One third of all food allergen anaphylactic events are related to tree nut ingestion.
With few exceptions, peanut antigens did not serologically cross-react with tree nuts. There is some limited peanut cross-reactivity with pistachio and walnut
Walnut, pecan, and hazelnut form a group of strongly cross-reactive tree nuts.
Hazelnut, cashew, Brazil nut, pistachio, and almond form a group of moderately cross-reactive tree nuts.
Cross-reactivities between these groups are less pronounced (there is limited cross-reactivity of walnut and pecan with Brazil nut).
The strongest cross-reactivities among tree nuts follow botanical family associations:
- walnut and pecan in the family Juglandaceae
- cashew and pistachio in the family Anacardiaceae
8 foods cause 90% of food allergies (click to enlarge the image). The likelihood of a negative oral food challenge is shown in relation to the respective values of skin prick test (SPT) and serum IgE (sIgE):
Cross-reactivity among edible nuts: double immunodiffusion, crossed immunoelectrophoresis, and human specific igE serologic surveys. Goetz DW, Whisman BA, Goetz AD. Ann Allergy Asthma Immunol. 2005 Jul;95(1):45-52.
Image source: Wikipedia, GNU Free Documentation License.
Comments from Twitter
Matthew Bowdish MD @MatthewBowdish: This is always a conundrum for me. Pt with rxn & strong (+) to 1 tree nut but eating others without adv effect. What do you recommend?