Unit size influences ad libitum intake in a snacking context via eating rate.

Geometric and textural properties of food, like unit size, have previously been shown to influence energy intake. While mechanism(s) driving this effect are unclear, unit size may relate to intake by affecting eating microstructure (e.g., eating rate, bite size). In a randomized crossover study, we investigated relationships between unit size, eating microstructure, and intake. Adults (n = 75, 75% women) consumed an ad libitum snack three times in our laboratory. This snack was a 70-g portion (∼2.5 servings) of one of three sizes of pretzel (small, medium, large). Intake was measured in grams by difference in weight before and after the snack. Each session was video recorded to measure eating microstructure; snack duration (min) and number of bites were annotated and used to calculate mean eating rate (g/min) and mean bite size (g/bite). Results revealed unit size influenced intake (grams and kcal; both p's ≤ 0.001), such that participants consumed 31% and 22% more of the large pretzels (16.9 ± 2.3 g) compared to the small (12.9 ± 2.3 g) and medium sizes (13.8 ± 2.3 g), respectively. Unit size also influenced eating rate and bite size (both p's < 0.001); the largest pretzel size yielded the fastest eating rate and largest mean bite size. Further analysis revealed that after accounting for eating microstructure, the effects of unit size on intake were no longer significant, suggesting eating microstructure was driving these effects. Together, these findings indicate that unit size influences intake by affecting eating microstructure and that food properties like unit size can be leveraged to moderate snack intake.

Reasons for meal termination, eating frequency, and typical meal context differ between persons with and without a spinal cord injury.

Overeating associated with neurogenic obesity after spinal cord injury (SCI) may be related to how persons with SCI experience satiation (processes leading to meal termination), their eating frequency, and the context in which they eat their meals. In an online, cross-sectional study, adults with (n = 688) and without (Controls; n = 420) SCI completed the Reasons Individuals Stop Eating Questionnaire-15 (RISE-Q-15), which measures individual differences in the experience of factors contributing to meal termination on five scales: Physical Satisfaction, Planned Amount, Decreased Food Appeal, Self-Consciousness, and Decreased Priority of Eating. Participants also reported weekly meal and snack frequency and who prepares, serves, and eats dinner with them at a typical dinner meal. Analysis revealed that while Physical Satisfaction, Planned Amount, and Decreased Food Appeal were reported as the most frequent drivers of meal termination in both groups, scores for the RISE-Q-15 scales differed across the groups. Compared to Controls, persons with SCI reported Physical Satisfaction and Planned Amount as drivers of meal termination less frequently, and Decreased Food Appeal and Decreased Priority of Eating more frequently (all p < 0.001). This suggests that persons with SCI rely less on physiological satiation cues for meal termination than Controls and instead rely more on hedonic cues. Compared to Controls, persons with SCI less frequently reported preparing and serving dinner meals and less frequently reported eating alone (all p < 0.001), indicating differences in meal contexts between groups. Individuals with SCI reported consuming fewer meals than Controls but reported a higher overall eating frequency due to increased snacking (p ≤ 0.015). A decrease in the experience of physical fullness, along with a dependence on a communal meal context and frequent snacking, likely contribute to overeating associated with neurogenic obesity after SCI.

Distinct Sensory Hedonic Functions for Sourness in Adults.

Over the last half-century, variable responses to sweetness have repeatedly been shown to fall into a small number of hedonic responses, implying that looking only at group means may can obfuscate meaningfully different response patterns. Comparative data for sourness is quite sparse, especially in adults. While increased liking with higher acid concentration has been reported for some children, in adults, sourness is classically assumed to be aversive, with a monotonic drop in liking with increasing sourness. Here, we test this assumption using a simple model system or experimental beverage in convenience samples of adults from the United States (increasing citric acid in water) and Italy (increasing citric acid in pear juice). Participants rated intensity and liking of sampled stimuli. For both cohorts, we find clear evidence of three distinct patterns of responses: a strong negative group where liking dropped with increased sourness, an intermediate group who showed a more muted drop in liking with more sourness, and a strong positive group where liking increased with more sourness. Strikingly, both cohorts showed similar proportions of response patterns, with ~63-70% in the strong negative group, and 11-12% in the strong positive group, suggesting these proportions may be stable across cultures. Notably, the three groups did not differ by age or gender. These data support the existence of different hedonic response profiles to sour stimuli in adults, once again highlighting the importance of looking at individual differences and potential consumer segments, rather than merely averaging hedonic responses across all individuals within a group.

Covid-19 affects taste independent of taste-smell confusions: results from a combined chemosensory home test and online survey from a large global cohort.

People often confuse smell loss with taste loss, so it is unclear how much gustatory function is reduced in patients self-reporting taste loss. Our pre-registered cross-sectional study design included an online survey in 12 languages with instructions for self-administering chemosensory tests with 10 household items. Between June 2020 and March 2021, 10,953 individuals participated. Of these, 5,225 self-reported a respiratory illness and were grouped based on their reported COVID test results: COVID-positive (COVID+, N = 3,356), COVID-negative (COVID-, N = 602), and COVID unknown for those waiting for a test result (COVID?, N = 1,267). The participants who reported no respiratory illness were grouped by symptoms: sudden smell/taste changes (STC, N = 4,445), other symptoms excluding smell or taste changes (OthS, N = 832), and no symptoms (NoS, N = 416). Taste, smell, and oral irritation intensities and self-assessed abilities were rated on visual analog scales. Compared to the NoS group, COVID+ was associated with a 21% reduction in taste (95% confidence interval (CI): 15-28%), 47% in smell (95% CI: 37-56%), and 17% in oral irritation (95% CI: 10-25%) intensity. There were medium to strong correlations between perceived intensities and self-reported abilities (r = 0.84 for smell, r = 0.68 for taste, and r = 0.37 for oral irritation). Our study demonstrates that COVID-19-positive individuals report taste dysfunction when self-tested with stimuli that have little to none olfactory components. Assessing the smell and taste intensity of household items is a promising, cost-effective screening tool that complements self-reports and may help to disentangle taste loss from smell loss. However, it does not replace standardized validated psychophysical tests.

The Adaptive Olfactory Measure of Threshold (ArOMa-T): a rapid test of olfactory function.

Many widely used psychophysical olfactory tests have limitations that can create barriers to adoption. For example, tests that measure the ability to identify odors may confound sensory performance with memory recall, verbal ability, and prior experience with the odor. Conversely, classic threshold-based tests avoid these issues, but are labor intensive. Additionally, many commercially available tests are slow and may require a trained administrator, making them impractical for use in situations where time is at a premium or self-administration is required. We tested the performance of the Adaptive Olfactory Measure of Threshold (ArOMa-T)-a novel odor detection threshold test that employs an adaptive Bayesian algorithm paired with a disposable odorant delivery card-in a non-clinical sample of individuals (n = 534) at the 2021 Twins Day Festival in Twinsburg, OH. Participants successfully completed the test in under 3 min with a false alarm rate of 7.5% and a test-retest reliability of 0.61. Odor detection thresholds differed by sex (~3.2-fold lower for females) and age (~8.7-fold lower for the youngest versus the oldest age group), consistent with prior studies. In an exploratory analysis, we failed to observe evidence of detection threshold differences between participants who reported a history of COVID-19 and matched controls who did not. We also found evidence for broad-sense heritability of odor detection thresholds. Together, this study suggests the ArOMa-T can determine odor detection thresholds. Additional validation studies are needed to confirm the value of ArOMa-T in clinical or field settings where rapid and portable assessment of olfactory function is needed.

Do children really eat what they like? Relationships between liking and intake across laboratory test-meals.

Liking plays a primary role in determining what and how much children eat. Despite this, the relationship between liking and intake of foods and beverages served as part of a meal is not often reported, even though pediatric feeding studies frequently collect such data. In addition, few studies have reported on the test-retest reliability of both hedonic ratings and laboratory intake among children. To address these gaps, this study was designed to assess the relationship between children's liking of items at a meal and subsequent intake. 61, 4-6 year-olds were recruited to participate in two identical laboratory sessions where liking of 7 foods (i.e., chicken nuggets, ketchup, potato chips, grapes, broccoli, cherry tomatoes, cookie) and 2 beverages (i.e., fruit punch, milk) was assessed (5-point hedonic scale) prior to ad libitum consumption of the same items at a meal. Spearman's correlations tested the relationship between liking and intake and intra-class correlations assessed inter-session reliability of both measures. Liking for potato chips (p < 0.01), grapes (p < 0.05), cherry tomatoes (p < 0.001), and fruit punch (p < 0.001) was positively associated with amount consumed, but no associations were found between liking and intake of other meal items. For the majority of meal items, test-retest reliability of liking and intake were significant (ranging from 0.34 for cookies to 0.93 for tomatoes). At a multi-component meal, children's hedonic ratings were both reliable and modestly predictive of subsequent intake, and the relationships were stronger for lower energy, less well-liked foods. Rather than eating what they like, these data are more consistent with the notion that children do not eat what they dislike.

Massively collaborative crowdsourced research on COVID19 and the chemical senses: Insights and outcomes.

In March 2020, the Global Consortium of Chemosensory Research (GCCR) was founded by chemosensory researchers to address emerging reports of unusual smell and taste dysfunction arising from the SARS-CoV-2 pandemic. Over the next year, the GCCR used a highly collaborative model, along with contemporary Open Science practices, to produce multiple high impact publications on chemosensation and COVID19. This invited manuscript describes the founding of the GCCR, the tools and approaches it used, and a summary of findings to date. These findings are contextualized within a summary of some of the broader insights about chemosensation (smell, taste, and chemesthesis) and COVID19 gained over the last 18 months, including potential mechanisms of loss. Also, it includes a detailed discussion of some current Open Science approaches and practices used by the GCCR to increase transparency, rigor, and reproducibility.

Infant and Toddler Responses to Bitter-Tasting Novel Vegetables: Findings from the Good Tastes Study.

BACKGROUND: Infants are born with the biological predisposition to reject bitterness. Dark green vegetables contain essential nutrients but also bitter compounds, making them more difficult to like. OBJECTIVE: The Good Tastes Study was designed to determine whether reducing bitterness by adding small amounts of sugar or salt would alter infant acceptance of kale purées. METHODS: Caregivers (n = 106, 94% mothers, 82% Non-Hispanic White) and children (53% male, aged 6-24 mo) participated in a videorecorded laboratory visit during which infants were offered 4 versions of puréed kale: plain, 1.2% or 1.8% added sugar, or 0.2% added salt. Caregivers rated their children's liking for each kale version. Videos were coded for the number of tastes accepted and for children's behaviors and acceptance of each kale version. A multilevel ordered logistic model was fit for the number of accepted tastes and caregiver ratings of child liking of kale versions with age, breastfeeding history, order effects, and kale version as predictors. RESULTS: Infants 6 to <12 mo accepted more tastes (b = 2.911, P < 0.001) and were rated by caregivers as liking the kale more than older toddlers (≥18 mo; b = 1.874, P = 0.014). The plain kale was more likely to be accepted (P < 0.001); also, the first version offered was more likely to be rejected (b = -0.586, P < 0.007). Older infants (≥18 mo) exhibited more avoidant behaviors (b = 1.279, P < 0.001), more playing (b = 2.918, P < 0.001), and more self-feeding (b = 1.786, P = 0.005) than younger infants (6 to <12 mo). Children who were reported to have been breastfed more in the last 7 d were more likely to self-feed (b = 0.246, P < 0.001) and play with food (b = 0.207, P < 0.005). CONCLUSIONS: Our findings support that there may be a sensitive period, during the early phase of complementary feeding, to improve success of introducing a novel, bitter, more difficult-to-like food. When low levels of sugar or salt were added, no advantage of bitterness reduction was observed. This study has been registered with ClinicalTrials.gov as NCT04549233.

Harsh and Sweet Sensations Predict Acute Liking of Electronic Cigarettes, but Flavor Does Not Affect Acute Nicotine Intake: A Pilot Laboratory Study in Men.

INTRODUCTION: Electronic cigarette use is increasing in popularity, and thousands of flavors are available. Adolescent vaping rates in the United States have nearly doubled in the past year. Unlike combustible tobacco, added flavors are not currently regulated for some types of electronic cigarette products. Here, we investigated the role of flavor in electronic cigarette liking and acute intake. METHODS: Men (n = 39) aged 18-45 vaped in a controlled laboratory setting after being randomized to one of four e-liquids: 6 mg nicotine/mL cherry, 18 mg/mL cherry, 6 mg/mL chocolate, or 18 mg/mL chocolate. They completed several questionnaires, and vaped ad libitum for 10 minutes. After the first puff, participants rated sensations (sweetness, bitterness, coolness, harshness/irritation) on general labeled magnitude scales (gLMS) and rated overall liking on a generalized hedonic scale. Once the 10-minute session ended, participants made another set of ratings. RESULTS: Liking was generally stable across the vaping session and liking varied substantially across the four conditions. Across all conditions, sensory ratings predicted liking: harshness/irritation was negatively associated with first puff liking, whereas perceived sweetness was positively associated with first puff liking. First puff liking associated with increased amount of e-liquid vaped, but not total nicotine intake. Participants appeared to titrate their nicotine intake regardless of assigned condition. CONCLUSION: Flavored e-liquids affect acute liking ratings, but not acute nicotine intake. IMPLICATIONS: These data suggest individuals who regularly vape may titrate their nicotine intake, regardless of flavor, and contrary to expectations, acute liking did not predict total nicotine intake. However, more-liked flavors may potentially make higher nicotine levels more tolerable by adding pleasant sensations directly, rather than by perceptual masking that reduces aversive sensations.

Differences in preferred fat level, sweetener type, and amount of added sugar in chocolate milk in a choice task relate to physical activity and orthorexia.

Fluid dairy milk consumption has decreased over the last 4 decades, and this drop has accelerated with the introduction of many competing beverage alternatives, such as plant-based milks and bottled water. Conversely, flavored milk sales remain strong, but many adults avoid flavored milk because of concerns about added sugar and calories and/or excessive sweetness. Here we used two discrete choice experiments to assess interest for a dark chocolate milk drink in adults, and explored whether there might be a consumer segment who prefers a more bitter, lower sugar chocolate milk. Adults were recruited from the Mid-Atlantic region of the United States for two conjoint analysis studies. In a general population cohort (n = 735), type of sweetener was the most important attribute (24%), followed by milk fat (19%), grams of added sugar (16%), front of pack messaging (15%), package type (12%), carton size (8%), and protein content (6%). Attribute importance was relatively consistent in a second study with a younger, more physically active cohort (n = 1017). Product choices in the active cohort were related to orthorexia and physically activity scores, indicating revealed preferences in a choice task are reflective of personal lifestyle and eating behavior. In both cohorts, three consistent consumer segments were identified and characterized: the calorie conscious, the average consumer, and the natural eaters. These data can help uncover lifestyle differences between adult consumers that impact their food product choices.

Female sweet-likers have enhanced cross-modal interoceptive abilities.

There are well known phenotypic differences in sweet-liking across individuals, but it remains unknown whether these are related to broader underlying differences in interoceptive abilities (abilities to sense the internal state of the body). Here, healthy women (N = 64) classified as sweet likers (SLs) or sweet dislikers (SDs) completed a bimodal interoception protocol. A heartbeat tracking and a heartbeat discrimination task determined cardiac interoception; both were accompanied by confidence ratings. A water load task, where participants consumed water to satiation and then to maximum fullness was used to assess gastric interoceptive abilities. Motivational state, psychometric characteristics and eating behaviour were also assessed. SLs performed significantly better than SDs on both heartbeat tasks, independently of impulsivity, anxiety, depression, and alexithymia. No differences in metacognitive awareness and subjective interoceptive measures were found. With gastric interoception, SLs were more sensitive to stomach distention, and they ingested less water than SDs to reach satiety when accounting for stomach capacity. SLs also scored higher on mindful and intuitive eating scales and on emotional eating particularly in response to negative stimuli; emotional overeating was fully mediated via interoceptive performance. Overall, our data suggest the SL phenotype may reflect enhanced responsiveness to internal cues more broadly.

Development and validation of the Reasons Individuals Stop Eating Questionnaire (RISE-Q): A novel tool to characterize satiation.

A variety of factors can influence satiation, and individual differences in reasons for meal termination may help to explain variability in food intake and susceptibility to overconsumption. We developed and validated a questionnaire to characterize the Reasons Individuals Stop Eating (RISE-Q). The initial RISE-Q was created by reviewing the published literature and identifying 47 reasons why individuals might stop eating. The RISE-Q asks respondents to rate how often each reason influences why they stop eating at a typical dinner meal by using a seven-point scale. Adults (N = 477, 77% women) from a participant database completed a survey online that included the initial RISE-Q and the satiation-related Satiety Responsiveness and Food Responsiveness scales of the Adult Eating Behavior Questionnaire (AEBQ). Self-reported height and weight were collected to calculate body mass index (BMI). The survey also assessed self-reported typical meal size. After factor analysis, the RISE-Q retained 31 items and identified five distinct scales of reasons for stopping eating: Decreased Food Appeal (mean ± SD: 2.6 ± 0.05, Cronbach's α = 0.89), Physical Satisfaction (5.0 ± 0.04, α = 0.85), Planned Amount (4.4 ± 0.05, α = 0.82), Self-Consciousness (2.4 ± 0.05, α = 0.88), and Decreased Priority of Eating (2.3 ± 0.04, α = 0.69). Thus, the most frequently reported reasons for meal termination were related to Physical Satisfaction and Planned Amount. Each RISE-Q scale was significantly correlated with at least one of the satiation-related AEBQ scales, suggesting that the RISE-Q has construct validity. RISE-Q scales were also correlated with BMI and measures of typical meal size. The RISE-Q provides a novel tool to assess differences across individuals in reported reasons for eating cessation. The RISE-Q can aid in further understanding risk factors for overconsumption and has potential clinical utility in the design of targeted weight-management interventions.

Predominant Qualities Evoked by Quinine, Sucrose, and Capsaicin Associate With PROP Bitterness, but not TAS2R38 Genotype.

Genetic variability in the ability to taste thiourea compounds has been studied for 80+ years. Over the last 3 decades, many studies have reported perceived intensity of concentrated propylthiouracil (PROP) associates with greater intensity from a broad range of stimuli, including nonbitter tastants, irritants, and retronasally delivered odorants. Thus, PROP phenotype has become a common measure of individual differences in orosensation. Much, but not all, of the phenotypic variation in PROP bitterness is explained by TAS2R38 polymorphisms. While differences in PROP bitterness are clearly due to genetic variation, mechanistically it is challenging to envision how this receptor (narrowly tuned to the N-C=S moiety) relates to overall orosensory response. Here, we report data for 200+ individuals who had been genotyped for TAS2R38 and phenotyped for PROP in a laboratory setting. Participants also reported the intensity of quinine, capsaicin, and sucrose on a general Labeled Magnitude Scale. Our data recapitulate earlier reports associating PROP bitterness with the intensity of the predominant qualities of sucrose, quinine, and capsaicin; however, we also find correlations between the intensities of sucrose, quinine, and capsaicin were much stronger with each other than with PROP. As expected, TAS2R38 diplotype did not associate with the intensity of sucrose, quinine, or capsaicin. The strength of PROP-capsaicin and PROP-sucrose relationships increased after grouping participants by TAS2R38 diplotype, with the greatest increases in association observed within homozygotes. Collectively, this suggests the suprathreshold intensity of PROP is a confounded phenotype that captures both genetic variation specific to N-C=S compounds and overall orosensation.

Studies of human twins reveal genetic variation that affects dietary fat perception.

To learn more about the mechanisms of human dietary fat perception, 398 human twins rated fattiness and liking for six types of potato chips that differed in triglyceride content (2.5, 5, 10, and 15% corn oil); reliability estimates were obtained from a subset (n = 50) who did the task twice. Some chips also had a saturated long-chain fatty acid (hexadecanoic acid, 16:0) added (0.2%) to evaluate its effect on fattiness and liking. We computed the heritability of these measures and conducted a genome-wide association study (GWAS) to identify regions of the genome that co-segregate with fattiness and liking. Perceived fattiness and liking for the potato chips were reliable (r = 0.31-0.62, p < 0.05) and heritable (up to h2 = 0.29, p < 0.001, for liking). Adding hexadecanoic acid to the potato chips significantly increased ratings of fattiness but decreased liking. Twins with the G allele of rs263429 near GATA3-AS1 or the G allele of rs8103990 within ZNF729 reported more liking for potato chips than did twins with the other allele (multivariate GWAS, p < 1×10-5), with results reaching genome-wide suggestive but not significance criteria. Person-to-person variation in the perception and liking of dietary fat was (a) negatively affected by the addition of a saturated fatty acid and (b) related to inborn genetic variants. These data suggest liking for dietary fat is not due solely to fatty acid content and highlight new candidate genes and proteins within this sensory pathway.

Blending dark green vegetables with fruits in commercially available infant foods makes them taste like fruit.

Vegetables are an important but under consumed part of a healthy diet. There is growing interest in promoting vegetable acceptance and consumption among infants to help establish life-long healthy eating patterns. A recent survey of commercial baby food products in the United States by Moding and colleagues revealed a lack of variety in the types of vegetables offered. Most notably, there were no commercially available single, dark green vegetable products. Instead, dark green vegetables were often mixed with fruits or red/orange vegetables (e.g., squash) that provide additional sweetness. In order for liking for vegetables to be learned, the flavors from the vegetables must still be perceptible within the mixture. Thus, the objective of the research reported here was to understand the sensory profiles of vegetable-containing Stage 2 infant products commercially available in the United States and how ingredient composition affects flavor profiles. We performed descriptive analysis to quantitatively profile the sensory properties of 21 commercial vegetable-containing infant foods and one prepared in our laboratory. Eleven experienced panelists participated in 14.5 h of lexicon generation and training prior to rating all 22 products (in triplicate) for 14 taste, flavor, and texture attributes. Products that contained fruit were not only sweeter than products that did not contain fruit but were also higher in fruit flavors and lower in vegetable flavors. In general, sensory profiles were driven by the first ingredient in the product. Because few products had dark green vegetables as a first ingredient, dark green vegetable flavor was not prevalent in this category. This suggests the sensory profiles of commercially available infant vegetables foods may not be adequate to facilitate increased acceptance of green vegetables.

Regional Variation of Bitter Taste and Aftertaste in Humans.

Despite widespread and persistent myths of a tongue map, all 5 prototypical taste qualities are sensed over the entire tongue. However, modern psychophysical data also suggest there may be more nuanced differences in suprathreshold intensity across oral loci, especially for bitterness. Here, we test whether bitter stimuli matched for whole-mouth intensity differ in perceived intensity across regions of the oral cavity in 2 experiments. Experiment 1 consisted of a whole-mouth sip and spit approach and Experiment 2 consisted of a spatial taste test using cotton swabs. In Experiment 1, participants (n = 63) rated overall intensity of 3 bitter solutions at 5 different loci (front, middle, back of tongue; roof of mouth; and lip). Temporal effects were explored using in-mouth and aftertaste ratings. In Experiment 2, participants (n = 48) rated the intensity of quinine and Tetralone solutions after solutions were painted on fungiform, circumvallate, and foliate papillae with a swab. After the spatial taste test, participants completed a questionnaire on self-reported beer intake. Analysis of variance results of both experiments show a significant locus by stimulus interaction, suggesting different bitterants were perceived differently across the various loci. This result was apparently driven by low-intensity ratings for Tetralone on the anterior tongue. Aftertaste ratings in Experiment 1 also revealed significant temporal effects: ratings on the anterior tongue decreased for all bitterants and ratings for quinine decreased at all loci. Reasons for these effects are not known but may suggest differential expression of bitter taste receptors or differences in bitter agonist-receptor binding affinity across tongue regions.

Evaluation of Sweetener Synergy in Humans by Isobole Analyses.

The chemical senses and pharmaceuticals fundamentally depend on similar biological processes, but novel molecule discovery has classically been approached from vastly different vantage points. From the perspective of ingredient and flavor companies, there are countless ingredients that act via largely unknown mechanisms, whereas the pharmaceutical industry has numerous mechanisms in search of novel compounds. Mixtures of agonists can result in synergistic (superadditive) responses, which can be quantified via isobole analysis, a well-proven clinical approach in pharmacology. For the food and beverage industries, bulk (caloric) sweeteners like sugars are a key ingredient in sweetened foods and beverages, but consumers also desire products with fewer calories, which has led to the development of sweet enhancers and sweetener blends intended to achieve synergy or superadditivity. Synergistic mixtures are highly attractive targets commercially as they enable lower usage levels and enhanced efficacy. Although the psychophysical literature contains numerous prior reports of sweetener synergy, others have also noted that classical additive models fail to account for nonlinear dose-response functions. To address this shortcoming, here we systematically apply the isobole method from pharmacology to quantify the presence or absence of psychophysical synergy for binary pairs of sweeteners in a series of 15 separate experiments, each with ~100 adult volunteers (total n = 1576). Generally, these data support the hypothesis that structurally similar sweeteners acting as agonists will not synergize, whereas structurally dissimilar sweeteners binding to overlapping or distal sites can act as allosteric agonists or agonist-antagonists, respectively.

Self-reported Smoking Status, TAS2R38 Variants, and Propylthiouracil Phenotype: An Exploratory Crowdsourced Cohort Study.

TAS2R38 gene variants, which confer sensitivity to specific bitter tastants (e.g., 6-n-propylthiouracil), have been repeatedly associated with lower alcohol use via greater bitterness perception, but research exploring TAS2R38 variation in relation to smoking shows mixed results. In both, the working hypothesis is that 1 or more copies of the functional allele increases bitterness and may provide a barrier to early use. Such a barrier to initiation may, conceivably, manifest as differential rates of current use across diplotypes. Here, an age-diverse convenience sample (n = 886) of Denver Museum of Nature and Science guests was used to explore cross-sectional relationships between TAS2R38 diplotype, self-reported tobacco use (current, former, never smokers), and a rapid measure of 6-n-propylthiouracil phenotype (bitterness of filter paper discs). TAS2R38 diplotypes were determined by Sanger sequencing. After excluding rare diplotypes, data from 814 participants were analyzed. A mix of current (~10%), former (25%), and never smokers (65%) were included. As expected, there was a relationship between TAS2R38 diplotype and 6-n-propylthiouracil bitterness. However, contrary to our hypothesis, there was no evidence of a relationship between diplotype and smoker status among participants with common TAS2R38 diplotypes. Notably, we observed a relationship between of 6-n-propylthiouracil bitterness and smoking status, but the effect was opposite of what was expected: current smokers perceived higher (not lower) bitterness than never smokers. When all the various factors (diplotype, age, sex, and smoking status) were included in ANOVA, all remained predictive of 6-n-propylthiouracil bitterness. Reasons for greater phenotypic bitterness among current smokers are unknown and merit further study.

Qualitative exploration of intrinsic and extrinsic factors that influence acceptability of semisoft vaginal suppositories.

BACKGROUND: Vaginal microbicides are a promising means to prevent the transmission of HIV and other sexually transmitted infections, by empowering women to initiate use prophylactically when they perceive themselves to be at risk. However, in clinical trials, microbicides have shown mixed results, with the consistent finding that effectiveness varies substantially as a function of user adherence. METHODS: Based on the assumption that adherence is driven, at least in part, by product properties that influence acceptability, we used softgel technology to develop vaginal drug delivery systems in the intermediate texture space between solids and liquids to overcome potential shortcomings of current dosage forms. Here, we used focus groups and surveys to determine women's initial reactions (i.e., acceptance and willingness-to-try) for semisoft vaginal suppositories intended for HIV and STI prevention, with a specific focus on how perception of and preferences for vaginal suppositories may be influenced by product characteristics such as size, shape, and firmness. RESULTS: Via focus groups, we identified intrinsic and extrinsic factors relevant to acceptability of semisoft suppository prototypes. Willingness-to-try depended on factors like intended functionality, anticipated leakage, type of sex, recommended frequency of use, type of sexual partner, and perceived risk. When handled ex vivo, shape, size, and firmness of suppositories communicated information about ease of imagined insertion and handling, perceived effectiveness, anticipated awareness and comfort of the product in the body. These impressions were partly based on prior experience with vaginal products. CONCLUSIONS: Sensory attributes appear to play a substantial role in women's preferences and willingness to try the semisoft suppositories. Using these methods during preclinical development should help efficiently optimize a final product that is both biologically efficacious and preferred by women, toward a goal of enhancing adherence and effectiveness.

Mary Poppins was right: Adding small amounts of sugar or salt reduces the bitterness of vegetables.

Only a quarter of adults and 7% of children consume recommended amounts of vegetables each day. Often vegetables are not initially palatable due to bitterness, which may lead children and adults to refuse to taste or eat them. The objective of this research was to determine if very small amounts of sugar or salt (common household ingredients) could lead to significant reductions in bitterness intensity and increased hedonic ratings of green vegetable purees. For Experiment 1, three different green vegetable purees (broccoli, spinach, and kale) were prepared with different levels of sugar (0%, 0.6%, 1.2%, and 1.8%) or salt (0 and 0.2%). Samples were evaluated using standard descriptive analysis techniques with nine adults who completed more than 20 h of green vegetable specific training as a group. For Experiment 2, each vegetable puree was prepared with either 0% or 2% sugar, and bitterness was assessed via a forced choice task with 84 adults. For Experiment 3, each vegetable puree was prepared with 0%, 1%, or 2% sugar and rated for liking on standard 9 point hedonic scales by 99 adults. Experiments 1 and 2 showed that addition of small amounts of sugar and salt each reduced the bitterness (and increased sweetness and saltiness) from all three vegetables without altering other sensory properties (e.g. texture or aroma). Experiment 3 showed that adding sugar to vegetable purees increased hedonic ratings for adult consumers. We also found parents had mixed attitudes about the idea of adding sugar to foods intended for infants and toddlers. Further research on the effects of bitterness masking especially for specific populations (e.g., infants and young children or adults who have higher sensitivity to bitter taste) is warranted.