Q:

9/18/2013
I'm often asked whether pine nuts should be avoided in other tree nut allergic patients. Pine nuts are generally considered a seed. Are there any studies evaluating cross-reactivity between pine nuts and either tree nuts or seeds?

A:

Thank you for your inquiry.

You are correct that pine nuts are actually seeds. We do not know, unfortunately, the major allergen of pine nuts, but there are several studies which have isolated components which were allergenic in the particular patients evaluated.

However, there is very little information on potential crossreactivity between pine nuts and other foods, including nuts. There is one study which showed crossreactivity with peanuts (1), and another with almonds (2).

In addition, there are patients who have had anaphylactic episodes to pine nuts who have demonstrated allergy to other nuts as well (3), but there are also patients who were only mono-sensitized to the pine nut (4). Thus, unfortunately, we cannot give you a definitive answer as to which nuts or other foods might be cross-reactive in your patient except to say that crossreactivity evidently does occur and has been demonstrated to almonds and peanuts. It is not known whether patients who have shown anaphylactic sensitivity to pine nuts as well as other nuts or seeds do so because of cross-reacting antigens or the fact that they simply are reacting separately because of their highly atopic nature.

The issue, therefore, of whether pine nuts should be avoided in patients who are allergic to nuts and seeds can only be decided by clinical judgment. However, in most instances, we advise that patients who are allergic to nuts to avoid all nuts, including pine "nuts".

Thank you again for your inquiry and we hope this response is helpful to you.

References:
1. A MA, Maselli JP, Sanz Mf ML, Fernandez-Benitez M. Allergy to pine nut. Allergol Immunopathol (Madr) 2002; 30(2):104-8.

2. de las Marinas D, Vila L, Sanz ML. Allergy to pine nuts. Allergy 1998; 53(2):220-2.

3. Rubira N, Botey J, Eseverri JL, Marin A. Allergy to pine nuts in children.
Allerg Immunol (Paris) 1998; 30(7):212-6.

4. Ibanez MD, Lombardero M, San Ireneo MM, Munoz MC. Anaphylaxis induced by pine nuts in two young girls. Pediatr Allergy Immunol 2003; 14(4):317-9.

Sincerely,
Phil Lieberman, M.D.

12/30/13
Addendum from Dr. Lieberman:
We have heard from one of our readers and one of our AAAAI members, Dr. Beatriz Cabanillas, who sent us some very helpful additional information to our original response.  Her letter is copied below:

Letter from Dr. Cabanillas:
I am writing concerning the following question posted on 9/18/2013:
I'm often asked whether pine nuts should be avoided in other tree nut allergic patients. Pine nuts are generally considered a seed. Are there any studies evaluating cross-reactivity between pine nuts and either tree nuts or seeds?

There is a study published in Molecular Nutrition & Food Research in 2012 regarding pine nut allergy (clinical features and major allergens characterization).

In this article, 80% of allergic reactions to pine nut in the ten patients included were severe. Most patients (70%) were monosensitized to this nut. Two major allergens with molecular weights of 6 and 50 kDa were purified and identified as albumin and vicilin, respectively.

AAAAI - American Academy of Allergy Asthma & Immunology