Thank you for your inquiry.
Chestnut is a nut. It is a member of the Fagaceae family. It has been known to cause IgE-mediated reactions on ingestion, and has a very complex potential cross-reactivity profile. The link copied below is a comprehensive discussion of its allergens, potential cross-reactivity, and reports of its induction of IgE-mediated events.
Thank you again for your inquiry and we hope this response is helpful to you.
Sweet chestnut: Thermo Fisher Scientific Inc.
Phil Lieberman, M.D.