Tree nuts include almonds, walnuts, hazelnuts, brazil nuts, cashew nuts and pistachios. People who are allergic to tree nuts sometimes ask us if they are likely to react to coconut because of the name. Foods that are close biological relatives often share similar proteins, which can lead to a process called cross-reactivity – where a person allergic to one food also reacts to another. But the coconut is a member of the palm family and only distantly related to tree nuts. The botanical distance between coconuts and tree nuts would suggest that people with tree nut allergy should be able to tolerate coconut and studies have shown that this is generally true. Therefore, there is no general recommendation that patients with tree nut allergy should avoid coconut.
Rare exceptions have been reported in scientific research papers. Two people allergic to walnuts were found to react to coconuts due to a cross-reacting protein. Another person who was allergic to coconut suffered symptoms of oral allergy to several tree nuts. A cross-reacting protein found in both coconut and hazelnut was identified as the cause.
The medical reviewer of this article, who works in a busy NHS allergy clinic, occasionally sees patients who had been mistakenly advised that they were allergic to coconut due to the misinterpretation of the results of a popular allergy blood test. The test is called ImmunoCAP fx1 Mixed Nuts and it is available to GPs in some areas. It checks to see if one or more nut antibodies (specifically peanut, hazelnut, brazil nut, almond or coconut) is present in the blood serum. If the test is positive, it indicates an allergy to at least one nut, but it does not mean that the patient is allergic to all of them. In order to confirm this, a separate test to each nut should be carried out. However, not all NHS laboratories do this as a matter of routine when the test is positive unless they have been specifically asked to do to so.
If you have been told you are allergic to coconut but are unsure if a separate coconut allergy test has been carried out, or if you are allergic to one or more tree nuts and don’t know if you are allergic to coconut, we would advise you to ask your GP to arrange for a coconut allergy test.
