Sweet liker status in children and adults: Consequences for beverage intake in adults

Secondary Analysis of Sweetness Liking from Pilot Study Replacing Sugar Sweetened Soda with Flavored, Unsweetened Sparkling Water

OBJECTIVE

This study aimed to evaluate changes in sensory ratings (liking, sweetness intensity, "just about right" (JAR) level of sweetness) of 0-10.7% w/w sugar in soda after 1 and 2 wk of replacing sugar-sweetened soda consumption with unsweetened, flavored, sparkling water.

METHODS

Consumers of sugar-sweetened sodas (17 men and women, average age 28 years) replaced their sodas with unsweetened, flavored sparkling waters for 2 wk. Changes in sensory ratings were evaluated for sodas ranging from 0-10.7% w/w added sugar. In a secondary analysis, cluster analysis identified "Sweet Likers" (liking increased with sugar concentration) and "Sweet Moderates" (liking peaked in the middle of the concentration range) in the baseline ratings, and models for changes in sensory ratings were reevaluated by sweet-liking group.

RESULTS

The primary analyses showed no significant effects of the intervention on sweetness intensity or liking ratings. However, the secondary analysis showed that Sweet Likers reduced liking ratings for all sodas, but particularly for the highest concentration (p = 0.0021) after the intervention. Sweet Moderates, however, increased liking ratings after the intervention, driven by an increase in liking for the lower concentrations of sugar (p = 0.0058). Additionally, Sweet Moderates increased their overall ratings for sweetness intensity in sodas (p = 0.00074).

CONCLUSION

These results suggest that the intervention may have been more successful in shifting sensory perception and acceptance of less-sweet sodas for Sweet Moderates than for Sweet Likers. These results should be verified in a larger sample that intentionally recruits by sweet liker status, to see if initial liking for sweetness may be a critical factor in interventions aiming to improve liking of less sweet beverages.

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.

Does sweetness exposure drive 'sweet tooth'?

It is widely believed that exposure to sweetened foods and beverages stimulates the liking and desire for sweetness. Here we provide an updated review of the empirical evidence from human research examining whether exposure to sweet foods or beverages influences subsequent general liking for sweetness (‘sweet tooth’), based on the conclusions of existing systematic reviews and more recent research identified from a structured search of literature. Prior reviews have concluded that the evidence for a relationship between sweet taste exposure and measures of sweet taste liking is equivocal, and more recent primary research generally does not support the view that exposure drives increased liking for sweetness, in adults or children. In intervention trials using a range of designs, acute exposure to sweetness usually has the opposite effect (reducing subsequent liking and desire for sweet taste), while sustained exposures have no significant effects or inconsistent effects. Recent longitudinal observational studies in infants and children also report no significant associations between exposures to sweet foods and beverages with measures of sweet taste preferences. Overall, while it is widely assumed that exposure to sweetness stimulates a greater liking and desire for sweetness, this is not borne out by the balance of empirical evidence. While new research may provide a more robust evidence base, there are also a number of methodological, biological and behavioural considerations that may underpin the apparent absence of a positive relationship between sweetness exposure and liking.

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.

Does vaping affect the taste and smell perception? An exploratory study with New Zealand young adults

OBJECTIVE

The study aimed to assess potential effects of vaping on individual taste and smell perception in a sample of young adult New Zealanders.

DESIGN

This cross-sectional study measured taste and smell perception using intensity and hedonic ratings to two olfactory (i.e., vanillin, methional) and two gustatory stimuli (i.e., sucrose, monosodium glutamate), representing sweet and savoury flavours. Detection sensitivities to sucrose and vanillin were also assessed using a forced choice detection paradigm aligned with the signal detection framework. MANCOVAs were employed to compare sensory perception between groups based on vaping use frequency. Additional regression analyses were conducted to identify potential predictors of intensity and hedonic sensory ratings.

SETTING

Participants were recruited from the University of Otago student population and surrounding neighbourhoods of Dunedin, New Zealand in 2023.

PARTICIPANTS

The study included 213 university students (98 vapers and 115 non-vapers) RESULTS: We found a significant difference in hedonic ratings for vanillin, indicating a stronger preference among non-vapers. However, no other differences between the two groups were significant. Notably, the use of tobacco and mint flavours were emerged as significant predictors for hedonic responses to the savoury smell and sweet taste stimulus, respectively. No significant differences were observed between groups in the ability to detect weak stimuli.

CONCLUSIONS

Our findings suggest that vape use, particularly with specific flavours, may be associated with alterations in hedonic responses to smells. This finding may have potential implications for how vaping affects on food preferences and dietary choices.

Understanding quality differences between kiwifruit varieties during softening

Research into variations between kiwifruit varieties particularly their softening quality during storage is important in improving kiwifruit quality. The potential reasons for ripening quality differences between 'Cuixiang' (CX) and 'Hayward' (HWD) kiwifruit were analyzed by physiology and metabolomic data combined with the random forests learning algorithm. The results showed that the storability difference between the two varieties mainly resulted from differences in polygalacturonase (PG) and β-galactosidase activities. The 1 °C slowed the fruit softening process of both varieties by decreasing their PG activities. A total of 368 metabolites were identified and amino acid, carbohydrate, cofactors and vitamins, as well as nucleotide metabolism are key metabolic modules that affect the ripening differences of CX and HWD kiwifruit. A total of 30 metabolites showed remarkable ability in distinguish the ripening quality of CX and HWD kiwifruit, in which d-glucose, d-maltose, 2-hydroxybutyric acid, phenyllactate, and vitamin B2 were noteworthy for their potential application on the evaluation of kiwifruit taste and nutritional value. These findings provide positive insights into the underlying mechanism of ripening quality differences between CX and HWD kiwifruit and new ideas for identifying key metabolic markers in kiwifruit.

The Effects of Acute Sleep Curtailment on Salt Taste Measures and Relationships with Energy-Corrected Sodium Intake: A Randomized Cross-Over Trial with Methodology Validation

(1) Background: Sleep may be a factor that influences the taste-dietary intake relationship. The effect of sleep on salt taste measures has not been adequately studied, and no standardized methodology has been developed for measuring salt taste preference. (2) Methods: A sweet taste forced-choice paired-comparison test was adapted and validated to determine salt taste preference. In a randomized cross-over trial, participants slept a curtailed night (33% reduction in sleep duration) and a habitual night, confirmed by a single-channel electroencephalograph. Salt taste tests were conducted the day after each sleep condition using five aqueous NaCl solutions. One 24-h dietary recall was obtained after each taste test. (3) Results: The adapted forced-choice paired-comparison tracking test reliably determined salt taste preference. No changes in salt taste function (intensity slopes: p = 0.844) or hedonic measures (liking slopes: p = 0.074; preferred NaCl concentrations: p = 0.092) were observed after the curtailed sleep condition compared to habitual sleep. However, sleep curtailment disrupted the association between liking slope and energy-corrected Na intake (p < 0.001). (4) Conclusions: The present study serves as the first step toward more standardized taste assessments to facilitate comparison between studies and suggests accounting for sleep when exploring taste-diet relationships.

A systematic review of the biological mediators of fat taste and smell

Taste and smell play a key role in our ability to perceive foods. Overconsumption of highly palatable energy-dense foods can lead to increased caloric intake and obesity. Thus there is growing interest in the study of the biological mediators of fat taste and associated olfaction as potential targets for pharmacologic and nutritional interventions in the context of obesity and health. The number of studies examining mechanisms underlying fat taste and smell has grown rapidly in the last 5 years. Therefore, the purpose of this systematic review is to summarize emerging evidence examining the biological mechanisms of fat taste and smell. A literature search was conducted of studies published in English between 2014 and 2021 in adult humans and animal models. Database searches were conducted using PubMed, EMBASE, Scopus, and Web of Science for key terms including fat/lipid, taste, and olfaction. Initially, 4,062 articles were identified through database searches, and a total of 84 relevant articles met inclusion and exclusion criteria and are included in this review. Existing literature suggests that there are several proteins integral to fat chemosensation, including cluster of differentiation 36 (CD36) and G protein-coupled receptor 120 (GPR120). This systematic review will discuss these proteins and the signal transduction pathways involved in fat detection. We also review neural circuits, key brain regions, ingestive cues, postingestive signals, and genetic polymorphism that play a role in fat perception and consumption. Finally, we discuss the role of fat taste and smell in the context of eating behavior and obesity.

The sweet tooth of infancy: Is sweetness exposure related to sweetness liking in infants up to 12 months of age?

Infants become increasingly exposed to sweet-tasting foods in their first year of life. However, it is still unclear whether repeated exposure to sweet taste is linked to infants' sweetness liking during this period. Making use of data from the OPALINE cohort, this study aimed to examine the link between sweetness exposure and sweetness liking during two important periods in early infant feeding: at the start of complementary feeding (3-6 months) and the transition to the family table (10-12 months). Infants' sweetness exposure was assessed using 7-d food records which were completed by mothers every month (n 312), reporting daily consumption rates of formula/breast milk or complementary food and the type of formula milk and/or complementary foods for each feeding occasion. Infants' sweetness liking was studied in the laboratory at 3, 6 and 12 months of age by assessing their response to a lactose-water solution and the amount drunk of this solution compared with plain water. Linear regressions and structural equation model assessed associations between exposure to and liking for sweetness at 6 and 12 months. Neither at 6 (n 182) nor at 12 months (n 197) was sweetness exposure associated with sweetness liking. While sweetness liking at 3 months was unrelated to liking at 6 months, the latter predicted sweetness liking at 12 months. These findings demonstrate no association between sweetness exposure at 3 to 12 months and liking at 6 and 12 months despite a sharp increase in sweetness exposure in that period. However, sweetness liking at 6 and 12 months was positively associated.

Characterizing Adolescents' Dietary Intake by Taste: Results From the UK National Diet and Nutrition Survey

The taste of foods is a key factor for adolescents' food choices and intakes, yet, exploring taste characteristics of adolescents' diet is limited. Using food records for 284 adolescents (10–19 years old) from the National Diet and Nutrition Survey (NDNS), year 9 (2016–2017), we classified diets according to taste. Tastes for each food consumed were generated from a previous survey that asked participants to allocate one main taste to each food. Responses from that survey were processed and included in a Hierarchical Cluster Analysis (HCA) to identify taste clusters. The resulting tastes were then applied to the adolescents' food records in the NDNS. For each individual, the total weight of food per day for each taste was calculated. A linear regression model was used to explore dietary intakes from each taste. Findings reveal that adolescents' daily energy intake was highest (34%) from foods that taste sweet. Sweet foods were the main calorie contributors at breakfast and daytime snacking, while energy intake from neutral-tasting foods was higher at lunch and dinner. Sweet food intake was significantly positively associated with higher energy, sugar, and fat intakes. For each percentage increase in sweet foods, energy increased by 10 kcal/d (95% CI 6, 15; P &lt; 0.01). Savory food intake was lower in carbohydrates and sugars; with neutral food consumption inversely associated with energy, carbohydrate, sugars, saturated and total fat. Higher salty food intake was linked to higher saturated fat as well as sodium consumption. Sweet and neutral foods dominate the UK adolescent diet, followed by savory tastes. Balancing the contributions of different tasting foods could assist in improving adolescent diet quality.

Parsing Intra- and Inter-Individual Covariation Between the Sensory Attributes and Appeal of E-Cigarettes: Associations and Gender Differences

INTRODUCTION

Perceived sensory attributes of e-cigarettes may associate with their appeal. However, limited studies have accounted for individuals' variability in sensory attributes or have addressed how associations of sensory attributes with appeal may differ by gender.

METHODS

Individuals (n = 119, 32.8% female) who currently used combustible cigarettes and/or e-cigarettes attended one laboratory session in which they completed a standardized e-cigarette puffing procedure according to a 10 Flavor (green apple, strawberry, chocolate, vanilla, menthol, koolada, peppermint, spearmint, subtle tobacco, and full-flavored tobacco) × 2 Nicotine Formulation (free-base, salt) double-blind factorial design. The mean nicotine concentration was 23.4 (SD = 0.9) mg/mL in the nicotine salt formulations and 23.8 (SD = 1.7) mg/mL in the free-base formulations. Following each trial, participants completed ratings of sensory attributes (sweet, smooth, cool, bitter, harsh) and appeal (mean of liking, disliking [reverse-scored], and willingness-to-use-again ratings). Sensory attributes were partitioned into between-person and within-person variables. Gender was tested as a moderator of associations of sensory attributes with appeal.

RESULTS

Sweet, smooth, and cool sensory attributes positively associated with appeal at the between- and within-person level (ps < .001). Bitter and harsh negatively associated with appeal at the between- and within-person level (ps < .001). The associations of between-person sweet, smooth, and cool ratings with appeal was larger in males compared to females. The associations of within-person smooth, bitter, and harsh with appeal was larger in females compared to males.

CONCLUSIONS

This study showed important gender differences in associations of sensory attributes and appeal.

IMPLICATIONS

While evidence suggests that sensory attributes may contribute to the appeal of e-cigarettes, there is little experimental evidence accounting for individual variability in sensory attributes and whether sensory attribute-appeal associations differ by gender. The current study provides evidence that average sweet, cool, and smooth ratings positively associated with appeal and that these associations were larger in males. Within-person bitter, harsh, and smooth ratings significantly associated with appeal in both genders, but these associations were larger in females compared to males. Data from the current report reinforces the need for researchers to study gender stratified effects in tobacco regulatory science.

Current Hydration Habits: The Disregarded Factor for the Development of Renal and Cardiometabolic Diseases

Improper hydration habits are commonly disregarded as a risk factor for the development of chronic diseases. Consuming an intake of water below recommendations (underhydration) in addition to the substitution of sugar-sweetened beverages (SSB) for water are habits deeply ingrained in several countries. This behavior is due to voluntary and involuntary dehydration; and because young children are exposed to SSB, the preference for a sweet taste is profoundly implanted in the brain. Underhydration and SSB intake lead to mild hyperosmolarity, which stimulates biologic processes, such as the stimulation of vasopressin and the polyol-fructose pathway, which restore osmolarity to normal but at the expense of the continued activation of these biological systems. Unfortunately, chronic activation of the vasopressin and polyol-fructose pathways has been shown to mediate many diseases, such as obesity, diabetes, metabolic syndrome, chronic kidney disease, and cardiovascular disease. It is therefore urgent that we encourage educational and promotional campaigns that promote the evaluation of personal hydration status, a greater intake of potable water, and a reduction or complete halting of the drinking of SSB.

Characterizing Individual Differences in Sweet Taste Hedonics: Test Methods, Locations, and Stimuli

Sweetness drives the consumption of added sugars, so understanding how to best measure sweet hedonics is important for developing strategies to lower sugar intake. However, methods to assess hedonic response to sweetness vary, making results across studies difficult to integrate. We compared methods to measure optimal sucrose concentration in 21 healthy adults (1) using paired-comparison preference tracking vs. ratings of liking, (2) with participants in the laboratory vs. at home, and (3) using aqueous solutions vs. vanilla milk. Tests were replicated on separate days to assess test-retest reliability. Test-retest reliability was similar between laboratory and home testing, but tended to be better for vanilla milk and preference tracking. Optimal sucrose concentration was virtually identical between laboratory and home, slightly lower when estimated via preference tracking, and about 50% lower in vanilla milk. However, optimal sucrose concentration correlated strongly between methods, locations, and stimuli. More than 50% of the variability in optimal sucrose concentration could be attributed to consistent differences among individuals, while much less variability was attributable to differences between methods. These results demonstrate convergent validity between methods, support testing at home, and suggest that aqueous solutions can be useful proxies for some commonly consumed beverages for measuring individual differences.

Re-evaluating how sweet-liking and PROP-tasting are related

Past research has identified distinct phenotypic differences in responses to sweet taste, although the origins of these differences remain unclear. One possibility is that these individual differences in sweet-liking are a manifestation of the more widely known differences in sensitivity to the bitter tastant 6-n-propylthiouracil (PROP), which has been related to wider differences in food liking and preference. However, previous studies exploring the relationship between sweet-liking and PROP-tasting have had mixed outcomes. This is possibly due to older studies using a more simplistic dichotic characterisation of sweet likers, whereas recent research suggests three sweet-liking phenotypes (extreme sweet likers, ESL; moderate sweet likers, MSL; and sweet dislikers, SD). To re-assess how sweet-liking and PROP tasting are inter-related, 236 volunteers evaluated their liking for 1.0 M sucrose and the intensity of three concentrations of each NaCl and PROP. Using three different methods for classifying PROP taster status, our analysis confirmed that all three sweet-liking phenotypes were represented in all three PROP taster groups (super-tasters, ST; medium tasters, MT; and non-tasters, NT), but relatively few ESL were classified as ST, or SD as NT. Overall, these data suggest that while PROP tasting and sweet-liking are not causally related, the SD phenotype may partly be explained by a broader tendency for anhedonia.

Relationships between Intensity and Liking for Chemosensory Stimuli in Food Models: A Large-Scale Consumer Segmentation

This study, which was conducted as part of the Italian Taste project, was aimed at exploring the relationship between actual liking and sensory perception in four food models. Each food model was spiked with four levels of prototypical tastant (i.e., citric acid, sucrose, sodium chloride, capsaicin) to elicit a target sensation (TS) at an increasing perceived intensity. Participants (N = 2258; 59% women, aged 18-60) provided demographic information, a stated liking for 40 different foods/beverages, and their responsiveness to tastants in water. A food-specific Pearson's coefficient was calculated individually to estimate the relationship between actual liking and TS responsiveness. Considering the relationship magnitude, consumers were grouped into four food-specific clusters, depending on whether they showed a strong negative (SNC), a weak negative (WNC), a weak positive (WPC), or a strong positive correlation (SPC). Overall, the degree of liking raised in parallel with sweetness responsiveness, fell as sourness and pungency perception increased, and showed an inverted U-shape relationship with saltiness. The SNC clusters generally perceived TSs at higher intensities, except for sourness. Clusters were validated by associating the level of stated liking towards food/beverages; however, some unexpected indications emerged: adding sugar to coffee or preferring spicy foods differentiated those presenting positive correlations from those showing negative correlations. Our findings constitute a step towards a more comprehensive understanding of food preferences.

Visual cues associated with sweet taste increase short-term eating and grab attention in healthy volunteers

Most studies that examine responses to food cues use images of actual foods as stimuli. Since foods are rewarding in multiple ways, it then becomes difficult to try and partial out the role of the importance of different aspects of food reward. Here we aimed to evaluate the impact of novel visual cues specifically associated with the immediate sensory reward from a liked sweet taste. In the training phase, one visual cue (CSsweet) was associated with the experience of sweet taste (10%sucrose) and a second, control cue (CSneutral) with a neutral taste (artificial saliva) using a disguised training procedure. In Experiment 1, participants (n = 45) were given an ad libitum snack intake test 30 min post-training, either labelled with CSsweet or CSneutral. Total caloric consumption was significantly higher in the CSsweet (650 ± 47 kcal) than CSneutral (477 ± 45 kcal) condition, but ratings of liking for the snacks did not differ significantly between conditions. In Experiment 2, participants (n = 80) exhibited an overall attentional bias (22.1 ± 9.9 ms) for the CSsweet relative to CSneutral cue (assessed using a dot-probe task), however rated liking for the CSsweet did not change significantly after cue-sweet training. Likewise, measures of expected satiety for drinks labelled with CSsweet did not differ significantly from CSneutral. Overall these two experiments provide evidence that associations between neutral visual cues and the experience of a liked sweet taste leads to cue-potentiated eating in the presence of the CSsweet cue. With no evidence that cue-sweet training altered rated liking for the visual cues, and in keeping with extant literature on the dissociation of hedonic and rewarding properties of food rewards, we propose this potentiation effect to reflect increased incentive salience.

Does Responsiveness to Basic Tastes Influence Preadolescents' Food Liking? Investigating Taste Responsiveness Segment on Bitter-Sour-Sweet and Salty-Umami Model Food Samples

The objective of this study was to investigate the relationships between taste responsiveness and food liking in preadolescents. Model food samples of grapefruit juice (GF) and vegetable broth (VB) modified with four additions of sucrose and sodium chloride, respectively, were employed. Intensity perception for sweetness, sourness, and bitterness were measured in GF while saltiness and umami were measured in VB. The children (N = 148) also completed food choice, familiarity, stated liking and neophobia questionnaires. The test was conducted at school, with instructions provided remotely via video call. Four segments were defined differing in basic taste responsiveness. Segments and sucrose concentrations significantly affected liking for GF, while no significant effect of segments and sodium chloride concentrations occurred on liking for VB. An increasing sucrose concentration was positively associated with liking for GF only in the segment with low responsiveness to bitter and sour tastes. No significant differences across segments were found for food choice, familiarity, stated liking, and neophobia. Conclusively, relationships between taste responsiveness and liking are product and basic taste-dependent in addition to being subject-dependent. Strategies to improve acceptance by using sucrose as a suppressor for warning sensations of bitterness and sourness can be more or less effective depending on individual responsiveness to the basic tastes.

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.

Food Preferences and Obesity

Obesity is a multifactorial disease with several potential causes that remain incompletely understood. Recent changes in the environment, which has become increasingly obesogenic, have been found to interact with individual factors. Evidence of the role of taste responsiveness and food preference in obesity has been reported, pointing to a lower taste sensitivity and a higher preference and intake of fat and, to a lesser extent, sweet foods in obese people. Studies in the last decades have also suggested that individual differences in the neurophysiology of food reward may lead to overeating, contributing to obesity. However, further studies are needed to confirm these findings. In fact, only a limited number of studies has been conducted on large samples, and several studies were conducted only on women. Larger balanced studies in terms of sex/gender and age are required in order to control the confounding effect of these variables. As many factors are intertwined in obesity, a multidisciplinary approach is needed. This will allow a better understanding of taste alteration and food behaviours in obese people in order to design more effective strategies to promote healthier eating and to prevent obesity and the related chronic disease risks.

Understanding sweet-liking phenotypes and their implications for obesity: Narrative review and future directions

Building on a series of recent studies that challenge the universality of sweet liking, here we review the evidence for multiple sweet-liking phenotypes which strongly suggest, humans fall into three hedonic response patterns: extreme sweet likers (ESL), where liking increases with sweetness, moderate sweet likers (MSL), who like moderate but not intense sweetness, and sweet dislikers (SD), who show increasing aversion as sweetness increases. This review contrasts how these phenotypes differ in body size and composition, dietary intake and behavioural measures to test the widely held view that sweet liking may be a key driver of obesity. Apart from increased consumption of sugar-sweetened beverages in ESL, we found no clear evidence that sweet liking was associated with obesity and actually found some evidence that SD, rather than ESL, may have slightly higher body fat. We conclude that ESL may have heightened awareness of internal appetite cues that could protect against overconsumption and increased sensitivity to wider reward. We note many gaps in knowledge and the need for future studies to contrast these phenotypes in terms of genetics, neural processing of reward and broader measures of behaviour. There is also the need for more extensive longitudinal studies to determine the extent to which these phenotypes are modified by exposure to sweet stimuli in the context of the obesogenic environment.

Longitudinal Associations Between Taste Sensitivity, Taste Liking, Dietary Intake and BMI in Adolescents

Taste sensitivity and liking drive food choices and ingestive behaviors from childhood to adulthood, yet their longitudinal association with dietary intake and BMI is largely understudied. Here, we examined the longitudinal relationship between sugar and fat sensitivity, sugar and fat liking, habitual dietary intake, and BMI percentiles in a sample of 105 healthy-weight adolescents (baseline: BMI %tile 57.0 ± 24.3; age 14–16 years) over a 4-year period. Taste sensitivity was assessed via a triangle fat and sweet taste discrimination test. Taste liking were rated on a visual analog scale for four milkshakes that varied in sugar and fat contents (high-fat/high-sugar (HF/HS), low-fat/high-sugar (LF/HS), high-fat/low-sugar (HF/LS), low-fat/low-sugar (LF/LS) milkshakes). A modified version of the reduced Block Food Frequency Questionnaire (BFFQ) was used to assess dietary intake. All measurements were repeated annually. Repeated measures correlations and linear mixed effects models were used to model the associations between the variables. Sugar sensitivity was negatively associated with liking for the LF/HS milkshake over the 4-year period. Low sugar sensitivity at baseline predicted increases in BMI percentile over time, but this association didn’t survive a correction for multiple comparisons. Percent daily intake from fat was positively associated with liking for the HF/HS milkshake and negatively associated with liking for the LF/LS milkshake over 4 years. Together, these results demonstrate that lower sensitivity to sweet taste is linked to increased hedonic response to high-sugar foods and increased energy intake from fat seems to condition adolescents to show increased liking for high-fat/high-sugar foods.

Phenol-Rich Food Acceptability: The Influence of Variations in Sweetness Optima and Sensory-Liking Patterns

The consumption of phenol-rich foods is limited by their prominent bitterness and astringency. This issue has been addressed by adding sweet tastes, which suppress bitterness, but this is not a complete solution since individuals also differ in their preference for sweetness. In this study, we aimed at identifying groups of consumers differing in sweetness optima and sensory-liking patterns. To this end, increasing concentrations of sucrose were added to a chocolate pudding base. This allowed us to (1) investigate if individual differences in sensory responses are associated with different sweet liking optima in a product context, (2) define the psychological and oro-sensory profile of sweet liker phenotypes derived using a product context, and (3) assess if individuals differing in sweet liking optima differ also in consumption and liking of phenol-rich foods and beverages as a function of their sensory properties (e.g., sweeter vs. more bitter and astringent products). Individuals (1208; 58.4% women, 18–69 years) were characterised for demographics, responsiveness to 6-n-propylthiouracil (PROP), personality traits and attitudes toward foods. Three clusters were identified based on correlations between sensory responses (sweetness, bitterness and astringency) and liking of the samples: liking was positively related to sweetness and negatively to bitterness and astringency in High and Moderate Sweet Likers, and the opposite in Inverted U-Shaped. Differences between clusters were found in age, gender and personality. Furthermore, the Inverted-U Shaped cluster was found to have overall healthier food behaviours and preferences, with higher liking and consumption of phenol-rich vegetables and beverages without added sugar. These findings point out the importance of identifying the individual sensory-liking patterns in order to develop more effective strategies to promote the acceptability of healthy phenol-rich foods.

An Exploration of the Role of Sugar-Sweetened Beverage in Promoting Obesity and Health Disparities

PURPOSE OF REVIEW

The mechanistic role of sugar-sweetened beverage (SSB) in the etiology of obesity is undetermined. We address whether, compared to other foods, does consumption of SSB (1) automatically lead to failure to compensate for the energy it contains? (2) fail to elicit homeostatic hormone responses? (3) promote hedonic eating through activation of the brain's reward pathways? We followed the evidence to address: (4) Would restriction of targeted marketing of SSB and other unhealthy foods to vulnerable populations decrease their prevalence of obesity?

RECENT FINDINGS

The data are lacking to demonstrate that SSB consumption promotes body weight gain compared with isocaloric consumption of other beverages or foods and that this is linked to its failure to elicit adequate homeostatic hormone responses. However, more recent data have linked body weight gain to reward activation in the brain to palatable food cues and suggest that sweet tastes and SSB consumption heightens the reward response to food cues. Studies investigating the specificity of these responses have not been conducted. Nevertheless, the current data provide a biological basis to the body of evidence demonstrating that the targeted marketing (real life palatable food cues) of SSB and other unhealthy foods to vulnerable populations, including children and people of color and low socioeconomic status, is increasing their risk for obesity. While the mechanisms for the association between SSB consumption and body weight gain cannot be identified, current scientific evidence strongly suggests that proactive environmental measures to reduce exposure to palatable food cues in the form of targeting marketing will decrease the risk of obesity in vulnerable populations.

Associations between Psycho-Hedonic Responses to Sweet and Savoury Tastes with Diet and Body Composition in a Sample of Asian Females

Taste preferences guide food choices and dietary behaviours, yet few studies have shown a relationship between sweet and savoury taste preference and differences in dietary intakes or energy consumed from different "taste clusters". We investigated differences in psycho-hedonic responses to sweet and savoury tastes and their association with energy intake, proportion of energy from macronutrients and energy intake from different "taste clusters". In addition, we evaluated correspondence between two methods to classify "sweet-liker" status and the overlap between sweet and savoury taste preferences. Psycho-hedonic responses to sweet and savoury tastes of female participants (n = 66) were captured via staircase paired preference and the "sweet-liker phenotype" classification method. Quantitative dietary energy and macronutrient intakes were measured using three-day food diary, and the relative contributions of specific taste clusters to energy intake were derived for each participant. All participants completed anthropometric assessments measuring body mass index (BMI) and adiposity. Results showed no association between sweet and savoury preferences with dietary energy or macronutrient intakes, though there was a trend towards higher sweet food consumption among "sweet-likers". A higher preference for savouriness was not associated with differences in daily energy intake, energy intake from protein, BMI or adiposity levels. There was little overlap in sweet and savoury preferences, suggesting a bi-modal split in taste preferences. "Sweet-likers" preferred a higher mean sucrose concentration than sweet "dislikers" (p < 0.001) indicating agreement between the two approaches. Future studies should consider comparing taste-liker differences using food choice tasks to address the current gap between taste preference measures and actual dietary behaviours.

Effects of Sweet-Liking on Body Composition Depend on Age and Lifestyle: A Challenge to the Simple Sweet-Liking-Obesity Hypothesis

Taste hedonics drive food choices, and food choices affect weight maintenance. Despite this, the idea that hyper-palatability of sweet foods is linked to obesity development has been controversial for decades. Here, we investigate whether interpersonal differences in sweet-liking are related to body composition. Healthy adults aged 18–34 years from the UK (n = 148) and the US (n = 126) completed laboratory-based sensory tests (sucrose taste tests) and anthropometric measures (body mass index; BMI, body fat; fat-free mass; FFM, waist/hips circumferences). Habitual beverage intake and lifestyle and behavioural characteristics were also assessed. Using hierarchical cluster analysis, we classified participants into three phenotypes: sweet liker (SL), sweet disliker (SD), and inverted-U (liking for moderate sweetness). Being a SD was linked to higher body fat among those younger than 21 years old, while in the older group, SLs had the highest BMI and FFM; age groups reflected different levels of exposure to the obesogenic environment. FFM emerged as a better predictor of sweet-liking than BMI and body fat. In the older group, sweetened beverage intake partially explained the phenotype–anthropometry associations. Collectively, our findings implicate underlying energy needs as an explanation for the variation in sweet-liking; the moderating roles of age and obesogenic environment require additional consideration.

Determinants of Sweetness Preference: A Scoping Review of Human Studies

Factors associated with sweetness preference are multi-faceted and incredibly complex. A scoping review was undertaken to identify determinants of sweetness preference in humans. Using an online search tool, ProQuest ™, a total of 99 publications were identified and subsequently grouped into the following categories of determinants: Age, dietary factors, reproductive hormonal factors, body weight status, heritable, weight loss, sound, personality, ethnicity and lifestyle, previous exposure, disease, and 'other' determinants. Methodologies amongst studies were heterogenous in nature (e.g., there was variability across studies in the sweetness concentrations tested, the number of different sweetness concentrations used to assess sweetness preference, and the methods utilized to measure sweetness preference), rendering interpretation of overall findings challenging; however, for certain determinants, the evidence appeared to support predictive capacity of greater sweetness preference, such as age during certain life-stages (i.e., young and old), being in a hungry versus satiated state, and heritable factors (e.g., similar sweetness preferences amongst family members). Recommendations for the design of future studies on sweetness preference determinants are provided herein, including an "investigator checklist" of criteria to consider.

Patterns of Oral Microbiota Diversity in Adults and Children: A Crowdsourced Population Study

Oral microbiome dysbiosis has been associated with various local and systemic human diseases such as dental caries, periodontal disease, obesity, and cardiovascular disease. Bacterial composition may be affected by age, oral health, diet, and geography, although information about the natural variation found in the general public is still lacking. In this study, citizen-scientists used a crowdsourcing model to obtain oral bacterial composition data from guests at the Denver Museum of Nature & Science to determine if previously suspected oral microbiome associations with an individual's demographics, lifestyle, and/or genetics are robust and generalizable enough to be detected within a general population. Consistent with past research, we found bacterial composition to be more diverse in youth microbiomes when compared to adults. Adult oral microbiomes were predominantly impacted by oral health habits, while youth microbiomes were impacted by biological sex and weight status. The oral pathogen Treponema was detected more commonly in adults without recent dentist visits and in obese youth. Additionally, oral microbiomes from participants of the same family were more similar to each other than to oral microbiomes from non-related individuals. These results suggest that previously reported oral microbiome associations are observable in a human population containing the natural variation commonly found in the general public. Furthermore, these results support the use of crowdsourced data as a valid methodology to obtain community-based microbiome data.

Individual Differences in Sweetness Ratings and Cross-Modal Aroma-Taste Interactions

Aroma-taste interactions, which are believed to occur due to previous coexposure (concurrent presence of aroma and taste), have been suggested as a strategy to aid sugar reduction in food and beverages. However, coexposures might be influenced by individual differences. We therefore hypothesized that aroma-taste interactions vary across individuals. The present study investigated how individual differences (gender, age, and sweet liker status) influenced the effect of aroma on sweetness intensity among young adults. An initial screening of five aromas, all congruent with sweet taste, for their sweetness enhancing effect was carried out using descriptive analysis. Among the aromas tested, vanilla was found most promising for its sweet enhancing effects and was therefore tested across three sucrose concentrations by 129 young adults. Among the subjects tested, females were found to be more susceptible to the sweetness enhancing effect of vanilla aroma than males. For males, the addition of vanilla aroma increased the sweet taste ratings significantly for the 22–25-year-olds, but not the 19–21-year-olds. Consumers were clustered according to their sweet liker status based on their liking for the samples. Although sweet taste ratings were found to vary with the sweet liker status, aroma enhanced the sweetness ratings similarly across clusters. These results call for more targeted product development in order to aid sugar reduction.

Cross-modal interactions as a strategy for sugar reduction in products targeted at children: Case study with vanilla milk desserts

The high availability of products with high sugar content, particularly among those targeted as children, has been identified as one of the factors that contribute to the childhood obesity epidemic. For this reason, product reformulation has been recommended as one of the strategies that can be implemented to achieve short-term reductions in children's sugar intake. In this context, the objective of this study was to evaluate the feasibility of using cross-modal (taste-odor-texture) interactions as a strategy for reducing the sugar content of products targeted at children, using milk desserts as case study. A series of 5 vanilla milk desserts were formulated: a control sample with 12% added sugar and 4 sugar-reduced samples (7% added sugar) prepared following a 2 × 2 experimental design by varying vanilla (0.4% and 0.6% w/w) and starch (4.3% and 4.7% w/w) concentrations. A total of 112 children (8-12 years old) tasted the desserts and performed a dynamic sensory characterization task using either temporal check-all-that-apply or temporal dominance of sensations. In addition, they assessed the overall liking of all samples. Results showed that sugar-reduced samples did not significantly differ from the control sample in terms of their average overall liking scores. However, individual differences in children's hedonic reaction were found; three clusters of children with distinctive liking patterns were identified. The increase in vanilla and starch concentration led to an increase in overall liking for over 80% of the children. Sensory dynamic profiles revealed significant but subtle differences among samples. Results from the present work suggest that cross-modal interactions could contribute to minimizing the sensory changes caused by sugar reduction, which could enable to achieve larger reductions if implemented in the context of gradual sugar reduction programs.

Preoperative liking and wanting for sweet beverages as predictors of body weight loss after Roux-en-Y gastric bypass and sleeve gastrectomy

Background/objectives:

Patients who receive Roux-en-Y gastric bypass (RYGB) lose more weight than those who receive vertical sleeve gastrectomy (VSG). RYGB and VSG alter hedonic responses to sweet flavor, but whether baseline differences in hedonic responses modulate weight loss after RYGB or VSG remains untested.

Participants/methods:

Male and female candidates (n=66) for RYGB or VSG were recruited and tested for their subjective liking and wanting ratings of sucrose solutions and flavored beverages sweetened with aspartame. Participants were classified by unsupervised hierarchical clustering for their liking and wanting ratings of sucrose and aspartame. Participant liking ratings were also used in a supervised classification using pre-established categories of liking ratings (liker, disliker, and inverted u-shape). Effects of categories obtained from unsupervised or supervised classification on body weight loss and their interaction with surgery type were analyzed separately at 3 and 12 months after surgery using linear models corrected for sex and age.

Results:

RYGB participants lost more body weight compared to VSG participants at 3 and 12 months after surgery (P < 0.001 for both time points). Unsupervised clustering analysis identified clusters corresponding to high and low wanting or liking ratings for sucrose or aspartame. RYGB participants in high-wanting clusters based on sucrose, but not aspartame, lost more weight than VSG at both 3 (P = 0.01) and 12 months (P = 0.03), yielding a significant cluster by surgery interaction. Categories based on supervised classification using liking ratings for sucrose or aspartame showed no significant effects on body weight loss between RYGB and VSG participants.

Conclusions:

Classification of patients into high/low wanting ratings for sucrose before surgery can predict differential body weight loss after RYGB or VSG in adults and could be used to advise on surgery type.

The Effect of Sleep Curtailment on Hedonic Responses to Liquid and Solid Food

It is currently unclear whether changes in sweet taste perception of model systems after sleep curtailment extend to complex food matrices. Therefore, the primary objective of this study was to use a novel solid oat-based food (crisps) and oat-based beverage stimulus sweetened with sucralose to assess changes in taste perception after sleep curtailment. Forty-one participants recorded a habitual and curtailed night of sleep using a single-channel electroencephalograph. The next morning, overall sweetness, flavor, and texture liking responses to energy- and nutrient-matched oat products across five concentrations of sweetness were measured. Overall (p = 0.047) and flavor (p = 0.017) liking slopes across measured concentrations were steeper after curtailment, suggesting that sweeter versions of the oat products were liked more after sleep curtailment. Additionally, a hierarchical cluster analysis was used to classify sweet likers and non-likers. While the effect of sleep curtailment on sweet liking did not differ between sweet liking classification categories, sleep curtailment resulted in decreased texture liking in the solid oat crisps for sweet non-likers (p < 0.001), but not in the oat beverage. These findings illustrate the varied effects of sleep on hedonic response in complex food matrices and possible mechanisms by which insufficient sleep can lead to sensory-moderated increases in energy intake.

Quantifying Sweet Taste Liker Phenotypes: Time for Some Consistency in the Classification Criteria

Taste hedonics is a well-documented driver of food consumption. The role of sweetness in directing ingestive behavior is largely rooted in biology. One can then intuit that individual differences in sweet-liking may constitute an indicator of variations in the susceptibility to diet-related health outcomes. Despite half a century of research on sweet-liking, the best method to identify the distinct responses to sweet taste is still debated. To help resolve this issue, liking and intensity ratings for eight sucrose solutions ranging from 0 to 1 M were collected from 148 young adults (29% men). Hierarchical cluster analysis (HCA) revealed three response patterns: a sweet-liker (SL) phenotype characterized by a rise in liking as concentration increased, an inverted U-shaped phenotype with maximum liking at 0.25 M, and a sweet-disliker (SD) phenotype characterized by a decline in liking as a function of concentration. Based on sensitivity and specificity analyses, present data suggest the clearest discrimination between phenotypes is seen with 1.0 M sucrose, where a liking rating between -15 and +15 on a -50/+50 scale reliably distinguished individuals with an inverted U-shaped response from the SLs and the SDs. If the efficacy of this approach is confirmed in other populations, the discrimination criteria identified here can serve as the basis for a standard method for classifying sweet taste liker phenotypes in adults.

Sweet Taste as a Predictor of Dietary Intake: A Systematic Review

Taste is frequently cited as an important factor in food choice, and while a number of studies have attempted to identify relationships between taste function and dietary intake, a systematic review of these studies has been lacking. This review identified studies that examined associations between taste function or taste perception and dietary intake. The purpose was to determine which taste measure was most closely associated with dietary intake in healthy adults. Studies that measured some component of dietary intake, either acutely or longer-term, were eligible for inclusion. Studies were grouped into three categories: those that measured sensitivity (thresholds), intensity, or hedonic responses to sweet stimuli. Sensitivity and intensity studies demonstrated little association with dietary intake measures. Hedonic measurements were more likely to be associated with dietary intake, especially if sweet likers were analyzed separately from sweet dislikers, but the degree of heterogeneity among stimulus concentrations and dietary measures as well as small sample sizes likely obscured more consistent relationships between hedonic evaluation and dietary intake. Due to the potential for within-day and between-day variability in both taste function and dietary intake, future work should explore obtaining more than one taste measurement before comparing results to longer-term dietary assessments and attempts to standardize methods.

A new sensory sweetness definition and sweetness conversion method of five natural sugars, based on the Weber-Fechner Law

This study's aim is to establish a new sensory sweetness definition and conversion method for five sugars. A "closed-type" question based on triangle test and paired comparison was used for sensory evaluation. The absolute threshold and nine sensory difference threshold values were determined and used to generate a sweet sensory difference strength curve. Defining absolute threshold of sucrose sweetness as 1, the sucrose sweetness at any concentration could be calculated via the curve. After taking the logarithm of each curve, sweetness index was calculated as 1, 1.12, 0.94, 1.29, and 1.25 for sucrose, glucose, fructose, lactose and maltose, respectively. Based on this, each sugar concentration and sweetness could be converted and calculated. Single sugar and mixed-sugars sweetness comparison experiments verified the new sweetness index and sweetness values were more accurate (83.3-100%) than those reported in previous studies. Therefore, this new definition and conversion method established more reliable references for sweet taste sensory applications.