Is There an Association Between Peanut and Treenut Allergies?

Question: Is There an Association Between Peanut and Treenut Allergies?

Answer: Yes, there appears to be. While peanuts are actually legumes, and not true nuts, people with peanut allergy appear to be at an increased risk for developing an allergy to treenuts. Allergy to treenuts, such as almonds, pecans, walnut, and cashews, is relatively common and can be severe. People with peanut allergy appear to have at least a 25% to 50% chance of being allergic to at least one type of treenut. In addition, people with an allergy to one treenut have about a 40% chance of being allergic to another treenut.

There is also the concern for cross-contamination among various nuts. For example, if a person is allergic to pecans, but wishes to eat cashews, there is the danger of pecan proteins contaminating a can of dry roasted cashews. This is because in most factories that process nuts, more than one type of nut is processed on the same machinery, leading to the possibility of accidental exposure to the unwanted nut. Therefore, based on the high level of cross-reactivity among peanuts and treenuts, as well as the cross-reactivity among the treenuts themselves, it is prudent for a person (especially a child) who is allergic to one type of nut to avoid all nuts.

Being allergic to all nuts is not an absolute, however. Many people who have an allergy to one type of treenut or peanut may be able to safely eat another type of treenut. Caution should be advised, and the person should always have injectable epinephrine available. If the question arises on whether a person can safely eat a particular nut, an allergist may decide to perform appropriate allergy testing, followed by an oral food challenge if needed.

Want to learn more? Find out about:

• Peanut Allergy
• Treenut-Free Diet
• Peanut-Free Diet

_Sources:

Sicherer SH, Sampson HA. Peanut Allergy: Emerging Concepts and Approaches for an Apparent Epidemic. J Allergy Clin Immunol. 2007; 120:491-503.

Sicherer SH. Clinical Implications of Cross-Reactive Food Allergens. J Allergy Clin Immunol. 2001; 108:881-90.

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