Preference for and sensitivity to flavanol mean degree of polymerization in model wines is correlated with body composition.

Bitterness and astringency (dryness) are characteristic sensory attributes of flavanol-rich foods. The degree of polymerization (DP) of flavanols influences their bitter and astringent sensations. Smaller DP compounds can enter the papillae on the tongue, eliciting a bitter response. Larger DP compounds are sterically inhibited from entering papillae and instead interact with oral proteins, cause precipitation, and elicit astringent sensations. Previous research has indicated that bitterness preference is related to health status, density of fungiform papillae on the tongue, and sensitivity to bitter compounds such as 6-n-propyl-thiouracil (PROP). The purpose of this study was to examine trends in liking, bitterness intensity, and astringency intensity of wine-like products with flavanols of different DP using a consumer sensory panel. Participants (n = 102) were segmented by phenotypes: body fat percentage (BF%), body mass index (BMI), PROP sensitivity, and stated bitter food preference. Differences in wine liking, perceived bitterness intensity, and astringency intensity were observed between three model wine samples of varying flavanol mean degrees of polymerization (mDP, i.e. the average size (polymer length) of flavanol compounds in a mixture). Specifically, with increased mDP, overall liking and bitterness liking decreased, with concurrent increased perception of bitterness and astringency intensity. Greater differences between phenotypes were observed when participants were segmented by BF% and BMI classification, than when segmented by PROP sensitivity classification. Reduced ability to detect differences in bitterness and astringency were noted in participants of higher weight status. Overall, these data suggest that weight status in adults is a greater predictor of liking of flavanol-rich foods than bitterness sensitivity (as determined by PROP classification), and that reduced perception of bitterness and astringency associated with weight gain may impact selection and preference for these foods.

Awareness of dysgeusia and gustatory tests in patients undergoing chemotherapy for breast cancer.

PURPOSE: We analyzed the prevalence of gustatory test abnormalities in breast cancer (BC) patients undergoing chemotherapy. METHODS: We enrolled 43 BC patients undergoing chemotherapy and 38 BC patients who had never undergone chemotherapy (control group). Two gustatory tests were conducted: an instillation method examining the threshold for four basic taste stimuli and an electrogustometry method measuring the threshold for perception with electric stimulation at the front two-thirds of the tongue (cranial nerve VII) and at the back third of the tongue (cranial nerve IX). The results of the two gustatory tests and clinicopathological factors were compared between the chemotherapy and control groups and between patients with and without awareness of dysgeusia in the chemotherapy group. RESULTS: In the chemotherapy group, 19 (44%) patients were aware of dysgeusia and 8 (19%) had hypogeusia using the instillation method. Although more patients had parageusia in the chemotherapy than control group, no significant differences in the results of the two gustatory tests were observed. Patients with dysgeusia awareness had a higher threshold at cranial nerve IX using the electrogustometry method than those without dysgeusia awareness; no significant differences in hypogeusia were observed using the instillation method. In fact, 74% (14/19) of patients with dysgeusia awareness could identify the four tastes accurately using the instillation method. Similar results were observed for the instillation and electrogustometry methods at cranial nerve VII. CONCLUSIONS: While approximately half of the chemotherapy patients were aware of dysgeusia, 81% (35/43) of them could accurately identify the four basic tastes using the instillation method.

Identifying and Characterizing Subpopulations of Heavy Alcohol Drinkers Via a Sucrose Preference Test: A Sweet Road to a Better Phenotypic Characterization?

AIMS: Sweet preference in individuals with alcohol use disorder (AUD) has been associated with family history of AUD and personality traits. Therefore, testing sweet preference may help identify subpopulations of AUD individuals. SHORT SUMMARY: Sweet preference has been associated with family history of AUD and personality traits. We compared heavy drinkers based on their sweet liker status and using two cutoffs. Our findings support the role of sweet preference in heavy drinkers and point to the importance of how sweet likers are defined. METHODS: This study aimed at describing and comparing heavy drinkers based on their sweet liker status, through demographic, neuroendocrine, inflammatory, behavioral and drinking characteristics. Participants rated the pleasantness and intensity of sucrose solutions (0.05, 0.10, 0.21, 0.42 and 0.83 M). Two cutoffs were used to identify likers versus dislikers: Grouping A likers preferred 0.83 M and Grouping B likers preferred 0.83 or 0.42 M; the rest were dislikers. RESULTS: Sweet likers were 36% (n = 20) using Grouping A and 58.2% (n = 32) using Grouping B. Grouping B, but not Grouping A, sweet likers had higher BMI (P = 0.01). In Grouping B, sweet likers had higher plasma leptin and insulin concentrations and higher insulin resistance (P's < 0.05). C-reactive protein concentrations were higher in sweet likers in Grouping A (P = 0.0015) and at a trend level in Grouping B (P = 0.07). Grouping A sweet likers had higher alcohol craving (P = 0.0004). Sweet likers preferred spirits compared to nonspirits (wine and beer) across both grouping (P's < 0.05). CONCLUSIONS: These results provide further support for the role of sweet liking phenotype in identifying subpopulations of AUD individuals. These findings also point to the importance of how sweet likers are defined, therefore highlighting the need for further research.

Taste sensitivity to sucrose is lower in outbred Sprague-Dawley phenotypic obesity-prone rats than obesity-resistant rats.

The purpose of the present study was to better understand the role of sweet taste perception in dietary behavior and body weight in outbred Sprague-Dawley phenotypic obesity-prone and obesity-resistant rats by measuring sucrose taste sensitivity using a conditioned taste aversion paradigm. Rats were given a high fat diet for 2 weeks and were assigned as obesity-prone (P, upper tertile) or obesity-resistant (R, lower tertile) based on weight gain. Each group was then given either chow (C, 10% fat) or the high fat diet (F, 46% fat) for the remainder of the experiment (∼18 weeks) such that there were four groups - obesity-prone on chow (C-P), obesity-prone on high fat (H-P), obesity-resistant on chow (C-R), obesity-resistant on high fat (H-R). The sucrose sensitivity of phenotypic obesity-prone rats is lower than that of obesity-resistant rats in either H-fed or C-fed group, and all H-fed rats were more sensitivity than their C-fed counterparts (H-P vs. C-P; H-R vs. C-R). Body weight gain and total calories intake of phenotypic obesity-prone rats are more than that of obesity-resistant rats. The results suggest that lower sucrose taste sensitivity may contribute to body weight gain and total calories intake of phenotypic obesity-prone rats compared to obesity-resistant rats, and there is correlation between the change in the sweet taste threshold and diet treatment.

Pungency Evaluation of Hydroxyl-Sanshool Compounds After Dissolution in Taste Carriers Per Time-Related Characteristics.

This study was conducted to investigate the sensory characteristics and temporal migration of hydroxyl-sanshool compounds at slight and moderate concentrations after dissolution in ethanol-water, saccharose, NaCl, and MSG via 2-AFC, time intensity (TI) and temporal dominance of sensations (TDS) methods. The pungency detection threshold (DT) was suppressed in saccharose while NaCl and MSG solutions showed no effect on pungency DT. The area under the curve (AUC) of pungency increased in NaCl and MSG solutions and decreased significantly in saccharose solution. Imax (maximal intensity) also increased in NaCl and MSG at low concentrations of hydroxyl-sanshool compounds. The temporally dominant sensations and migration of said sensations across the oral cavity differed among different carriers. Low levels of pungency compounds were characterized by tingling first in the tongue tip and ending in the lips, while moderate levels of the compound produced tingling, astringency, vibrating, and numbing from the tongue tip to the bilateral sides of the tongue, lips, palate, cheek mucosa, and surface of the tongue over time. There were significant differences in the maximum rate, peak time, and duration of any dominant sensation, as well as in the duration of sensation in the lips, tongue tip, and bilateral sides of the tongue. This study provides a dynamic profile of consuming pungent food, which provides a reference not only for the design of new food products with desirable pungency, but also as a scientific basis for the application of pungent compounds within the food and catering industry.

Comparison of the Tastes of L-Alanine and Monosodium Glutamate in C57BL/6J Wild Type and T1r3 Knockout Mice.

Previous research showed that L-alanine and monosodium L-glutamate elicit similar taste sensations in rats. This study reports the results of behavioral experiments designed to compare the taste capacity of C57BL/6J wild type and T1r3- mice for these 2 amino acids. In conditioned taste aversion (CTA) experiments, wild-type mice exhibited greater sensitivity than knockout mice for both L-amino acids, although knockout mice were clearly able to detect both amino acids at 50 mM and higher concentrations. Generalization of CTA between L-alanine and L-glutamate was bidirectionally equivalent for both mouse genotypes, indicating that both substances elicited similar tastes in both genotypes. This was verified by the discrimination experiments in which both mouse genotypes performed at or near chance levels at 75 and 150 mM. Above 150 mM, discrimination performance improved, suggesting the taste qualities of the 2 L-amino acids are not identical. No differences between knockout and wild-type mice in discrimination ability were detected. These results indicate that while the T1r3 receptor is important for tasting L-alanine and L-glutamate, other receptors are also important for tasting these amino acids.

Oil Perception-Detection Thresholds for Varying Fatty Stimuli and Inter-individual Differences.

Multiple lines of research have demonstrated that humans can perceive fat in the form of free fatty acids (FFAs). However, the dietary concentration of FFAs is generally very low and fat is mainly consumed as triacylglycerol (TAG). The aim of this study was to examine the perception of different fatty stimuli and possible associations between them. Therefore, detection thresholds for 4 fatty stimuli (oleic acid [FFA], paraffin oil [mixture of hydrocarbon molecules], canola oil [TAG-rich], and canola oil spiked with oleic acid [rich in TAGs and FFAs]) were determined in 30 healthy participants. Additionally, inter-individual differences in fat perception were examined. It was observed that oleic acid was perceivable at significantly lower concentrations than all other stimuli (P < 0.001). Similarly, canola oil with oleic acid was detectable at lower concentrations than canola oil alone (P < 0.001). Moreover, canola oil detection thresholds were significantly lower than paraffin oil detection thresholds (P = 0.017). Participants who were sensitive for low concentrations for oleic acid showed lower detection thresholds for canola oil with and without oleic acid, compared with participants that were less sensitive for oleic acid. The results of this study demonstrate that the higher the concentrations of FFAs in the stimuli, the lower the individual fat detection threshold. Moreover, participants being sensitive for lower concentrations of FFAs are also more likely to detect low concentrations of TAG-rich fats as it is found in the human diet.

Relationship of Phenylthiocarbamide (PTC) Taster Status to Olfactory and Gustatory Function in Patients with Chemosensory Disturbances.

Poor sensitivity to the bitter taste of phenylthiocarbamide (PTC) and related substances has been associated with a number of diseases. We determined, in patients with chemosensory dysfunction from multiple etiologies, whether PTC "tasters" (n = 511) exhibit less smell and taste dysfunction than their non-PTC-tasting counterparts (n = 432) on a comprehensive battery of olfactory and gustatory tests. The proportion of tasters (54%) in our study population was much lower than that calculated from 11 North American population studies (76.5%; P < 0.0001). This taster/nontaster ratio was maintained across a range of etiologic categories. More women (60.7%) than men (45.5%) were PTC tasters (P < 0.0001). Although PTC tasting status was unrelated to scores on the olfactory tests (which included tests of odor identification, detection threshold, and odor memory/discrimination), tasters significantly outperformed nontasters on suprathreshold identification and intensity taste tests employing both bitter (caffeine) and nonbitter (sucrose, citric acid, sodium chloride) tasting stimuli. Regardless of PTC taster status, women outperformed men on the taste tests. Our findings suggest the possibility that the T2R38 gene may protect against significant olfactory dysfunction, but once such dysfunction becomes manifest at a level where professional help is sought, such protection is not evident. However, other hypotheses for this phenomenon are possible. This study demonstrates that patients with chemosensory disturbances who are PTC tasters outperform their non-PTC taster counterparts in both identifying and perceiving the intensity of a range of suprathreshold tastants, including ones that do not taste bitter.

Value: Changes in the Detection and Recognition Thresholds of Three Basic Tastes in Lung Cancer Patients Receiving Cisplatin and Paclitaxel and Its Association with Nutritional and Quality of Life Parameters.

We evaluated the effects of cisplatin and paclitaxel on taste acuity and their associations with nutritional and health-related quality of life (HRQL) in patients with advanced non-small-cell lung cancer (NSCLC). Forty chemotherapy (CT)-naïve patients were assessed at baseline and after two cycles of paclitaxel and cisplatin. The taste evaluation was performed using a rinsing technique to identify detection and recognition thresholds (DT and RT) of bitter, sweet, and umami tastes. At baseline, 37.5% of the patients reported dysgeusia. After CT, the patients showed lower medians DT (p = 0.017) and RT (p = 0.028) for umami taste. These decreases were associated with clinical neuropathy, worse HRQL, and a tendency toward increased appetite loss. Additionally, CT did not significantly reduce the median DT for sweet (p = 0.09), which is associated with lower intake of protein (p = 0.015), animal protein (p = 0.010), fat (p = 0.004), and iron (p = 0.047). CT decreased the median DT for bitter (p = 0.035); however, this decrease was not associated with nutritional parameters or with HRQL. Sensitivity to taste increased with paclitaxel and cisplatin CT, making foods more unpleasant, and it was associated with neuropathy, worse HRQL, and reduced nutrient intake in advanced NSCLC patients. The protocol was registered at clinicaltrials.gov (NCT01540045).

Flavour and identification threshold detection overview of Slovak adepts for certified testing.

OBJECTIVES: During certification process of sensory assessors of Slovak certification body we obtained results for basic taste thresholds and lifestyle habits. MATERIALS AND METHODS: 500 adult people were screened during experiment with food industry background. For analysis of basic and non basic tastes, we used standardized procedure of ISO 8586-1:1993. RESULTS: In flavour test experiment, group of (26-35 y.o) produced the lowest error ratio (1.438), highest is (56+ y.o.) group with result (2.0). Average error value based on gender for women was (1.510) in comparison to men (1.477). People with allergies have the average error ratio (1.437) in comparison to people without allergies (1.511). Non-smokers produced less errors (1.484) against the smokers (1.576). Another flavour threshold identification test detected differences among age groups (by age are values increased). The highest number of errors made by men in metallic taste was (24%) the same as made by women (22%). Higher error ratio made by men occurred in salty taste (19%) against women (10%). Analysis detected some differences between allergic/non-allergic, smokers/non-smokers groups.

"A spoonful of sugar helps the medicine go down": bitter masking by sucrose among children and adults.

Sweeteners are often added to liquid formulations of drugs but whether they merely make them better tasting or actually reduce the perception of bitterness remains unknown. In a group of children and adults, we determined whether adding sucrose to urea, caffeine, denatonium benzoate, propylthiouracil (PROP), and quinine would reduce their bitterness using a forced-choice method of paired comparisons. To better understand individual differences, adults also rated each solution using a more complex test (general Labeled Magnitude Scale [gLMS]) and were genotyped for the sweet taste receptor gene TAS1R3 and the bitter receptor TAS2R38. Sucrose suppressed the bitterness of each agent in children and adults. In adults, sucrose was effective in reducing the bitterness ratings from moderate to weak for all compounds tested, but those with the sensitive form of the sweet receptor reported greater reduction for caffeine and quinine. For PROP, sucrose was most effective for those who were genetically the most sensitive, although this did not attain statistical significance. Not only is the paired comparison method a valid tool to study how sucrose improves the taste of pediatric medicines among children but knowledge gleaned from basic research in bitter taste and how to alleviate it remains an important public health priority.

Temperature Affects Human Sweet Taste via At Least Two Mechanisms.

The reported effects of temperature on sweet taste in humans have generally been small and inconsistent. Here, we describe 3 experiments that follow up a recent finding that cooling from 37 to 21 °C does not reduce the initial sweetness of sucrose but increases sweet taste adaptation. In experiment 1, subjects rated the sweetness of sucrose, glucose, and fructose solutions at 5-41 °C by dipping the tongue tip into the solutions after 0-, 3-, or 10-s pre-exposures to the same solutions or to H2O; experiment 2 compared the effects of temperature on the sweetness of 3 artificial sweeteners (sucralose, aspartame, and saccharin); and experiment 3 employed a flow-controlled gustometer to rule out the possibility the effects of temperature in the preceding experiments were unique to dipping the tongue into a still taste solution. The results (i) confirmed that mild cooling does not attenuate sweetness but can increase sweet taste adaptation; (ii) demonstrated that cooling to 5-12 °C can directly reduce sweetness intensity; and (iii) showed that both effects vary across stimuli. These findings have implications for the TRPM5 hypothesis of thermal effects on sweet taste and raise the possibility that temperature also affects an earlier step in the T1R2-T1R3 transduction cascade.

No Difference in Perceived Intensity of Linoleic Acid in the Oral Cavity between Obese and Nonobese Individuals.

Findings from studies examining interactions between fat taste and dietary fat intake or body weight are mixed. A convenience sample of 735 visitors to the Denver Museum of Nature & Science ≥8 years old rated the taste intensity of edible taste strips impregnated with varying concentrations (%v/v) of linoleic acid (LA) (blank = 0.0, low = 0.06, medium = 0.15, high = 0.38). Percent body fat (BF%) was measured using bioelectrical impedance. Fat taste intensity was rated as significantly different across all concentrations (P < 0.001) except between the blank and low concentrations (P = 0.1). Ratings increased monotonically across concentrations. Children (<18 years; N = 180) rated all concentrations as more intense than adults (P < 0.001 for all). Women and girls rated the highest concentration as more intense than men and boys (P < 0.02 for all). BF% was not correlated with fat taste intensity ratings. Self-reported dietary intake indicated that obese individuals' intensity ratings for medium and high concentrations of LA were inversely related to recent mono- and poly-unsaturated fat exposure (r = -0.19 to -0.27; P < 0.03 for all). No such associations were observed in the nonobese group. Findings suggest that factors other than simple adiposity status influence fat taste intensity ratings, and that participants in fat taste studies should receive standardized meals prior to testing.

Electrogustometry and contact endoscopy findings in patients with head and neck malignancies treated with chemotherapy, radiotherapy, or radiochemotherapy.

This study aimed to investigate in parallel changes in gustatory function, changes in morphology of the fungiform papillae, as well as changes in the shape and density of the vessels of the tip of the tongue in patients treated with chemotherapy, radiotherapy, or radiochemotherapy. Twenty patients (7 females and 13 males; age range: 42-78 years) with head and neck malignancies (hypopharynx, larynx, oropharynx, and parotid) treated with radiochemotherapy (n = 8), chemotherapy (n = 8), or radiotherapy (n = 4) were prospectively studied. In all patients, electrogustometry and contact endoscopy were performed. Radiotherapy-treated patients exhibited higher electrogustometry thresholds and greater alterations in the morphology and vascularization of the fungiform papillae than the other two groups. Radiochemotherapy patients had less pronounced changes of the electrogustometry threshold and fungiform papillae structure compared with radiotherapy patients. Chemotherapy alone caused less severe change in both electrogustometry threshold and fungiform papillae structure than radiotherapy or radiochemotherapy. Radiotherapy alone caused greater disorders of taste-related anatomic parameters and electrogustometry thresholds compared with chemotherapy and combined radiochemotherapy.

Alcoholic beverage strength discrimination by taste may have an upper threshold.

BACKGROUND: Given the association between alcohol consumption and negative health consequences, there is a need for individuals to be aware of their consumption of ethanol, which requires knowledge of serving sizes and alcoholic strength. This study is one of the first to systematically investigate the ability to discriminate alcoholic strength by taste. METHODS: Nine discrimination tests (total n = 413) according to International Standardization Organization (ISO) 4120 sensory analysis methodology "triangle test" were performed. RESULTS: A perceptible difference was found for vodka in orange juice (0.0 vs. 0.5% vol; 0 vs. 1% vol), pilsner and wheat beer (0.5 vs. 5% vol), and vodka in orange juice (5 vs. 10% vol, 20 vs. 30% vol, and 30 vs. 40% vol). The percentage of the population perceiving a difference between the beverages varied between 36 and 73%. Alcoholic strength (higher vs. lower) was correctly assigned in only 4 of the 7 trials at a significant level, with 30 to 66% of the trial groups assigning the correct strength. For the trials that included beverages above 40% vol (vodka unmixed, 40 vs. 50% vol and vodka in orange juice, 40 vs. 50% vol), testers could neither perceive a difference between the samples nor assign correct alcoholic strength. CONCLUSIONS: Discrimination of alcoholic strength by taste was possible to a limited degree in a window of intermediate alcoholic strengths, but not at higher concentrations. This result is especially relevant for drinkers of unlabeled, over-proof unrecorded alcoholic beverages who would potentially ingest more alcohol than if they were to ingest commercial alcohol. Our study provides strong evidence for the strict implementation and enforcement of labeling requirements for all alcoholic beverages to allow informed decision making by consumers.

Major haplotypes of the human bitter taste receptor TAS2R41 encode functional receptors for chloramphenicol.

A complete understanding of bitterness perception requires identification of cognate bitter substances for all human bitter taste receptors (TAS2Rs). However, so far, no agonists have been identified for five of the 25 TAS2Rs, i.e., TAS2R41, TAS2R42, TAS2R45, TAS2R48 and TAS2R60. Due to substantial genetic variability several haplotypes exist for most bitter receptor genes. For some of the deorphaned TAS2Rs, haplotypes have been identified coding for proteins with severely impaired or even lacking receptor function, proposing that the use of non-functional receptor variants in previous investigations accounted for the failure to identify cognate bitter agonists for the orphan TAS2Rs. In the present report we reasoned that at least one out of the major genetically encoded TAS2R variants is functional. Therefore, we expressed the major haplotypes of the five orphan TAS2Rs in our functional assay and challenged the cells with 106 bitter compounds. Chloramphenicol was identified as agonist for TAS2R41. Further studies revealed that TAS2R41 is a 'specialist' receptor highly selective for this antibiotic. None of the other TAS2R variants responded to any of the 106 compounds, suggesting that the use of non-functional variants does not explain the failure to identify cognate agonists for the other four TAS2Rs. Probably, these TAS2Rs are highly selective for bitter substances absent in our compound library.

Superiority of experts over novices in trueness and precision of concentration estimation of sodium chloride solutions.

Several studies have reported that experts outperform novices in specific domains. However, the superiority of experts in accuracy, taking both trueness and precision into consideration, has not yet been explored. Here, we examined differences between expert and novice performances by evaluating the accuracy of their estimations of physical concentrations of sodium chloride in solutions while employing a visual analog scale. In Experiment 1, 14 experts and 13 novices tasted 6 concentrations of the solutions until they had learned their intensities. Subsequently, they repeatedly rated the concentration of 3 other solutions in random order. Although we did not find a difference between the performances of the 2 groups in trueness (difference between rating and correct concentration), the precision (consistency of ratings for each participant) of experts was higher than that of novices. In Experiment 2, 13 experts who had participated in Experiment 1 and 10 experts and 12 novices who had not participated in Experiment 1 rated the salt concentration in sodium chloride/sucrose mixtures in the same way as in Experiment 1. Both trueness and precision of performance were higher in both expert groups than in the novice group. By introducing precision and trueness parameters, we succeeded in quantifying the estimations of experts and novices in rating the concentration of solutions, revealing experts' superiority even for a task they had not been trained for.

Experience with sugar modifies behavioral but not taste-evoked medullary responses to sweeteners in mice.

Dietary exposure to sugars increases the preference for and intake of sugar solutions in mice. We used brief-access lick tests and multiunit electrophysiological recordings from the nucleus of the solitary tract (NST) to investigate the role of taste in diet-induced changes in sucrose responsiveness. We exposed C57BL/6J (B6) and 129X1/SvJ (129) mice to either a sucrose diet (chow, water, and a 500mM sucrose solution) or a control diet (chow and water) for 3 days. In B6 mice, exposure to the sucrose diet decreased the appetitive response (i.e., number of trials initiated) but had no effect on the consummatory response (i.e., rate of licking) to 500mM sucrose and 20mM saccharin. In 129 mice, exposure to the sucrose diet increased the appetitive response but had no effect on the consummatory response to the sweetener solutions. In the NST recordings, the B6 mice exhibited larger multiunit responses to sweeteners than 129 mice, but there was no effect of the sucrose diet in either strain. Our results indicate that sucrose exposure alters the appetitive response of B6 and 129 mice to sweeteners in diametrically opposed ways and that these changes are mediated by structures in the gustatory neuraxis above the NST (e.g., ventral forebrain).

Evaluation of gustatory function in HIV-infected subjects with and without HAART.

BACKGROUND: Alteration in gustatory function among patients with human immunodeficiency virus (HIV) infection is sparsely studied and provides contradictory findings. The objectives of the study were to evaluate taste perversion in HIV-infected subjects and compare taste acuity between patients with and without Highly active antiretroviral therapy (HAART). MATERIALS AND METHODS: Fifty HIV-infected subjects aged 25-55 years were selected and divided into two subgroups: patients with HAART and patients without HAART. Control group included 50 healthy, age-, sex-, gender-, and socioeconomic status-matched individuals. Taste complaints were recorded on a structured questionnaire, and formal taste testing was carried out with triadic forced choice whole-mouth, above-threshold taste test for four tastants - sweet, salt, sour, and bitter. Taste identification, detection threshold, and intensity of tastant were recorded. RESULTS: Twenty-four (48%) among study group complained of taste perversion when compared to none among the control group (P < 0.001). During taste testing, identification and intensity scores were lower, while detection threshold scores for four tastants were higher in study group than in control group (P < 0.05). Among those patients with taste complaints, 16 were with HAART, while eight were without HAART (P = 0.043). Formal taste testing revealed greater taste perversion for sour and bitter tastants among patients with HAART medication. CONCLUSION: The results document significant taste losses in HIV-infected subjects, and HAART contributes considerably to such taste perversion.

Receptor agonism and antagonism of dietary bitter compounds.

Food contains complex blends of structurally diverse bitter compounds that trigger bitterness through activation of one or more of the ∼25 human TAS2 bitter taste receptors. It remains unsolved, however, whether the perceived bitterness of binary bitter-compound mixtures can be considered an additive function of all bitter-inducing chemicals in the mouth, suggesting that little mutual interaction takes place among bitter substances or if mixture suppression and synergism occurs. Here we report on two natural sesquiterpene lactones from edible plants, which stimulate distinct sets of hTAS2Rs in transfected cells. Both chemicals also robustly inhibit different but overlapping subsets of agonist-activated hTAS2Rs. These findings demonstrate that mixtures of bitter compounds, because they normally occur in human foodstuff, likely elicit bitter perception in a complex and not in a merely additive manner. An unexpected implication of this discovery is that, during evolution, the naturally occurring bitter taste receptor antagonists have shaped some of the pharmacological properties of the receptors, such as overlapping recognition profiles and breadth of tuning.