Background/Objectives: Taste disorders have a negative impact on meal enjoyment, which is essential for maintaining adequate nutrition and quality of life. Japan is a rapidly aging society with an increasing number of individuals with taste disorders. However, despite the increasing prevalence of taste disorders, the correlation between oral frailty and taste sensitivity remains largely unknown. The objective of this study was to assess the relationship between oral health status and taste sensitivity among the Japanese population. Methods: Participants were recruited from Kanagawa Dental University Hospital Medical-Dental Collaboration Center between 2018 and 2021. The exclusion criteria were severe systemic infections, pregnancy, or lactation. Clinical examinations, oral function assessments, and taste tests were conducted using tap water and 1% sweet, 0.3% salty, 0.03% umami, and 0.1% umami tastants. The relationships between oral function, systemic indicators, and taste sensitivity were statistically evaluated. Results: Of the 169 participants included in this cross-sectional study, 39.6% were male and 60.4% were female (median age, 68 years). Participants with low taste sensitivity showed a decline in tongue-lip motor function, independent of age, sex, or smoking status. A multiple logistic regression analysis conducted using two age categories-younger than 65 years and older than 65 years-revealed an association between tongue-lip motor function and taste sensitivity among participants younger than 65 years. Conclusions: Decreased taste sensitivity is associated with tongue-lip motor function. Therefore, the early maintenance of oral function and taste sensitivity may be beneficial for optimal tongue-lip motor function.

Prevention and treatment protocols for taste changes observed during hematopoietic cell transplantation (HCT) are not well-established. The purpose of this study was to assess the efficacy of photobiomodulation (PBM) in relieving taste changes and preventing lingual papillae atrophy. HCT patients received PBM (n = 42) on the tongue dorsum using an InGaAIP laser (660 nm, 100 mW, 1.1 W/cm2, 8.8 J/cm2). During the HCT conditioning (T0), severe neutropenia (T1), and after neutrophil engraftment (T2), taste acuity for sweet, bitter, sour, and salty solutions, and clinical appearance of lingual papillae were compared with those of a placebo group (n = 43). PBM significantly reduced hypogeusia, ageusia, and parageusia at T1 and T2, and also successfully prevented papillae atrophy during all the analyzed HCT periods. In conclusion, PBM enhanced taste acuity during HCT. The decrease in papillae atrophy indicated a potential regenerative effect of this therapy on tongue mucosa.

BACKGROUND: Although patients with advanced pancreatic cancer (PC) often experience dysgeusia with zinc deficiency during chemotherapy, data on zinc supplementation for dysgeusia and its effects on nutritional status are scarce. We aimed to examine the efficacy of zinc supplementation in patients with advanced PC.
METHODS: Thirty-three patients with unresectable PC who presented with dysgeusia and zinc deficiency during chemotherapy and received zinc acetate hydrate between January 2018 and December 2022 were included. We evaluated the changes in serum zinc levels and the improvement in dysgeusia. Among the 26 patients who received zinc supplementation for 12 weeks, we also compared patient characteristics and changes in serum zinc and albumin levels between patients who showed improvement in dysgeusia (effective group) and those who did not (non-effective group).
RESULTS: The serum zinc level increased significantly after zinc supplementation (median: 60 µg/dL at baseline, 99.5 µg/dL at 4 weeks, 101 µg/dL at 8 weeks and 101 µg/dL at 12 weeks). The rate of improvement in dysgeusia increased over time (18.2% at 4 weeks, 33.3% at 8 weeks, and 42.4% at 12 weeks). Comparing the effective group and non-effective group revealed that while the median serum albumin level of the effective group did not change, the non-effective group showed a significant decrease from baseline to 12 weeks (3.2 g/dL to 3.0 g/dL, p = 0.03).
CONCLUSIONS: Zinc supplementation significantly increased serum zinc levels, improving dysgeusia. Zinc supplementation might also contribute to maintaining nutritional status in patients with unresectable PC.

UNASSIGNED: This study aimed to investigate the clinical features of long COVID cases presenting with upper respiratory symptoms, a topic not yet fully elucidated.
UNASSIGNED: Prospective cohort study.
UNASSIGNED: A multicenter study involving 26 medical facilities in Japan.
UNASSIGNED: Inclusion criteria were patients aged ≥18 years old with a confirmed COVID-19 diagnosis via severe acute respiratory syndrome coronavirus 2 polymerase chain reaction or antigen testing, who were hospitalized at the participating medical facilities. Analyzing clinical information and patient-reported outcomes from 1009 patients were analyzed. The outcome measured the degree of initial symptoms for taste or olfactory disorders and assessed the likelihood of these symptoms persisting as long COVID, as well as the impact on quality of life if the upper respiratory symptoms persisted as long COVID.
UNASSIGNED: Patients with high albumin, low C-reactive protein, and low lactate dehydrogenase in laboratory tests tended to experience taste or olfactory disorders as part of long COVID. Those with severe initial symptoms had a higher risk of experiencing residual symptoms at 3 months, with an odds ratio of 2.933 (95% confidence interval [CI], 1.282-6.526) for taste disorders and 3.534 (95% CI, 1.382-9.009) for olfactory disorders. Presence of upper respiratory symptoms consistently resulted in lower quality of life scores.
UNASSIGNED: The findings from this cohort study suggest that severe taste or olfactory disorders as early COVID-19 symptoms correlate with an increased likelihood of persistent symptoms in those disorders as long COVID.

BACKGROUND: This study aims to assess the relationship between use of tobacco products and taste and smell disorders.
METHODS: A secondary dataset analysis of cross-sectional data from the National Health Interview Survey (NHIS) 2021 survey cycle, a nationally representative annual cross-sectional interview of non-institutionalized US civilians, was used. Participants\' senses of smell and taste are assessed using self-reported questions. Participants were categorized into five groups based on their tobacco use: non-tobacco users; cigarettes only; e-cigarettes only; cigar, pipe, or smokeless tobacco; and poly-tobacco product users. Disorders were defined as any self-reported difficulty in smelling, tasting, or reporting unpleasant odors or persistent tastes. Weighting procedures were used to estimate the national prevalence of taste, smell, and other disorders, stratified by tobacco products used. Adjusted logistic regression models were used to determine the association between tobacco products used and taste or smell compared to non-tobacco users.
RESULTS: A total of 40.2 million US adults reported experiencing smell or taste disorders. Nearly one in 10 adults reported a taste disorder (9.8%), and 13.4% indicated a smell disorder. The prevalence of taste or smell disorder was higher among females (17.5%), Hispanics (19.5%), individuals identified as \'other\' racial minorities (21.1%), and lower income groups (21%). Compared to non-tobacco users, the highest odds of experiencing smell or taste disorders were among poly-tobacco product users (adjusted odds ratio, AOR=1.44; 95% CI: 1.31-1.58), followed by e-cigarette-only users (AOR=1.38; 95% CI: 1.02-1.87), cigarette-only smokers (AOR=1.17; 95% CI: 1.04-1.32), and users of cigars, pipes, or smokeless tobacco (AOR=1.15; 1.00; and 1.33; respectively).
CONCLUSIONS: Tobacco product use was associated with an increased risk of smell and taste disorders. The rising use of e-cigarettes among adolescents and young adults is particularly concerning given the limited understanding of the sensory effects of e-cigarettes and their growing popularity among younger populations. The study findings highlight the need for interventions aimed at reducing tobacco use of all kinds.

Drug-induced taste disorders are a serious problem in an aging society. This study investigated the mechanisms underlying taste disturbances induced by diclofenac, a non-steroidal anti-inflammatory drug that reduces pain and inflammation by inhibiting the synthesis of prostaglandins by cyclooxygenase enzymes (COX-1 and COX-2). RT-PCR analyses demonstrated the expression of genes encoding arachidonic acid pathway components such as COX-1, COX-2 and prostaglandin synthases in a subset of mouse taste bud cells. Double-staining immunohistochemistry revealed that COX-1 and cytosolic prostaglandin E synthase (cPGES) were co-expressed with taste receptor type-1 member-3 (T1R3), a sweet/umami receptor component, or gustducin, a bitter/sweet/umami-related G protein, in a subset of taste bud cells. Long-term administration of diclofenac reduced the expression of genes encoding COX-1, gustducin and cPGES in mouse taste buds and suppressed both the behavioral and taste nerve responses to sweet and umami taste stimuli but not to other tastants. Furthermore, diclofenac also suppressed the responses of both mouse and human sweet taste receptors (T1R2/T1R3, expressed in HEK293 cells) to sweet taste stimuli. These results suggest that diclofenac may suppress the activation of sweet and umami taste cells acutely via a direct action on T1R2/T1R3 and chronically via inhibition of the COX/prostaglandin synthase pathway inducing down-regulated expression of sweet/umami responsive components. This dual inhibition mechanism may underlie diclofenac-induced taste alterations in humans.

UNASSIGNED: Taste disorders in patients with thymoma accompanied by myasthenia gravis (MG) is rare.
UNASSIGNED: The first case was a male in his 50s who underwent surgery for Masaoka stage III type B3 thymoma. He experienced a loss of taste before surgery, which showed no improvement after surgery. Due to a MG crisis 44 days after surgery, the patient underwent intensive treatment with mechanical ventilation, steroid pulse therapy, and intravenous immunoglobulin (IVIG) therapy. The patient recovered taste when he started oral food intake after the treatment for the MG crisis (about 3 months after surgery). Despite the recovery of taste after steroid pulse therapy and IVIG therapy, taste disorder gradually worsened about 1 year and 9 months after surgery, resulting in an almost complete loss of sweet taste 2 years after surgery. The second case was a male in his 60s who underwent surgery for Masaoka stage II type B1 thymoma. He experienced loss of taste before surgery, which showed no improvement after surgery. Five years and two months after surgery, the patient was diagnosed with a MG crisis and underwent steroid pulse therapy. Along with improvements in MG symptoms, taste disorders gradually improved. After 6 years and 10 months of surgery, the patient is still alive without MG symptoms (only pyridostigmine, 180 mg/body/day), taste disorder, and thymoma recurrence.
UNASSIGNED: The autoimmune mechanism may contribute to taste disorders in patients with thymoma, which can be recovered by immunosuppressive treatment in our cases.

Drug-induced taste disorders reduce quality of life, but little is known about the molecular mechanisms by which drugs induce taste disturbances. In this study, we investigated the short-term and long-term effects of the antiarrhythmic drug flecainide, which is known to cause taste dysfunction. Analyses of behavioral responses (licking tests) revealed that mice given a single intraperitoneal injection of flecainide exhibited a significant reduction in preference for a sour tastant (HCl) but not for other taste solutions (NaCl, quinine, sucrose, KCl and monopotassium glutamate) when compared with controls. Mice administered a single dose of flecainide also had significantly higher taste nerve responses to HCl but not to other taste solutions. Compared with controls, mice administered flecainide once-daily for 30 d showed a reduced preference for HCl without any changes in the behavioral responses to other taste solutions. The electrophysiological experiments using HEK293T cells transiently expressing otopetrin-1 (Otop1; the mouse sour taste receptor) showed that flecainide did not alter the responses to HCl. Taken together, our results suggest that flecainide specifically enhances the response to HCl in mice during short-term and long-term administration. Although further studies will be needed to elucidate the molecular mechanisms, these findings provide new insights into the pathophysiology of drug-induced taste disorders.

Since the worldwide spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, treating taste and saliva secretory disorders associated with coronavirus disease 2019 (COVID-19) has become a critical issue. The aim of the present study was to update information on treatments applicable to such oral symptoms and discuss their pathogenic mechanisms. The literature search indicated that different treatments using tetracycline, corticosteroids, zinc, stellate ganglion block, phytochemical curcumin, traditional herbal medicine, nutraceutical vitamin D, photobiomodulation, antiviral drugs, malic acid sialagogue, chewing gum, acupuncture, and/or moxibustion have potential effects on COVID-19-associated ageusia/dysgeusia/hypogeusia and xerostomia/dry mouth/hyposalivation. These treatments have multiple modes of action on viral cellular entry and replication, cell proliferation and differentiation, immunity, and/or SARS-CoV-2 infection-induced pathological conditions such as inflammation, cytokine storm, pyroptosis, neuropathy, zinc dyshomeostasis, and dysautonomia. An understanding of currently available treatment options is required for dental professionals because they may treat patients who were infected with SARS-CoV-2 or who recovered from COVID-19, and become aware of their abnormal taste and salivary secretion. By doing so, dentists and dental hygienists could play a crucial role in managing COVID-19 oral symptoms and contribute to improving the oral health-related quality of life of the relevant patients.

Loss of taste (ageusia) is a symptom observed following recovery from COVID-19 infection. The loss of taste and smell sensation may negatively affect patients\' quality of life (QoL). The present study aimed to evaluate the effectiveness of the Diode Laser in managing loss of taste sensation in patients with post-COVID syndrome versus the placebo.
The study sample was 36 patients who complained of persistent loss of taste sensation following COVID-19. The patients were randomly assigned to one of the two groups according to the received treatment: Group I (laser treatment) and Group II (light treatment), with each patient receiving a diode laser treatment or placebo from the same operator. Taste sensation was subjectively measured after treatment for four weeks.
The results demonstrated a significant difference between both groups regarding taste restoration after one month (p = 0.041), with Group II having a significantly higher percentage of cases 7 (38.9%) with partial taste restoration. In contrast, a significantly higher proportion of Group I 17 cases (94.4%) had complete taste restoration (p < 0.001).
The present study concluded that using a Diode laser 810 nm aided in a more rapid recovery from loss of taste dysfunction.