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Food imageries that have inspired and embellished medical learning are, distressingly, vanishing from medical writings. A host of references to the aromas, shape, colour and texture of food have reinforced and stimulated generations of physicians to identify and understand disease. They have piqued interest in foods from lands afar and introduced an unsought dimension and enrichment to the medical lexicon. It is time to revisit this powerful tool and secure its place in medical teaching and records., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.)

Abstract Recent literature indicates that post-COVID-19 patients suffer from a plethora of complications, including chemosensory dysfunction. However, little attention has been given to understand the interactions between chemosensory, trigeminal, and salivary dysfunctions in these patients. The aims of this study were (1) to investigate the prevalence and combinations of chemosensory, trigeminal, and salivary dysfunctions, (2) to identify the odorants/tastants that are compromised, and (3) to explore possible associations between the four dysfunctions in post-COVID-19 patients. One hundred post-COVID-19 patients and 76 healthy controls (pre-COVID-19) were included in this cross-sectional, case-controlled study. Participants' smell, taste, trigeminal, and salivary functions were assessed. The patients had a significantly higher prevalence of parosmia (80.0%), hyposmia (42.0%), anosmia (53.0%), dysgeusia (34.0%), complete ageusia (3.0%), specific ageusia (27.0%), dysesthesia (11.0%) and dry mouth (18.0%) compared to controls (0.0% for all parameters, except 27.6% for hyposmia). Complete loss of bitter taste was the most prevalent specific ageusia (66.7%) and coffee was the most common distorted smell (56.4%). Seven different combinations of dysfunction were observed in the patients, the most common being a combination of olfactory and gustatory dysfunction (48.0%). These findings indicate that post-COVID-19 patients experience a range of chemosensory, trigeminal, and salivary disturbances, occurring in various combinations.

Olfaction is one of the five basic human senses, and it is known to be one of the most primitive senses. The sense of olfaction may have been critical for human survival in prehistoric society, and although many believe its importance has diminished over time, it continues to have an impact on human interaction, bonding, and propagation of the species. Even if we are unaware of it, the sense of smell greatly affects our lives and is closely related to overall quality of life and health. Nonetheless, olfaction has been neglected from a scientific perspective compared to other senses. However, olfaction has recently received substantial attention since the loss of smell and taste has been noted as a key symptom of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Studies investigating olfaction loss in association with coronavirus disease 2019 (COVID-19) have revealed that olfactory dysfunction can be both conductive and sensorineural, possibly causing structural changes in the brain. Olfactory training is an effective treatment for olfactory dysfunction, suggesting the reorganization of neural associations. A reduced ability to smell may also alert suspicion for neurodegenerative or psychiatric disorders. Here, we summarize the basic knowledge that we, as otorhinolaryngologists, should have about the sense of smell and the peripheral and central olfactory pathways for managing and helping patients with olfactory dysfunction.

Recently, smell and taste disorders have seen renewed interest, as these symptoms are frequent complications of SARS-CoV-2 infection, since approximately 60% of patients affected by COVID-19 have shown olfactory and gustatory alterations. Otolaryngology pays attention to taste and smell abnormalities (TSAs), especially when associated with oncology. TSAs are common symptoms in people affected by cancer, yet they are ignored and underestimated. The clinical outcome of TSAs in cancer evidences the importance of identifying them with chemotherapy or radiotherapy in general, and they are associated with many types of cancer. We recognize the findings of the literature on TSAs in cancer, evaluating how it is important to consider and identify these disorders concerning reduced food enjoyment or inappropriate nutrient intake, and modulating the nutritional status, quality of life, and impact of therapy. This review aims to critically evaluate and recognize the assessment and clinical perspectives of taste and smell disorders in a cancer population.

Bees are important pollinators of agricultural crops, but their populations are at risk when pesticides are used. One of the largest risks bees face is poisoning of floral nectar and pollen by insecticides. Studies of bee detection of neonicotinoids have reported contradictory evidence about whether bees can taste these pesticides in sucrose solutions and hence avoid them. Here, we use an assay for the detection of food aversion combined with single-sensillum electrophysiology to test whether the mouthparts of the buff-tailed bumblebee (Bombus terrestris) detect the presence of pesticides in a solution that mimicked the nectar of oilseed rape (Brassica napus). Bees did not avoid consuming solutions containing concentrations of imidacloprid, thiamethoxam, clothianidin, or sulfoxaflor spanning six orders of magnitude, even when these solutions contained lethal doses. Only extremely high concentrations of the pesticides altered spiking in gustatory neurons through a slight reduction in firing rate or change in the rate of adaptation. These data provide strong evidence that bumblebees cannot detect or avoid field-relevant concentrations of pesticides using information from their mouthparts. As bees rarely contact floral nectar with other body parts, we predict that they are at high risk of unwittingly consuming pesticides in the nectar of pesticide-treated crops.

Tastes typically evoke innate behavioral responses that can be broadly categorized as acceptance or rejection. However, research in Drosophila melanogaster indicates that taste responses also exhibit plasticity through experience-dependent changes in mushroom body circuits. In this study, we develop a novel taste learning paradigm using closed-loop optogenetics. We find that appetitive and aversive taste memories can be formed by pairing gustatory stimuli with optogenetic activation of sensory neurons or dopaminergic neurons encoding reward or punishment. As with olfactory memories, distinct dopaminergic subpopulations drive the parallel formation of short- and long-term appetitive memories. Long-term memories are protein synthesis-dependent and have energetic requirements that are satisfied by a variety of caloric food sources or by direct stimulation of MB-MP1 dopaminergic neurons. Our paradigm affords new opportunities to probe plasticity mechanisms within the taste system and understand the extent to which taste responses depend on experience.

Objective: To identify the clinical presentation and factors associated with anosmia and ageusia in patients with COVID-19 in a health center in a province of Peru for the period 2020-2021. Methods: Cross-sectional analytical study through data from the COVID-19 program of the Essalud Polyclinic in Jauja, Peru. Sociodemographic characteristics, symptoms and comorbidities of the patients were detailed. A bivariate analysis identified the factors associated with anosmia and ageusia. Results: 356 patients were identified: 53.1 % were women, mean age was 48.7 years (±17.8) and 261 (73.3%) with mild COVID-19. Of the total, 22.2% had anosmia and 19.9% ageusia; of which the majority were under 65 and female. Associated symptoms were found in 86.1% of patients with anosmia and 83.1% with ageusia. The main factors associated with anosmia were age younger than 65 years (p=0.027), cough (p

Objective:To evaluate the smell and taste impairment in Coronavirus disease-2019 (COVID-19) pediatric patients according to the disease severity.Method:Ninety polymerase chain reaction test-confirmed COVID-19 patients were enrolled from January 2021 to July 2021. Patients were categorized into three main groups according to the stage of disease (stage 1: Outpatients, stage 2: Inpatients, stage 3: Intensive care unit patients). There were 30 pediatric patients in each group. Subjects were evaluated with a questionnaire. Visual analog scale was used to evaluate smell and taste impairment patients.Results:The impairment of smell and taste were evaluated separately, and the rates were found to be 31.1% and 35.6%, respectively. The impairment of smell showed a statistically significant difference between the groups (p=0.002). The rate of smell impairment in the outpatients was found to be significantly higher than in the patients treated in the intensive care unit. The taste impairment did not show a statistically significant difference between the groups (p=0.109; p>0.01). Persistence of smell and taste impairment was found in 5.5% of the patients.Conclusion:The rate of smell impairment in the outpatients was found to be significantly higher than in the cases treated in the intensive care unit.

According to the medical tradition, the temperament of bodies came from the balance of their primary qualities – hot, cold, dry, and moist. However, physicians associated additional sensory properties with temperament in the field of pharmacology. These sensations included taste, color, and odor, which allow an appraisal of the constitution and active powers of drugs. The present paper examines this theme in late-Renaissance medicine, through the accounts of the French physician Jean Fernel (ca. 1497–1558) and the Italian physician Andrea Cesalpino (1519–1603). As will be shown, their respective interpretations of drug "faculties" offered original views on the relationship between temperament, sensory properties, and matter theories. Such discussions, in turn, revealed the Renaissance reception of Arabic-Latin pharmacology, Galenic medicine, and the Aristotelian physics of matter and form. [ABSTRACT FROM AUTHOR]

Background: Homeopathy is applied as a supportive in the treatment of viral infections and in relieving their symptoms. Objective: To create an awareness that effective remedial results can be obtained by homeopathy in patients with loss of smell and taste in Coronavirus Disease 2019. Methods: A prospective, cohort and randomized study was conducted. The main inclusion criterion was the loss of smell and taste for at least one week. Homeopathic remedies were also applied as supportive therapy. Visual Analog Scale (VAS) was used to evaluate the loss of smell and taste perception before and after treatment. Results: A total of 30 patients, 32.17±10.25 years, were included in the study. The mean pre-treatment VAS-smell perception of the patients was 0.67±1.24, while the mean VAS-taste perception was 2.57±3.01. After the treatment, the mean of VAS-smell perception was 8.67±1.92, while the mean of VAS-taste increased to 9.43±1.22. There was a strong positive correlation between ΔVAS-smell perception and ΔVAS-taste perception (r: 0.563, p: 0.001). There was also a strong negative correlation between ΔVAS-taste perception and the level of ferritin (r: -0.552, p: 0.002). Conclusion: The present study on the effective improvement via homeopathy treatment in patients with loss of smell and taste in COVID-19 that “has spoiled the taste of life and living” should be supported by further studies.

Breast milk is the optimal feeding, which meets all the newborn’s body needs. For nutritional support and development of the baby, at certain periods of life it is required to introduce complementary foods into the diet, which is an important intermediate link between the milk nutrition and the general diet. In addition, complementary foods contribute to the development of taste habits, introduce a baby to a variety of foods and tastes, to a more complex food texture, and contribute to the development of such important physiological skills as chewing and swallowing. Nutrition in infancy may influence eating behaviour and eating habits at a later age. The babies become familiar with scents in the mother’s womb via amniotic fluid and then during breastfeeding when scents and flavours from the mother’s diet are tasted.The article provides evidence in support of the recommended age when complementary foods should be introduced, the main factors affecting the eating behaviour of babies: exposure to sweet, salty, sour, bitter, or specific tastes. The impact of sweet foods on the health of babies in the future is of great importance, for example, it may increase a risk of developing overweight/obesity as compared to those who had the lowest intake of sweet foods. Attention is paid to the most important risk factor for developing early sensitization, namely the nature of feeding babies in the early period, and the immunogenicity evaluation of the first complementary foods. The article provides a rich selection of commercial first complementary foods that contribute to the correct development of eating habits in babies from an early age.

A fundamental question in sensory processing is how different channels of sensory input are processed to regulate behavior. Different input channels may converge onto common downstream pathways to drive the same behaviors, or they may activate separate pathways to regulate distinct behaviors. We investigated this question in the Drosophila bitter taste system, which contains diverse bitter-sensing cells residing in different taste organs. First, we optogenetically activated subsets of bitter neurons within each organ. These subsets elicited broad and highly overlapping behavioral effects, suggesting that they converge onto common downstream pathways, but we also observed behavioral differences that argue for biased convergence. Consistent with these results, transsynaptic tracing revealed that bitter neurons in different organs connect to overlapping downstream pathways with biased connectivity. We investigated taste processing in one type of downstream bitter neuron that projects to the higher brain. These neurons integrate input from multiple organs and regulate specific taste-related behaviors. We then traced downstream circuits, providing the first glimpse into taste processing in the higher brain. Together, these results reveal that different bitter inputs are selectively integrated early in the circuit, enabling the pooling of information, while the circuit then diverges into multiple pathways that may have different roles.

In recent months it has emerged that the novel coronavirus — responsible for the COVID-19 pandemic — causes reduction of smell and taste in a large fraction of patients. The chemosensory deficits are often the earliest, and sometimes the only signs in otherwise asymptomatic carriers of the SARS-CoV-2 virus. The reasons for the surprisingly early and specific chemosensory dysfunction in COVID-19 are now beginning to be elucidated. In this hypothesis review, we discuss implications of the recent finding that the prevalence of smell and taste dysfunction in COVID-19 patients differs between populations, possibly because of differences in the spike protein of different virus strains or because of differences in the host proteins that enable virus entry, thus modifying infectivity. We review recent progress in defining underlying cellular and molecular mechanisms of the virus-induced anosmia, with a focus on the emerging crucial role of sustentacular cells in the olfactory epithelium. We critically examine the current evidence whether and how the SARS-CoV-2 virus can follow a route from the olfactory epithelium in the nose to the brain to achieve brain infection, and we discuss the prospects for using the smell and taste dysfunctions seen in COVID-19 as an early and rapid diagnostic screening tool. Original article: Butowt R, von Bartheld CS. Anosmia in COVID-19: Underlying Mechanisms and Assessment of an Olfactory Route to Brain Infection. Neuroscientist. 2021;27(6):582-603. DOI: 10.1177/1073858420956905 The article was translated into Russian and published under the terms of the Creative Commons Attribution 4.0 license.

Background. The problem of the 21st century both in Poland and around the world is overweight and obesity, and diabetes. Due to the increased incidence of these diseases, the consumption of intense sweeteners, which are used as substitutes for sucrose, has increased. The purpose of this study was to evaluate the sweet taste intensity of selected sweeteners in comparison with the benchmark - beet sugar. Methods. The material for the study consisted of four sweeteners: sugar, xylitol, stevia, and cane sugar. The substances were subjected to dilution in an infusion of black tea. This tea was then divided into 4 portions and each portion was sweetened with a different sweetener at a rate of 20g per 1l of infusion. The samples were coded with 3-digit codes, and the paired method was used for sensory evaluation. A total of 78 people participated in the study. Results. Differences in the intensity of sweet taste between beet sugar and the substitutes used were confirmed. Cane sugar and xylitol were characterized by a lower intensity of sweet taste, but these substitutes were preferred compared to beet sugar. Stevia is characterized by greater sweetness than beet sugar, while survey respondents strongly preferred beet sugar. Conclusions. Consumers, participating in the survey, prefer products with a less intensely sweet taste. Learning about consumers' preferences for sweet taste will allow the use of appropriately preferred substances in the production of food and dishes. This will have a positive effect on the sugar content of the daily ration and its overall consumption.

Background and Objectives The association between chemosensory dysfunction (CSD) and coronavirus disease 2019 (COVID-19) remains unclear. The aim of the present study was to determine the incidence of olfactory and taste dysfunction in asymptomatic and mildly symptomatic patients with COVID-19 and to evaluate the symptoms associated with CSD in patients with COVID-19. Materials and Method On March 9, 2020, 309 patients with asymptomatic or mildly symptomatic COVID-19 confirmed by real-time polymerase chain reaction (RT-PCR) were admitted to the No. 7 Community Treatment Center in Korea. An internet-based survey about symptomatology was administered to these patients, with responses obtained from 244 (79.0%). Subjects who completed the survey were enrolled in this study and were categorized into either a CSD group or a normal chemosensory group based on the presence or absence of CSD, respectively. Results General symptoms, including fever, myalgia, and chills, were most common (29.1%), followed by upper respiratory tract infection (URI) symptoms (20.9%), CSD (20.5%), and nasal symptoms (13.5%). In patients with CSD (n=50), 10 (4.1%) reported no other symptoms. After adjustment for age, sex, past medical history, and other symptoms, general symptoms [odds ratio (OR), 3.63; confidence interval (CI), 1.70-7.76] and nasal symptoms (OR, 7.00; CI, 2.61-18.80) were significantly associated with CSD. Conclusion The incidence of CSD was relatively high (20.5%) in asymptomatic and mildly symptomatic patients with COVID-19. General symptoms were independent risk factors of CSD, suggesting a sensorineural mechanism for the observed olfactory and taste dysfunction.

Otopetrin (OTOP) channels are proton-selective ion channels conserved among vertebrates and invertebrates, with no structural similarity to other ion channels. There are three vertebrate OTOP channels (OTOP1, OTOP2, and OTOP3), of which one (OTOP1) functions as a sour taste receptor. Whether extracellular protons gate OTOP channels, in addition to permeating them, was not known. Here, we compare the functional properties of the three murine OTOP channels using patch-clamp recording and cytosolic pH microfluorimetry. We find that OTOP1 and OTOP3 are both steeply activated by extracellular protons, with thresholds of pHo pH 9.0). Strikingly, we could change the pH-sensitive gating of OTOP2 and OTOP3 channels by swapping extracellular linkers that connect transmembrane domains. Swaps of extracellular linkers in the N domain, comprising transmembrane domains 1–6, tended to change the relative conductance at alkaline pH of chimeric channels, while swaps within the C domain, containing transmembrane domains 7–12, tended to change the rates of OTOP3 current activation. We conclude that members of the OTOP channel family are proton-gated (acid-sensitive) proton channels and that the gating apparatus is distributed across multiple extracellular regions within both the N and C domains of the channels. In addition to the taste system, OTOP channels are expressed in the vertebrate vestibular and digestive systems. The distinct gating properties we describe may allow them to subserve varying cell-type specific functions in these and other biological systems.

Taste detection and hunger state dynamically regulate the decision to initiate feeding. To study how context-appropriate feeding decisions are generated, we combined synaptic resolution circuit reconstruction with targeted genetic access to specific neurons to elucidate a gustatory sensorimotor circuit for feeding initiation in adult Drosophila melanogaster. This circuit connects gustatory sensory neurons to proboscis motor neurons through three intermediate layers. Most neurons in this pathway are necessary and sufficient for proboscis extension, a feeding initiation behavior, and respond selectively to sugar taste detection. Pathway activity is amplified by hunger signals that act at select second-order neurons to promote feeding initiation in food-deprived animals. In contrast, the feeding initiation circuit is inhibited by a bitter taste pathway that impinges on premotor neurons, illuminating a local motif that weighs sugar and bitter taste detection to adjust the behavioral outcomes. Together, these studies reveal central mechanisms for the integration of external taste detection and internal nutritive state to flexibly execute a critical feeding decision.

Objective: Swallowing disorders are systematically present in patients with severe brain injury, disorders of consciousness, and subsequently poor quality of life. The study hypothesis was that taste and smell could improve swallowing function and quality of life in such patients, who are fed by gastrostomy tube. Methods: Eight patients with unresponsive wakefulness syndrome were included in this study. All patients had been in a stable state for at least 2 years, and the delay between the neurological event and the study was always more than 2 years. Strong tastes and smells were selected using the Pfister olfactory classification. Taste and smell stimulations were performed every weekday, Monday to Friday, for 1 week (5 sessions) by a speech and language therapist. Evaluation of swallowing was performed before the first session and after the fifth session, and included the number of spontaneous swallows during 10 min, the presence of drooling, and spontaneous tongue and velum mobility. Results: The number of spontaneous swallows at the initial evaluation was 6.8 ± 5.1 n/min. At the final evaluation there was a significant increase in the number of spontaneous swallows (9.1 ± 4.1 n/min, p < 0.01). Conclusion: This clinical observation has shown that taste and smell stimulations are relevant in clinical practice to improve spontaneous swallowing.

Introduction: Monosodium glutamate (MSG) is known as a flavor-enhancing compound and also the fifth basic taste (umami). About the safety of using MSG as a food additive, some studies show indications that there is no threat and others show the opposite. There is no consensus about the advantages and disadvantages of using MSG. Objective: To systematically review studies in the international literature on the knowledge of the pros and cons of using glutamate in food. Methods: Systematic review of studies published in journals indexed in ScienceDirect and PubMed databases. Articles published until 2020 were included. The aspects involving the advantages and disadvantages were discussed, as well as the health risks related to the MSG intake from diet. Results: The revised studies showed that MSG can reduce the amount of sodium in foods without modifying flavor. Although authorities indicate that MSG is safe for human consumption, some studies highlight that health risk is real. The use of MSG is still controversial because there are some misunderstandings in the applied amounts of MSG absorption and metabolism. Conclusion: MSG is widely applied in industrial and homemade food. The need for further studies is crucial, and aspects such as metabolism and amounts of MSG effectively consumed must be better evaluated.

Introduction The COVID-19 virus has already caused a pandemic and needs no fresh introduction. Many studies in western literature have described the prevalence of anosmia and ageusia as symptoms of COVID-19. However, to our knowledge, there is no study describing the trend of new onset ageusia amongst covid positive patients in the Indian population. The objective of this study is to analyze the trend of new onset ageusia in COVID-19 affected individuals in the Indian population. Materials and Methods This is a retrospective observational study conducted in a treatment facility set up in Eastern part of India. The data was collected from Sep 2020 to Dec 2020. The study included 422 patients who were laboratory confirmed COVID-19 positive cases. Clinical data was extracted from the medical records of the patients. All the patients were treated as inpatients. The data was collected by Critical care specialist and Physician. All patients were classified as asymptomatic and symptomatic. The presence or absence of new onset ageusia was documented and statistically analyzed. Results Of 422 cases studied, 401 (95.0%) were male and 21 (5.0%) were female with the mean age of 37.9 ± 8.3 years. 147 (34.8%) were symptomatic and 275 (65.2%) were asymptomatic with 18 % (76/422) patients having ageusia in the study population. Conclusion The prevalence of ageusia amongst covid positive patients in Indian population is lesser as compared to reports in the western literature. The cause of this difference in prevalence of ageusia in different ethnicities is unknown. Apparently healthy individuals with new onset ageusia should be considered as asymptomatic covid carriers and should be treated accordingly.

Abstract Background Wolfram syndrome is a rare genetic disease characterized by insulin-dependent diabetes, optic nerve atrophy, sensorineural hearing loss and neurodegeneration. Although olfactory dysfunction, a classical clinical marker of neurodegenerative processes, has been reported in Wolfram syndrome, its use as a clinical marker in Wolfram is limited due to data scarcity. In addition, it is unknown whether Wolfram syndrome affects the sense of taste. Methods Smell and taste perception were assessed in participants with Wolfram syndrome (n = 40) who were 15.1 ± 6.0 years of age (range: 5.1–28.7 years) and two sex- and age-matched control groups: one group with type 1 diabetes mellitus (T1D; n = 25) and a healthy control group (HC; n = 29). Smell sensitivity was assessed by measuring n-butanol detection thresholds and smell identification by using the University of Pennsylvania Smell Identification Test (UPSIT). Taste function was assessed using NIH Toolbox, which includes the assessment of sucrose (sweet) taste preference, and perceived intensity of sucrose, sodium chloride (salty), and quinine hydrochloride (bitter) both in the tip of the tongue (regional test) and the whole mouth. Results Smell sensitivity was not significantly different among groups; however, smell identification was impaired in Wolfram syndrome, as reflected by significantly lower UPSIT scores in Wolfram syndrome compared to HC and T1D (P

To survive in an ever-changing environment, animals must detect and learn salient information. The anterior insular cortex (aIC) and medial prefrontal cortex (mPFC) are heavily implicated in salience and novelty processing, and specifically, the processing of taste sensory information. Here, we examined the role of aIC-mPFC reciprocal connectivity in novel taste neophobia and memory formation, in mice. Using pERK and neuronal intrinsic properties as markers for neuronal activation, and retrograde AAV (rAAV) constructs for connectivity, we demonstrate a correlation between aIC-mPFC activity and novel taste experience. Furthermore, by expressing inhibitory chemogenetic receptors in these projections, we show that aIC-to-mPFC activity is necessary for both taste neophobia and its attenuation. However, activity within mPFC-to-aIC projections is essential only for the neophobic reaction but not for the learning process. These results provide an insight into the cortical circuitry needed to detect, react to- and learn salient stimuli, a process critically involved in psychiatric disorders.

Chemosensory systems are critical for evaluating the caloric value and potential toxicity of food. While animals can discriminate between thousands of odors, much less is known about the discriminative capabilities of taste systems. Fats and sugars represent calorically potent and attractive food sources that contribute to hedonic feeding. Despite the differences in nutritional value between fats and sugars, the ability of the taste system to discriminate between different rewarding tastants is thought to be limited. In Drosophila, taste neurons expressing the ionotropic receptor 56d (IR56d) are required for reflexive behavioral responses to the medium-chain fatty acid, hexanoic acid. Here, we tested whether flies can discriminate between different classes of fatty acids using an aversive memory assay. Our results indicate that flies are able to discriminate medium-chain fatty acids from both short- and long-chain fatty acids, but not from other medium-chain fatty acids. While IR56d neurons are broadly responsive to short-, medium-, and long-chain fatty acids, genetic deletion of IR56d selectively disrupts response to medium-chain fatty acids. Further, IR56d+ GR64f+ neurons are necessary for proboscis extension response (PER) to medium-chain fatty acids, but both IR56d and GR64f neurons are dispensable for PER to short- and long-chain fatty acids, indicating the involvement of one or more other classes of neurons. Together, these findings reveal that IR56d is selectively required for medium-chain fatty acid taste, and discrimination of fatty acids occurs through differential receptor activation in shared populations of neurons. Our study uncovers a capacity for the taste system to encode tastant identity within a taste category.

Embryonic taste bud primordia are specified as taste placodes on the tongue surface and differentiate into the first taste receptor cells (TRCs) at birth. Throughout adult life, TRCs are continually regenerated from epithelial progenitors. Sonic hedgehog (SHH) signaling regulates TRC development and renewal, repressing taste fate embryonically, but promoting TRC differentiation in adults. Here, using mouse models, we show TRC renewal initiates at birth and coincides with onset of SHHs pro-taste function. Using transcriptional profiling to explore molecular regulators of renewal, we identified Foxa1 and Foxa2 as potential SHH target genes in lingual progenitors at birth and show that SHH overexpression in vivo alters FoxA1 and FoxA2 expression relevant to taste buds. We further bioinformatically identify genes relevant to cell adhesion and cell locomotion likely regulated by FOXA1;FOXA2 and show that expression of these candidates is also altered by forced SHH expression. We present a new model where SHH promotes TRC differentiation by regulating changes in epithelial cell adhesion and migration.

The COVID-19 pandemic, driven by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has currently infected more than 61 million people and caused the death of more than 1.4 million around the world (November 2020 figures). As a result, many countries and health organizations have had to investigate the reasons for the pandemic and improve their health care programs to cope with the emergency while trying to develop an effective vaccine.

Introduction: There is increasing anecdotal evidence that olfactory and gustatory dysfunction may be associated with Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). Aim: The aim of this systematic review and meta-analysis was to find the association of olfactory and gustatory symptoms with Coronavirus Disease-19 (COVID-19) and estimate their pooled prevalence. Materials and Methods: PubMed, Embase, EBSCO and Cochrane databases were searched for cross-sectional, cohort and case-control studies evaluating olfactory and gustatory symptoms in patients with COVID-19. The search terms included COVID-19, severe acute respiratory syndrome coronavirus-2, coronavirus, olfaction disorders, anosmia, hyposmia, dysgeusia and ageusia. Random effects model was used to calculate a pooled Odds Ratio (OR) and pooled prevalence. Results: Total 14 studies were included in qualitative synthesis and 13 studies were incorporated in quantitative synthesis, involving 3,125 patients. The pooled OR was 15.59 reflecting that smell and taste disorders were strongly associated with COVID-19. The pooled prevalence of olfactory and gustatory dysfunction was 56% and 44%, respectively. Conclusion: It can be concluded that there is a significant association between olfactory and gustatory symptoms and COVID-19. Majority of the studies support the use of these symptoms as screening tools for COVID-19.

Introduction Subjective chemosensory function can differ from measured function. Previous studies on olfactory assessment have found a positive correlation between subjective and measured scores. However, information on gustatory correlation between measured and subjective functions is sparse in patients who have undergone an initial ear, nose and throat (ENT) evaluation. Objectives To evaluate the correlation between subjective and measured olfactory and gustatory dysfunctions in a population complaining of taste and/or smell dysfunction after an initial ENT evaluation without chemosensory testing. Furthermore, we aimed to assess the need for chemosensory testing depending on the type of subjective chemosensory dysfunction. Methods A case series in which subjective chemosensory function was assessed through a questionnaire and measured chemosensory function was assessed by validated clinical tests. Results In total, 602 patients with complaints of olfactory and/or gustatory dysfunction were included. We found that 50% of the patients with normal gustatory function and an olfactory impairment classified their olfactory impairment as a subjective taste disorder. Furthermore, 98% of the patients who rated their olfactory function as absent did have a measurable olfactory impairment, but only 64% were anosmic. Conclusion Subjective gustatory dysfunction was poorly correlated with measured gustatory dysfunction, and was often found to reflect olfactory dysfunction. Contrarily, subjective olfactory dysfunction was positively correlated with measurable olfactory dysfunction. Although subjective anosmia was a strong indicator of measured anosmia or hyposmia, the existence of remaining olfactory function was frequently found in these patients. Validated chemosensory testing should be performed in patients with perceived olfactory or gustatory deficits, as this could help ensure increased diagnostic precision and a relevant treatment.

INTRODUCTION: There is an existing variability in eating patterns between adolescents and children. Consequently, with the adoption of westernised way of life, this translates to a change in eating habits and food choices. This study was designed to investigate the dietary patterns and nutritional status of the female adolescents in Amai Secondary Commercial School, Delta State, Nigeria. METHODS: a cross-sectional study was conducted among 201 adolescent female students (12-18 years) using simple random sampling techniques. A self-administered questionnaire was used to obtain the information while anthropometric measurement was carried out to obtain the height and weight of the respondents. Data generated were analysed using SPSS version 22.0. RESULTS: majority of the respondents 129 (64.20%) were between the ages of 16-18 years. Measurement of nutritional status confirmed that 46.80% and 31.80% of the respondents were underweight and healthy weight respectively. In addition, the dietary pattern of the respondents demonstrated that they consumed proteinous, carbohydrate, and snacks occasionally. Factors that motivated respondents for good food choices include; nutritional status 71 (35.30%), taste 54 (26.90%), and popularity 15 (7.50%). CONCLUSION: under nutrition remains a challenge among rural adolescent girls in Amai community. Therefore sustained strategic nutritional campaigns should be carried out among female adolescents in Amai community in order to improve their nutritional status.

A 53-year-old woman presented during the SARS-CoV-2 pandemic with an 18-day history of pyrexia, myalgia, progressive dyspnoea and loss of taste and smell after a close contact had tested positive for SARS-CoV-2. In this period two swabs had been negative for SARS-CoV-2. Clinical examination was normal. During this admission a third SARS-CoV-2 swab was negative, and investigations showed mildly elevated inflammatory markers, mildly deranged liver function, atypical lymphocytes on a blood film and a normal chest x-ray. Her Epstein–Barr virus serology was positive and thus the diagnosis was infectious mononucleosis.

A novel, pleasant taste stimulus becomes aversive if associated with gastric malaise, a form of learning known as conditioned taste aversion (CTA). CTA is common to vertebrates and invertebrates and is an important survival response: eating the wrong food may be deadly. CTA depends on the gustatory portion of the insular cortex (GC) and the basolateral nucleus of the amygdala (BLA) however, its synaptic underpinnings are unknown. Here we report that CTA was associated with decreased expression of immediate early genes in rat GC of both sexes, and with reduced amplitude of BLA-GC synaptic responses, pointing to long-term depression (LTD) as a mechanism for learning. Indeed, association of a novel tastant with induction of LTD at the BLA-GC input in vivo was sufficient to change the hedonic value of a taste stimulus. Our results demonstrate a direct role for amygdalocortical LTD in taste aversion learning.

It is known that an eye-like image promotes generosity. It is also known that the evaluation of the visual deliciousness of food is improved in the presence of an emotionally positive stimulus. The purpose of the present study was to examine whether the presence of open eyes (OPEN) causes generous behavior altering the evaluation of the visual deliciousness of food, and how the images of open and closed eyes (CLOSED) affect human emotions. Seventeen women participated in the present study. A picture of food was presented on a computer screen, and the participants predicted and evaluated its visual deliciousness. An image of OPEN or that of CLOSED was presented simultaneously with a picture of food. There was a significant difference between the OPEN and CLOSED conditions, as demonstrated by the scores on a nine-point Likert scale for visual deliciousness; the ratings in the OPEN condition were significantly higher than those in the CLOSED condition (p = 0.004). There was no significant difference in the image of watchful eyes for the perceived relaxation state; the ratings in the OPEN condition were not significantly higher than those in the CLOSED condition (p = 0.716). The results of the present study revealed that the evaluation of the visual deliciousness of food based on its appearance was likely due to the presence of an image of open watchful eyes, increasing the perceived visual deliciousness of the food without any changes in the participants’ emotions.

From humans to vinegar flies, exposure to diets rich in sugar and fat lowers taste sensation, changes food choices, and promotes feeding. However, how these peripheral alterations influence eating is unknown. Here we used the genetically tractable organism D. melanogaster to define the neural mechanisms through which this occurs. We characterized a population of protocerebral anterior medial dopaminergic neurons (PAM DANs) that innervates the β’2 compartment of the mushroom body and responds to sweet taste. In animals fed a high sugar diet, the response of PAM-β’2 to sweet stimuli was reduced and delayed, and sensitive to the strength of the signal transmission out of the sensory neurons. We found that PAM-β’2 DANs activity controls feeding rate and satiation: closed-loop optogenetic activation of β’2 DANs restored normal eating in animals fed high sucrose. These data argue that diet-dependent alterations in taste weaken satiation by impairing the central processing of sensory signals.

The article presents modern data on the main molecular and genetic determinants of shaping the taste preferences. The authors present the structure and mechanism of the functioning of sweet taste receptors, umami taste, acidic and bitter tastes, as well as other molecules and cellular structures influencing the perception of flavors – the gust protein, toll-like receptors. They described the role of structures ensuring perception of taste outside the oral cavity – the cells of the hypothalamus. The article underlines the importance of the genetic polymorphism of these structures and the importance of interaction of genetic factors and environmental factors in shaping the taste preferences and eating behavior of the infant. Particular attention is given to the practical significance of the presented data in the context of introduction of supplemental foods for infants.

Abstract Background The salt-taste threshold can influence the salt appetite, and is thought to be another marker of sodium intake. Many studies have mentioned the relationship between the sodium intake and blood pressure (BP). The aim of this study was to evaluate the relationship between the salt-taste threshold and urinary sodium excretion in normotensive and hypertensive groups. Methods We analyzed 199 patients (mean age 52 years, male 47.3%) who underwent 24-h ambulatory BP monitoring (ABPM). Hypertension was diagnosed as an average daytime systolic BP of ≥135 mmHg or diastolic BP of ≥85 mmHg by the ABPM. We assessed the salt-taste threshold using graded saline solutions. The salt-taste threshold, 24-h urinary sodium and potassium excretion, and echocardiographic data were compared between the control and hypertensive groups. Results The detection and recognition threshold of the salt taste did not significantly differ between the control and hypertensive groups. The 24-h urinary sodium excretion of hypertensive patients was significantly higher than that of the control group (140.9 ± 59.8 vs. 117.9 ± 57.2 mEq/day, respectively, p = 0.011). Also, the urinary sodium-potassium ratio was significantly higher in the hypertensive patients. There was no correlation between the salt-taste threshold and 24-h urinary sodium excretion. Conclusions The salt-taste threshold might not be related to the BP status as well as the 24-h urinary sodium excretion.

Scientists from Oregon State University, USA, came up with the newest theory of the sixth taste – starch taste that might soon join the basic five tastes. This argument is supported by studies done on both animals and humans, the results of which seem to indicate the existence of separate receptors for starch taste, others than for sweet taste. Starch is a glucose homopolymer that forms an α-glucoside chain called glucosan or glucan. This polysaccharide constitutes the most important source of carbohydrates in food. It can be found in groats, potatoes, legumes, grains, manioc and corn. Apart from its presence in food, starch is also used in textile, pharmaceutical, cosmetic and stationery industries as well as in glue production. This polysaccharide is made of an unbranched helical structure – amylose (15–20%), and a structure that forms branched chains – amylopectin (80–85%). The starch structure, degree of its crystallisation or hydration as well as its availability determine the speed of food-contained starch hydrolysis by amylase. So far, starch has been considered tasteless, but the newest report shows that for people of different origins it is associated with various aliments specific for each culture. Apart from a number of scientific experiments using sweet taste inhibitors, the existence of the sixth taste is also confirmed by molecular studies. However, in order to officially include starch taste to the basic human tastes, it must fulfil certain criteria. The aim of the study is to present contemporary views on starch.

BACKGROUND AND AIM: The sense of taste is a chemical sense which allows everyone to perceive the flavor of what is eaten or drunk. Also, the sense of olfaction is also a chemical sense contributing to the sense of taste to perceive the taste and flavor of food. In the present work, the gustatory and olfactory function in pre- and postmenopausal women and men were studied and compared to each other. METHODS: Fifty postmenopausal women, 50 age-matched men, 50 young women and 50 young men were evaluated in this study and enrolled through simple sampling method. The aim of this study was explained for patients and in case of their consent, they were given the questionnaire. Taste threshold for each of the four main tastes for all of the participants in the study was determined at one step between 8 am to 11 am while they had not consumed any food since one hour before the test. The whole mouth taste method was used in this study. Also, the Davidson and Murphy tests were performed and the quality identification and intensity ratings of olfaction were measured. RESULTS: Three individuals among the postmenopausal women group and 2 old men were not able to detect sweet taste even in high concentration; in the group of young men, one man was not able to detect bitter taste even in high concentration. This study showed that 2% of postmenopausal women and 4% of matched men were not able to detect the odor of isopropanol even at a concentration of 70% and there was a significant relationship between odor perception of isopropanol and olfactory intensity between the two groups of pre- and postmenopausal women as well as men. CONCLUSION: Taste dysfunction directly influences nutritional status. In this study, the strength of the sweet taste perception was significantly lower among women after menopause; however, there was no significant difference between the perception of other tastes among postmenopausal women and men of same age.

The COVID-19 infection is caused by SARS-CoV-2 and it is considered by the WHO as a pandemic disease since February 2020. It is still an evolving disease, with new symptoms being discovered as time progress. A peculiar and interesting symptoms that has been frequently investigated by researchers across the globe are anosmia (loss of smell) and ageusia (loss of taste), as some subjects complain of diminution in the sense of smell and taste. Moreover, these symptoms may be the only or first clinical findings of the disease. Therefore, it is of utmost importance to isolate at home the individuals with recent smell and taste abnormalities (STA) without any other features of COVID-19 to prevent the transmission of the infection to healthy people [1].

It has been known for more than a century that, in adult vertebrates, the maintenance of taste buds depends on their afferent nerves. However, the initial formation of taste buds is proposed to be nerve-independent in amphibians, and evidence to the contrary in mammals has been endlessly debated, mostly due to indirect and incomplete means to impede innervation during the protracted perinatal period of taste bud differentiation. Here, by genetically ablating, in mice, all somatic (i.e. touch) or visceral (i.e. taste) neurons for the oral cavity, we show that the latter but not the former are absolutely required for the proper formation of their target organs, the taste buds.

Taste circuits are genetically determined to elicit an innate appetitive or aversive response, ensuring that animals consume nutritious foods and avoid the ingestion of toxins. We have examined the response of Drosophila melanogaster to acetic acid, a tastant that can be a metabolic resource but can also be toxic to the fly. Our data reveal that flies accommodate these conflicting attributes of acetic acid by virtue of a hunger-dependent switch in their behavioral response to this stimulus. Fed flies show taste aversion to acetic acid, whereas starved flies show a robust appetitive response. These opposing responses are mediated by two different classes of taste neurons, the sugar- and bitter-sensing neurons. Hunger shifts the behavioral response from aversion to attraction by enhancing the appetitive sugar pathway as well as suppressing the aversive bitter pathway. Thus a single tastant can drive opposing behaviors by activating distinct taste pathways modulated by internal state.

The regulation of feeding plays a key role in determining the fitness of animals through its impact on nutrition. Elucidating the circuit basis of feeding and related behaviors is an important goal in neuroscience. We recently used a system for closed-loop optogenetic manipulation of neurons contingent on the feeding behavior of Drosophila to dissect the impact of a specific subset of taste neurons on yeast feeding. Here, we describe the development and validation of this system, which we term the optoPAD. We use the optoPAD to induce appetitive and aversive effects on feeding by activating or inhibiting gustatory neurons in closed-loop – effectively creating virtual taste realities. The use of optogenetics allowed us to vary the dynamics and probability of stimulation in single flies and assess the impact on feeding behavior quantitatively and with high throughput. These data demonstrate that the optoPAD is a powerful tool to dissect the circuit basis of feeding behavior, allowing the efficient implementation of sophisticated behavioral paradigms to study the mechanistic basis of animals’ adaptation to dynamic environments.

Sensation and action are necessarily coupled during stimulus perception – while tasting, for instance, perception happens while an animal decides to expel or swallow the substance in the mouth (the former via a behavior known as ‘gaping’). Taste responses in the rodent gustatory cortex (GC) span this sensorimotor divide, progressing through firing-rate epochs that culminate in the emergence of action-related firing. Population analyses reveal this emergence to be a sudden, coherent and variably-timed ensemble transition that reliably precedes gaping onset by 0.2–0.3s. Here, we tested whether this transition drives gaping, by delivering 0.5s GC perturbations in tasting trials. Perturbations significantly delayed gaping, but only when they preceded the action-related transition - thus, the same perturbation impacted behavior or not, depending on the transition latency in that particular trial. Our results suggest a distributed attractor network model of taste processing, and a dynamical role for cortex in driving motor behavior.

A modest archetypal of satiation is that it boils down primarily to two categories of signals transmitted from the gastrointestinal tract to the brain: stomach and intestine sensing and metabolism. Novel investigations endow us with the view that an extension of this traditional model is conceivable and called for, wherein intestinal satiation is the byproduct not only from signals related to the caloric content of ingested nutrients, but also from noncaloric properties of ‘tastant molecules’ in foodstuff. On this paper we discuss a recently published paper regarding the impact of tastants (e.g., noncaloric substance widely used as taste enhancers) on hunger and food intake. We gather the in vivo results (nasoduodenal infusions of tastants) with a recently developed mathematical model for ghrelin by the author and co-workers and we successfully replicate in silico part of the findings. The key results from the abovementioned paper and replicated herein is that tastant can inhibit hunger; with different levels of impact, umami being the strongest one, and the union of them being even stronger.