Genetic variation in the hTAS2R38 taste receptor and food consumption among Finnish adults

Bitter Taste Sensitivity, Food Cravings, and Risk of Chronic Disease: A Cross-Sectional Study

INTRODUCTION

Variation in common taste receptor type 2 member 38 (TAS2R38) haplotypes is associated with bitter taste sensitivity, but there is not much or inconsistent evidence on association with food cravings and with chronic disease risk factors. We have conducted a cross-sectional study to assess whether genetically defined taster groups would differ in their sensitivity to bitter-tasting compounds, cravings for various food groups, and risk of chronic disease risk factors.  Methodology: A total of 116 non-diabetic individuals were recruited from the Loma Linda University (LLU) campus. Various measures were carried out to examine genetic variations, bitter sensitivity, anthropometrics, food cravings, and participant demographics. Taster status was determined based on TAS2R38 haplotypes, classifying participants as super-tasters, tasters, or non-tasters. Analysis of Covariance (ANCOVA) models were used to examine differences among the three TAS2R38 genetic groups in bitter taste sensitivity, food cravings, body mass index (BMI), non-fasting blood glucose, and family history of type 2 diabetes (T2D).

RESULTS

A significant difference in sensitivity to the bitter taste compounds thiourea and phenylthiocarbamide (PTC) was observed among the three TAS2R38 genetic groups (P < 0.01). The sensitivity scores of the bitter taste compounds thiourea and PTC were lowest for super-tasters and highest for non-tasters (-41.283 and -0.233 for thiourea; -32.983 and 3.380 for PTC, respectively). Moreover, super-tasters had a significantly higher cravings score than non-tasters for starchy foods (2.641 vs. 2.183, respectively). Tasters had a significantly higher cravings score than non-tasters for bitter foods (2.306 vs. 1.740, respectively). No significant differences were observed across the TAS2R38 genetic-based taste groups for the chronic disease risk factors, BMI non-fasting blood glucose, and family history of T2D.

CONCLUSIONS

Super-tasters had the lowest taste sensitivity for bitter compounds and the highest cravings for bitter foods, which suggests that they might be more likely to consume bitter foods. Examining the genetic differences in taste preferences and sensitivities may pave the way for effective and individualized dietary plans and intervention strategies targeting chronic disease prevention, treatment, and management.

Association of the bitter taste genes TAS2R38 and CA6 and breast cancer risk; a case-control study of Polish women in Poland and Polish immigrants in USA

It is known that the perception of bitterness is mediated by type 2 bitter taste receptors (TAS2Rs). However, recent reports have suggested that the carbonic anhydrase 6 (CA6) gene may also influence bitterness sensing. Genetic variants in these genes could influence dietary intake of brassica vegetables, whose increased consumption has been observed in the literature, though inconsistently, to decrease breast cancer (BC) risk. We hypothesized that the estimated odds ratios (ORs) for the association between BC and taster diplotype (PAV/PAV) and/or genotype A/A, will be in the direction of increased BC risk, potentially due to reduced consumption of brassica vegetables. Using a case-control study of BC in Polish women in Poland (210 cases and 262 controls) and Polish immigrant women to USA (78 cases and 170 controls) we evaluated the association of the taster diplotypes in TAS2R38 gene and genotypes in the CA6 gene and BC risk in these two populations individually and jointly. No significant increase in risk was observed for the TAS2R38 PAV/PAV diplotype (tasters) in each population individually or in the joint population. For the CA6 gene, in the joint population, we observed an increased BC risk for the combined G/A and G/G genotypes (non-tasters) vs A/A (tasters), OR = 1.41 (95% CI 1.04-1.90, p = 0.026) which after adjustment for False Discovery Rate (FDR), was not significant at p≤0.05 level. However, for the joint population and for the combined genotype of the two genes AVI/AVI+G* (non-tasters) vs. PAV/*+A/A (tasters), we observed a significant increase in BC risk, OR = 1.77 (95%CI 1.47-2.74, p = 0.01), for the non-tasters, which remained significant after FDR adjustment. In conclusion for the joint population and the joint effect for the two bitter sensing genes, we observed an increase in BC risk for the bitterness non-tasters, association which is in the opposite direction to our original hypothesis.

Differential Activation of TAS2R4 May Recover Ability to Taste Propylthiouracil for Some TAS2R38 AVI Homozygotes

Bitterness from phenylthiocarbamide and 6-n-propylthiouracil (PROP) varies with polymorphisms in the TAS2R38 gene. Three SNPs form two common (AVI, PAV) and four rare haplotypes (AAI, AAV, PVI, and PAI). AVI homozygotes exhibit higher detection thresholds and lower suprathreshold bitterness for PROP compared to PAV homozygotes and heterozygotes, and these differences may influence alcohol and vegetable intake. Within a diplotype, substantial variation in suprathreshold bitterness persists, and some AVI homozygotes report moderate bitterness at high concentrations. A second receptor encoded by a gene containing a functional polymorphism may explain this. Early work has suggested that PROP might activate TAS2R4 in vitro, but later work did not replicate this. Here, we identify three TAS2R4 SNPs that result in three diplotypes-SLN/SLN, FVS/SLN, and FVS/FVS-which make up 25.1%, 44.9%, and 23.9% of our sample. These TAS2R4 haplotypes show minimal linkage disequilibrium with TAS2R38, so we examined the suprathreshold bitterness as a function of both. The participants (n = 243) rated five PROP concentrations in duplicate, interleaved with other stimuli. As expected, the TAS2R38 haplotypes explained ~29% (p < 0.0001) of the variation in the bitterness ratings, with substantial variation within the haplotypes (AVI/AVI, PAV/AVI, and PAV/PAV). Notably, the TAS2R4 diplotypes (independent of the TAS2R38 haplotypes) explained ~7-8% of the variation in the bitterness ratings (p = 0.0001). Given this, we revisited if PROP could activate heterologously expressed TAS2R4 in HEK293T cells, and calcium imaging indicated 3 mM PROP is a weak TAS2R4 agonist. In sum, our data are consistent with the second receptor hypothesis and may explain the recovery of the PROP tasting phenotype in some AVI homozygotes; further, this finding may potentially help explain the conflicting results on the TAS2R38 diplotype and food intake.

TAS2R38 Bitter Taste Receptor Polymorphisms in Patients with Chronic Rhinosinusitis with Nasal Polyps Preliminary Data in Polish Population

Chronic rhinosinusitis (CRS) affects 5-12% of the general population, and the most challenging patients are those with nasal polyposis (CRSwNP). Its complexity, unpredictability, and difficulties in selecting a treatment plan individually for each patient prompted scientists to look for possible genetic causes of this disease. It was proven that single nucleotide polymorphisms (SNPs) in the TAS2R38 gene may affect the mobility and the activity of the ciliated epithelium of the upper respiratory tract what can contribute to individual differences in susceptibility to CRS. There are two common haplotypes: a "protective" type (PAV), and a "non-protective" type (AVI). CRS patients who are homozygous PAV/PAV are considered as less susceptible to the severe course of the disease, whereas patients with AVI/AVI haplotype are more vulnerable. The aim of this study was to examine TAS2R38 gene polymorphisms among CRSwNP patients and control group (N = 544) with the evaluation of the association between the distribution of studied polymorphic variants and the incidence as well as severity of CRSwNP in the study group. Whole blood samples from CRSwNP patients (N = 106) and the control group (N = 438) were analyzed for alleles of the TAS2R38 gene using real-time PCR single nucleotide polymorphism genotyping assays for rs713598, rs1726866, and rs10246939. PAV (SG: 41%; CG: 49%) and AVI (SG: 59%; CG: 51%) haplotypes were the only ones detected in the study. The AVI haplotypes were 1.5 times more frequent in the study group than in the control group (p = 0.0204; OR = 1.43). AVI/AVI individuals tended to have more severe symptoms in the VAS scale, less QoL in the SNOT-22 test, and a bigger nasal obstruction upon endoscopic examination. Patients with PAV/PAV were twice more likely to have minor changes in preoperative CT scans (p = 0.0158; OR = 2.1; Fi = 0.24). Our study confirmed that the PAV/PAV diplotype might have some protective properties and carrying the AVI haplotype might predispose to the development of CRSwNP.

An Investigation of TAS2R38 Haplotypes, Dietary Intake, and Risk Factors for Chronic Disease in the Canadian Longitudinal Study on Aging

BACKGROUND

Variation in common taste receptor type 2 member 38 (TAS2R38) haplotypes is associated with bitter-taste sensitivity, but associations with dietary intake and risk factors for chronic disease are inconsistent.

OBJECTIVES

To determine whether common TAS2R38 haplotypes are associated with dietary intake and risk factors for chronic disease using cross-sectional data from the Canadian Longitudinal Study on Aging (n = 26,090). Outcomes were assessed among the full sample and stratified by sex.

METHODS

Taster status was determined from TAS2R38 haplotypes, and the respondents were classified as supertasters, tasters, and nontasters. Primary outcome variables were the consumption frequencies of vegetables, sweet-tasting foods, alcoholic beverages, and visceral adiposity index (VAI). Secondary outcome variables were the individual VAI components. Multivariable regression models adjusted for sociodemographic and lifestyle factors were used to assess associations between the taster status and outcome variables.

RESULTS

Among the sample, 5655, 12,821, and 7614 respondents were classified as supertasters, tasters, and nontasters, respectively. Vegetable consumption was significantly higher among nontasters than among supertasters (1.23 ± 0.26 and 1.20 ± 0.22, respectively, P = 0.02). Among males, the consumption of sweet-tasting foods (0.40 ± 8.80 and 0.38 ± 7.55, P = 0.02) and green salad (0.35 ± 0.31 and 0.33 ± 0.27, P = 0.02) was also higher for nontasters than supertasters. Nontasters were more likely to be regular alcohol consumers compared with supertasters among the full sample (odds ratio [95% confidence interval]: 1.12 [1.03, 1.22]; P = 0.01) and among females (OR: 1.13; 95% CI: 1.01, 1.27; P = 0.04). No significant associations were observed between TAS2R38 haplotypes and VAI, although high-density lipoprotein cholesterol was significantly lower among supertasters than nontasters (1.45 ± 0.59 and 1.47 ± 0.63, respectively; P = 0.04).

CONCLUSIONS

Among middle- to older-aged adults, minor associations are observed between TAS2R38 haplotypes, dietary intake, and high-density lipoprotein cholesterol. Genetic predisposition to bitter-taste sensitivity is linked to diet; however, further research is needed to understand the relevance for chronic disease risk.

Effect of Age and Gender on Taste Function as Measured by the Waterless Empirical Taste Test

The effect of age and gender on taste function is rarely investigated. Therefore, we tried to study the effect of age and gender on taste function as evaluated by the Waterless Empirical Taste Test (WETT®). The WETT® consists of 40 strips that are coated with one of five tastants (sucrose, citric acid, sodium chloride, caffeine, or monosodium glutamate). Each tastant is prepared with four different concentrations. These 40 strips are interspersed with an additional 13 tasteless strips. To implement the WETT®, a strip was placed on the middle portion of the tongue. The subjects closed their mouth and tasted the strip. They then chose one of six answers (sweet, sour, salty, bitter, brothy, or no taste at all). If the answer was correct, one score was acquired. One-hundred-and-twenty healthy men and women were collected in this study. Among them, there were 40 subjects in each age group of 20-39 years, 40-59 years, and ≥60 years. The overall taste and individual tastant function decreased with age, particularly between subjects aged 20-39 years and those aged ≥60 years. The overall taste and individual tastant function were better in females than in males, especially for subjects aged older than 59 years. Our results show that taste function is affected by both age and gender.

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.

Comparison of sensitivity to taste and astringency stimuli among vegans and omnivores

Taste perception plays a crucial role in determining food choices. It has been described in literature a relationship between diet composition and taste perception. Nowadays, with the rising concern in climate change and animal welfare, the number of people following a vegan diet is increasing to become a real trend. Research about differences in taste perception between vegan and omnivore is lacking. The aim of the study was to compare detection threshold for bitter, sour, umami and astringency stimuli (quinine monohydrochloride dihydrate, citric acid anhydrous, monosodium glutamate and tannic acid, respectively) participants following a vegan diet (n=24) and participants following an omnivore diet (n=30). Participants reported their consumption frequency for main food categories. The mean detection thresholds between the two groups narrowly missed significance with p-values of 0.07, 0.08, 0.06, for bitter, umami and astringency perception, respectively. No differences were found for sour taste (p-value=0.33). Further research is required to validate such findings and to understand the origin of the relationship between diet style and taste sensitivity.

TAS2R38 gene in relation to Helicobacter pylori infection and blood groups in different age groups

Of the factors predisposing to gastric cancer is Helicobacter pylori infection affecting more than 50% of the general population. Genetic variation is an established player in certain diseases susceptibility. TAS2R38 gene polymorphisms have been found to influence bitter taste ability to chemicals with malicious characteristics and consequently affect metabolism and disease development. This study aimed to investigate the correlation between TAS2R38 gene polymorphisms and H. pylori seropositivity. The study involved 105 apparently healthy individuals. They were grouped into four groups according to their age and gender; young male, young female, middle-aged male and middle-aged female. All groups were tested for H. pylori serum antibody using screening rapid test. Participants were also tested for tasting PTC for TAS2R38 gene detection by using Bartovation PTC test paper and grouped accordingly into: homozygote (highly bitter taste), heterozygote (slight to moderate bitter taste), or negative gene carrier (no taste at all). ABO and Rhesus- blood grouping was determined by standard serological analysis. Of the 105 patients, 22.85% were tested homozygotes for TAS2R38 gene, 40.95% were heterozygotes and 36.19% were nontasters, no significant difference (p &gt; 0.9). H. pylori seropositivity was encountered in 16.19% of the whole participants, 11.5% of the male participants and 20.75% of the female participants (p &gt; 0.9). No significant difference in seropositivity was monitored among the four age groups (p &gt; 0.3) and the ABO/Rh blood groups (p &gt; 0.9). A lack of significant correlation (r = 0.046) between H. pylori antibody test positivity and tasting PTC (TAS2R38 gene) was reported. Similarly, no association was found between PTC tasting and participants’ ABO blood grouping, age or gender (r = 0.086, 0.083 and 0.029, respectively). Yet, weak negative (reverse) relationship (r = -0.29, p-value = 0.002) was gained between PTC and Rh grouping. No correlation was revealed between TAS2R38 polymorphism and the studied variable; age, gender and blood group indicating the absence of an apparent role of the gene in vulnerability to H. pylori infection. Further studies involving a larger sample size is required to confirm the obtained result.

Taste Preference-Related Genetic Polymorphisms Modify Alcohol Consumption Behavior of the Hungarian General and Roma Populations

Harmful alcohol consumption has been considered a major public health issue globally, with the amounts of alcohol drunk being highest in the WHO European Region including Hungary. Alcohol consumption behaviors are complex human traits influenced by environmental factors and numerous genes. Beyond alcohol metabolization and neurotransmitter gene polymorphisms, taste preference-related genetic variants may also mediate alcohol consumption behaviors. Applying the Alcohol Use Disorders Identification Test (AUDIT) we aimed to elucidate the underlying genetic determinants of alcohol consumption patterns considering taste preference gene polymorphisms (TAS1R3 rs307355, TAS2R38 rs713598, TAS2R19 rs10772420 and CA6 rs2274333) in the Hungarian general (HG) and Roma (HR) populations. Alcohol consumption assessment was available for 410 HG and 387 HR individuals with 405 HG and 364 HR DNA samples being obtained for genotyping. No significant associations were found between TAS1R3 rs307355, TAS2R19 rs10772420, and CA6 rs2274333 polymorphisms and alcohol consumption phenotypes. Significant associations were identified between TAS2R38 rs713598 and the number of standard drinks consumed in the HG sample (genotype GG negatively correlated with the number of standard drinks; coef: -0.136, p = 0.028) and the prevalence of having six or more drinks among Roma (a negative correlation was identified in the recessive model; genotype GG, coef: -0.170, p = 0.049), although, none of these findings passed the Bonferroni-corrected probability criterion (p > 0.05). Nevertheless, our findings may suggest that alcohol consumption is partially driven by genetically determined taste preferences in our study populations. Further studies are required to strengthen the findings and to understand the drivers of alcohol consumption behavior in more depth.

Bitter- and Umami-Related Genes are Differentially Associated with Food Group Intakes: the Framingham Heart Study

BACKGROUND

As suboptimal diet quality remains the leading modifiable contributor to chronic disease risk, it is important to better understand the individual-level drivers of food choices. Recently, a genetic component of food choices was proposed based on variants (SNPs) in genes related to taste perception (taste-related SNPs).

OBJECTIVES

This study aimed to determine the cumulative contribution of taste-related SNPs for basic tastes (bitter, sweet, umami, salt, and sour), summarized as "polygenic taste scores," to food group intakes among adults.

METHODS

Cross-sectional analyses were performed on 6230 Framingham Heart Study participants (mean age ± SD: 50 ± 14 y; 54% female). Polygenic taste scores were derived for tastes with ≥2 related SNPs identified in prior genome-wide association studies, and food group intakes (servings per week [sev/wk]) were tabulated from food frequency questionnaires. Associations were determined via linear mixed-effects models, using false discovery rates and bootstrap resampling to determine statistical significance.

RESULTS

Thirty-three taste-related SNPs (9 bitter, 19 sweet, 2 umami, 2 sour, 1 salt) were identified and used to derive polygenic taste scores for bitter, sweet, umami, and sour. Per additional allele for higher bitter perception, whole grain intakes were lower by 0.17 (95% CI: -0.28, -0.06) sev/wk, and for higher umami perception, total and red/orange vegetable intakes were lower by 0.73 (95% CI: -1.12, -0.34) and 0.25 (95% CI: -0.40, -0.10) sev/wk, respectively. Subsequent analyses at the SNP level identified four novel SNP-diet associations-two bitter-related SNPs with whole grains (rs10960174 and rs6782149) and one umami-related SNP with total and red/orange vegetables (rs7691456)-which may have been driving the identified associations.

CONCLUSIONS

Taste-related genes for bitter and umami were differentially associated with food choices that may impact diet quality. Hence, a benefit could be derived from leveraging knowledge of taste-related genes when developing personalized risk reduction dietary guidance.

Bitter Taste Receptor TAS2R38 Genetic Variation (rs10246939), Dietary Nutrient Intake, and Bio-Clinical Parameters in Koreans

Differential bitterness perception associated with genetic polymorphism in the bitter taste receptor gene taste 2 receptor member 38 (TAS2R38) may influence an individual's food preferences, nutrition consumption, and eventually chronic nutrition-related disorders including cardiovascular disease. Therefore, the effect of genetic variations on nutritional intake and clinical markers needs to be elaborated for health and disease prevention. In this study, we conducted sex-stratified analysis to examine the association between genetic variant TAS2R38 rs10246939 A > G with daily nutritional intake, blood pressure, and lipid parameters in Korean adults (males = 1,311 and females = 2,191). We used the data from the Multi Rural Communities Cohort, Korean Genome and Epidemiology Study. Findings suggested that the genetic variant TAS2R38 rs10246939 was associated with dietary intake of micronutrients including calcium (adjusted p = 0.007), phosphorous (adjusted p = 0.016), potassium (adjusted p = 0.022), vitamin C (adjusted p = 0.009), and vitamin E (adjusted p = 0.005) in females. However, this genetic variant did not influence blood glucose, lipid profile parameters, and other blood pressure markers. These may suggest that this genetic variation is associated with nutritional intake, but its clinical effect was not found. More studies are needed to explore whether TAS2R38 genotype may be a potential predictive marker for the risk of metabolic diseases via modulation of dietary intake.

Genetic variations in the bitter taste receptor gene TAS2R38 are related to cigarette smoking behavior in Han Chinese smokers

BACKGROUND

Smoking behavior is influenced by multiple genes, including the bitter taste gene TAS2R38. It has been reported that the correlation between TAS2R38 and smoking behavior has ethnicity-based differences. However, the TAS2R38 status in Chinese smokers is still unclear.

OBJECTIVE

This study aims to investigate the possible relationship between genetic variations in TAS2R38 (A49P, V262A and I296V) and smoking behaviors in the Han Chinese population.

METHODS

The haplotype analyses were performed and smoking behavior questionnaire was completed by 1271 individuals. Genetic association analyses for smoking behavior were analyzed using chi-square test. Further, for investigating the molecular mechanism of TAS2R38 variants effect on smoking behavior, we conducted TAS2R38-PAV and TAS2R38-AVI expression plasmids and tested the cellular calcium assay by cigarette smoke compounds stimulus in HEK293.

RESULTS

Significant associations of genetic variants within TAS2R38 were identified with smoking behavior. We found a higher PAV/PAV frequency than AVI/AVI in moderate and high nicotine dependence (FTND ≥ 4; X² = 4.611, 1 df, p = 0.032) and strong cigarette smoke flavor intensity preference (X² = 4.5383, 1 df, p = 0.033) in participants. Furthermore, in the in vitro cellular calcium assay, total particle matter (TPM), N-formylnornicotine and cotinine, existing in cigarette smoke, activated TAS2R38-PAV but not TAS2R38-AVI-transfected cells.

CONCLUSION

Our data highlights that genetic variations in TAS2R38 are related to smoking behavior, especially nicotine dependence and cigarette smoke flavor intensity preference. Our findings may encourage further consideration of the taste process to identify individuals susceptible to nicotine dependence, particularly Han Chinese smokers.

Data-Driven Clustering Approach to Derive Taste Perception Profiles from Sweet, Salt, Sour, Bitter, and Umami Perception Scores: An Illustration among Older Adults with Metabolic Syndrome

BACKGROUND

Current approaches to studying relations between taste perception and diet quality typically consider each taste-sweet, salt, sour, bitter, umami-separately or aggregately, as total taste scores. Consistent with studying dietary patterns rather than single foods or total energy, an additional approach may be to study all 5 tastes collectively as "taste perception profiles."

OBJECTIVE

We developed a data-driven clustering approach to derive taste perception profiles from taste perception scores and examined whether profiles outperformed total taste scores for capturing individual variability in taste perception.

METHODS

The cohort included 367 community-dwelling adults [55-75 y; 55% female; BMI (kg/m2): 32.2 ± 3.6] with metabolic syndrome from PREDIMED-Plus, Valencia. Cluster analysis identified subgroups of individuals with similar patterns in taste perception (taste perception profiles); quantitative criteria were used to select the cluster algorithm, determine the optimal number of clusters, and assess the profiles' validity and stability. Goodness-of-fit parameters from adjusted linear regression evaluated the individual variability captured by each approach.

RESULTS

A k-means algorithm with 6 clusters best fit the data and identified the following taste perception profiles: Low All, High Bitter, High Umami, Low Bitter & Umami, High All But Bitter and High All But Umami. All profiles were valid and stable. Compared with total taste scores, taste perception profiles explained more variability in bitter and umami perception (adjusted R2: 0.19 vs. 0.63, respectively; 0.40 vs. 0.65, respectively) and were comparable for sweet, salt, and sour. In addition, taste perception profiles captured differential perceptions of each taste within individuals, whereas these patterns were lost with total taste scores.

CONCLUSIONS

Among older adults with metabolic syndrome, taste perception profiles derived via data-driven clustering may provide a valuable approach to capture individual variability in perception of all 5 tastes and their collective influence on diet quality. This trial was registered at https://www.isrctn.com/ as ISRCTN89898870.

Association of single nucleotide polymorphisms with taste and food preferences of the Hungarian general and Roma populations

It is reasonable to suppose that poor diet underlies the unfavorable health status of the Roma population of Europe. Previously in the framework of a complex health survey, fruit and vegetable consumption, quantity of sugar added, salting frequency; bitter, salty, sweet and fat taste preferences were evaluated of Hungarian (HG, n = 410) and Roma (HR, n = 387) populations. In the present study the associations of taste and food preferences with TAS1R3, CD36, SCNN1B, TRPV1, TAS2R38, TAS2R19 and CA6 polymorphisms were tested in the same samples. Genotype frequencies did not differ significantly between the two populations. Although we initially observed associations between certain genetic polymorphisms and taste and food preferences in our study samples, none of the p values remained significant after the multiple test correction. However, some of our results could be considered promising (0.05<corrected p < 0.20), which showed potential ethnicity-specific effects (CA6 rs2274333 with salty taste and raw kohlrabi preference, CD36 rs1527483 with fat taste preference, TAS2R19 rs10772420 with grapefruit preference, and TAS2R38 rs713598 with quantity of sugar added). Our results may suggest that genetics may mediate food preferences, and individuals with different ethnic background may require personalized interventions to modify diet. Further investigations with greater sample sizes are essential to explore the effect of these genetic variants on taste and food preferences.

COVID-19 as a worldwide selective event and bitter taste receptor polymorphisms: An ecological correlational study

Background

Given the observed olfactory and gustatory dysfunctions in patients with COVID-19 and recent findings on taste receptors possible important activities in the immune system, we elected to estimate the correlation between COVID-19 mortality and polymorphism of a particular type of bitter taste receptor gene called TAS2R38, in a worldwide epidemiological point of view.

Methods

Pooled rate of each of the rs713598, rs1726866, rs10246939, and PAV/AVI polymorphisms of the TAS2R38 gene was obtained in different countries using a systematic review methodology and its relationship with the mortality of COVID-19. Data were analyzed by the comprehensive meta-analysis software and SPSS.

Results

There was only a significant reverse Pearson correlation in death counts and PAV/AVI ratio, p = 0.047, r = −0.503. Also, a significant reverse correlation of PAV/AVI ratio and death rate was seen, r = −0.572 p = 0.021. rs10246939 ratio had a significant positive correlation with death rate, r = 0.851 p = 0.031. Further analysis was not significant. Our results showed that the higher presence of PAV allele than AVI, and a higher rate of G allele than A in rs10246939 polymorphism in a country, could be associated with lower COVID-19 mortality. While assessing all three polymorphisms showed a huge diversity worldwide.

Conclusion

Due to extraoral activities of bitter taste receptor genes, especially in mucosal immunity, this gene seems to be a good candidate for future studies on COVID-19 pathophysiology. Also, the high worldwide diversity of TAS2R38 genes polymorphism and its possible assassination with mortality raises concerns about the efficiency of vaccine projects in different ethnicities.

The Microbiota and Malnutrition: Impact of Nutritional Status During Early Life

According to the developmental origins of health and disease hypothesis, our health is determined by events experienced in utero and during early infancy. Indeed, both our prenatal and postnatal nutrition conditions have an impact on the initial architecture and activity of our microbiota. Recent evidence has underlined the importance of the composition of the early gut microbiota in relation to malnutrition, whether it be undernutrition or overnutrition, that is, in terms of both stunted and overweight development. It remains unclear how early microbial contact is linked to the risk of disease, as well as whether alterations in the microbiome underlie the pathogenesis of malnutrition or are merely the end result of it, which indicates that thequestion of causality must urgently be answered. This review provides information on the complex interaction between the microbiota and nutrition during the first 1,000 days of life, taking into account the impact of both undernutrition and overnutrition on the microbiota and on infants' health outcomes in the short- and long-term.

Factors related to sensory properties and consumer acceptance of vegetables

Many consumers perceive the bitter taste or other sensory characteristic of vegetables as unpleasant, posing a challenge to dietary recommendations aiming to increase vegetable consumption. Food experience is multisensory, with complex interactions between the senses and individual differences in sensory perception. This review focuses on the factors affecting sensory properties of vegetables and sensory perception of vegetables among adults. Topical examples of sensory quality and evaluation of vegetable samples are presented. Cultivar and growing conditions are related to the internal sensory quality of vegetables. The effects of different processing methods, such as freezing and cooking, on the sensory properties of vegetables are also reviewed. Flavor modification of vegetables with seasonings may be used to improve palatability and incorporating vegetables to meals may increase the intake of vegetables. Recently, external factors (e.g. visual and odor stimuli) have been tested in multisensory research in the context of vegetable perception and choice. These options to achieve better sensory quality, more palatable meals and pleasant eating context may be used to promote vegetable intake among adults.

Taste sensitivity and lifestyle are associated with food preferences and BMI in children

Oral food perception together with lifestyle may affect food preferences and choices, influencing weight gain and obesity development. The present study was designed to evaluate the association of biological (taste sensitivity) and lifestyle variables with children food preferences, assessing whether all these variables contribute to explain BMI percentile. After anthropometric evaluation, 387 children were classified for bitter and sweet taste sensitivities. Socioeconomic/lifestyle aspects and hedonics for 36 foods were collected. Watching TV during meals associate with lower preference for several vegetables, as well as being sweet taste low sensitive, in the case of girls. Moreover, regression analysis showed that bitter taste sensitivity is one of the variables contributing to explain high BMI percentiles. These results present evidences that both biological and socioeconomic and the attention that is given to food (eating in the presence or absence of distractors) are aspects that should be considered in children nutrition to prevent obesity.

Genetic Differences in Taste Receptors: Implications for the Food Industry

Inborn genetic differences in chemosensory receptors can lead to differences in perception and preference for foods and beverages. These differences can drive market segmentation for food products as well as contribute to nutritional status. This knowledge may be essential in the development of foods and beverages because the sensory profiles may not be experienced in the same way across individuals. Rather, distinct consumer groups may exist with different underlying genetic variations. Identifying genetic factors associated with individual variability can help better meet consumer needs through an enhanced understanding of perception and preferences. This review provides an overview of taste and chemesthetic sensations and their receptors, highlighting recent advances linking genetic variations in chemosensory genes to perception, food preference and intake, and health. With growing interest in personalized foods, this information is useful for both food product developers and nutrition health professionals alike.

Genetic Background of Taste Perception, Taste Preferences, and Its Nutritional Implications: A Systematic Review

Background: The rise in nutrition-related morbidity and mortality requires public health intervention programs targeting nutritional behavior. In addition to socio-economical, socio-cultural, psychological determinants, taste is one of the main factors that influence food choices. Differences in taste perception and sensitivity may be explained by genetic variations, therefore the knowledge of the extent to which genetic factors influence the development of individual taste preferences and eating patterns is important for public policy actions addressing nutritional behaviors. Our aim was to review genetic polymorphisms accounting for variability in taste and food preferences to contribute to an improved understanding of development of taste and food preferences.

Methods: The electronic databases PubMed, Scopus, and Web of Science were searched using MeSH in PubMed and free text terms for articles published between January 1, 2000 and April 13, 2018. The search strategy was conducted following the PRISMA statement. The quality of the included studies was assessed by the validated Q-Genie tool.

Results: Following the PRISMA flowchart, finally 103 articles were included in the review. Among the reviewed studies, 43 were rated to have good quality, 47 were rated to have moderate quality, and 13 were rated to have low quality. The majority of the studies assessed the association of genetic variants with the bitter taste modality, followed by articles analyzing the impact of polymorphisms on sweet and fat preferences. The number of studies investigating the association between umami, salty, and sour taste qualities and genetic polymorphisms was limited.

Conclusions: Our findings suggest that a significant association exists between TAS2R38 variants (rs713598, rs1726866, rs10246939) and bitter and sweet taste preference. Other confirmed results are related to rs1761667 (CD36) and fat taste responsiveness. Otherwise further research is essential to confirm results of studies related to genetic variants and individual taste sensitivity. This knowledge may enhance our understanding of the development of individual taste and related food preferences and food choices that will aid the development of tailored public health strategy to reduce nutrition-related disease and morbidity.

Taste Sensitivity Is Associated with Food Consumption Behavior but not with Recalled Pleasantness

As taste perception varies between individuals, it might be important in explaining food consumption behavior. Previous studies have focused on sensitivity to the bitter tastant PROP (6-n-propylthiouracil) concerning eating with little attention paid to other tastants. For the first time, connections between food consumption behavior, pleasantness, and taste sensitivity are studied with five taste modalities. Sensitivity to bitterness, sourness, umami, saltiness, and sweetness as well as an overall taste sensitivity score was determined with intensity evaluation for 199 Finnish adults. Recalled pleasantness and food consumption behavior were enquired with online questionnaires. Consumption concerned intake of vegetables, fruits, and berries; use-frequency of specific foods; and tendency to mask or modify tastes of foods. All modality-specific taste sensitivities were related to some consumption behavior but none to recalled pleasantness. A higher taste sensitivity score indicated avoidance of coffee, lower consumption of pungent foods, and a more frequent habit of adding ketchup to a meal. In conclusion, it may be more informative to study the influence of taste sensitivity on food consumption behavior with taste modalities separately rather than with a general indicator of taste sensitivity. Additionally, these results highlight the importance of studying actual behavior toward food and not just liking.

Variation in the TAS2R38 Bitterness Receptor Gene Was Associated with Food Consumption and Obesity Risk in Koreans

Bitterness-sensing protein taste receptor type-2 member 38 (TAS2R38, T2R38) mediates taste perception and various physiological responses, including energy- and adiposity-related mechanisms. This study examined whether the genetic variant rs10246939 C > T in TAS2R38 was associated with food intake and body size as well as obesity risk. Data from the Korean Multi-Rural Communities Cohort study (1338 males and 2229 females) were analyzed to obtain the intake of six food groups, alcohol consumption, smoking status and anthropometric measurements, including height, weight, waist and hip circumference, and body mass index (BMI), according to the rs10246939 genotype. Findings suggested that females with the TT genotype consumed more fruit (adjusted p = 0.025) and had significantly higher body weights (adjusted p = 0.046) and BMIs (adjusted p = 0.003) than individuals with other genotypes. Having the TT genotype also increased the risk of obesity by 1.75-fold (95% confidence interval: 1.31–2.36) in females. The genetic variation had a minimal influence on the males’ dietary intake, but tended to increase the adiposity risk. In conclusion, TAS2R38 rs10246939 variation was associated with Koreans’ dietary intake and increased their risk of obesity. Although more detailed statistical analyses in the larger cohort are required, current study suggested that, as a genetic predictive marker, TAS2R38 bitterness receptor variations may have a large implication in obesity prevention and treatment.

Taste Receptors: New Players in Sperm Biology

Taste receptors were first described as sensory receptors located on the tongue, where they are expressed in small clusters of specialized epithelial cells. However, more studies were published in recent years pointing to an expression of these proteins not only in the oral cavity but throughout the body and thus to a physiological role beyond the tongue. The recent observation that taste receptors and components of the coupled taste transduction cascade are also expressed during the different phases of spermatogenesis as well as in mature spermatozoa from mouse to humans and the overlap between the ligand spectrum of taste receptors with compounds in the male and female reproductive organs makes it reasonable to assume that sperm "taste" these different cues in their natural microenvironments. This assumption is assisted by the recent observations of a reproductive phenotype of different mouse lines carrying a targeted deletion of a taste receptor gene as well as the finding of a significant correlation between human male infertility and some polymorphisms in taste receptors genes. In this review, we depict recent findings on the role of taste receptors in male fertility, especially focusing on their possible involvement in mechanisms underlying spermatogenesis and post testicular sperm maturation. We also highlight the impact of genetic deletions of taste receptors, as well as their polymorphisms on male reproduction.

Study protocol: optimized complementary feeding study (OTIS): a randomized controlled trial of the impact of a protein-reduced complementary diet based on Nordic foods

Background

What we eat as infants and children carries long-term consequences. Apart from breastfeeding, the composition of the complementary diet, i.e. the foods given to the infant during the transition from breast milk/infant formula to regular family foods affects the child’s future health. A high intake of protein, a low intake of fruits, vegetables and fish and an unfavorable distribution between polyunsaturated and saturated fats are considered to be associate with health risks, e.g. obesity, type 2 diabetes and dyslipidemia later in life.

Methods

In a randomized, controlled study from 6 to 18 months of age we will compare the currently recommended, Swedish complementary diet to one based on Nordic foods, i.e. an increased intake of fruits, berries, vegetables, tubers, whole-grain and game, and a lower intake of sweets, dairy, meat and poultry, with lower protein content (30% decrease), a higher intake of vegetable fats and fish and a systematic introduction of fruits and greens. The main outcomes are body composition (fat and fat-free mass measured with deuterium), metabolic and inflammatory biomarkers (associated with the amount of body fat) in blood and urine, gut microbiota (thought to be the link between early diet, metabolism and diseases such as obesity and insulin resistance) and blood pressure.

We will also measure the participants’ energy and nutrient intake, eating behavior and temperament through validated questionnaires, acceptance of new and unfamiliar foods through video-taped test meals and assessment of cognitive development, which we believe can be influenced through an increased intake of fish and milk fats, notably milk fat globule membranes (MFGM).

Discussion

If the results are what we expect, i.e. improved body composition and a less obesogenic, diabetogenic and inflammatory metabolism and gut microbiota composition, a more sustainable nutrient intake for future health and an increased acceptance of healthy foods, they will have a profound impact on the dietary recommendations to infants in Sweden and elsewhere, their eating habits later in life and subsequently their long-term health.

Trial registration

NCT02634749. Registration date 18 December 2015.

Taste disorders are partly genetically determined: Role of the TAS2R38 gene, a pilot study

OBJECTIVES/HYPOTHESIS

Taste sensitivity varies greatly among individuals influencing eating behavior and health, consequently the disorders of this sense can affect the quality of life. The ability to perceive the bitter of thiourea compounds, such as phenylthiocarbamide (PTC), has been largely reported as a marker of the general taste sensitivity, food preferences, and health. PTC sensitivity is mediated by the TAS2R38 receptor and its genetic common variants. We study the role of the TAS2R38 receptor in taste disorders with the aim of understanding if these can be genetically determined.

STUDY DESIGN

Prospective cohort study.

METHODS

Differences in the PTC responsiveness between the patients cohort and healthy controls were assessed. All subjects received standardized tests for smell and taste function and were genotyped for the TAS2R38 gene.

RESULTS

PAV/PAV homozygous patients gave high PTC ratings, whereas PAV/AVI genotypes reported lower values, which are similar to those determined in AVI/AVI or rare genotypes. In addition, the patients cohort did not meet the Hardy-Weinberg equilibrium at the TAS2R38 locus, showing a very low frequency of subjects carrying the PAV/AVI diplotype. Independently, in healthy controls who were in equilibrium at the locus, PAV/PAV homozygous and heterozygous rated PTC bitterness higher compared to AVI/AVI or rare genotypes.

CONCLUSIONS

Our findings, by showing that an only taster haplotype (PAV) is not sufficient to evoke high responses of TAS2R38 receptor in patients with taste disorders, suggest that the genetic constitution may represent a risk factor for the development of taste disorders.

LEVEL OF EVIDENCE

2c Laryngoscope, 129:E307-E312, 2019.

TAS2R38 Bitterness Receptor Genetic Variation and Risk of Gastrointestinal Neoplasm: A Meta-Analysis

Genetic variation in TAS2R38 bitterness taste receptor could alter the efficacy of molecular sensing, hence may be associated with cancer risk. Thus, we performed a meta-analysis to verify the association between the risk of gastrointestinal (GI) neoplasm and TAS2R38 genetic variation. Studies with TAS2R38 diplotype distribution and GI neoplasm phenotypes were searched from PubMed, EMBASE and SCOPUS, and five articles including eight studies were finally selected. The association between diplotype and neoplasm risk was estimated with summarized odds ratios (ORs) and 95% confidence intervals (CIs), applying of fixed- or random-effects models. The findings suggested TAS2R38 diplotype was not associated with GI neoplasms susceptibility [AVI vs. PAV: OR = 1.03 (95%CI: 0.97-1.09), AVI/PAV vs. PAV/PAV: OR = 1.05, (95%CI: 0.94-1.17), AVI/* vs. PAV/PAV: OR = 1.04 (95%CI: 0.94-1.16)]. Because of the presence of heterogeneity under the two genetic models (AVI/AVI vs. PAV/PAV and AVI/AVI vs. PAV/*), further subgroup analyses by ethnicity and neoplasm type were performed. However, results failed to show the neoplasm risk was altered by diplotype. In conclusion, the meta-analysis indicates that TAS2R38 diplotype minimally modified the GI neoplasm risk. Given the limited study size and resources, further well-designed and larger studies are required to validate the true effect of TAS2R38 polymorphisms on neoplasm risk.

6-n-propylthiouracil taste disruption and TAS2R38 nontasting form in Parkinson's disease

BACKGROUND

The few studies that evaluated taste function in Parkinson's disease (PD) showed inconsistent results. The inherited ability to taste the bitter compound of 6-n-propylthiouracil has been considered to be a paradigm of general taste perception. 6-n-propylthiouracil taste perception is mediated by the TAS2R38 receptor, and reduced 6-n-propylthiouracil sensitivity has been associated with several diseases not typically related to taste function.

OBJECTIVES

We evaluated the 6-n-propylthiouracil taste perception and the TAS2R38 gene as genetic risk factors for the development of idiopathic PD in PD patients and healthy controls (HC).

METHODS

The 6-n-propylthiouracil taste perception was assessed by testing the responsiveness, and the ability to recognize, 6-n-propylthiouracil and sodium chloride. The participants were classified for 6-n-propylthiouracil taster status and genotyped for the TAS2R38 gene.

RESULTS

A significant increase in the frequency of participants classified as 6-n-propylthiouracil nontasters and a reduced ability to recognize bitter taste quality of 6-n-propylthiouracil were found in PD patients when compared with healthy controls. The results also showed that only 5% of PD patients had the homozygous genotype for the dominant tasting variant of TAS2R38, whereas most of them carried the recessive nontaster form and a high number had a rare variant.

CONCLUSIONS

Our results show that 6-n-propylthiouracil taster status and TAS2R38 locus are associated with PD. The 6-n-propylthiouracil test may therefore represent a novel, simple way to identify increased vulnerability to PD. Moreover, the presence of the nontasting form of TAS2R38 in PD may further substantiate that disease-associated taste disruption may represent a risk factor associated with the disease. © 2018 International Parkinson and Movement Disorder Society.

Effect of chemical interaction between oleic acid and L-Arginine on oral perception, as a function of polymorphisms of CD36 and OBPIIa and genetic ability to taste 6-n-propylthiouracil

Oral sensitivity to fats varies in individuals influencing nutritional status and health. Variations in oleic acid perception are associated with CD36 and odorant binding protein (OBPIIa) polymorphisms, and 6-n-propylthiouracil (PROP) sensitivity, which is mediated by TAS2R38 receptor. L-Arginine (L-Arg) supplementation was shown to modify the perception of the five taste qualities. Here we analyzed the effect of three concentrations (5, 10, 15 mmol/L) of L-Arg on oral perception of oleic acid in forty-six subjects classified for PROP taster status and genotyped for TAS2R38, CD36 and OBPIIa polymorphisms. L-Arg supplementation was effective in increasing the perceived intensity of oleic acid in most subjects. The lowest concentration was the most effective, especially in PROP non-tasters or medium tasters, and in subjects with at least an allele A in CD36 and OBPIIa loci. Density Functional Theory (DFT) calculations were exploited to characterize the chemical interaction between L-Arg and oleic acid, showing that a stable 1:1 oleate·ArgH⁺ adduct can be formed, stabilized by a pair of hydrogen bonds. Results indicate that L-Arg, acting as a ‘carrier’ of fatty acids in saliva, can selectively modify taste response, and suggest that it may to be used in personalized dietetic strategies to optimize eating behaviors and health.

Effect of Salt Reduction on Consumer Acceptance and Sensory Quality of Food

Reducing salt (NaCl) intake is an important public health target. The food industry and catering services are searching for means to reduce the salt content in their products. This review focuses on options for salt reduction in foods and the sensory evaluation of salt-reduced foods. Simple salt reduction, mineral salts and flavor enhancers/modifiers (e.g., umami compounds) are common options for salt reduction. In addition, the modification of food texture and odor-taste interactions may contribute to enhanced salty taste perception. Maintaining consumer acceptance of the products is a challenge, and recent examples of the consumer perception of salt-reduced foods are presented.

Variations in the bitterness perception-related genes TAS2R38 and CA6 modify the risk for colorectal cancer in Koreans

Bitterness perception is known to be an important factor in individuals' dietary behaviors and is also associated with the sensing of nutritious/noxious molecules for subsequent metabolic responses in multiple organs. Therefore, the genetic variation in bitterness sensing may be associated with diet-related diseases, including colorectal cancer (CRC). We investigated the influence of variations in the bitterness-sensing genes taste receptor type 2 member 38 (TAS2R38) and carbonic anhydrase 6 (CA6) on the consumption of food, tobacco and alcohol and the risk of CRC in Koreans. The study population consisted of 681 cases and 1361 controls, and their intake of vegetables, fruits, fiber, fat-food and sweets was analyzed. The genotypes for TAS2R38 A49P, V262A and I296V and CA6 rs2274333 A/G were assessed using the MassArray technique. Our findings suggested that the TAS2R38 diplotype, CA6 rs2274333 and their combined genotype had a negligible influence on dietary and alcohol intake. The combined TAS2R38-CA6 AVI/AVI-AA genotype was associated with higher tobacco consumption than the other genotypes in CRC cases only. However, the genetic variations were a significant risk factor for CRC. The TAS2R38 AVI/AVI diplotype and CA6 G allele were associated with a reduced risk of CRC. Moreover, when the combined genotypes of the subjects were analyzed, possessing both the variant diplotype/variant allele (AVI/AVI+G*) was associated with a greater reduction in the risk of CRC (adjusted OR = 0.49; 95%CI: 0.34-0.74). In summary, variations in the bitterness perception genes TAS2R38 and CA6 did not influence the examined food intake in Koreans. However, those genetic variants were a decisive modifying factor of CRC susceptibility.

Taste Perception of Sweet, Sour, Salty, Bitter, and Umami and Changes Due to l-Arginine Supplementation, as a Function of Genetic Ability to Taste 6-n-Propylthiouracil

Behavioral reaction to different taste qualities affects nutritional status and health. 6-n-Propylthiouracil (PROP) tasting has been reported to be a marker of variation in taste perception, food preferences, and eating behavior, but results have been inconsistent. We showed that l-Arg can enhance the bitterness intensity of PROP, whilst others have demonstrated a suppression of the bitterness of quinine. Here, we analyze the taste perception of sweet, sour, salty, bitter, and umami and the modifications caused by l-Arg supplementation, as a function of PROP-taster status. Taste perception was assessed by testing the ability to recognize, and the responsiveness to, representative solutions of the five primary taste qualities, also when supplemented with l-Arg, in subjects classified as PROP-tasting. Super-tasters, who showed high papilla density, gave higher ratings to sucrose, citric acid, caffeine, and monosodium l-glutamate than non-tasters. l-Arg supplementation mainly modified sucrose perception, enhanced the umami taste, increased NaCl saltiness and caffeine bitterness only in tasters, and decreased citric acid sourness. Our findings confirm the role of PROP phenotype in the taste perception of sweet, sour, and bitter and show its role in umami. The results suggest that l-Arg could be used as a strategic tool to specifically modify taste responses related to eating behaviors.

First objective evaluation of taste sensitivity to 6-n-propylthiouracil (PROP), a paradigm gustatory stimulus in humans

Practical and reliable methods for the objective measure of taste function are critically important for studying eating behavior and taste function impairment. Here, we present direct measures of human gustatory response to a prototypical bitter compound, 6-n-propyltiouracil (PROP), obtained by electrophysiological recordings from the tongue of subjects who were classified for taster status and genotyped for the specific receptor gene (TAS2R38), and in which taste papilla density was determined. PROP stimulation evoked negative slow potentials that represent the summated depolarization of taste cells. Depolarization amplitude and rate were correlated with papilla density and perceived bitterness, and associated with taster status and TAS2R38. Our study provides a robust and generalizable research tool for the quantitative measure of peripheral taste function, which can greatly help to resolve controversial outcomes on the PROP phenotype role in taste perception and food preferences, and be potentially useful for evaluating nutritional status and health.

Variations in TAS1R taste receptor gene family modify food intake and gastric cancer risk in a Korean population

SCOPE

Human taste receptor type 1 (TAS1R, T1R) gene family mediates the perception of umami and sweet tastes and regulates metabolism. This study investigated whether variants in the TAS1R are associated with food intake and susceptibility to gastric cancer (GC).

METHODS AND RESULTS

A total of 1131 Koreans including 377 GC cases were analyzed to determine the dietary intake and genotype for 25 variants in TAS1R genes. Among the genotyped polymorphisms, six loci with a minor allele frequency >0.05 were tested for an association with dietary intake and GC risk. Findings suggest that TAS1R polymorphisms were associated with a variety of food intake that is beyond the known T1R-taste association. Furthermore, differential consumption for cigarettes and citrus fruits by TAS1R genetic variants may be linked to GC risk in males and females, respectively. Additionally, in males, TAS1R1 rs34160967 heterozygote showed an increased risk of GC (odds ratio: 1.52, 95% confidence interval: 1.10-2.09), independent of dietary intake. However, this GC-risk effect of TAS1R variants was not evident in females.

CONCLUSIONS

Genetic variants in TAS1R were associated with dietary consumption, which may be associated with GC risk. TAS1R1 rs34160967 may also modify the risk for GC independent of diet in Korean males.

Characterizing and improving the sensory and hedonic responses to polyphenol-rich aronia berry juice

Interest in nutrient-rich berry juices is growing, but their high polyphenol levels render them sensorily unappealing. Fifty adults, who were assessed for sensory phenotype and dietary behaviors, provided sensory and palatability ratings of juices from 'Viking' aronia berries for each of seven harvest weeks. By peak harvest, juice preference increased two-fold, averaging neither like/dislike. This hedonic shift was associated with: increases in juice sugars paralleling increases in perceived sweetness (maximum = weak); reductions in percent acidity paralleling reductions in sourness (minimum = moderate), astringency (minimum = to just above weak) and bitterness (minimum = just below weak). About 25% of adults liked the aronia juice, including adults who also liked an aqueous citric acid solution (average rating = moderately sour) or those who reported adventurous eating behaviors. Bitter taste phenotype, measured by propylthiouracil or quinine bitterness, failed to explain significant variation in juice sensation or preference. We also collected sensory and preference ratings from juice collected at peak harvest blended with sugar and/or sweet olfactory flavoring (10 ppm ethyl butyrate). Increasing juice sweetness by adding 5% sucrose decreased sourness and improved preference from weak dislike to weak like. Adding sweet olfactory flavoring decreased juice sourness without changing preference. Adding sweet flavoring and 3% sucrose resulted in reduction of sourness and improvements in preference ratings comparable to 5% added sucrose. Neither added sugar nor flavoring blocked juice astringency. In summary, these findings suggest that aronia juice, even from berries picked at peak harvest, appealed to only a few adults (sour likers or adventurous eaters). Although enhanced sweetness, with added sugar and sweet olfactory flavoring, improved aronia juice preference, broader sensory approaches are required to blunt astringency for greater consumer appeal.

Genetic Variation in the TAS2R38 Bitter Taste Receptor and Gastric Cancer Risk in Koreans

The human TAS2R38 gene encodes a bitter taste receptor that regulates the bitterness perception and differentiation of ingested nutritional/poisonous compounds in the oral cavity and gastrointestinal tract. TAS2R38 gene variants are associated with alterations in individual sensitivity to bitter taste and food intake; hence, these genetic variants may modify the risk for diet-related diseases, including cancer. However, little is known about the association between TAS2R38 polymorphisms and gastric cancer susceptibility. The present case-control study examined the influence of TAS2R38 polymorphisms on food intake and determined whether they predict gastric cancer risk in Koreans. A total of 1,580 subjects, including 449 gastric cancer cases, were genotyped for TAS2R38 A49P, V262A, I296V and diplotypes. Dietary data were analysed to determine the total consumption of energy, fibre, vegetables, fruits, sweets, fats, alcohol and cigarettes. TAS2R38 diplotype was not associated with food, alcohol or cigarette consumption, either independent or dependent of gastric cancer phenotype. However, the PAV/AVI diplotype significantly increased gastric cancer risk (adjusted odds ratio: 1.513; 95% confidence interval: 1.148–1.994) independent of dietary intake. Findings suggest that TAS2R38 may be associated with the risk for gastric cancer in Koreans, although the TAS2R38 diplotype did not influence dietary intake.

A Genome-Wide Association Study in isolated populations reveals new genes associated to common food likings

Food preferences are the first factor driving food choice and thus nutrition. They involve numerous different senses such as taste and olfaction as well as various other factors such as personal experiences and hedonistic aspects. Although it is clear that several of these have a genetic basis, up to now studies have focused mostly on the effects of polymorphisms of taste receptor genes. Therefore, we have carried out one of the first large scale (4611 individuals) GWAS on food likings assessed for 20 specific food likings belonging to 4 different categories (vegetables, fatty, dairy and bitter). A two-step meta-analysis using three different isolated populations from Italy for the discovery step and two populations from The Netherlands and Central Asia for replication, revealed 15 independent genome-wide significant loci (p < 5 × 10(-8)) for 12 different foods. None of the identified genes coded for either taste or olfactory receptors suggesting that genetics impacts in determining food likings in a much broader way than simple differences in taste perception. These results represent a further step in uncovering the genes that underlie liking of common foods that in the end will greatly help understanding the genetics of human nutrition in general.

Genetic variations of the bitter taste receptor TAS2R38 are associated with obesity and impact on single immune traits

SCOPE

Changes in genetic variations affecting the taste receptor, type 2, member 38 (TAS2R38) may identify the interacting mechanism leading to obesity and potential associations with proteins partaking in innate immunity, such as surfactant protein D (SPD) and mannan-binding lectin (MBL).

METHODS AND RESULTS

We evaluated haplotypes of the bitter-taste receptor TAS2R38 in an identification sample of 210 women in different weight conditions, including anorexia nervosa and obesity. The association with SPD and MBL was tested in an independent sample picturing general population (n = 534). The relationship with obesity was validated in an extended final sample of 1319 participants. In the sample comprised of women in extreme weight conditions, increased obesity was identified in AVI/AVI subjects (OR = 2.5 [1.06-6.11], p = 0.035). In the sample picturing general population, increased SPD and MBL concentrations were found in nonsmoking AVI carriers. In this cohort, smoking and obesity blunted associations between TAS2R38 haplotypes and SPD and MBL. In the extended sample, the association of AVI/AVI haplotypes with increased obesity was also identified (OR = 1.4 [0.99/1.85], p = 0.049), being more robust in subjects aged <40 years (OR = 1.9 [1.06/3.42], p = 0.031).

CONCLUSION

Current data reinforce the impact of TAS2R38 gene on phenotypic and clinical outputs affecting obesity, showing significant associations with extreme weight conditions (i.e., obesity and anorexia nervosa), and changes in both olfactory capacity and immune traits.

Impact of sensory-based food education in kindergarten on willingness to eat vegetables and berries

Background

Children use all of their senses when exploring new foods, and sensory-based food education provides new possibilities for promoting healthy dietary habits.

Objective

To evaluate the effect of sensory-based food education activities on children's willingness to eat test samples of selected vegetables and berries.

Design

Two kindergartens in Hanko, Finland, participated in the study and the subjects were children aged 3–6 years, divided in the intervention (n=44) and control (n=24) kindergarten. In the intervention kindergarten, five sensory-based food education sessions focusing on vegetables and berries were implemented, once per week for 5 weeks. A tasting protocol was performed with the children at baseline and after the intervention. The willingness to eat (5 different vegetables and 3 Finnish berries) was categorised. Parents also filled in a questionnaire on the children's food preferences at home.

Results

In the intervention kindergarten, the willingness to eat the samples increased significantly (p≤0.001, Wilcoxon and Friedman), while in the control kindergarten, no significant change was observed when all of the test samples were taken into account. The parental report of their children's preferences and children's actual eating of the test samples corresponded relatively weakly.

Conclusions

Sensory-based food education activities may promote a willingness to eat vegetables and berries. Child-centred test methods are important for evaluating the effects of dietary interventions among children.

Rare haplotypes of the gene TAS2R38 confer bitter taste sensitivity in humans

Background

The TAS2R38 gene is widely responsible for the well-known bimodal response to a family of bitter chemicals which includes 6-n-propylthiouracial (PROP). There are two common haplotypes of this gene, the recessive AVI and the dominant PAV, both of which are well studied. Conversely, the role of rare TAS2R38 haplotypes on bitter taste sensitivity has been notoriously difficult to study due to small sample sizes. Here we present PROP sensitivity data of 97 individuals that have been observed to carry rare haplotypes (AAV, AAI, PAI, PVI) of the TAS2R38 gene.

Results

Participants rated their bitter taste perception to a PROP filter disc then provided a buccal DNA sample from which the TAS2R38 gene was sequenced and analyzed. We found the prevalence of the PAV haplotype to be 42.3 %, AVI 53.1 %, AAV 2.5 %, AAI 1.2 %, PAI 0.8 % and PVI 0.1 %. We found that the AAI, AAV, and PAI haplotypes present intermediate taste sensitivity.

Conclusions

These data are further evidence that bitter taste sensitivity to PROP exists as a broad range, and not exclusively as nontasters, medium tasters, and supertasters.

Using Animal Models to Determine the Role of Gustatory Neural Input in the Control of Ingestive Behavior and the Maintenance of Body Weight

INTRODUCTION

Decades of research have suggested that nutritional intake contributes to the development of human disease, mainly by influencing the development of obesity and obesity-related conditions. A relatively large body of research indicates that functional variation in human taste perception can influence nutritional intake as well as body mass accumulation. However, there are a considerable number of studies that suggest that no link between these variables actually exists. These discrepancies in the literature likely result from the confounding influence of a variety of other, uncontrolled, factors that can influence ingestive behavior.

STRATEGY

In this review, the use of controlled animal experimentation to alleviate at least some of these issues related to the lack of control of experimental variables is discussed. Specific examples of the use of some of these techniques are examined.

DISCUSSION AND CONCLUSIONS

The review will close with some specific suggestions aimed at strengthening the link between gustatory neural input and its putative influence on ingestive behaviors and the maintenance of body weight.