Do changes in Nitric Oxide and Zn Levels Affect the Gustatory and Olfactory Functions of Smokers?

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Abstract: Several studies have focused on the impact of smoking on taste and smell thresholds that depend primarily on chemoreceptors and messenger molecules present both on the tongue and in the nasal passages. The present study was designed to evaluate the effect of smoking on salivary zinc and NO levels (two molecules of major importance in taste and smell acuity) and to correlate this with diminished taste and smell sensations manifested in smokers. The study was conducted on 100 individuals that were divided into two groups; smokers and non-smokers. Whole unstimulated saliva (WUS) was collected from selected cases and controls for estimation of salivary Zn and NO level then a validated taste and smell testing were performed. The obtained results revealed significantly higher thresholds for all examined taste sensations in heavy smokers followed by light smokers then non smokers at p value <0.001. Bitter taste sensation was the most affected by smoking as smokers needed much higher concentrations to recognize bitter taste than non smokers. Regarding the olfactory test results; a statistically significant difference was found in mint, lemon and strawberry odorants between heavy smokers and the other groups, while there was no significant difference between light smokers and non smokers as both showed the significantly lowest values. As for NO and Zinc levels, non smokers showed the significantly highest mean of NO level when compared to light and heavy smokers at p value <0.001. From these results we can conclude that smoking increases significantly the risk of impairment of olfactory and gustatory functions and this may be mediated by lower salivary Zn and NO levels detected in the smokers of the current study.

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