Coconut, an uncommon food allergen, is actually the fruit (seed) of coconut palm trees. So why are coconuts on the FDA’s tree-nut allergen list? The most common-sense explanation is that the FDA’s tree-nut allergen classification is a culinary one, a broad grouping of nuts and nut-like foods. Even almonds, pine nuts, and pecans are not botanically classified as nuts but are categorized as nuts for cooking, baking, and snacking purposes.
Keeping It Simple
If there were separate allergen lists for “true” nuts, drupes, and seeds it would arguably be more cumbersome and confusing for food-allergic consumers:
- Nuts are fruits composed of a hard shell containing a generally edible seed (e.g., hazelnuts, acorns, and chestnuts).
- A drupe is a type of fruit with an outer fleshy part that surrounds a shell or pit with a seed inside (e.g., peaches, cherries). Walnuts, almonds, and pecans are drupes where we eat the pit’s seed.
- Seeds are small embryonic plants enclosed in a seed coat (e.g., pine nuts).
Although our science texts distinguish these different types of fruits and seeds from each other, our recipe books usually do not. Consumers and cooks typically call most of them “nuts,” and coconut fits best into this culinary-allergen category.
A more scientific reason for putting coconuts on the tree-nut list has to do with cross-reactivity. Cross-reactions occur when people are triggered by a food other than the food they developed an allergy to. This can happen when different foods contain similar allergenic proteins.
A few people who had serious reactions* to coconut, were also found to have walnut and hazelnut allergies. This suggests that walnuts, hazelnuts, and coconuts contain similar allergy-triggering proteins. If so, an individual with an allergy to hazelnut might also react to coconut, or someone sensitized to coconut might cross-react with walnut.
Though the incidence of apparent cross-reactivity between coconut and other nut varieties is rare, reactions are possible—and caution is recommended.
“While allergic reactions to coconut have been documented, most people who are allergic to tree nuts can safely eat coconut. If you are allergic to tree nuts, talk to your allergist before adding coconut to your diet.” ~ The American College of Allergy, Asthma & Immunology.