Family: Anacardiaceae.

From the acaju tree of the Sumac or Cashew family. Native to Brazil. Also exported from southern India, Mozambique, Tanzania and Kenya. The family is a dermatitis-inducing group including poison ivy, poison oak, poison sumac and lacquer sumac. Kidney-shaped nut with smooth, creamy kernel which grows at the base of the fruit.

The cashew tree flowers once a year between January and March, but pollination is mostly entomophilous.

Allergens/Function:

Allergens:
Ana o 1, a vicilin-like protein, is a major food allergen in cashews. Cashew and peanut vicilins do not share linear epitopes. The recombinant protein bound with 50% of sera from 20 patients with cashew allergy and 25% of 8 cashew-tolerant patients with allergies to other tree nuts. (Wang 2002 ref.6293 4)

Ana o 2, a major allergen, a legumin-like protein (an 11S globulin), constituting a major band at approximately 33 kD and a minor band at approximately 53 kD. (Wang 2003 ref.8557 3)

By IgE immunoblotting, 13 of 21 sera (62%) from cashew-allergic patients were reactive to Ana o 2. (Wang 2003 ref.8557 3)

Of 42 children with cashew allergy, the mean age at first allergic reaction was 2 years and the mean age at diagnosis of cashew allergy was 2.7 years. One in five children (12%) had a prior history of exposure to cashew nuts. Fifty-six per cent had skin symptoms, 25% had respiratory signs and 17% had digestive signs. Eighteen children had proven, associated food allergies (pistachio, seven; egg, five; mustard, three; shrimp, two; cow milk, one). The mean wheal diameter of the skin prick tests was 7 mm (3-16 mm) and the mean specific IgE level was 3.1 kUA/L (<0.35->100 kUA/L). Eight children had positive food challenges. The study concludes that the increase in cashew allergy is worrying because it affects young children who may have a reaction without ever having been exposed to cashews. Almost one-third of children are allergic to pistachios, which belong to the same botanical family as cashews. Clinical history is generally and sufficiently suggestive to diagnose cashew allergy without recourse to food challenges. (Rance 2003 ref.8663 4)

Adverse Reactions:

IGE AND IMMUNE:
Accidental exposures to cashew are less frequent than exposures of peanut allergic subjects to peanut, but the reactions caused are equally severe, and occur with similar speed. (Harris 2000 ref.3569 3)

Shortness of breath, widespread urticaria, angioedem. (Rasanen 1998 ref.2172 4) (Kraut 1992 ref.2174 2) Anaphylaxis (Marks 1984 ref.2185 4) and 'idiopathic' anaphylaxis. (Stricker) Explore allergic reactions to this food in older individuals. Perianal contact dermatitis due to cashew ingestion. (Rosen 1994 ref.2181 6)

Between April 4 and May 10, 1982, 54 individuals developed a poison ivy-like dermatitis 1 to 8 days after eating imported cashew nuts (contaminated by urushiol from the cashew shell oil). The patients had a very pruritic, erythematous, maculopapular eruption that was accentuated in the flexural areas of the body. Three had blistering of the mouth and four had rectal itching. Nine tested who reacted to the cashew extract also reacted to poison ivy urushiol. (Marks 1984 ref.2185 4)

Cashew nut tree pollen triggers asthmatic response in allergic individuals. (Fernandes 1995 ref.2180 2)

Oleoresins cause contact dermatitis.

In 165 patients aged 4 months to 22 years, 7 foods (milk, egg, peanut, soy, wheat, cod/catfish, cashew) accounted for 89% of the positive challenges. (Burks 1998 ref.2143 2)

The urushiol (see) dermatitis caused by plants of the Anacardiaceae family is the most common cause of acute allergic contact dermatitis, but with the precautions taken today to avoid contamination of food products with cashew urushiols, it is rare to find a case of cashew nut dermatitis in the United States. (Rosen 1994 ref.2181 6)

This study reports that 48% of their patients reacted to minimal contact with cashew, i.e., smelling, touching, or tasting, but not eating cashew. The authors point out that severe reactions are as severe as those from peanut allergy. (Hourihane 2001 ref.4093 8)

This study reports on an allergic reaction (upper airway obstruction) to cashew that was initially misdiagnosed as foreign body aspiration. (Nguyen 2003 ref.7396 3)

An anaphylactic reaction to cashew nut developed in a nonatopic 60-year-old man 25 days after receiving a liver allograft from a 15-year-old atopic boy who died of anaphylaxis after peanut ingestion. The liver recipient had no history of nut allergy. Posttransplantation skin prick test results were positive for peanut, cashew nut, and sesame seed, and the donor had allergen-specific IgE antibodies to the same 3 allergens. This illustrates that transfer of IgE-mediated hypersensitivity can occur after liver transplantation and have potentially serious consequences. (Phan 2003 ref.7439 1)

OCCUPATIONAL EXPOSURE:
Food industry

Systemic contact dermatitis (Hamilton 1998 ref.2176 8) and a report of contact dermatitis among cashew nut workers. (Diogenes 1996 ref.2178 8) (Srinivas 1990 ref.2858 7)

Decreased sensitivity or no sensitivity to poison ivy/oak developed in 9 of the 13 cashew nut shell oil factory employees previously affected. (Reginella 1989 ref.2183 6)

In evaluating 163 asthmatic children with food allergy for food-induced asthma, using DBPCFC the most frequent offending foods were, sometimes in association, peanut (30.6%), egg (23.1%), cow's milk (9.3%), mustard (6.9%), codfish (6%), shrimp (4.5%), kiwi fruit (3.6%), hazelnut (2.7%), cashew nut (2.1%), almond (1.5%), garlic (1.2%). (Rance 2002 ref.7671 1)

NON IMMUNE:
Oral submucous fibrosis among cashew workers (Varghese 1986 ref.2859 8)