Context: metallic taste is known to vanish with nasal occlusion, suggesting it should be termed 'aroma' rather than metallic 'taste'. However, it also appears after neurological injuries, such as a chorda tympani section, which suppresses taste perception mediated by the facial nerve. Methods: in 120 healthy volunteers, the perception of an iron sulfate solution was assessed at different lingual locations, corresponding to the facial and glossopharyngeal nerves, and with either open (n=60) or closed (n=60) noses to evaluate if it is a taste or an aroma. Results: Nasal occlusion significantly reduced the perception of iron sulfate. It prevented perception in 31.7% of participants, though it did not completely eliminate it in the remaining 68.3%. Additionally, in open-nosed subjects, the intensity of iron sulfate perception was significantly greater when applied to the base of the tongue (glossopharyngeal nerve) than to the tip (facial nerve). These differences did not persist with nasal occlusion. Conclusion: Nasal occlusion diminished but did not abolish the perception of iron sulfate. With an open nose, a differential taste perception was significant, but not with a closed nose. Therefore, metallic perception involves both retro-olfactory and gustatory components, suggesting it is a metallic flavor.

The authors have declared no competing interest.

This study was funded by 'la Ligue contre le Cancer'

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CPP Est IV on 16/12/2021 (no. 2021-A02149-32) for the open nose and on 05/08/2022 (no. 2022-A01475-38) for the occluded nose

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All data produced in the present study are available upon reasonable request to the authors