Heightened olfactory dysfunction and oral irritation among chronic smokers and heightened propylthiouracil (PROP) bitterness among menthol smokers

Chronic cigarette smoking may influence chemosensory function, which in turn, may affect cigarette usage. Because menthol in cigarettes can attenuate nicotine bitterness, choice of menthol/nonmenthol cigarettes may be influenced by ability to perceive bitterness. We examined chemosensory function of chronic smokers, hypothesizing they would show altered function in comparison to non-smokers and by menthol cigarette preference. In laboratory-based measures, chronic smokers (N = 135; 84 menthol smokers) self-reported their chemosensory function and participated in smell (identification task with perceived intensity) and taste (quinine and NaCl intensity on tongue-tip and whole mouth) testing. A taste genetics probe (propylthiouracil (PROP) bitterness) also was assessed. Self-reported and measured chemosensory function were compared with nationally-representative 2013-2014 National Health and Nutrition Examination Survey (NHANES) data generated with similar measures. The taste measures also were compared between smokers and age- and sex-matched nonsmokers from a laboratory database. Frequencies of self-reported smell and taste alterations among smokers exceeded NHANES prevalence estimates for non-smokers. The rate of measured smell dysfunction also exceeded NHANES prevalence for hyposmia. Compared to non-smokers, smokers reported elevated tongue-tip and whole mouth intensities from 1 M NaCl, with no significant differences in whole mouth quinine or 0.32 M NaCl. Inconsistent with previous hypotheses, smokers were not more likely to report depressed PROP bitterness than non-smokers. However, as expected, menthol smokers reported greater PROP bitterness than non-menthol smokers. In conclusion, chemosensory alterations were more frequent among chronic smokers, including hyposmia and heightened intensity from NaCl at an oral-irritant concentration. PROP supertasters were most likely to prefer mentholated cigarettes.