Evaluating the 'Labeled Magnitude Scale' for measuring sensations of taste and smell

Adherence to mediterranean diet and aromatic plants intake are related with gustatory function: A case-study from a Portuguese region

The Mediterranean Diet has been recognized as one of the healthiest and most sustainable dietary patterns and is flavor rich due to the use of different seasonings, such as aromatic plants, in dish confection. Based on the hypotheses that: 1) gustatory function will affect food choices; 2) seasoning flavors may be differently accepted according to individuals' gustatory functions; the aim of the present study was to assess the association between taste sensitivity and/or preference with Mediterranean Diet adherence and seasoning consumption. A total of 383 adults (18-59 years old; 198 female, 185 male) from North Alentejo region of Portugal were enrolled in this study, with 291 (145 female and 146 male) also evaluated for gustatory function. Recognition thresholds were obtained for four tastes (sweet, sour, salty, and bitter) and astringency, as well as preference level for the highest concentration of each stimulus tested. A validated Food Frequency Questionnaire was filled out, and MD adherence was extrapolated from the answers of the Food Frequency Questionnaire according to the Mediterranean Diet Adherence Screener (MEDAS) score. In total, 20.8% of the individuals presented low, 58.2% medium, and 21.0% high adherence. Adherence was higher in women than men and in older individuals than younger adults. Adherence to the Mediterranean Diet was positively correlated with aromatic plants consumption but not spices. Seasonings were associated with gustatory function, and the cluster with higher consumption presented higher preferences for bitter and salty tastes. Total sodium intake was also higher in this cluster, suggesting that these individuals prefer stronger oral sensations. In conclusion, this study shows that MD adherence is not high, even in regions with rural characteristics. The observed association of MD and seasoning intake with gustatory function do underline the usefulness of this information in strategies aimed at promoting healthy and sustainable eating patterns.

Reprint of: Sex differences in appeal, reward, and sensory experience of E-cigarette flavors among adults who smoke cigarettes

OBJECTIVE

Flavors enhance nicotine e-cigarette appeal by altering sensory experience. Females may be more sensitive to tobacco-associated cues and uniquely affected by flavor. The current study is an exploratory analysis to examine differences by sex on reward, appeal, and sensory experience of popular e-cigarette flavors.

METHODS

Adults (N = 121) who use cigarettes (≥1 cigarette/day) were enrolled in a laboratory study in which they vaped four e-cigarette flavors (tobacco, cherry, menthol, vanilla; in separate lab sessions) in one of two freebase nicotine concentrations (6 mg/ml,18 mg/ml). Following exposures, participants rated e-cigarette reward using the Drug Effects Questionnaire (DEQ), flavor and overall e-cigarette appeal using Labeled Hedonic Scales (LHS), and intensity of flavor, irritation, coolness, fruitiness, and sweetness using Generalized Labeled Magnitude Scales (gLMS). Linear mixed models were conducted for outcomes to analyze effects of sex, flavor, and sex x flavor interaction.

RESULTS

For DEQ ratings, there was a trend (p = .08) toward a sex x flavor interaction, in which menthol flavor produced more reward than other flavors for females, but not males. For LHS ratings, there was a significant sex x flavor interaction (p = .03) for overall e-cigarette experience with females but not males rating menthol higher than other flavors. All gLMS scales but irritation showed that females generally had greater differences between flavors compared to males (ps ≤ 0.03).

CONCLUSION

Menthol in e-cigarettes may play an important role in mediating appeal and/or reward among females. This may be due in part to their ability to better detect sensory effects of e-cigarettes.

Topical application of a P2X2/P2X3 purine receptor inhibitor suppresses the bitter taste of medicines and other taste qualities

BACKGROUND AND PURPOSE

Many medications taste intensely bitter. The innate aversion to bitterness affects medical compliance, especially in children. There is a clear need to develop bitter blockers to suppress the bitterness of vital medications. Bitter taste is mediated by TAS2R receptors. Because different pharmaceutical compounds activate distinct sets of TAS2Rs, targeting specific receptors may only suppress bitterness for certain, but not all, bitter-tasting compounds. Alternative strategies are needed to identify universal bitter blockers that will improve the acceptance of every medication. Taste cells in the mouth transmit signals to afferent gustatory nerve fibres through the release of ATP, which activates the gustatory nerve-expressed purine receptors P2X2/P2X3. We hypothesized that blocking gustatory nerve transmission with P2X2/P2X3 inhibitors (e.g. 5-(5-iodo-4-methoxy-2-propan-2-ylphenoxy)pyrimidine-2,4-diamine [AF-353]) would reduce bitterness for all medications and bitter compounds.

EXPERIMENTAL APPROACH

Human sensory taste testing and mouse behavioural analyses were performed to determine if oral application of AF-353 blocks perception of bitter taste and other taste qualities but not non-gustatory oral sensations (e.g. tingle).

KEY RESULTS

Rinsing the mouth with AF-353 in humans or oral swabbing it in mice suppressed the bitter taste and avoidance behaviours of all compounds tested. We further showed that AF-353 suppressed other taste qualities (i.e. salt, sweet, sour and savoury) but had no effects on other oral or nasal sensations (e.g, astringency and oral tingle).

CONCLUSION AND IMPLICATIONS

This is the first time a universal, reversible taste blocker in humans has been reported. Topical application of P2X2/P2X3 inhibitor to suppress bitterness may improve medical compliance.

One of the major challenges of masking the bitter taste in medications: an overview of quantitative methods for bitterness

Objective

The aim of the present study was to carry out a systematic research on bitterness quantification to provide a reference for scholars and pharmaceutical developers to carry out drug taste masking research. Significance: The bitterness of medications poses a significant concern for clinicians and patients. Scientifically measuring the intensity of drug bitterness is pivotal for enhancing drug palatability and broadening their clinical utility.

Methods

The current study was carried out by conducting a systematic literature review that identified relevant papers from indexed databases. Numerous studies and research are cited and quoted in this article to summarize the features, strengths, and applicability of quantitative bitterness assessment methods.

Results

In our research, we systematically outlined the classification and key advancements in quantitative research methods for assessing drug bitterness, including in vivo quantification techniques such as traditional human taste panel methods, as well as in vitro quantification methods such as electronic tongue analysis. It focused on the quantitative methods and difficulties of bitterness of natural drugs with complex system characteristics and their difficulties in quantification, and proposes possible future research directions.

Conclusion

The quantitative methods of bitterness were summarized, which laid an important foundation for the construction of a comprehensive bitterness quantification standard system and the formulation of accurate, efficient and rich taste masking strategies.

Expression of a single-chain monellin (MNEI) mutant with enhanced stability in transgenic mice milk

Monellin is a sweet protein that may be used as a safe and healthy sweetener. However, due to its low stability, the application of monellin is currently very limited. Here, we describe a wild-type, a double-sites mutant (E2N/E23A) and a triple-sites mutant (N14A/E23Q/S76Y) of single-chain monellin (MNEI) expressed in transgenic mice milk. Based on enzyme-linked immunoassay (ELISA), Western blot, and sweetness intensity testing, their sweetness and stability were compared. After boiling for 2 min at different pH conditions (2.5, 5.1, 6.8, and 8.2), N14A/E23Q/S76Y-MNEI showed significantly higher sweetness and stability than the wild-type and E2N/E23A-MNEI. These results suggest that N14A/E23Q/S76Y-MNEI shows remarkable potential as a sweetener in the future.

Sex differences in appeal, reward, and sensory experience of E-cigarette flavors among adults who smoke cigarettes

OBJECTIVE

Flavors enhance nicotine e-cigarette appeal by altering sensory experience. Females may be more sensitive to tobacco-associated cues and uniquely affected by flavor. The current study is an exploratory analysis to examine differences by sex on reward, appeal, and sensory experience of popular e-cigarette flavors.

METHODS

Adults (N = 121) who use cigarettes (≥1 cigarette/day) were enrolled in a laboratory study in which they vaped four e-cigarette flavors (tobacco, cherry, menthol, vanilla; in separate lab sessions) in one of two freebase nicotine concentrations (6 mg/ml,18 mg/ml). Following exposures, participants rated e-cigarette reward using the Drug Effects Questionnaire (DEQ), flavor and overall e-cigarette appeal using Labeled Hedonic Scales (LHS), and intensity of flavor, irritation, coolness, fruitiness, and sweetness using Generalized Labeled Magnitude Scales (gLMS). Linear mixed models were conducted for outcomes to analyze effects of sex, flavor, and sex x flavor interaction.

RESULTS

For DEQ ratings, there was a trend (p = .08) toward a sex x flavor interaction, in which menthol flavor produced more reward than other flavors for females, but not males. For LHS ratings, there was a significant sex x flavor interaction (p = .03) for overall e-cigarette experience with females but not males rating menthol higher than other flavors. All gLMS scales but irritation showed that females generally had greater differences between flavors compared to males (ps ≤ 0.03).

CONCLUSION

Menthol in e-cigarettes may play an important role in mediating appeal and/or reward among females. This may be due in part to their ability to better detect sensory effects of e-cigarettes.

Placebo treatment affects brain systems related to affective and cognitive processes, but not nociceptive pain

Drug treatments for pain often do not outperform placebo, and a better understanding of placebo mechanisms is needed to improve treatment development and clinical practice. In a large-scale fMRI study (N = 392) with pre-registered analyses, we tested whether placebo analgesic treatment modulates nociceptive processes, and whether its effects generalize from conditioned to unconditioned pain modalities. Placebo treatment caused robust analgesia in conditioned thermal pain that generalized to unconditioned mechanical pain. However, placebo did not decrease pain-related fMRI activity in brain measures linked to nociceptive pain, including the Neurologic Pain Signature (NPS) and spinothalamic pathway regions, with strong support for null effects in Bayes Factor analyses. In addition, surprisingly, placebo increased activity in some spinothalamic regions for unconditioned mechanical pain. In contrast, placebo reduced activity in a neuromarker associated with higher-level contributions to pain, the Stimulus Intensity Independent Pain Signature (SIIPS), and affected activity in brain regions related to motivation and value, in both pain modalities. Individual differences in behavioral analgesia were correlated with neural changes in both modalities. Our results indicate that cognitive and affective processes primarily drive placebo analgesia, and show the potential of neuromarkers for separating treatment influences on nociception from influences on evaluative processes.

Children's odor pleasantness ratings may not differ according to pubertal status: Preliminary results from a sample of 11-14-year-old Czech children

Puberty tends to be viewed as a "turning point" in hedonic perception of body odor (BO)-related smells. The pubertal stage, a potential proxy for the underlying physiological changes, may contribute to variation in odor hedonic perception. Other potential modulators of odor hedonics are general semantic knowledge about odors (which also tends to be subsumed under the term "age") and perceived odor intensity. The present cross-sectional study examined differences in hedonic odor perception across puberty in 205 Czech children aged 11-14 (89 boys). We investigated whether children differ in the hedonic appraisal of BO-related (16-androstenes and castoreum control), but also food and non-food odors according to their pubertal (penis/breast and pubic hair) development and general semantic knowledge about odors (operationalized as odor identification), controlling for age and perceived odor intensity. As a subsidiary aim, we examined variation in odor identification. We asked the children to self-stage themselves using drawings depicting Tanner's penis/breast and pubic hair stages of pubertal development, estimated their general semantic knowledge about odors with a Sniffin' Sticks identification test, and obtained their pleasantness and intensity ratings of body odor-related, food, a non-food smells. We found that the participants' ratings of the 16-androstenes and those of the perceptually similar odor of castoreum differed according to perceived intensity and, in the latter case, in boys vs. girls as well, but there were no influences of pubertal status or odor identification on the perceived pleasantness. Similarly, hedonic appraisal of non-food (but not food) odors was only influenced by perceived intensity. Regarding odor identification, differences between boys and girls were limited to younger children and did not become more marked throughout puberty. Perceived pleasantness of odors, irrespective of whether they are associated with body smells, food, or other, does not appear to vary across puberty, and boys and girls seem to achieve similar levels of semantic odor knowledge as they grow up.

Comparing body composition between the sweet-liking phenotypes: experimental data, systematic review and individual participant data meta-analysis

BACKGROUND

Legislation aimed at reducing sugar intake assumes that sweet-liking drives overconsumption. However, evidence that a greater liking for sweet taste is associated with unhealthier body size is mixed and complicated by relatively small samples, an overreliance on body mass index (BMI) and lack of classification using sweet-liking phenotypes.

METHODS

We first examined body size data in two larger samples with sweet-liking phenotyping: extreme sweet-likers, moderate sweet-likers and sweet-dislikers. Adults (18-34yrs), attended a two-session lab-based experiment involving phenotyping for sweet-liking status and a bioelectrical impedance body composition measurement (Experiment One: N = 200; Experiment Two: N = 314). Secondly, we conducted an individual participant data (IPD) meta-analysis: systematic searches across four databases identified 5736 potential articles. Of these, 53 papers met our search criteria: a taste assessment that measured liking using sucrose (>13.7% w/v), which allowed sweet-liking phenotyping and included either BMI, body fat percentage (BF%), fat-free mass (FFM) or waist-circumference.

RESULTS

A significant effect of sweet-liking phenotype on FFM was found in both Experiment One and Two, with extreme sweet-likers having significantly higher FFM than sweet-dislikers. In Experiment One, sweet-dislikers had a significantly higher BF% than extreme sweet-likers and moderate sweet-likers. However, as these data are from one research group in a young, predominantly westernised population, and the results did not perfectly replicate, we conducted the IPD meta-analyses to further clarify the findings. Robust one-stage IPD meta-analyses of 15 studies controlling for sex revealed no significant differences in BF% (n = 1836) or waist-circumference (n = 706). For BMI (n = 2368), moderate sweet-likers had slightly lower BMI than extreme sweet-likers, who had the highest overall BMI. Most interestingly, for FFM (n = 768), moderate sweet-likers and sweet-dislikers showed significantly lower FFM than extreme sweet-likers.

CONCLUSION

The higher BMI often seen in sweet-likers may be due to a larger FFM and questions the simple model where sweet liking alone is a risk factor for obesity.

Gene Methylation Affects Salivary Levels of the Taste Buds' Trophic Factor, Gustin Protein

The salivary protein, Gustin/carbonic anhydrase VI, has been described as a trophic factor responsible for the growth of taste buds. We found, in a genetically homogeneous population, that the polymorphism rs2274333 (A/G) of the Gustin gene is crucial for the full functionality of the protein and is associated with taste sensitivity. However, other studies have failed to find this evidence. Here, we verified if Gustin gene methylation can affect the salivary levels of the protein, also concerning the polymorphism rs2274333 and PROP bitter responsiveness. The Gustin gene methylation profiling and the quantification of the Gustin salivary levels were determined in sixty-six volunteers genotyped for the polymorphism rs2274333 (A/G) (Ser90Gly in the protein sequence). The fungiform papillae density was also determined. The results confirm our earlier observations by showing that AA genotypes had a greater density of fungiform taste papillae, whereas the GG genotypes showed a lower density. We also found variations in the protein levels in the three genotype groups and an inverse relationship between Gustin gene methylation and the salivary levels of the protein, mostly evident in AA and ST volunteers, i.e., in volunteers who would be carriers of the functional isoform of the protein. These findings could justify the conflicting data in the literature.

Increased functional connectivity following ingestion of dried bonito soup

Soup, including dried bonito broth, is customarily consumed as an umami taste during meals in Japan. Previous functional magnetic resonance imaging (fMRI) studies have investigated neuronal activation following human exposure to carbohydrates and umami substances. However, neuronal activity following ingestion of dried bonito soup has not been investigated. Additionally, recent progress in fMRI has enabled us to investigate the functional connectivity between two anatomically separated regions, such as the default mode network. In this study, we first investigated the altered functional connectivity after ingesting dried bonito soup in healthy volunteers. Functional connectivity in several brain regions, including the connection between the vermis, part of the cerebellum, and bilateral central opercular cortex, was markedly increased after ingesting dried bonito soup, compared to the ingestion of hot water. Physiological scaling showed that satiety was substantially increased by ingesting hot water rather than dried bonito soup. These results indicate that increased functional connectivity reflects the post-ingestive information pathway of dried bonito soup.

Influence of taste sensitivity on preference and sensory perception of mezcal

The perception of orosensory stimuli, which includes flavor, can vary between individuals. These individual variations in oral sensations can be due to genetic factors and it would appear that they can predict food liking and consumption. The most studied source of variation is related to bitter taste perception associated with 6-n-propylthiouracil (PROP) responsiveness. In this context, humans can be classified as non-tasters (NT), medium tasters (MT) and supertasters (ST). Evidence suggests that genetic variation in bitter taste perception contributes to differences in the level of irritation caused by alcohol perception in solutions. The aim of this investigation was to study the bitter taste sensitivity among a group of mezcal consumers and its relationship with sensory perception and preference through PROP taster status. The tests were carried out in the state of Oaxaca in Mexico. A total of 83 mezcal consumers were classified by their PROP taster status and were asked to provide sensory descriptors for five mezcal samples and rate them according to the level of liking. The three-solution test was used to classify the subjects as NT, MT, and ST, while a Multiple Factor Analysis (MFA) was used to visualize the sensory descriptors provided by these three groups. The proportion of MT subjects was 16%, while the proportion of NT and ST was 34 and 51%, respectively. The MT provided higher liking ratings for at least three mezcal samples. According to MFA, the mezcal samples were organized in a similar configuration along the two dimensions. However, NT mentioned a limited number of simple terms (strong flavor, tasteless, burning in the mouth) to describe the samples, whereas ST used a more complex vocabulary (astringent, smoky, scratchy aftertaste). These data suggest that the preference for mezcal samples was similar for non-taster and supertasters, but there are indications that the sensory perception of mezcal differs between groups.

Taste-Active Peptides from Triple-Enzymatically Hydrolyzed Straw Mushroom Proteins Enhance Salty Taste: An Elucidation of Their Effect on the T1R1/T1R3 Taste Receptor via Molecular Docking

The objective of our study was to analyze and identify enzymatic peptides from straw mushrooms that can enhance salty taste with the aim of developing saltiness enhancement peptides to reduce salt intake and promote dietary health. We isolated taste-related peptides from the straw mushroom extract using ultrafiltration and identified them using UPLC-Q-TOF-MS/MS. The study found that the ultrafiltration fraction (500-2000 Da) of straw mushroom peptides had a saltiness enhancement effect, as revealed via subsequent E-tongue and sensory analyses. The ultrafiltration fractions (500-2000 Da) were found to contain 220 peptides, which were identified through UPLC-Q-TOF-MS/MS analysis. The interaction of these peptides with the T1R1/T1R3 receptor was also assessed. The investigation highlighted the significant involvement of Asp223, Gln243, Leu232, Asp251, and Pro254 in binding peptides from triple-enzymatically hydrolyzed straw mushrooms to T1R1/T1R3. Based on the binding energy and active site analysis, three peptides were selected for synthesis: DFNALPFK (-9.2 kcal/mol), YNEDNGIVK (-8.8 kcal/mol), and VPGGQEIKDR (-8.9 kcal/mol). Importantly, 3.2 mmol of VPGGQEIKDR increased the saltiness level of a 0.05% NaCl solution to that of a 0.15% NaCl solution. Additionally, the addition of 0.8 mmol of YNEDNGIVK to a 0.05% NaCl solution resulted in the same level of saltiness as a 0.1% NaCl solution.

Leveraging Multi-echo EPI to Enhance BOLD Sensitivity in Task-based Olfactory fMRI

Functional magnetic resonance imaging (fMRI) using blood-oxygenation-level-dependent (BOLD) contrast relies on gradient echo echo-planar imaging (GE-EPI) to quantify dynamic susceptibility changes associated with the hemodynamic response to neural activity. However, acquiring BOLD fMRI in human olfactory regions is particularly challenging due to their proximity to the sinuses where large susceptibility gradients induce magnetic field distortions. BOLD fMRI of the human olfactory system is further complicated by respiratory artifacts that are highly correlated with event onsets in olfactory tasks. Multi-Echo EPI (ME-EPI) acquires gradient echo data at multiple echo times (TEs) during a single acquisition and can leverage signal evolution over the multiple echo times to enhance BOLD sensitivity and reduce artifactual signal contributions. In the current study, we developed a ME-EPI acquisition protocol for olfactory task-based fMRI and demonstrated significant improvement in BOLD signal sensitivity over conventional single-echo EPI (1E-EPI). The observed improvement arose from both an increase in BOLD signal changes through a T 2 * -weighted echo combination and a reduction in non-BOLD artifacts through the application of the Multi-Echo Independent Components Analysis (ME-ICA) denoising method. This study represents one of the first direct comparisons between 1E-EPI and ME-EPI in high-susceptibility regions and provides compelling evidence in favor of using ME-EPI for future task-based fMRI studies.

Oral stimulation with glucose and fructose, but not sucrose, accelerates gastric emptying in humans

Postprandial regulation of the gastric emptying (GE) rate plays an important role in food intake. Although oral sweetening with glucose may accelerate GE, the effects of different sweetness intensities of glucose (10% and 20%, w/v) and other energy sweeteners (e.g. fructose and sucrose) remain uncertain. The purpose of this study was to determine the effects of different glucose concentrations (Experiment 1) and different sugars with the same sweet taste intensity (Experiment 2) on postprandial GE. In both experiments, after ingesting a 200 kcal carbohydrate solution containing 50 g of maltodextrin, participants repeatedly sipped, but did not swallow, one of three (water, 10% and 20%, w/v glucose) or four (water and equally sweet 20%, w/v glucose, 12%, w/v fructose, and 14%, w/v sucrose) solutions for 1 min every 5 min over a 30 min period. GE was evaluated by measuring the temporal change in the cross-sectional area of the gastric antrum using ultrasound. In Experiment 1, oral stimulation with 20% (w/v) glucose resulted in greater GE than the control stimulus (i.e. water), but the effect of stimulation with 10% (w/v) glucose on GE was not different from that of the control stimulus. In Experiment 2, stimulation with 20% (w/v) glucose or 12% (w/v) fructose resulted in greater GE than the control stimulus. However, the effect of stimulation with 14% (w/v) sucrose on GE did not differ from that of the control stimulus. Consequently, oral stimulation with glucose or fructose solutions of moderate to high sweetness following a meal facilitates postprandial GE.

More spice, less salt: How capsaicin affects liking for and perceived saltiness of foods in people with smell loss

People who lose their sense of smell self-report consuming more salt to compensate for a lack of flavor and enhance eating enjoyment. However, this may contribute to excess sodium intake. Capsaicin may help increase salt taste intensity and eating enjoyment in people with smell loss, but this has not been studied in this population. The purpose of this study was to determine 1) whether salt intake in those with smell loss differs from population averages, 2) whether capsaicin increases flavor and salt taste intensity, and 3) if adding spice to foods increases liking in individuals with smell loss. Thirty-three participants 18-65 years old with confirmed smell loss for at least 12 weeks completed two sets of replicate test sessions (four total). In two sessions participants rated overall flavor intensity, taste qualities' intensities, spicy intensity, and liking for model tomato soups with low or regular sodium content and three levels of capsaicin (none, low, or moderate). In the other two sessions, participants rated the same sensory attributes for model food samples with three levels of added spice (none, low, or moderate). 24-hour urine samples were collected to determine sodium intake. Results indicate that although sodium intake is higher than recommended (<2300 mg/day) in those with smell loss (2893 ± 258 mg/day), they do not consume more sodium than population averages (3039 ± 100 mg/day; p = 0.3). Adding low and moderate amounts of capsaicin to a model tomato soup increased the intensity of overall flavor (p < 0.001) and saltiness (p = 0.004) compared to a model tomato soup without capsaicin. However, capsaicin's effect on liking differed by food type. Thus, capsaicin can improve flavor, salt taste intensity, and eating enjoyment in people with smell loss.

Orthonasal olfactory influences on consumer food behaviour

It is often suggested in the popular press that food chains deliberately introduce enticing product aromas into (and in the immediate vicinity of) their premises in order to attract customers. However, despite the widespread use of odours in the field of sensory marketing, laboratory research suggests that their effectiveness in modulating people's food behaviours depends on a range of contextual factors. Given the evidence that has been published to date, only under a subset of conditions is there likely to be a measurable effect of the presence of ambient odours on people's food attitudes and choices. This narrative historical review summarizes the various ways in which food odours appear to bias people's food preferences (appetite) and food choices (food consumption and purchase). Emphasis is placed on those experimental studies that have been designed to investigate how the characteristics of the olfactory stimuli (e.g., the congruency between the olfactory cues and the foods, intensity and duration of exposure to odours, and taste properties of odours) modulate the effects of olfactory cues on food behaviour. The review also explores the moderating roles of individual differences, such as dietary restraint, Body Mass Index (BMI), genetic and cultural differences in odour sensitivity and perception. Ultimately, following a review of empirical studies on food-related olfaction, current approaches in scent marketing are discussed and a research agenda is proposed to help encourage further studies on the effective application of scents in promoting healthy foods.

Recruitment of grid-like responses in human entorhinal and piriform cortices by odor landmark-based navigation

Olfactory navigation is universal across the animal kingdom. Humans, however, have rarely been considered in this context. Here, we combined olfactometry techniques, virtual reality (VR) software, and neuroimaging methods to investigate whether humans can navigate an olfactory landscape by learning the spatial relationships among discrete odor cues and integrating this knowledge into a spatial map. Our data show that over time, participants improved their performance on the odor navigation task by taking more direct paths toward targets and completing more trials within a given time period. This suggests that humans can successfully navigate a complex odorous environment, reinforcing the notion of human olfactory navigation. fMRI data collected during the olfactory navigation task revealed the emergence of grid-like responses in entorhinal and piriform cortices that were attuned to the same grid orientation. This result implies the existence of a specialized olfactory grid network tasked with guiding spatial navigation based on odor landmarks.

Odour-imagery ability is linked to food craving, intake, and adiposity change in humans

It is well-known that food-cue reactivity (FCR) is positively associated with body mass index (BMI)1 and weight change2, but the mechanisms underlying these relationships are incompletely understood. One prominent theory of craving posits that the elaboration of a desired substance through sensory imagery intensifies cravings, thereby promoting consumption3. Olfaction is integral to food perception, yet the ability to imagine odours varies widely4. Here we test in a basic observational study whether this large variation in olfactory imagery drives FCR strength to promote adiposity in 45 adults (23 male). We define odour-imagery ability as the extent to which imagining an odour interferes with the detection of a weak incongruent odour (the 'interference effect'5). As predicted in our preregistration, the interference effect correlates with the neural decoding of imagined, but not real, odours. These perceptual and neural measures of odour imagery are in turn associated with FCR, defined by the rated craving intensity of liked foods and cue-potentiated intake. Finally, odour imagery exerts positive indirect effects on changes in BMI and body-fat percentage over one year via its influences on FCR. These findings establish odour imagery as a driver of FCR that in turn confers risk for weight gain.

More spice, less salt: how capsaicin affects liking for and perceived saltiness of foods in people with smell loss

People who lose their sense of smell self-report consuming more salt to compensate for a lack of flavor and enhance eating enjoyment. However, this can contribute to excess sodium intake and a poor diet. Capsaicin may help increase salt taste intensity and eating enjoyment in this population, but this has not been studied. The purpose of this study was to determine 1) whether salt intake in those with smell loss differs from population averages, 2) whether capsaicin increases flavor and salt taste intensity, and 3) if adding spice to foods increases food liking in individuals with smell loss. Participants 18-65 years old with confirmed partial or total smell loss for at least 12 weeks completed two sets of replicate test sessions (four total). In two sessions participants rated overall flavor intensity, taste qualities' intensities, spicy intensity, and liking for model tomato soups with low or regular sodium content and three levels of capsaicin (none, low, or moderate). In the other two sessions, participants rated the same sensory attributes for model food samples with three levels of added spice (none, low, or moderate). 24-hour urine samples were also collected to determine sodium intake. Results indicate that although sodium intake is higher than recommended in those with smell loss (2893 ± 258 mg/day), they do not consume more sodium than population averages. Adding low and moderate amounts of capsaicin to a model tomato soup increased the intensity of overall flavor and saltiness compared to a model tomato soup without capsaicin. However, the effect of capsaicin on liking differed by food type. In conclusion, the addition of capsaicin can improve flavor, salt taste intensity, and eating enjoyment in people with smell loss.

Relation of Overweight/Obesity to Reward Region Response to Food Reward and the Moderating Effects of Parental History of Eating Pathology in Adolescent Females

OBJECTIVE

To test whether overweight/obesity is associated with an elevated reward region response to milkshake cues and a low reward region response to milkshake receipt. To test whether the risk for eating pathology moderates the effects of weight status on the neural response to milkshake cues and milkshake receipt.

METHOD

The current study used functional magnetic resonance imaging (fMRI) to examine the neuronal responses of female adolescents (n = 80; M age = 14.6 ± 0.9; M BMI = 21.9 ± 3.6; 41% with a biological parental history of eating pathology) during a food receipt paradigm.

RESULTS

Females with overweight/obesity showed a greater ventromedial prefrontal cortex (vmPFC), and ventral anterior cingulate (ACC) response to milkshake cues and a greater ventral striatum, subgenual ACC, and dorsomedial prefrontal cortex response to milkshake receipt than those with a healthy weight. Females with overweight/obesity plus a parental history of eating pathology showed a greater vmPFC/medial orbitofrontal cortex response to milkshake cues than those without a parental history of eating pathology and those with a healthy weight. Females with overweight/obesity and without a parental history of eating pathology showed a greater thalamus and striatum response to milkshake receipt.

CONCLUSIONS

Overweight/obesity is associated with an elevated reward region response to palatable food cues and food receipt. A risk for eating pathology enhances the reward region response to food cues in those with excess weight.

Association between Genetic Variation in the TAS2R38 Bitter Taste Receptor and Propylthiouracil Bitter Taste Thresholds among Adults Living in Japan Using the Modified 2AFC Procedure with the Quest Method

Individual taste sensitivity influences food preferences, nutritional control, and health, and differs greatly between individuals. The purpose of this study was to establish a method of measuring and quantifying an individual's taste sensitivity and to evaluate the relationship between taste variation and genetic polymorphisms in humans using agonist specificities of the bitter taste receptor gene, TAS2R38, with the bitter compound 6-n-propylthiouracil (PROP). We precisely detected the threshold of PROP bitter perception by conducting the modified two-alternative forced-choice (2AFC) procedure with the Bayesian staircase procedure of the QUEST method and examined genetic variation in TAS2R38 in a Japanese population. There were significant differences in PROP threshold between the three TAS2R38 genotype pairs for 79 subjects: PAV/PAV vs AVI/AVI, p < 0.001; PAV/AVI vs AVI/AVI, p < 0.001; and PAV/PAV vs PAV/AVI, p < 0.01. Our results quantified individual bitter perception as QUEST threshold values: the PROP bitter perception of individuals with the PAV/PAV or PAV/AVI genotypes was tens to fifty times more sensitive than that of an individual with the AVI/AVI genotype. Our analyses provide a basic model for the accurate estimation of taste thresholds using the modified 2AFC with the QUEST approach.

Consumer perceptions and antioxidant profiling of acidified cold-brewed sorghum bran beverages

Sumac sorghum (Sorghum bicolor L. Moench) bran contains polyphenolic compounds with health-promoting properties. Functional food product development can add economic value to sorghum bran, but acceptability may be limited by bitter taste. An acidified cold-brewed sorghum bran beverage was developed, and simplified sweetened (SB) and unsweetened (UB) versions were analyzed for antioxidant profiles (total phenolic content, phenolic profiling via HPLC, condensed tannins, oxygen radical absorbance capacity, and 2,2-diphenyl-1-picrylhydrazyl radical scavenging) and sensory properties. Beverages contained condensed tannins (average of 0.33 mg catechin equivalents per milliliter) along with other flavonoids and demonstrated in vitro antioxidant capacity (3.32-3.96 mmol Trolox equivalents per milliliter). One hundred fourteen consumers, grouped by 6-n-propylthiouracil (bitterness) taster status, rated acceptability (9-point hedonic scales), bitterness intensity (5-point scale), and purchase intent (PI; yes/no) of model beverages. Although the concept was novel, SB was clearly more acceptable to consumers regardless of preference for sweet versus unsweet tea (as a reference product concept). Mean mouthfeel and flavor liking scores were significantly higher for SB (6.2 and 5.1, respectively) than UB (4.8 and 3.0, respectively). Bitterness was suppressed by the sweetness in SB (mean bitterness intensity of 1.8 vs. 2.6 for UB), although 21% of consumers still found it "too bitter." However, consumers' taster status did not affect beverage acceptability nor bitterness perceptions at present phenolic levels (0.53 gallic acid equivalents per milligram). After a sorghum/antioxidant information message, positive PI increased to 56% for SB, impacting more females than males. Enhanced familiarity and effective product messaging can improve acceptability of acidified cold-brewed sorghum bran beverages as a novel functional food product concept. PRACTICAL APPLICATION: New food applications of cereal bran can provide value in terms of byproduct utilization and delivery of health-promoting ingredients. Sorghum bran beverages demonstrated antioxidant activity, and the sweetened formulation showed decreased bitterness and increased acceptability. Consumers were positively influenced by antioxidant information, although most had not previously consumed sorghum.

Investigating the Relationships between Taste Preferences and Beverage Intake in Preadolescents

Sugar-sweetened beverages are known promotors of adverse health outcomes. This study aimed to find a relation between taste perception, preferences for beverages, anthropometric parameters, and frequency of beverage consumption. Taste perception of sweetness was tested using an adopted sensitivity test with sucrose and different concentrations of sugar-sweetened apple juice. Furthermore, bitter-compound 6-n-propylthiouracil (PROP) and salty perception were tested and accompanied by a questionnaire on beverage intake. We did not find a clear relationship between taste perception, anthropometrics, and beverage intake. Nevertheless, in males, the bitter intensity perception of PROP was positively correlated with the BMI percentiles (CDC, r = 0.306, p ≤ 0.043) and the waist circumference (r = 0.326, p = 0.031). Furthermore, the liking of sweet taste (p < 0.05) and sweet intensity rating (p < 0.05) of apple juice increased with intensity, and adolescents with overweight or obesity had a higher intake of free sugars from beverages (p < 0.001). The role of taste perception on anthropometric measures and beverage intake remains unclear and requires further investigation.

Environmental chamber studies of eye and respiratory irritation from use of a peracetic acid-based hospital surface disinfectant

Objective

To characterize personal exposures and measures of eye and respiratory tract irritation in controlled environmental chamber studies of 44 healthy adult volunteers simulating upper-bound use of peracetic acid (PAA)-based surface disinfectant for terminal cleaning of hospital patient rooms.

Design

Experimental, within-subject, double-blinded cross-over design.

Methods

Objective and subjective exposure effects were assessed for PAA and its components: acetic acid (AA) and hydrogen peroxide (HP). Deionized water was included as a control. Breathing-zone concentrations of PAA, AA, and HP were assessed for 8 female multiday volunteers (5 consecutive days) and 36 single-day volunteers (32 females and 4 males). Wetted cloths were used to wipe high-touch surfaces for 20 minutes per trial. Also, 15 objective measures of tissue injury or inflammation and 4 subjective odor or irritation scores were assessed.

Results

Disinfectant trials showed 95th percentile breathing zone concentrations of 101 ppb PAA, 500 ppb AA, and 667 ppb HP. None of the volunteers observed over 75 test days exhibited significant increases in IgE or objective measures of eye and respiratory tract inflammation. Subjective ratings for disinfectant and AA-only trials showed similar increases for odor intensity and nose irritation, with lower ratings for eye and throat irritation. Females were 2.5-fold more likely than males to assign moderate + irritation ratings.

Conclusions

Simulated upper-bound hospital use of PAA-based disinfectant led to no significant increases in objective markers of tissue injury, inflammation, or allergic sensitization, and no frank signs of eye or respiratory tract irritation.

Trigeminal stimulation is required for neural representations of bimodal odor localization: A time-resolved multivariate EEG and fNIRS study

Whereas neural representations of spatial information are commonly studied in vision, olfactory stimuli might also be able to create such representations via the trigeminal system. We explored in two independent multi-method electroencephalography-functional near-infrared spectroscopy (EEG+fNIRS) experiments (n1=18, n2=14) if monorhinal odor stimuli can evoke spatial representations in the brain. We tested whether this representation depends on trigeminal properties of the stimulus, and if the retention in short-term memory follows the "sensorimotor recruitment theory", using multivariate representational similarity analysis (RSA). We demonstrate that the delta frequency band up to 5 Hz across the scull entail spatial information of which nostril has been stimulated. Delta frequencies were localized in a network involving primary and secondary olfactory, motor-sensory and occipital regions. RSA on fNIRS data showed that monorhinal stimulations evoke neuronal representations in motor-sensory regions and that this representation is kept stable beyond the time of perception. These effects were no longer valid when the odor stimulus did not sufficiently stimulate the trigeminal nerve as well. Our results are first evidence that the trigeminal system can create spatial representations of bimodal odors in the brain and that these representations follow similar principles as the other sensory systems.

Habitual daily intake of a sweet and fatty snack modulates reward processing in humans

Western diets rich in fat and sugar promote excess calorie intake and weight gain; however, the underlying mechanisms are unclear. Despite a well-documented association between obesity and altered brain dopamine function, it remains elusive whether these alterations are (1) pre-existing, increasing the individual susceptibility to weight gain, (2) secondary to obesity, or (3) directly attributable to repeated exposure to western diet. To close this gap, we performed a randomized, controlled study (NCT05574660) with normal-weight participants exposed to a high-fat/high-sugar snack or a low-fat/low-sugar snack for 8 weeks in addition to their regular diet. The high-fat/high-sugar intervention decreased the preference for low-fat food while increasing brain response to food and associative learning independent of food cues or reward. These alterations were independent of changes in body weight and metabolic parameters, indicating a direct effect of high-fat, high-sugar foods on neurobehavioral adaptations that may increase the risk for overeating and weight gain.

Characterization of Ethyl Butyrate-Induced Cough Before and After Breath Control Techniques in Healthy Adults

PURPOSE

Methods for cough elicitation frequently involve aerosolized tussive agents. Here, we sought to determine whether healthy individuals demonstrate a quantifiable cough response after inhaling a volatile ester and if breath control techniques modify this chemically induced cough response.

METHOD

Sixty adult male and female participants inhaled prepared liquid dilutions of ethyl butyrate dissolved in paraffin oil at 20%, 40%, and 60% v/v concentrations in triplicate, with presentation order randomized. We delivered stimuli through a face mask connected to an olfactometer and respiratory pneumotachograph. Participants rated sensations of their urge to cough and pleasantness of the odor while cough airflow was measured. Following baseline testing, participants were randomized to implement pursed-lip breathing or slow-paced breathing after inhaling ethyl butyrate to determine the effects of breath control on cough measures.

RESULTS

Inhaled ethyl butyrate elicited cough in 70% of participants. Higher concentrations of ethyl butyrate resulted in significantly greater sensation of the urge to cough, F(2, 80) = 10.72, p < .001, and significantly more generated coughs, F(2, 63) = 13.14, p < .001. Compared to baseline, participants rated significantly decreased urge to cough during breath control techniques, F(1, 40) = 11.01, p = .0019. No significant changes were observed in the number of generated coughs between baseline and breath control techniques, F(1, 31) = 7.23, p = .01.

CONCLUSIONS

Airborne ethyl butyrate is a tussigenic agent in humans. Our findings provide opportunities for future research directions in normal and disordered cough responses to volatile compounds.

Examining the Influence of Chemosensation on Laryngeal Health and Disorders

Inhaled airborne stimuli are associated with laryngeal disorders affecting respiration. Clinically, several themes emerged from the literature that point to specific gaps in the understanding and management of these disorders. There is wide variation in the types of airborne stimuli that trigger symptoms, lack of standardization in provocation challenge testing using airborne stimuli, and vague reporting of laryngeal symptoms. Scientifically, evidence exists outside the field of voice science that could prove useful to implement among patients with impaired laryngeal-respiration. To expand this area of expertise, here we provide a thematic overview of relevant evidence and methodological tools from the discipline of chemosensory sciences. This review provides distinctions across the three chemosensory systems of olfaction, trigeminal chemesthesis, and gustation, guidance on selecting and delivering common chemosensory stimuli for clinical testing, and methods of quantifying sensory experiences using principles of human psychophysics. Investigating the science of chemosensation reveals that laryngeal responses to inhaled airborne stimuli have explanations involving physiological mechanisms as well as higher cognitive processing. Fortunately, these findings are consistent with current pharmacological and nonpharmacological interventions for impaired laryngeal-respiration. Based on the close relationships among inhaled airborne stimuli, respiration, and laryngeal function, we propose that new perspectives from chemosensory sciences offer opportunities to improve patient care and target areas of future research.

Odor imagery but not perception drives risk for food cue reactivity and increased adiposity

Mental imagery has been proposed to play a critical role in the amplification of cravings. Here we tested whether olfactory imagery drives food cue reactivity strength to promote adiposity in 45 healthy individuals. We measured odor perception, odor imagery ability, and food cue reactivity using self-report, perceptual testing, and neuroimaging. Adiposity was assessed at baseline and one year later. Brain responses to real and imagined odors were analyzed with univariate and multivariate decoding methods to identify pattern-based olfactory codes. We found that the accuracy of decoding imagined, but not real, odor quality correlated with a perceptual measure of odor imagery ability and with greater adiposity changes. This latter relationship was mediated by cue-potentiated craving and intake. Collectively, these findings establish odor imagery ability as a risk factor for weight gain and more specifically as a mechanism by which exposure to food cues promotes craving and overeating.

Role of dairy proteins in the reduction of capsaicin-induced oral burning pain

Capsaicin-induced burning sensation in the oral mucosa can be relieved by skimmed and whole milk. The mechanism behind this effect, however, is unknown. This study aimed to asses the role of milk proteins in reducing capsaicin-induced oral burning sensation. 24 healthy participants were included in this single-blinded cross-over study consisting of four sessions. In each sessions, mucosal burning sensation was evoked by having the participants dip their tongues in a cup containing 0.1% capsaicin gel for a total of 8 min. The perceived levels of unpleasantness and burning intensity were scored on two different numerical rating scales. After capsaicin exposure, the participants rinsed their mouth for 10 s with a different solution in each session (3.5% casein, 3.5% whey, 3.5% lactose (non-protein control) and skimmed milk (active/positive control)). Mechanical (64, 128 and 256 mN pinprick) and thermal (5, 40, 45 and 50 ̊C) sensitivity of the tongue was measured using semi-quantative sensory testing at baseline, immediately after capsaicin exposure and when the scores for unpleasantness and burning intensity reached the minimum value of 0. Thermographic images of the tongue were taken at the same time-points. Overall, no statistically significant difference in unpleasantness and burning intensity was found between the four sessions (P ≥ 0.070). Explorative pair-wise comparisons, however, showed slight short-term reduction in unpleasantness and burning intensity when comparing the casein solution with the lactose solution (P ≤ 0.020). Scores for burning intensity and unpleasantness varied over time (P ≤ 0.001). Statistically significant changes in heat and mechanical sensitivity was observed between time-points (P < 0.001) but not sessions (P ≥ 0.410). An increased sensitivity towards heat and a decreased sensitivity towards mechanical stimuli was observed after capsaicin exposure compared with baseline (P < 0.001). Similarly, changes in thermographic temperature of the tongue was observed between time-points (P < 0.001), but not sessions (P ≥ 0.827). An increased maximum, minimum and average temperature of the tongue was observed immediately after capsaicin exposure compared with baseline (P < 0.001). In conclusion, short-term rinsing with room temperature milk proteins did not robustly alter capsaicin-induced oral burning sensation, unpleasantness, somatosensory changes or tongue temperature compared with control. Further studies exploring the effects of increased rinsing time and concentrations are needed in the future.

Oral Exposure to Sodium Chloride without Subsequent Consumption Does Not Alter Salt Taste Function in Adults: A Cross-Over Intervention Study

BACKGROUND

Reduction in dietary sodium increases salt taste sensitivity; however, non-oral sodium supplementation does not, suggesting that oral exposure is more important for modulating taste perception than consumption without tasting.

OBJECTIVE

Using psychophysical methods, we assessed the effect of a two-week intervention involving oral exposure to a tastant without consumption on modulating taste function.

METHODS

In a cross-over intervention study, n = 42 adults (age, mean ± SD: 29.7 ± 8.0 years) completed 4 intervention treatments requiring participants to rinse their mouths with 30 mL of a tastant, 3 times daily for 2 weeks. Treatments included oral exposure to 400 mM sodium chloride (NaCl), monosodium glutamate (MSG), monopotassium glutamate, and sucrose. Participants' taste function for salty, umami, and sweet [detection threshold (DT), recognition threshold (RT), and suprathreshold (ST)], and the glutamate-sodium discrimination status was evaluated before and after the tastant treatments. Effects of the interventions on taste function were assessed by using linear mixed models including treatment, time, and treatment x time interactions as fixed effects; significance was set at P > 0.05.

RESULTS

There was no treatment × time interaction on DT and RT for all tastes assessed (P > 0.05). The only change in ST was following the NaCl intervention, participants' salt ST decreased at the highest concentration (400 mM) compared with the pre-NaCl treatment taste assessment (mean difference (MD): -0.052 [95% CI: -0.093, -0.010] labeled magnitude scale, P = 0.016). Compared with the pre-MSG treatment taste assessment, participants improved their ability to perform the glutamate-sodium discrimination task after the MSG intervention (MD:1.64 [95% CI: 0.395, 2.878] correct discrimination tasks, P = 0.010).

CONCLUSION

Saltiness of an adult's free-living diet is unlikely to influence salt taste function, as oral exposure without consumption to a salt concentration greater than normally found in food, only attenuated taste responses to highly salty stimuli. This provides preliminary evidence that regulating salt taste function may require a coordinated response between oral activation and consumption of sodium.

Effect of the addition of soluble polysaccharides from red and white grape skins on the polyphenolic composition and sensory properties of Tempranillo red wines

Soluble polysaccharides from white (PSW) and red (PSR) grape skins were obtained to be evaluated as potential modulators of the unbalanced astringency of a Tempranillo red wine. The modulation of astringency was evaluated by a sensory panel and it seemed to be related to the changes in the polyphenolic profile. Isothermal Titration Calorimetry (ITC) studies, employed to characterize flavan-3-ol-polysaccharide interactions, showed that PSR decreased noticeably wine astringency causing a great flavan-3-ol loss (ca. 40 %), since they interacted more spontaneously with the flavan-3-ols (ca. ΔGtotal = -2.14 × 10⁴ cal/mol) than PSW (ca. ΔGtotal = -1.32 × 10⁴ cal/mol). The strength of these interactions seems to be related to the polysaccharide molecular size and to the presence of arabinogalactans in the structure. On the contrary, PSW showed no relevant effects on wine astringency. Furthermore, potential variations of color were also assessed and no deleterious effect was observed after the addition of any polysaccharide.

Mouth rinsing and ingesting salty or bitter solutions does not influence corticomotor excitability or neuromuscular function

PURPOSE

To explore the effect of tasting unpleasant salty or bitter solutions on lower limb corticomotor excitability and neuromuscular function.

METHODS

Nine females and eleven males participated (age: 27 ± 7 years, BMI: 25.3 ± 4.0 kg m^-2). Unpleasant salty (1 M) and bitter (2 mM quinine) solutions were compared to water, sweetened water, and no solution, which functioned as control conditions. In a non-blinded randomized cross-over order, each solution was mouth rinsed (10 s) and ingested before perceptual responses, instantaneous heart rate (a marker of autonomic nervous system activation), quadricep corticomotor excitability (motor-evoked potential amplitude) and neuromuscular function during a maximal voluntary contraction (maximum voluntary force, resting twitch force, voluntary activation, 0-50 ms impulse, 0-100 impulse, 100-200 ms impulse) were measured.

RESULTS

Hedonic value (water: 47 ± 8%, sweet: 23 ± 17%, salt: 71 ± 8%, bitter: 80 ± 10%), taste intensity, unpleasantness and increases in heart rate (no solution: 14 ± 5 bpm, water: 18 ± 5 bpm, sweet: 20 ± 5 bpm, salt: 24 ± 7 bpm, bitter: 23 ± 6 bpm) were significantly higher in the salty and bitter conditions compared to control conditions. Nausea was low in all conditions (< 15%) but was significantly higher in salty and bitter conditions compared to water (water: 3 ± 5%, sweet: 6 ± 13%, salt: 7 ± 9%, bitter: 14 ± 16%). There was no significant difference between conditions in neuromuscular function or corticomotor excitability variables.

CONCLUSION

At rest, unpleasant tastes appear to have no influence on quadricep corticomotor excitability or neuromuscular function. These data question the mechanisms via which unpleasant tastes are proposed to influence exercise performance.

Olfactory decoding is positively associated with ad libitum food intake in sated humans

The role of olfaction in eating behavior and body weight regulation is controversial. Here we reanalyzed data from a previous functional magnetic resonance imaging study to test whether central olfactory coding is associated with hunger/satiety state, food intake, and change in body weight over one year in healthy human adults. Since odor quality and category are coded across distributed neural patterns that are not discernible with traditional univariate analyses, we used multi-voxel pattern analyses to decode patterns of brain activation to food versus nonfood odors. We found that decoding accuracies in the piriform cortex and amygdala were greater in the sated compared to hungry state. Sated decoding accuracies in these and other regions were also associated with post-scan ad libitum food intake, but not with weight change. These findings demonstrate that the fidelity of olfactory decoding is influenced by meal consumption and is associated with immediate food intake, but not longer-term body weight regulation.

Enhanced sweet taste perception in obesity: Joint analysis of gustatory data from multiple studies

Introduction

While sweet taste perception is a potential determinant of feeding behavior in obesity, the supporting evidence is inconsistent and is typically associated with methodological limitations. Notably, possible associations between sweet taste perception and measures of food reward remain undetermined.

Materials and methods

We conducted a cross-sectional analysis comparing 246 individuals with severe obesity and 174 healthy volunteers using a validated method for taste perception assessment. We included gustatory variables, namely intensity and pleasantness ratings of sour, salt, sweet, and bitter tastants, and taste thresholds assessed by electrogustometry. Reward-related feeding behavior, including hedonic hunger, food addiction, feeding behavior traits, and acceptance of foods and alcohol, was evaluated using self-rated scales for comparison with gustatory measures.

Result

In logistic regressions adjusted for age, gender, educational level, and research center, we found that a greater likelihood of belonging to the obesity group was associated with higher sweet intensity ratings (OR = 1.4, P = 0.01), hedonic hunger, food addiction symptoms, restrained and emotional eating (1.7 < OR ≤ 4.6, all P ≤ 0.001), and lower alcohol acceptance (OR = 0.6, P = 0.0002). Using principal component analysis, we found that while hedonic hunger, food addiction, and emotional eating were strongly interrelated, they were not associated with sweet intensity perception that, in turn, had a closer relationship with alcohol acceptance and restrained eating.

Conclusion

We found that individuals with obesity report higher sweet taste intensity ratings than healthy controls. Furthermore, while psychological measures of reward-related feeding behavior assess a common construct, sweet intensity perception may represent a different obesity-related dimension.

Overlapping activation pattern of bitter taste receptors affect sensory adaptation and food perception

The composition of menus and the sequence of foodstuffs consumed during a meal underlies elaborate rules. However, the molecular foundations for the observed taste- and pleasure-raising effects of complex menus are obscure. The molecular identification and characterization of taste receptors can help to gain insight into the complex interrelationships of food items and beverages during meals. In our study, we quantified important bitter compounds in chicory and chicory-based surrogate coffee and used them to identify responsive bitter taste receptors. The two receptors, TAS2R43 and TAS2R46, are exquisitely sensitive to lactucin, lactucopicrin, and 11β,13-dihydrolactucin. Sensory testing demonstrated a profound influence of the sequence of consumption of chicory, surrogate coffee, and roasted coffee on the perceived bitterness by human volunteers. These findings pave the way for a molecular understanding of some of the mixture effects underlying empirical meal compositions.

A New Viscous Budesonide Formulation for the Treatment of Eosinophilic Esophagitis in Children: A Preliminary Experience and Review of the Literature

Eosinophilic esophagitis (EoE) is a chronic disease, characterized clinically by esophageal disfunction. Topical corticosteroids (tCS), predominantly fluticasone and budesonide, are considered the effective first line treatment, as well as an option of maintenance therapy in EoE. The way that tCS are administered significantly affects their effectiveness. There is still no ready-to-use steroid drug to be applied topically to the esophagus in children-a few experimental viscous slurries (mainly of budesonide) have been shown in trials to be more effective than steroids administered via metered dose inhalers (MDIs) and swallowed. The best examined steroid solvent of all is sucralose, a high-intensity artificial sweetener. Although it has been shown in a critical review that it is non-toxic and safe for all consumers, there are still some concerns among patients about its potential adverse effect on humans. Due to that fact, we developed a new viscous formulation and evaluated its effectiveness in the treatment of children with EoE. In an open, prospective, single-center study, we administered our new formulation of viscous budesonide twice daily for 8 weeks in patients with an active EoE. After treatment, we performed a control gastroscopy with the collection and evaluation of histopathological samples. We have proven our formulation effectiveness at 64%, as far as histological remission is concerned. We have also shown a reduction in the mean endoscopic reference score (EREFS) from 3.1 points at the beginning of the study to 1.6 points at the end of the study. Bearing in mind how important the acceptance of the solvent is for long-time compliance, especially among children, we also decided to assess the taste of the formulation. Therefore, we asked 46 adults and 10 children to swallow a sample of the solvent and fill in a short anonymous questionnaire about its taste, smell, consistency and easiness of swallowing. General acceptance for the proprietary solvent was high, reaching 7.5/10 among adults and 6.5/10 in children. To be able to compare the results of our preliminary experience, we reviewed the studies which evaluated substances that have been used so far as steroid solvents for the treatment of EoE. The overall effectiveness of the oral viscous budesonide (OVB) ranged from 65% to 90%, which is consistent with the results obtained in our study. Unfortunately, the high heterogeneity of the studies did not allow us to draw reliable conclusions.

Psychophysiological Responses of Cut Flower Fragrances as an Olfactory Stimulation by Measurement of Electroencephalogram in Adults

Horticultural therapy (HT) is green care that can help improve and recover the health of modern people living in cities through natural experiences. Many studies have been conducted to determine HT's therapeutic effects and underlying mechanisms, but investigation for developing readily applicable clinical techniques is insufficient. We aimed to investigate adults' brain activity and emotional state during flower arrangement (FA) with different flowers in an HT program. We recruited thirty adults and used a randomized cross-over study method to set them to participate in five FA tasks at 90-s intervals. While performing FA tasks, the participants' prefrontal cortex brain waves were measured by a wireless electroencephalography device and their emotional states between FA tasks were measured by questionnaires. Results showed that each FA task resulted in a different attention level of the participants. The participants showed the highest attention level during FA with stocks and carnations, while FA with lilies showed the lowest attention level among the five FA tasks. Instead, the participants showed the highest arousal, tension, and anxiety for emotional states during FA with lilies. Therefore, this study confirmed the differences in attention level and emotional changes according to flower types for using clinical techniques of HT for various clients.

Glutamate-Sodium Discrimination Status in Adults Is Associated with Salt Recognition Threshold and Habitual Intake of Discretionary Food and Meat: A Cross-Sectional Study

Umami non-discriminators (NDs) are a sub-group of the population with a reduced ability to discriminate between monosodium glutamate (MSG) and sodium chloride (NaCl) compared to umami discriminators (UDs). No research has investigated umami and salty taste perception associations across detection threshold (DT), recognition threshold (RT), and suprathreshold intensity perception (ST) or the habitual dietary intake of ND. Adults (n = 61, mean age of 30 ± 8 years, n = 40 females) completed taste assessments measuring their DT, RT, and ST for salty, umami (MSG and monopotassium glutamate (MPG)), and sweet tastes. To determine the umami discrimination status, participants completed 24 triangle tests containing 29 mM NaCl and 29 mM MSG, and those with ≥13 correct identifications were considered UDs. Habitual dietary intake was recorded via a food frequency questionnaire. NDs made up 14.8% (n = 9) of the study population, and UDs made up 85.2% (n = 52). NDs were less sensitive to salt at RT (mean step difference: -1.58, p = 0.03), and they consumed more servings of meat and poultry daily (1.3 vs. 0.6 serves, p = 0.006); fewer servings of discretionary food (1.6 vs. 2.4, p = 0.001); and, of these, fewer salty discretionary foods (0.9 vs. 1.3, p = 0.003) than NDs. Identifying these NDs may provide insight into a population at risk of the overconsumption of discretionary foods and reduced intake of protein-rich meat foods.

Dietary adaptation for weight loss maintenance at Yale (DAWLY): Protocol and predictions for a randomized controlled trial

Background

Current therapies for obesity treatment are effective at producing short-term weight loss, but weight loss maintenance remains a significant challenge. Here we investigate the impact of pre-intervention dietary fat intake on the efficacy of a dietary supplement to support weight loss maintenance. Preclinical work demonstrates that a vagal afferent pathway critical for sensing dietary lipids is blunted by a high-fat diet (HFD), resulting in a reduced preference for a low-fat emulsion and severe blunting of the dopamine (DA) response to the gastric infusion of lipids. Infusion of the gut lipid messenger oleoylethanolamide (OEA), which is also depleted by HFD, immediately reverses this DA blunting and restores preference for the low-fat emulsion. Studies of OEA supplementation for weight loss in humans have had limited success. Given the strong effect of HFD on this pathway, we designed a study to test whether the efficacy of OEA as a weight loss treatment is related to pre-intervention habitual intake of dietary fat.

Methods/Design

We employed a randomized, double-blind, placebo-controlled trial in which 100 adults with overweight/obesity (OW/OB) were randomized to receive either OEA or placebo daily for 16 months. Following a baseline evaluation of diet, metabolic health, adiposity, and brain response to a palatable an energy dense food, participants in both groups underwent a 4-month behavioral weight loss intervention (LEARN®) followed by a 1-year maintenance period. The study aims are to (1) determine if pre-intervention dietary fat intake moderates the ability of OEA to improve weight loss and weight loss maintenance after a gold standard behavioral weight loss treatment; (2) identify biomarkers that predict outcome and optimize a stratification strategy; and (3) test a model underlying OEA's effectiveness.

Discussion

Focusing on interventions that target the gut-brain axis is supported by mounting evidence for the role of gut-brain signaling in food choice and the modulation of this circuit by diet. If successful, this work will provide support for targeting the gut-brain pathway for weight loss maintenance using a precision medicine approach that is easy and inexpensive to implement.

Clinical Trial Registration

[www.ClinicalTrials.gov], identifier [NCT04614233].

Testing Links of Food-Related Olfactory Perception to Peripheral Ghrelin and Leptin Concentrations

The peptide hormones ghrelin and leptin play major roles in the regulation of appetite and food intake. However, the precise effects of these hormones on sensory processing remain a subject of debate, particularly with food related stimuli and its small body of evidence. Here, we test for relationships between ghrelin and leptin levels against olfactory performance with multiple food-related odours. Specifically, a total of 94 Caucasian males were tested for their supra-threshold sensitivity (i.e., d′), intensity, and valence perception to three odour compounds (i.e., vanilla, potato, and dairy odours). These sensory data were then analysed against peripheral ghrelin and leptin levels, both assessed in plasma samples. Participants’ body adiposity measures were also obtained. Results lent strong support to one of our original hypotheses, with ghrelin levels being positively correlated to the supra-threshold sensitivity of the dairy odour, (r = 0.241, p = 0.020), and intensity ratings to most of the food odours tested [dairy (r = 0.216, p = 0.037) and vanilla (r = 0.241, p = 0.020)]. By contrast, peripheral leptin levels were not significantly linked to any of the olfactory measures (p > 0.05). These relationships remained similar after controlling for variabilities of adiposity measures. The present study brings novel insights by identifying positive links between supra-threshold olfactory perception and ghrelin. This new knowledge is highly relevant for future research linking olfactory shifts to hormonal dysregulation and obesity.

Oral processing behaviours of liquid, solid and composite foods are primarily driven by texture, mechanical and lubrication properties rather than by taste intensity

The aim of this study was to understand the influence of saltiness and sweetness intensity on oral processing behaviours of liquid, solid and composite foods. As salty foods, tomato sauce (liquid), penne pasta (solid) and their combination (composite food) were used at two levels of saltiness intensity (low/high). As sweet foods, strawberry sauce (liquid), milk gels (solid) and their combination (composite foods) were used at two levels of sweetness intensity (low/high). Saltiness, sweetness, hardness, chewiness, and liking were quantified using generalized labelled magnitude scales (gLMS). Oral processing behaviours were determined using video recordings (n = 39, mean age 25 ± 3 years) in a home-use-test (HUT) providing fixed bite sizes for all foods. As expected, taste intensity differed significantly between samples within the same food category. No significant effects of taste intensity on oral processing behaviours were found for sweet and salty foods. As expected, consistency strongly affected the consumption time per bite, number of chews per bite, number of chews per gram and eating rate. Solid foods were masticated for the longest time with the highest number of chews per bite, followed by composite foods as the liquid added to the solid foods enhanced lubrication. Liquid foods were masticated for the shortest time. We conclude that large differences in saltiness and sweetness intensity of liquid, solid and composite foods cause no differences in oral processing behaviours. We suggest that oral processing behaviours are primarily driven by texture, mechanical and lubrication properties of foods rather than by their taste intensity.

Topical Capsaicin in Poly(lactic-co-glycolic)acid (PLGA) Nanoparticles Decreases Acute Itch and Heat Pain

BACKGROUND

Capsaicin, the hot pepper agent, produces burning followed by desensitization. To treat localized itch or pain with minimal burning, low capsaicin concentrations can be repeatedly applied. We hypothesized that alternatively controlled release of capsaicin from poly(lactic-co-glycolic acid) (PLGA) nanoparticles desensitizes superficially terminating nociceptors, reducing burning.

METHODS

Capsaicin-loaded PLGA nanoparticles were prepared (single-emulsion solvent evaporation) and characterized (size, morphology, capsaicin loading, encapsulation efficiency, in vitro release profile). Capsaicin-PLGA nanoparticles were applied to murine skin and evaluated in healthy human participants (n = 21) for 4 days under blinded conditions, and itch and nociceptive sensations evoked by mechanical, heat stimuli and pruritogens cowhage, β-alanine, BAM8-22 and histamine were evaluated.

RESULTS

Nanoparticles (loading: 58 µg capsaicin/mg) released in vitro 23% capsaicin within the first hour and had complete release at 72 h. In mice, 24 h post-application Capsaicin-PLGA nanoparticles penetrated the dermis and led to decreased nociceptive behavioral responses to heat and mechanical stimulation (desensitization). Application in humans produced a weak to moderate burning, dissipating after 3 h. A loss of heat pain up to 2 weeks was observed. After capsaicin nanoparticles, itch and nociceptive sensations were reduced in response to pruritogens cowhage, β-alanine or BAM8-22, but were normal to histamine.

CONCLUSIONS

Capsaicin nanoparticles could be useful in reducing pain and itch associated with pruritic diseases that are histamine-independent.