew Grows
The growth structure of the cashew is unique and contributes to its misclassification. The Anacardium occidentale tree produces an accessory fruit, known as the cashew apple. This fleshy, pear-shaped structure is a brightly colored, edible part of the plant that develops from the flower’s stem.
Hanging below the cashew apple is the actual fruit, a small, kidney-shaped drupe that houses the single cashew seed. The shell of this true fruit is inedible because it contains cashew nutshell liquid, a caustic resin containing urushiol.
Urushiol is the same toxic oil found in poison ivy and poison oak. This necessitates a complex roasting or steaming process before the seed can be safely shelled and consumed. This hazardous processing ensures that commercially sold cashews are always shelled and cooked, which visually and practically links them to other tree nuts.
Why Cashews Are Grouped With Tree Nuts
Cashews are commercially and culinarily grouped with tree nuts due to their similar physical and nutritional properties. Like walnuts and almonds, cashews have high fat and protein content, a rich flavor, and a satisfying crunch. These shared attributes mean they are used interchangeably in recipes, snacks, and manufactured food products.
The resemblance to true nuts has led to a practical, non-botanical definition in the food industry. Cashews are consistently labeled as a “tree nut” for consumer information and regulatory compliance. Federal regulations, such as those in the United States, mandate that cashews be identified as a major food allergen alongside true tree nuts.
This required labeling alerts consumers to the presence of cashews in processed foods, regardless of their botanical origin. The grouping simplifies storage, handling, and merchandising. Ultimately, the classification is functional, driven by consumer expectation and the need for standardized public health warnings.
Cashew Allergies and Medical Classification
Despite being botanically a seed, the medical classification of the cashew is firmly within the tree nut category due to the nature of the allergic response. Cashew allergies are recognized as common and severe reactions among food allergies. The proteins within the cashew seed are potent allergens that can trigger life-threatening anaphylaxis, even from minimal exposure.
Allergists often test for cashew allergy alongside other tree nuts because of high rates of cross-reactivity. Cashews and pistachios are closely related botanically, both belonging to the Anacardiaceae plant family. This means their allergenic proteins are highly similar, and individuals with a cashew allergy frequently react to pistachios as well.
Because of this cross-reactivity and the severity of the reaction, patients diagnosed with a cashew allergy are often advised to avoid all tree nuts. The medical community prioritizes the common allergic pathway over the plant’s reproductive biology when classifying this food, grouping cashews with tree nuts for public health protection.