Thank you for your recent inquiry.
First of all, let me preface the response by saying there is no definitive answer to your questions. There is a body of literature that deals with this issue, and your question has been dealt with on our website previously.
I have copied below the answer to a very similar question as previously posted on our site dated May 22, 2010. I have also copied below an abstract which deals with cross reacting antigens that could potentially produce cross reactivity between tree nuts and peanuts, as well as two reviews of potential cross reactivities. One of these (Teuber, et al.) is a review of tree nut allergy alone, and the other (Sicherer) is an excellent overall review of the cross reactivity between foods in general. I have copied the quotes from the Sicherer abstract dealing with tree nuts and legumes.
I hope you will find these sources helpful. There are some additional comments, however, regarding your particular patient that should be made.
First of all, the response from Dr. Hugh Sampson to a previous inquiry relates to the strategy for approaching the issue in toddlers. You did not mention the age of the patient under discussion, but I presume, by "reading between the lines," you are talking about an adult. It may be that the approach to an adult would be different because of the probability that there will be less of a chance of acquiring new allergies than in a toddler. Therefore your strategy of advising the patient to continue eating almond, hazelnut, and peanut (since he has tolerated these in the past) would, in my opinion, be more acceptable in an adult than in a toddler. In fact, I suggest the same in patients I have seen with isolated cashew allergy.
Finally, as you probably know, cashew and pistachio nuts are related taxonomically. For this reason, I ask patients who are allergic to either of these to avoid the other. But, as you have advised your patient, in an adult with cashew allergy, who can tolerate peanuts and other tree nuts, I do not normally withhold these other nuts. There are no definitive data, however, to support this contention, as you have noted, and the strategy remains based on clinical judgment.
Thank you again for your inquiry, and we hope this response is of help to you.
Avoidance of peanuts in a cashew-sensitive patient
A 3 year has anaphylaxis/angioedema to cashew nut. She eats peanuts from a shell with no problem. Skin testing is very positive to cashew and negative to peanut. Do you tell her to avoid peanut from a shell assuming there is no contamination from tree nuts or continue eating peanut from a shell?
Thank you for your recent inquiry.
To answer your question, I refer you to a response to a similar inquiry posted on our website on May 7, 2008. For your convenience, I have copied below the inquiry and the response to the question from Dr. Hugh Sampson.
Thank you again for your inquiry and we hope this response is helpful to you.
Avoidance of peanuts in a patient with tree nut allergy
I ask this question as a pediatrician (in practice almost 10 years) and as a parent. I always felt fairly knowledgeable about food allergy as a general pediatrician UNTIL one of my children had an anaphylactic reaction to cashews. Since then I have become much more knowledgeable about food allergy and feel that I give much better advise.
I need your help in devising recommendations for families whose children test positive for nut allergy... if a patient tests positive for allergy to a single tree nut such as a cashew, but negative for other tree nuts and peanuts, do they JUST avoid cashew or should they avoid ALL tree nuts and peanuts (or avoid tree nuts but enjoy peanuts)?
Interestingly, I was at a party this weekend where the child has a cashew allergy. The house was deemed "nut safe" by the hosts. There were about 20 bowls of peanuts mixed with M & M's (which are also made, I believe, in a factory that also processes nuts - I'm not sure if just peanuts) scattered throughout the house. To me this really highlighted the topic.
I was glad my daughter with cashew allergy was not there. WE AVOID ALL NUTS, INCLUDING PEANUTS, AT THE RECOMMENDATION OF OUR VERY GOOD ALLERGIST, DR. ACETA. I know the other family can do what they want with their own children, but I'm sure their pediatrician told them its okay to just avoid tree nuts and peanuts are fine.
I am asking the question in general. I understand that with more information (grade of allergy, hx of anaphylaxis or not, etc) your answers could be modified.
In answering your question, first I would like to quote Dr. Hugh Sampson, who is a world recognized expert on food allergy. He responded to a similar question submitted to us a few months ago. The question was a little different in that he was asked whether or not a patient who is known to have a peanut allergy should avoid tree nuts. His answer, taken from our web site, is seen below:
" If you have a toddler who is allergic to peanut supported by history and skin testing, should they empirically avoid tree nuts despite there different protein structures since we know tree nuts might be sensitizers- and vice versus, tree nut allergic....avoid peanut?"
Dr. Sampson's Response:
"If a toddler has a clear-cut, recent reaction to peanut and a positive skin test, I generally tell the parents that they should eliminate peanuts and tree nuts from the child's diet. [I also obtain a peanut-specific IgE level so that I can get some idea of whether this toddler may fall into the 20% of young children who will outgrow their peanut allergy] There is little evidence to support the notion that tree nuts 'cross-react' with peanuts and therefore avoidance for this reason seems unjustified. However, two other factors that support tree nut avoidance must be considered. (1) Studies indicate that about 35% of American toddlers with peanut allergy will have [or develop] concomitant tree nut allergy. (2) In a young child, it is very confusing to distinguish the difference between peanut and 'safe' tree nuts, since many adults refer to both as nuts and are unaware of situations where peanuts may be included with specific tree nuts. We have seen too many accidents where a child receives peanut-containing products because of misidentification, cross-contamination, or substitution with some peanut product. Consequently we think it is safer to avoid tree nuts until the child is old enough to understand the nuances of avoiding peanut contaminated foods. We often will skin test the child to various tree nuts [and obtain nut-specific IgE if the skin test is positive] so that the parents will know whether the child is likely to experience an allergic reaction if the child inadvertently ingests a tree nut-containing food"
I favor this policy, and would also employ it in the converse state - that is, "when a patient is known to be allergic to tree nuts, should they avoid peanuts?" Thus, I, for the same reasons cited by Dr. Sampson, and probably utilized by Dr. Aceta to give you advice, would suggest that such patients avoid all nuts including peanuts.
This of course is as much a philosophical as a scientific, evidence-based answer. But the reasons that Dr. Sampson cited are quite cogent, and represent the safest course of action.
Thank you again for your inquiry, and I hope this information has been of help to you.
Phil Lieberman, M.D.
Immunological analysis of allergenic cross-reactivity between peanut and tree nuts M. P. de Leon, I. N. Glaspole, A. C. Drew, J. M. Rolland, R. E. O'Hehir and C. Suphioglu
Summary -Background Peanut and tree nut allergy is characterized by a high frequency of life-threatening anaphylactic reactions and typically lifelong persistence. Peanut allergy is more common than tree nut allergy, but many subjects develop hypersensitivity to both peanuts and tree nuts. Whether this is due to the presence of cross-reactive allergens remains unknown.
Objective - The aim of this study was to investigate the presence of allergenic cross-reactivity between peanut and tree nuts.
Methods Western blotting and ELISA were performed using sera from subjects with or without peanut and tree nut allergy to assess immunoglobulin E (IgE) reactivity to peanut and tree nut extracts. Inhibition ELISA studies were conducted to assess the presence of allergenic cross-reactivity between peanut and tree nuts.
Results Western blot and ELISA results showed IgE reactivity to peanut, almond, Brazil nut, hazelnut and cashew nut for peanut- and tree nut-allergic subject sera. Raw and roasted peanut and tree nut extracts showed similar IgE reactivities. Inhibition ELISA showed that pre-incubation of sera with almond, Brazil nut or hazelnut extracts resulted in a decrease in IgE binding to peanut extract, indicating allergenic cross-reactivity. Pre-incubation of sera with cashew nut extract did not cause any inhibition.
Conclusion These results show that multiple peanut and tree nut sensitivities observed in allergic subjects may be due to cross-reactive B cell epitopes present in different peanut and tree nut allergens. The plant taxonomic classification of peanut and tree nuts does not appear to predict allergenic cross-reactivity.
SOURCE: Clinical & Experimental Allergy, Volume 33 Issue 9, Pages 1273 - 1280 Published Online: 8 Sep 2003
Abstract 2 (Teuber):
Suzanne S. Teuber, Sarah S. Comstock, Shridhar K. Sathe and Kenneth H. Roux
Tree nuts are clinically associated with severe immunoglobulin E-mediated systemic allergic reactions independent of pollen allergy and with reactions that are usually confined to the oral mucosa in patients with immunoglobulin E directed toward cross-reacting pollen allergens. The latter reactions can progress to severe and life-threatening episodes in some patients. Many patients with severe tree nut allergy are co-sensitized to peanut. Clinical studies on cross-reactivity between the tree nuts are few in number, but based on reports to date, avoidance of the other tree nuts once sensitivity is diagnosed appears prudent unless specific challenges are performed to ensure clinical tolerance. Even then, great care must be taken to avoid crosscontamination. As with other severe food allergies, a recurrent problem in clinical management is the failure of physicians to prescribe self-injectable epinephrine to patients who are at risk of anaphylaxis.
SOURCE: Tree nut allergy
Current Allergy and Asthma Reports
Current Medicine Group LLC
ISSN 1529-7322 (Print) 1534-6315 (Online)
Issue Volume 3, Number 1 / January, 2003
Abstract 3 (Sicherer):
Assessment of cross-reactivity among tree nuts is complicated by shared allergens among the nuts and between nuts and other plant-derived foods and pollens. Clinical reactions to tree nuts can be severe,24 potentially fatal, and can occur from a first exposure to a nut in patients allergic to other nuts.25Serologic studies have indicated a high degree of IgE binding to multiple tree nuts.16, 26, 27 In our studies of children with tree nut allergy,16 92% of 111 patients with peanut allergy, tree nut allergy, or both had IgE antibody to more than 1 tree nut, and 37% of 54 had experienced convincing reactions and had specific IgE antibody to more than 1 nut.
Because of the frequency of severe reactions, there are no comprehensive studies on cross-reactivity to tree nuts. Bock and Atkins15 performed challenges to 1 or more nuts in 14 children, and at least 2 reacted to multiple nuts (as many as 5 types). Similar to our studies,16 Ewan24 has reported coallergy to multiple tree nuts in over a third of 34 patients evaluated for tree nut allergy. Considering the potential severity of the allergy and issues with accurate identification of particular nuts in prepared foods, caution would seem prudent, and total elimination of the nut family (perhaps with the exception of previously tolerated nuts eaten in isolation) is suggested.16, 28 These recommendations are potentially overrestrictive. Some nut allergens may be homologous and cause reactions (eg, in pistacchio-cashew29), whereas others may be homologous but rarely elicit clinical cross-reactivity (eg, proteins in coconut and walnut30).
Legumes, tree nuts, and seeds
Cosensitization to allergenic foods, such as peanut, tree nuts, and seeds (sesame, poppy, and mustard) is common. In a study of 731 subjects in the United Kingdom, 59% sensitized to peanut were also sensitized to hazelnut, Brazil nut, or both.26 Although clinically significant cross-reacting proteins have not yet been described, coallergy to peanut and tree nut has been reported between 23% and 50% in referral populations of atopic patients.16, 24, 31, 32 The rate of coallergy is much lower in unselected populations (2.5%).33 The clinician must consider the age of the patient, history, and perhaps sensitization in considering categoric elimination of these allergenic foods.34 Reactions to seeds, such as sesame, mustard, and poppy, are reported,27, 35, 36 and cross-reactivity with foods (hazel, kiwi, and other seeds) and pollens is potentially important, but the full clinical implications are far from established.
SOURCE:Clinical implications of cross-reactive food allergens
Scott H. Sicherer,
The Journal of Allergy and Clinical Immunology, December 2001 (Vol. 108, Issue 6, Pages 881-890)
Phil Lieberman, M.D.