Not all peanut allergy sufferes react in the same manner. Some will only have mild oral itching after eating a handful of peanuts, while others will have catastrophic anaphylaxis after minor exposure to airborne peanut allergen. Some peanut allergy sufferers will also have reactions to other seeds such as Sesame or tree nuts such as Brazil nut, Hazelnut and Walnut.  While others may only react to legumes such as beans, peas and lentils. Yet others may have allergic cross-reactions to soybean and lupin flour.

This has all been rather unpredictable and guess work until recently when a new blood tests was developed which can show with accuracy which part of the peanut an allergy suffer has or will react to in the future. For example there is a particular peanut protein called Ara h 2 which is likely to cause anaphylactic reactions. This type of component allergy test is useful in predicting whether a cross-reaction to nuts, beans, seeds or fruit is likely to occur.

Peanut component allergy testing and likely cross-reactivity:

Ara h 2 High risk anaphylaxis to peanut and nuts

Ara h 1 – cross-reactions with legume (pea, bean, lentil) and nuts

Ara h 3 – cross-reactions with soybean and lupin flour

Ara h 8 – localised oral reactions to peanut and stone-fruit only.

Reference: Astler C et al. Journal Allergy and Clinical immunology 2007: 118; 250