Taste function in children: normative values and associated factors

Background Although less frequent than in adults, taste loss also occurs in childhood. “Taste Strips” are frequently used for diagnosing taste dysfunction; however, normative values are lacking for children. In this study, we will create normative values for the “Taste Strips” in children. Methods This cross-sectional study included 609 children aged 6–15 years. “Taste Strips” were used to determine sweet, sour, salty, and bitter taste scores by a non-forced procedure. The 10th percentile was used to distinguish normal taste function from a reduced sense of taste. Multivariable generalized linear models (GLM) were estimated to study the effect of age (group), sex, and 6‐n‐propylthiouracil (PROP) status on taste function. Results Taste function changed with age, allowing for a distinction of three age groups: (I) 6–7 years, (II) 8–9 years, and (III) 10–15 years. Normative values were created for the age groups and boys and girls separately. Additionally, GLM showed a significant effect of (1) age (group) on sweet, salty, bitter, and total taste scores; (2) sex on sweet, sour, and total taste scores; and (3) PROP status on total taste scores. Conclusions This study provided normative values for the “Taste Strips” in children, highlighting age- and sex-related differences. Impact Taste dysfunction can be harmful and impacts quality of life, a topic that became increasingly important since the COVID-19 pandemic. Although taste dysfunction is thought to be rare in childhood, the detrimental impact of such dysfunction might be large, as children’s eating habits are strongly influenced by input from the chemical senses. Measuring taste function may elucidate the relationship between taste dysfunction and disease, fostering the development of more appropriate supportive strategies. However, adequate tools are lacking for children. Normative values of the “Taste Strips” are now available for children, which bolster the clinical utility of this test.

The impact of chemosensory dysfunctions on weight loss

Background: The role of chemosensory senses (olfaction, taste, and trigeminal) is crucial, and their dysfunctions profoundly affect the quality of life, potentially impacting eating behaviors. However, it is unclear which chemosensory symptoms could lead to undernutrition. This study aims to investigate which findings in patients' smell and taste workup are predictors of weight loss. Methods: This is a retrospective study based on a validated questionnaire consecutively given to adult patients presented in smell and taste consultations during a 10-year period. Psychophysical tests were used to measure chemosensory function (Sniffin' Sticks, taste powder, and Taste Strips tests). Results: We included 555 patients (307 females) with a median age of 51 years (IQR 23). Among them, 76 (13.7%) reported involuntary weight loss due to chemosensory disorders occurred over periods ranging from 3 to 36 months. We found that the odds of losing weight were 2.1 times higher when patients reported changes in aroma perception (p-value=0.012; 95% CI 1.15 - 3.83). Parosmia, but not phantosmia nor smell loss, was a significant predictor of weight loss (OR 2.22; p-value=0.015; 95% CI 1.17 - 4.2). Furthermore, the duration of symptoms for more than two years was protective for weight loss (OR 0.44; p-value=0.014; 95% CI 0.23 - 0.85). Regarding putative etiologies, post-traumatic chemosensory dysfunction was also a significant predictor (OR 2.08; p-value=0.039; 95% CI 1.04 - 4.16). Concerning psychophysical tests, we found that the probability of a patient to present weight loss increased by 8% for every 1-unit reduction in Taste Strips score (p-value=0.006; 95% CI 0.87 - 0.98). Conclusion: We recommend investigating weight loss in smell and taste consultations, especially when patients report changes in aroma perception, parosmia, duration of symptoms for less than two years, head injury, and when low Taste Strips score is measured.

Qualitative smell/taste disorders as sequelae of acute COVID-19

Background Qualitative smell/taste disorders (such as phantosmia, parosmia, phantogeusia, and parageusia) have not yet been fully characterized in patients who had COVID-19, whereas quantitative disturbances (i.e., reduction/loss of smell/taste) have been widely investigated. Objective To simultaneously assess the presence of both quantitative and qualitative smell/taste dysfunctions in patients who suffered from COVID-19. Methods We enrolled 17 consecutive patients who suffered from COVID-19 over the last 6 months and 21 healthy controls, matched for sex and age. After a negative nasopharyngeal swab, the Sniffin’ Sticks Test and the Taste Strips were used to assess olfactory and taste function, respectively. At the same time, the presence of phantosmia, parosmia, phantogeusia, and parageusia was investigated with a standardized questionnaire. Results Qualitative disturbances of smell and/or taste were found in 6/17 (35.3%) patients. Phantosmia was reported in 2/17 (11.8%) patients and parosmia in 4/17 (23.5%). There were no significant differences in smell test scores between patients who reported phantosmia and/or parosmia and patients who did not. Phantogeusia was described in 3/17 (17.6%) patients, and parageusia was identified in 4/17 (23.5%) patients. All tested patients were normogeusic. Conclusion Around one-third of patients who recover from COVID-19 may have persistent qualitative dysfunction in smell/taste domains. Detection of phantogeusia in long-term COVID-19 patients represents a further novel finding. Further investigation is needed to better characterize the pathophysiology of phantosmia, parosmia, phantogeusia, and parageusia in patients who had COVID-19.

Bitter Taste Perception of the Human Tongue Mediated by Quinine and Caffeine Impregnated Taste Strips

Objectives: Tests for gustatory function have become increasingly important in diagnosis and treatment of patients with taste disorders. While caffeine and quinine hydrochloride solutions have been used for global testing of bitter perception, only quinine has been used to test regional bitter perception by means of taste strips. The aim of the present study was to validate caffeine impregnated taste strips as an alternative to quinine taste strips for assessment of regional bitter perception. Methods: A total of 46 healthy volunteers (mean age/range, 23/19-27 years) were included in this study. Quinine and caffeine impregnated taste strips were pairwise presented at different parts of the tongue. Perceived intensity and hedonic dislike were evaluated using labeled magnitude scales. Additionally, gustatory function was assessed using the taste strips test and overall sense of taste was rated using visual analog scales. Results: Assessment of gustatory function demonstrated scores within the normogeusic range in most included subjects (mean/SD, 13.1/2.5). Notably, equally concentrated quinine and caffeine impregnated taste strips placed on different regions of the tongue did not lead to significant differences in perceived intensity or hedonic dislike, whereas quinine and caffeine impregnated taste strips of different concentrations placed on the same region on the tongue led to significant differences of perceived intensity and hedonic dislike. Furthermore, no correlation was found between self-assessment of gustatory function and taste strips scores. Conclusion: Caffeine seems to be a valid bitter compound for regional testing using taste strips and may be used alternatively to quinine.

Smell and Taste Impairment After Total Laryngectomy

Objective: Aim of this observational study is the evaluation of olfactory and gustatory impairments in laryngectomized long-term survivors compared to control subjects. Correlation between smell and taste alterations, age, and previous adjuvant treatments in laryngectomees was investigated. Methods: Fifty control subjects and 50 patients who underwent total laryngectomy for advanced laryngeal carcinoma were evaluated. All subjects underwent symptoms evaluation, oropharyngeal exam, endoscopic fiberoptic nasal examination, and Taste Strips and Sniffin’ Sticks tests. Results: Hyposmia was reported by all laryngectomees and hypogeusia by 54% of patients. Sniffin’ Sticks and Taste Strips tests demonstrated a statistically significant difference between controls and laryngectomees regarding olfactory threshold, odor discrimination and identification, Threshold Discrimination Identification (TDI) score, and sour, salty, and gustatory Total Taste score ( P < .05). Multivariate analysis for Total Taste score in laryngectomees showed a statistically significant correlation with aging, having an odds ratio of 0.127 for age ≥65 years, but not with TDI score, radiotherapy, and follow-up time, whereas multivariate analysis for TDI score demonstrated no correlation with radiotherapy, age, and follow-up time. Conclusions: Total laryngectomy determines olfactory and gustatory impairments that should be taken into account in clinical practice. Relationships between sensorial alterations, aging, follow-up period, and adjuvant treatments should be further evaluated in prospective studies.

A new extension to the Taste Strips test

Objective: Assessment of gustatory function in human subjects using the 'taste strips' test is an easy and validated procedure. The aim of this study was to extend this test in order to detect subjects with superior gustatory sensitivity. Methods: The investigation included 134 subjects (29.5±12.6 years, range 18-84 years) with normal gustatory function. Four concentrations of sweet, sour, salty, and bitter were augmented with additional low concentrations (sweet: 25/12.5 mg/ml sucrose; sour: 27/15 mg/ml citric acid; salty: 6.4/2.6 mg/ml sodium chloride, bitter: 0.15/0.06 mg/ml quinine hydrochloride), resulting in a maximum extended taste score (ETS) of 24. Results: The mean ETS was 14.5 ± 3.2. Specifically, it was 4.5 ± 1.2 for sweet, 2.8 ± 1.0 for sour, 4.0 ± 1.3 for salty, and 3.2 ± 1.2 for bitter. In contrast to the original version of the taste strips test, no ceiling effect was observed. Cluster analysis separated three groups of subjects by ETS, whereas test scores derived from the original four concentrations were insufficient to discriminate the subgroup with higher gustatory sensitivity. Conclusions: The extended taste strips test seems to be a useful tool for the detection of patients with low gustatory thresholds for sweet, sour, salty, or bitter taste.