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Taste and smell are critical for food intake and maintaining adequate energy balance, particularly in isolated, confined, and extreme (ICE) environments. Hypoxic conditions, low humidity, and limited chemosensory exposure at Concordia Station in Antarctica may impair taste and smell functions, though research remains scarce. Gustatory and olfactory functions were assessed in 19 participants (39.2 ± 10.9 years) during two overwintering missions at Antarctic Concordia Station. Testing occurred six weeks pre-departure, three times during isolation, and six months post-isolation. Gustatory function was evaluated using ODOFIN Taste Strips; olfactory function using ODOFIN Sniffin’ Sticks. Additionally, subjective sensory reports were collected. Hyposmia increased during isolation, accompanied by a trend toward declining smell identification ( p  = 0.054), with limited follow-up data offering no clear evidence of recovery. Hypogeusia was primarily reflected in an elevated prevalence of reduced salt sensitivity during mid- to late isolation ( p  = 0.036), returning to baseline levels post-expedition. Subjective evaluations only partially aligned with psychophysical test results. A one-year stay at Concordia Station revealed individual variability in chemosensory responses, highlighting the sensitivity of taste and smell to environmental extremes. While causality remains unclear, the findings emphasize the need to monitor chemosensory function in extreme settings and constrained environments in everyday life.

Background Patients with Alzheimer’s disease dementia (ADD) are thought to exhibit taste disorders; however, this has not been extensively studied. We investigated gustatory functions and factors affecting taste in patients with ADD or mild cognitive impairment (MCI) and in non-demented controls (NDCs) and evaluated associations between cognitive impairment and gustatory functions. Methods We recruited 29 patients with ADD, 43 with MCI, and 14 with NDCs. We obtained medical and medication history, measured salivary secretion volumes, and performed cognitive function tests, blood tests, whole-mouth gustatory tests, and dietary and gustatory questionnaires. Results Patients with ADD showed significantly higher recognition threshold values than NDCs ( p  < 0.05). Many individuals did not recognize umami at the maximum concentration, and this happened more frequently in patients with ADD or MCI than in NDCs. Evaluation items other than cognitive function tests did not show significant differences among the groups, but many individuals had decreased salivation, low serum zinc levels, and were on multiple medications. We found a significant correlation between recognition threshold and age (r = 0.229, p  < 0.05) and cognitive function test score ( r  = 0.268, p  < 0.05). Conclusions Patients with ADD showed impairment of gustatory function. Gustatory impairment in patients with MCI could not be confirmed. However, many individuals with MCI did not recognize umami, either. Our results suggest that taste disorders in elderly people with cognitive decline occur independently of factors affecting taste such as salivation, zinc levels, or prescription drugs. Trial registration The study was registered in the UMIN Clinical Trials Registry on February 10, 2017, with reference number UMIN000026087 .

Background Neither hormone levels nor malabsorption alone fully explains the distinct weight loss after bariatric surgery in morbidly obese patients. Postoperatively, patients regularly report a change in the sense of taste and the development of food aversions. Hedonic and sensory components like olfactory and gustatory stimuli significantly affect appetite and flavour. Methods We prospectively analysed the orthonasal olfactory and gustatory function with psychophysical testing in 44 patients undergoing laparoscopic Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy (SG) or adjustable gastric banding (AGB) and in 23 healthy controls. Results About 22.7 % of morbidly obese patients were hyposmic, showing significantly lower threshold-discrimination-identification (TDI) scores ( p  = 0.009) with decreased discrimination and identification ability. In addition, 22.7 % of patients were tested to be limited in gustatory function, with significantly lower taste strip test (TST) scores ( p  = 0.003). Six months after surgery, olfactory and gustatory function was not different when compared to healthy controls. Conclusions Due to obesity, patients frequently show impaired olfactory and gustatory function. Six months after laparoscopic bariatric surgery, both chemosensory functions improve. The TDI test is an appropriate tool to measure olfactory function in obese patients.

Background: Sour taste is associated with acid-base homeostasis, which is critical to cell metabolism and health conditions. Vinegar, which contains acetic acid as the main component, is a sour food considered the second most common condiment in Italy. Objectives: The aim of the study was to assess differences in sourness perception in subjects with olfactory deficits compared to controls and evaluate myrtle aromatization’s potential effect in modulating sourness perception in subjects with hyposmia. Methods: To this end, olfactory function was assessed with the Sniffin’ Sticks test and gustatory function by the Taste Strips test. Sensory perception of a traditional white wine vinegar (WV) and a WV aromatized with myrtle (AWV) was evaluated. The sourness perception of the two vinegars was estimated through the rates of odor and taste pleasantness, intensity, and familiarity using a labeled hedonic Likert-type scale. Results: Our data indicated that in patients with hyposmia, a significant decrease was observed only in sour taste perception compared to controls. The increase in vinegar aroma due to the myrtle aromatization modulated sourness perception in patients with hyposmia. Conclusions: Myrtle aromatization increased the number of significant correlations between odor and the taste dimensions of the vinegar in controls and in patients with hyposmia in a different manner.

The coronavirus disease 2019 (COVID-19), as a severe respiratory disease, affects many parts of the body, and approximately 20–85% of patients exhibit functional impairment of the senses of smell and taste, some of whom even experience the permanent loss of these senses. These symptoms are not life-threatening but severely affect patients’ quality of life and increase the risk of depression and anxiety. The pathological mechanisms of these symptoms have not been fully identified. In the current study, we aimed to identify the important biomarkers at the expression level associated with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection-mediated loss of taste or olfactory ability, and we have suggested the potential pathogenetic mechanisms of COVID-19 complications. We designed a machine-learning-based approach to analyze the transcriptome of 577 COVID-19 patient samples, including 84 COVID-19 samples with a decreased ability to taste or smell and 493 COVID-19 samples without impairment. Each sample was represented by 58,929 gene expression levels. The features were analyzed and sorted by three feature selection methods (least absolute shrinkage and selection operator, light gradient boosting machine, and Monte Carlo feature selection). The optimal feature sets were obtained through incremental feature selection using two classification algorithms: decision tree (DT) and random forest (RF). The top genes identified by these multiple methods (H3-5, NUDT5, and AOC1) are involved in olfactory and gustatory impairments. Meanwhile, a high-performance RF classifier was developed in this study, and three sets of quantitative rules that describe the impairment of olfactory and gustatory functions were obtained based on the optimal DT classifiers. In summary, this study provides a new computation analysis and suggests the latent biomarkers (genes and rules) for predicting olfactory and gustatory impairment caused by COVID-19 complications.

Background and Objectives: Age-related declines in taste function are common. Taste acuity can be affected by nutritional status and sleep quality. This research aims to examine the effect of nutritional status and sleep quality on gustatory function in community-dwelling older adults. Materials and Methods: This cross-sectional study included 119 community-dwelling older adults (50.4% of whom were female). The gustatory function was evaluated using four liquid taste solutions (sweet, bitter, sour, and salty) each at four different concentrations and the Mini Nutritional Assessment (MNA) and Pittsburgh Sleep Quality Index (PSQI) was applied. Additionally, anthropometric measurements were taken. Results: The mean scores on the gustatory test for the sweet, bitter, sour, and salty tastes were 2.11 ± 1.27, 2.12 ± 1.03, 2.28 ± 1.03, and 1.98 ± 1.41, respectively. There were significant differences according to gender, polypharmacy, nutritional status, and sleep quality in identifying sweet tastes (all p < 0.05). It was also found that females and participants without polypharmacy had better scores for bitter tastes. When the gustatory functions were evaluated according to BMI classification, it was determined that underweight participants had a higher sour taste score than the obese ones. Multiple regression analysis revealed that age, MNA score, PSQI score, and gender accounted for a total of 20.4% of the variance in the sweet taste score. Conclusions: Determining the relationship between taste function, nutritional status, and sleep quality in older adults is important in terms of developing new strategies for older adults who have these problems.

ObjectiveTo evaluate the association between the severity of dementia and taste recognition abilities in older persons with Alzheimer’s disease (AD).MethodsAnthropometric measurements were performed and body mass index was used to determine the nutritional status. The taste strips were used to test gustatory functions of the five basic tastes (sweet, salty, sour, bitter and umami).ResultsA total of 30 healthy younger subjects, 30 healthy older subjects, 37 with mild stage AD and 23 with moderate stage AD were recruited. The older subjects with moderate AD showed a significant reduction of taste, less recognition of bitter and salty taste (score: 10.6 ± 2.6; 2.6 ± 0.9; 1.7 ± 1.5) when compared to older people without cognitive impairment (score: 13.3 ± 1.8; 3.4 ± 0.9; 3.2 ± 0.9), and less recognition of sweet taste (score: 2.9 ± 1.2) when compared to subjects with mild stage AD (score: 3.6 ± 0.8). Impaired recognition of salty taste was detected since the early stages of AD. Among the factors that possibly influence gustatory function, a significant correlation was detected between taste ability and age, medication intake, mini-mental state examination and the nutritional status.ConclusionThe severity of dementia is directly associated with greater impairment of taste sensitivity, especially among older subjects with moderate stage disease.

Introduction: Obesity is a major health burden in children and adolescents. One influential factor is the choice of food, which is partly determined by gustatory perception. Cross-sectional studies have provided evidence that gustatory function is reduced in patients with obesity compared to individuals with normal weight. This longitudinal study was aimed at investigating potential effects of a multimodal lifestyle intervention program on gustatory function in pediatric patients with obesity. Methods: Gustatory perception of five different taste qualities (sweet, sour, salty, bitter, and umami) was assessed in n = 102 patients (age 6–18) with obesity (BMI >97th percentile). Testing was performed before (T0) and after (T1) a residential multimodal weight reduction program between June and December 2015 using well-established taste strips. Results: Overall, identification performance increased between T0 and T1. Patients were most successful at identifying the taste quality sweet at both time points and reached higher scores at identifying umami and bitter at T1 compared to T0. Moreover, patients rated the highest concentration of sweet significantly sweeter at T1 compared to T0. Conclusion: Gustatory function can improve after a multimodal lifestyle intervention program in pediatric patients with obesity. This may lead to a modified choice of food, possibly resulting in a long-term therapeutic success. Therefore, these findings underline the importance of professional nutritional counseling as part of treatment for obesity.

Purpose: Decreased olfactory and gustatory functions are present in various systemic autoimmune diseases. However, little is known about the chemosensory functions of patients with inflammatory bowel disease (IBD). The present study aimed to investigate olfactory and gustatory functions in patients with IBD and their correlation with clinical disease activity. Methods: A total of 103 patients with IBD were included (52 men, 51 women, mean age 40.3 ± 1.2 years) in the present study. Chemosensory functions were assessed utilizing the “Sniffin’ Sticks” olfactory function test and “taste sprays” gustatory function test. The clinical disease activity of patients was graded as remission, mild, and moderate–severe. In addition, inflammatory markers (fecal calprotectin, C-reactive protein and blood leucocyte count) were recorded. Results: In total, 70% of IBD patients were normosmic, 30% were hyposmic, and none of them was functionally anosmic; 6% of the patients showed signs of hypogeusia. Patients with moderate–severe IBD reached a higher olfactory threshold score compared with patients with remission (p = 0.011) and mild IBD (p < 0.001). The BMI of IBD patients was inversely correlated with their olfactory threshold (r = −0.25, p = 0.010). Olfactory and gustatory function in IBD patients did not correlate with duration of disease, blood leucocyte count, CRP level, or fecal calprotectin level. However, patients’ olfactory function significantly increased after 4 months of TNF-α inhibitor treatment (p = 0.038). Conclusions: IBD patients are more likely to present with hyposmia. Olfactory thresholds were mainly affected. They were significantly associated with clinical disease activity and BMI. As shown in a subgroup, treatment with TNF-α inhibitors appeared to improve olfactory function.

Patients with Alzheimer’s disease (AD) develop olfactory and gustatory disorders. However, the order of failure and relevance of the pathophysiology are unclear. We compared olfactory identification and whole mouth gustation in patients with AD to those with mild cognitive impairment (MCI) and to healthy controls (HC) and assessed correlations with pathophysiology. Patients with AD (n = 40), MCI (n = 34), and HC (n = 40) were recruited. We performed the Odor Stick Identification Test for Japanese (OSIT-J), gustatory test by the intraoral dropping method using taste solutions, Mini-Mental State Examination (MMSE), Alzheimer’s Disease Assessment Scale-cognitive subscale Japanese version (ADAS-J cog), Touch Panel-type Dementia Assessment Scale (TDAS), and measurement of amyloid β (Aβ) 42 and phosphorylated tau (p-tau) 181 levels in cerebrospinal fluid (CSF). Patients with AD and MCI had lower OSIT-J scores than did the HC. The OSIT-J score was correlated with the MMSE, ADAS-J cog, TDAS, and Aβ42 results. There were no significant differences in the gustatory test scores among the three groups. The gustatory test score was only correlated with the MMSE, ADAS-J cog, and TDAS results. Olfactory function decreased in AD and MCI patients and was associated with CSF biomarker levels and cognitive disorders. The results suggest that olfactory function is impaired in early stage of AD. Gustatory function was not correlated with CSF biomarkers, which suggests that it may not be impaired in early stage of AD.