Salty taste acuity is affected by the joint action of αENaC A663T gene polymorphism and available zinc intake in young women

Quantitive Assessment of Gustatory Function and Its Association with Demographics, and Systemic Morbidity

This study aimed to analyze the associations of gustatory dysfunction as measured by validated taste strips with demographics and co-morbidities. This cross-sectional study retrospectively analyzed records of patients who attended the Orofacial Chemosensory Center of Hadassah Medical Center between 2017 and 2020. Taste strips were used as a validated method to determine taste dysfunction. A total of 272 subjects were included, 137 (50.4%) women and 135 (49.6%) men, with a mean age of 53.5 ± 19.3 years and age range of 18-98 years. The total taste score among the study population was 8.53 ± 4.03 (scale range 0-16). Age had a significant negative correlation with the total taste score (p = 0.001), and men exhibited worse total (p < 0.001), salty (p = 0.003), and bitter (p < 0.001) scores. Major trauma was associated with worse total (p < 0.001) and specialized taste assessments (sweet (p = 0.001), sour (p = 0.002), salty (p = 0.016), and bitter (p < 0.001)). Chemotherapy was associated with reduced total (p < 0.001), salty (p = 0.003), and bitter (p = 0.001) taste scores. Zinc deficiency exhibited worse salty (p = 0.027) and total (p = 0.038) taste scores. Patients with burning mouth syndrome (BMS) showed higher salty scores (p = 0.017). Patients who experienced exposure to toxic chemicals exhibited worse salty scores (p = 0.024). We conclude that gustatory dysfunction is associated with older age, male sex, and co-morbidities of major trauma, current chemotherapy, zinc deficiency, BMS, and exposure to toxins. The study highlights the importance of systemic evaluation and quantitive gustatory dysfunction assessment as part of the diagnostic process of patients with subjective complaints of taste disorders.

Smell, taste and food habits changes along body mass index increase: an observational study

PURPOSE

To evaluate the changes in gustatory and olfactory sensitivity and dietary habits between healthy lean subjects (LS) and participants affected by overweight (OW), stage I and II obesity and to estimate possible impact of these factors on body mass index (BMI).

METHODS

After a general and ear-nose-throat evaluation, taste and olfactory function testing by means of taste strips and sniffin' stick tests, respectively, and food habits analysis by means of food frequency questionnaire (FFQ), 221 participants (68 LS [33 female; mean age = 53.01 ± 7.54 years]; 51 OW [26 female; mean age = 51.5 ± 12.16 years]; 50 stage I obesity [24 female; mean age = 50.78 ± 13.71 years] and 52 stage II obesity [24 female; mean age = 52.21 ± 13.35 years]) were enrolled in the study.

RESULTS

Significant (p < 0.008) reductions in total and subtest taste and smell scores were found in stage I and II obesity when compared to LS and OW participants. FFQ depicted a progressive intake increase of nutrients along the BMI stages. Significant associations were found between BMI and taste/smell subtests sugar taste carbs, saturated, monounsaturated and polyunsaturated fatty acids.

CONCLUSIONS

These data demonstrated for the first time a parallel impairment in smell and taste in a large sample size of participants from lean to stage II obesity and could reinforce those previous theories claiming that the greater the ability in taste or smell qualities perception, the lower the preference for them, resulting in a lower intake of specific foods.

Taste Function in Adult Humans from Lean Condition to Stage II Obesity: Interactions with Biochemical Regulators, Dietary Habits, and Clinical Aspects

Differences in gustatory sensitivity, nutritional habits, circulating levels of modulators, anthropometric measures, and metabolic assays may be involved in overweight (OW) development. The present study aimed at evaluating the differences in these aspects between 39 OW (19 female; mean age = 53.51 ± 11.17), 18 stage I (11 female; mean age = 54.3 ± 13.1 years), and 20 II (10 female; mean age = 54.5 ± 11.9) obesity participants when compared with 60 lean subjects (LS; 29 female; mean age = 54.04 ± 10.27). Participants were evaluated based on taste function scores, nutritional habits, levels of modulators (leptin, insulin, ghrelin, and glucose), and bioelectrical impedance analysis measurements. Significant reductions in total and subtests taste scores were found between LS and stage I and II obesity participants. Significant reductions in total and all subtests taste scores were found between OW and stage II obesity participants. Together with the progressive increase in plasmatic leptin levels, insulin, and serum glucose, decrease in plasmatic ghrelin levels, and changes in anthropometric measures and nutritional habits along with body mass index, these data for the first time demonstrated that taste sensitivity, biochemical regulators, and food habits play a parallel, concurring role along the stages evolving to obesity.

Association of αENaC p. Ala663Thr Gene Polymorphism With Sudden Sensorineural Hearing Loss

Objective: The etiology of sudden sensorineural hearing loss (SSNHL) is still unknown. It has been demonstrated that normal endolymph metabolism is essential for inner ear function and that epithelial sodium channels (ENaC) may play an important role in the regulation of endolymphatic Na⁺. This study aimed to explore the potential association between αENaC p. Ala663Thr gene polymorphism and SSNHL. Methods: Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to examine the genotype and allele frequency of the αENaC p. Ala663Thr polymorphism in 20 cases of low-frequency SSNHL (LF-SSNHL), 19 cases of high-frequency SSNHL (HF-SSNHL), 31 cases of all frequency SSNHL (AF-SSNHL), 42 cases of profound deafness SSNHL (PD-SSNHL), and 115 normal controls. Results: The T663 allele was found to be significantly associated with an increased risk of LF-SSNHL (p = 0.046, OR = 2.16, 95% CI = 1.01-4.62). The TT genotype and T663 allele, on the other hand, conferred a protective effect for PD-SSNHL (AA vs. TT: p = 0.012, OR = 0.25, 95% CI = 0.08-0.74; A vs. T: p = 0.001, OR = 0.36, 95% CI = 0.21-0.61). However, there was no statistically significant difference in genotype or allele frequency between the two groups (HF-SSNHL and AF-SSNHL) and the control group. Conclusion: The αENaC p. Ala663Thr gene polymorphism plays different roles in different types of SSNHL.

Impact of Nutritional Intervention on Taste Perception-A Scoping Review

The aim of the present scoping review was to evaluate the impact of experimental meal loads or observational diet changes/habits on taste tests in both healthy subjects and patients. A systematic search performed in PubMed, Scopus, and Institute for Scientific Information (ISI) Web of Science electronic databases retrieved, respectively 2981, 6258, and 7555 articles from January 2000 to December 2020. A total of 17 articles were included for full-text review. Literature results were stratified according to the observational/interventional approach, the involvement of healthy subjects or patients, the taste test, and the meal/dietary changes. The present scoping review reinforced the notions postulating that certain taste tests (for example focusing on fatty acid, salt, or sugar) might be specifically influenced by the nutritional intervention and that other ones might be susceptible to a wide span of changes beyond the extent of tastant included in the specific food changes. This could also depend on the inhomogeneity of literature trend: The short duration of the intervention or the random type of meal load, unsuitability of the taste test chosen, and the presence of underlying disorders. Future studies for a better comprehension of taste tests reliability in relation to specific food changes are thus to be fostered.

COVID-19 as a worldwide selective event and bitter taste receptor polymorphisms: An ecological correlational study

Background

Given the observed olfactory and gustatory dysfunctions in patients with COVID-19 and recent findings on taste receptors possible important activities in the immune system, we elected to estimate the correlation between COVID-19 mortality and polymorphism of a particular type of bitter taste receptor gene called TAS2R38, in a worldwide epidemiological point of view.

Methods

Pooled rate of each of the rs713598, rs1726866, rs10246939, and PAV/AVI polymorphisms of the TAS2R38 gene was obtained in different countries using a systematic review methodology and its relationship with the mortality of COVID-19. Data were analyzed by the comprehensive meta-analysis software and SPSS.

Results

There was only a significant reverse Pearson correlation in death counts and PAV/AVI ratio, p = 0.047, r = −0.503. Also, a significant reverse correlation of PAV/AVI ratio and death rate was seen, r = −0.572 p = 0.021. rs10246939 ratio had a significant positive correlation with death rate, r = 0.851 p = 0.031. Further analysis was not significant. Our results showed that the higher presence of PAV allele than AVI, and a higher rate of G allele than A in rs10246939 polymorphism in a country, could be associated with lower COVID-19 mortality. While assessing all three polymorphisms showed a huge diversity worldwide.

Conclusion

Due to extraoral activities of bitter taste receptor genes, especially in mucosal immunity, this gene seems to be a good candidate for future studies on COVID-19 pathophysiology. Also, the high worldwide diversity of TAS2R38 genes polymorphism and its possible assassination with mortality raises concerns about the efficiency of vaccine projects in different ethnicities.

Elevated Salt Taste Threshold Is Associated with Increased Risk of Coronary Heart Disease

High salt intake has been associated with coronary heart disease (CHD). The salt taste threshold could affect the salt intake, but its role in CHD is uncertain. We studied the association of salt taste threshold with CHD. In this study, the levels of salt detection threshold, recognition threshold, and taste preference were higher in CHD than in controls. The salt taste recognition threshold was significantly associated with CHD, and the significant association persisted after adjustment for traditional risk factors. Individuals with high level of salt taste recognition threshold were at a greater risk of CHD. Coincident occurrence of high level of salt taste recognition threshold, hypertension, and diabetes increased the risk of CHD. Thus, a high level of salt taste recognition threshold increases the risk of CHD, and the concurrence of high level of salt taste recognition threshold, hypertension, and diabetes further increases the risk of CHD.

Dietary Sodium Intake is Predicted by Antihypertensive Medication Regimen in Patients With Heart Failure

BACKGROUND

Low-sodium diet adherence is foundational to heart failure (HF) self-management. Altered salt taste perception caused by angiotensin-converting enzyme (ACE) inhibitors commonly prescribed to patients with HF may increase sodium consumption. We hypothesized sodium intake, indicated by dietary sodium density, would be significantly higher among patients with HF prescribed ACE inhibitors compared with those not prescribed the drug.

OBJECTIVE

The aim of this study was to assess the association between prescribed ACE inhibitors and dietary sodium density in patients with HF.

METHODS

We conducted a secondary analysis of baseline data from patients with HF in an observational longitudinal study. Sodium density was derived by dividing averaged daily sodium intake from 4-day food diaries by averaged kilocalories consumed. Medical chart review was conducted to ascertain prescribed medications. Patients were categorized as prescribed and not prescribed an ACE inhibitor. t Tests were conducted to compare sodium intake between groups, and linear regression was conducted to examine whether prescribed ACE inhibitors independently predicted sodium density controlling for age, gender, New York Heart Association class, prescribed diuretics, and β-blockers.

RESULTS

Analyses included 255 patients with HF aged 61 ± 12 years, with 67% male, 44% New York Heart Association class III/IV, and 68% prescribed an ACE inhibitor. Compared with those not prescribed an ACE inhibitor, 13% more sodium per kilocalorie was consumed by patients prescribed an ACE inhibitor. Prescribed ACE inhibitor independently predicted dietary sodium density (β = 0.238, P = .009).

CONCLUSIONS

Sodium intake was higher among patients prescribed ACE inhibitors. Interventions to assist patients with HF with dietary sodium adherence can be informed by assessing medication regimens.

Impact of Taste on Food Choices in Adolescence-Systematic Review and Meta-Analysis

Studies of adults report that perceived taste affects food choices and intake, which in turn may have an impact on health. However, corresponding evidence on adolescents is limited.  Our aim was to summarize current evidence of the impact of taste perception on food choice preferences or dietary intakes among adolescents (mean age 10-19.9 years). Systematic searches identified 13 papers, 12 cross-sectional and one cohort study published between 1 January 2000 to 20 February 2020 assessing the impact of taste (using phenotypic and/or genotypic markers) on food choices in adolescents without any disease conditions. Qualitative assessment in the current review indicated that individuals sensitive to bitter tastes often have a lower preference of bitter-tasting food and higher preference for sweet-tasting food. A meta-analysis of three studies on bitter-taste sensitivity revealed no difference in preference for bitter-tasting vegetables between bitter tasters and non-tasters (standardized mean difference (SMD) = 0.04; 95% CI: -0.18, 0.26; p = 0.72). Overall, a limited number of studies were available for review. As a result, we report no clear relationship between taste perception and food choices or intake in adolescents. More studies are needed to evaluate the link between adolescents' taste perceptions and dietary intake.

TAS2R38 Haplotype Predicts 24-Hour Urinary Sodium Excretion in Patients With Heart Failure and Their Family Caregivers

BACKGROUND

Adherence to a low-sodium diet is essential to self-care of heart failure (HF). Genetic determinants of preference for high-sodium foods may impede adherence but have not been well-studied.

OBJECTIVE

Our purpose was to examine if TAS2R38 haplotype predicted salt taste sensitivity and dietary sodium intake among patients with HF.

METHOD

This pilot study used baseline data from a large interventional randomized control trial to support adherence to a low-sodium diet in patients with HF and their family caregivers. Participants were tested for salt taste sensitivity and provided a 24-hour urinary sodium sample and a blood sample for DNA analysis at baseline. Fungiform papillae were counted. χ2 Test and 1-way analysis of variance were used to compare haplotype groups. Linear regression was performed to examine predictors of salt taste sensitivity and 24-hour urinary sodium excretion, controlling for age, gender, ethnicity, smoking status, and fungiform papillae density.

RESULTS

There were 42 patients with HF and their family caregivers (age, 64.6 ± 13.4 years, 46.5% male, 97.7% white, and 90.7% nonsmoker). Pronine-alanine-valine homozygous haplotype predicted lower urinary sodium excretion (b = -1780.59, t41 = -2.18, P = .036), but genotype was not a significant predictor of salt taste sensitivity.

CONCLUSIONS

The results of our study partially supported our hypothesis that PAV homozygous haplotype predicts 24-hour urinary sodium excretion. With our small sample size, more research is needed. Understanding genetic influences on taste can lead to development of educational interventions tailored to patients with HF and their family caregivers to better support dietary adherence.

Association between taste perception and adiposity in overweight or obese older subjects with metabolic syndrome and identification of novel taste-related genes

BACKGROUND

The relation between taste perception, diet, and adiposity remains controversial. Additionally, there is a lack of knowledge on the polymorphisms influencing taste given the scarcity of genome-wide association studies (GWASs) published.

OBJECTIVES

We studied the relation between perception of the basic tastes, i.e., sweet, salty, bitter, sour, and umami (separately and jointly in a "taste score"), and anthropometric measurements in older subjects with metabolic syndrome (MetS). GWASs were undertaken to identify genes associated with basic tastes and their score.

METHODS

Taste perception was cross-sectionally determined by challenging subjects (381 older individuals with MetS) with solutions (5 concentrations) of the basic tastes with the use of standard prototypical tastants (phenylthiocarbamide and 6-n-propylthiouracil, NaCl, sucrose, monopotassium glutamate, and citric acid, for bitter, salt, sweet, umami, and sour, respectively). Taste perception intensities were expressed on a scale. A total taste score was derived.

RESULTS

The total taste score was inversely associated with body weight, body mass index, and waist circumference (P < 0.05). Subjects having a total taste score higher than or equal to the median (11 points for concentration V) were less likely to be classified as obese than subjects below the median (OR: 0.36; 95% CI: 0.22, 0.59; P < 0.001). Associations were similar, albeit less strong, for some taste qualities. In the GWASs, the highest associations were for bitter taste (rs1726866-TAS2R38, with P = 7.74 × 10-18 for phenylthiocarbamide and P = 3.96 × 10-19 for 6-n-propylthiouracil). For other tastes, several single-nucleotide polymorphisms (SNPs) exceeded the P threshold of 1 × 10-5. However, the top-ranked SNPs independently explained a low percentage of taste variability, hence their use as single proxies for the association between taste perception and adiposity is limited.

CONCLUSIONS

We found a strong inverse association between greater taste perception and body weight, body mass index, and waist circumference in older subjects with MetS and identified some taste-related SNPs. It would be advantageous to identify additional genetic proxies for taste and to develop polygenic scores. Data used in this study were derived from the clinical trial PREDIMED PLUS at baseline, registered at http://www.isrctn.com as ISRCTN89898870.

Unstimulated saliva: Background noise in taste molecules

Saliva is a highly complex bodily fluid composed of many proteins, peptides, small organic molecules, and ions. Saliva is produced and secreted by the major and minor salivary glands to protect the mouth and to participate in digestion. Generally, a distinction is made between unstimulated saliva that is a result of autonomic stimulation and stimulated saliva that is produced during chewing and taste stimulation. The link between saliva and sensory perception can thus be regarded in two ways: the role of unstimulated saliva as a background taste and the mechanistic role of stimulated saliva during eating. Indeed, unstimulated saliva (and its components) is continuously bathing our oral cavity and as such stimulates our taste receptors, thus playing a role in taste sensitivity. However, the role of unstimulated salivary components in mediating taste has been studied only in very few substances. To explore this question, this review attempts to compare data from the literature on unstimulated salivary composition with those on taste sensitivity. The main conclusion centres around the concept that the gustatory self-adaptation phenomenon may be relevant for only a few salivary compounds. Further studies at the level of the salivary Von Ebner glands and salivary pellicle are necessary before arriving at definitive conclusions on this subject. PRACTICAL APPLICATION: Unstimulated saliva contains taste substances that can influence sensory perception through taste adaptation. However, large inter-individual variability exists in unstimulated salivary composition both qualitatively and quantitatively. These differences may explain the variability in taste perception and thus the food choices and behaviors of an individual. Thus, in the context of providing personalized food and nutrition to the consumer, variability of unstimulated saliva should be considered for specific formulation of food products.

Effect of Salt Reduction on Consumer Acceptance and Sensory Quality of Food

Reducing salt (NaCl) intake is an important public health target. The food industry and catering services are searching for means to reduce the salt content in their products. This review focuses on options for salt reduction in foods and the sensory evaluation of salt-reduced foods. Simple salt reduction, mineral salts and flavor enhancers/modifiers (e.g., umami compounds) are common options for salt reduction. In addition, the modification of food texture and odor-taste interactions may contribute to enhanced salty taste perception. Maintaining consumer acceptance of the products is a challenge, and recent examples of the consumer perception of salt-reduced foods are presented.

Arginyl dipeptides increase the frequency of NaCl-elicited responses via epithelial sodium channel alpha and delta subunits in cultured human fungiform taste papillae cells

Salty taste is one of the five basic tastes and is often elicited by NaCl. Because excess sodium intake is associated with many health problems, it could be useful to have salt taste enhancers that are not sodium based. In this study, the regulation of NaCl-induced responses was investigated in cultured human fungiform taste papillae (HBO) cells with five arginyl dipeptides: Ala-Arg (AR), Arg-Ala (RA), Arg-Pro (RP), Arg-Glu (RE), and Glu-Arg (ER); and two non-arginyl dipeptides: Asp-Asp (DD) and Glu-Asp (ED). AR, RA, and RP significantly increased the number of cell responses to NaCl, whereas no effect was observed with RE, ER, DD, or ED. We also found no effects with alanine, arginine, or a mixture of both amino acids. Pharmacological studies showed that AR significantly increased responses of amiloride-sensitive but not amiloride-insensitive cells. In studies using small interfering RNAs (siRNAs), responses to AR were significantly decreased in cells transfected with siRNAs against epithelial sodium channel ENaCα or ENaCδ compared to untransfected cells. AR dramatically increased NaCl-elicited responses in cells transfected with NHE1 siRNA but not in those transfected with ENaCα or ENaCδ siRNAs. Altogether, AR increased responses of amiloride-sensitive cells required ENaCα and ENaCδ.

The changes of zinc transporter ZnT gene expression in response to zinc supplementation in obese women

Obesity is associated with an alteration in zinc metabolism. This alteration may be associated with changes in gene expression of zinc transporters. In this study, we examined the leukocyte expression of zinc transporter ZnTs in response to zinc supplementation in young obese women. Thirty-five young obese women (BMI ≥ 25 kg/m(2)), aged 18-28 years, were randomly assigned to two groups: a placebo group or a zinc group (30 mg zinc/day for 8 weeks). Usual dietary zinc intake was estimated from 3-day diet records. Serum zinc and urinary zinc concentrations were measured by atomic absorption spectrometry. Messenger RNA (mRNA) levels of leukocyte ZnT transporters were examined using quantitative real-time PCR. Expression levels of two ZnT transporters, ZnT1 and ZnT5, in obese women, increased significantly after zinc supplementation. At the end of the study, mRNA levels of ZnT1 and ZnT5 showed no correlation with serum zinc or urinary zinc concentration in obese women. In addition, a further study was conducted to identify whether the association between the gene expression levels of leukocyte ZnT1 and ZnT5 and dietary zinc intake remained consistent in 216 healthy young adults aged 20-29 years. A positive correlation between ZnT1 and dietary zinc intake (r = 0.181, P = 0.089) was also observed in healthy men although the significance was marginal. Taken together, these results show that the gene expression levels of ZnT1 and ZnT5 may be changed by zinc intake, suggesting that zinc supplementation could potentially restore ZnT transporter expression in obese women with altered zinc metabolism.