Genetic sensitivity to bitter taste of 6-n Propylthiouracil: A useful diagnostic aid to detect early childhood caries in pre-school children

Association between Severe Early Childhood Caries, Dietary Preferences, and 2nd Digit-4th Digit (2D:4D) Ratio

Background and aim

To evaluate the association between severe early childhood caries (S-ECC), dietary preferences, and 2nd digit-4th digit (2D:4D) ratio. The objective is to contrast the detection and prevalence of dental caries in children with different sensitivity levels to the bitter taste of 6-n-propylthiouracil (PROP) and its association with 2D:4D.

Materials and methods

A total of 300 children below 71 months of age were assigned to two study groups-group I (caries-free) and group II (caries). PROP sensitivity test was carried out to determine the inherent genetic ability to taste a bitter or sweet substance. Evaluation of dietary preferences was carried out using a food preference questionnaire, which was completed by the parents of the children to know the child's dietary habits and their sweet, sour, and strong taste preferences. The length of the index (2D) and ring (4D) finger was measured with the help of digital vernier caliper to record the 2D:4D ratio. The data obtained was subjected to statistical analysis using Pearson's Chi-squared test and one-way analysis of variance (ANOVA).

Results

The results suggested a positive association between S-ECC and dietary preferences but could not establish a straightforward 1:1 relation between 2D:4D ratio and S-ECC.

Conclusion

An individual considered as nontaster by PROP test was a sweet liker with low 2D:4D ratio having high caries index. The association between 2D:4D ratio and S-ECC should further be explored by taking other influencing factors into consideration before arriving at a definitive conclusion.

How to cite this article

Srivastava SK, Garg N, Pathivada L, et al. Association between Severe Early Childhood Caries, Dietary Preferences, and 2nd Digit-4th Digit (2D:4D) Ratio. Int J Clin Pediatr Dent 2023;16(5):740-744.

Clinical Associations of Bitter Taste Perception and Bitter Taste Receptor Variants and the Potential for Personalized Healthcare

Bitter taste receptors (T2Rs) consist of 25 functional receptors that can be found in various types of cells throughout the human body with responses ranging from detecting bitter taste to suppressing pathogen-induced inflammation upon activation. Numerous studies have observed clinical associations with genetic or phenotypic variants in bitter taste receptors, most notably that of the receptor isoform T2R38. With genetic variants playing a role in the response of the body to bacterial quorum-sensing molecules, bacterial metabolites, medicinal agonists and nutrients, we examine how T2R polymorphisms, expression levels and bitter taste perception can lead to varying clinical associations. From these genetic and phenotypic differences, healthcare management can potentially be individualized through appropriately administering drugs with bitter masking to increase compliance; optimizing nutritional strategies and diets; avoiding the use of T2R agonists if this pathway is already activated from bacterial infections; adjusting drug regimens based on differing prognoses; or adjusting drug regimens based on T2R expression levels in the target cell type and bodily region.

Daily Exposure to a Cranberry Polyphenol Oral Rinse Alters the Oral Microbiome but Not Taste Perception in PROP Taster Status Classified Individuals

Diet and salivary proteins influence the composition of the oral microbiome, and recent data suggest that TAS2R38 bitter taste genetics may also play a role. We investigated the effects of daily exposure to a cranberry polyphenol oral rinse on taste perception, salivary proteins, and oral microbiota. 6-n-Propylthiouracil (PROP) super-tasters (ST, n = 10) and non-tasters (NT, n = 10) rinsed with 30 mL of 0.75 g/L cranberry polyphenol extract (CPE) in spring water, twice daily for 11 days while consuming their habitual diets. The 16S rRNA gene sequencing showed that the NT oral microbiome composition was different than that of STs at baseline (p = 0.012) but not after the intervention (p = 0.525). Principal coordinates analysis using unweighted UniFrac distance showed that CPE modified microbiome composition in NTs (p = 0.023) but not in STs (p = 0.096). The intervention also altered specific salivary protein levels (α-amylase, MUC-5B, and selected S-type Cystatins) with no changes in sensory perception. Correlation networks between oral microbiota, salivary proteins, and sensory ratings showed that the ST microbiome had a more complex relationship with salivary proteins, particularly proline-rich proteins, than that in NTs. These findings show that CPE modulated the oral microbiome of NTs to be similar to that of STs, which could have implications for oral health.

Association of Mothers’ Genetic Taste Perception to Eating Habits and Its Influence on Early Childhood Caries in Preschool Children: An Analytical Study

Aims

To examine (1) the association of mothers’ 6-n-propylthiouracil (PROP) sensitivity with snacking habits and caries experience of both the mother and their 2-5-year-old preschool children and (2) the association of feeding habits with caries prevalence in 2-5-year-old children.

Materials and methods

In this analytical cross-sectional study, 2-5-year-old preschool children were clinically examined by a single calibrated examiner and divided into two groups of 80 children with early childhood caries (ECC) and 80 without. Mothers of the children were clinically examined and a second blinded investigator determined their genetic taste type using PROP. Data regarding feeding practices of the child and snacking habits of the mother and child were obtained using questionnaires. The data obtained were statistically analyzed.

Results

Cariogenic snack consumption was more among nontaster mothers and their children (p value < 0.001). More number of children of the nontaster mothers in the ECC group were bottle-fed with sweetened beverages (n = 24) and received sweet snacks as rewards (n = 32). Caries prevalence of 73%, 20%, and 7% was seen in children of nontaster, medium taster, and supertaster mothers, respectively (p value < 0.05). Significant association was found between mother's caries activity, past bottle-feeding, receiving sweet snacks as reward and their child's caries experience.

Conclusion

Mothers’ PROP sensitivity was significantly associated with snacking habits and caries experience of their children. Mothers’ PROP type could be an important factor that may determine and explain the dental caries experience in their 2-5-year-old preschool children.

Clinical significance

Early identification of nontaster mothers may prove beneficial in guiding them and consecutively their children toward healthy dietary habits, leading to lesser incidence of caries and their better overall wellbeing.

How to cite this article

Nellamakkada K, Patil SS, Kakanur M, et al. Association of Mothers’ Genetic Taste Perception to Eating Habits and Its Influence on Early Childhood Caries in Preschool Children: An Analytical Study. Int J Clin Pediatr Dent 2022;15(S-2):S135-S139.

Taste perception in children with different caries activity

PURPOSE

The aim of the study was to investigate whether caries-active and caries-free children differ in terms of their taste perception for sweet, sour, salty and bitter.

METHODS

The study group consisted of 100 children aged 5-10 years: 50 caries-free children and 50 children with at least four untreated carious lesions. Taste perception was analysed using two test systems. First, filter paper strips impregnated with four taste qualities (sweet, sour, salty, and bitter) at four defined intensities were used ("taste strips"). Then a tasting spray in suprathreshold concentration of the respective taste was applied. The children were asked to name the perceived taste. The parents answered a questionnaire about the children's dietary habits.

RESULTS

The children with high caries activity scored lower on average on the taste strips than the caries-free participants. For the taste sprays, the perception of the taste quality "bitter" was significantly worse in the children with caries than in caries-free children (Mann-Whitney U test p < 0.05).

CONCLUSION

The results of this study suggest that taste preferences in children are associated with increased susceptibility to tooth decay.

Tissue-Dependent Expression of Bitter Receptor TAS2R38 mRNA

TAS2R38 is a human bitter receptor gene with a common but inactive allele; people homozygous for the inactive form cannot perceive low concentrations of certain bitter compounds. The frequency of the inactive and active forms of this receptor is nearly equal in many human populations, and heterozygotes with 1 copy of the active form and 1 copy of the inactive form have the most common diplotype. However, even though they have the same genotype, heterozygotes differ markedly in their perception of bitterness, perhaps in part because of differences in TAS2R38 mRNA expression. Other tissues express this receptor too, including the nasal sinuses, where it contributes to pathogen defense. We, therefore, wondered whether heterozygous people had a similar wide range of TAS2R38 mRNA in sinonasal tissue and whether those with higher TAS2R38 mRNA expression in taste tissue were similarly high expressers in nasal tissue. To that end, we measured gene expression by quantitative PCR in taste and sinonasal tissue and found that expression abundance in one tissue was not related to the other. We confirmed the independence of expression in other tissue pairs expressing TAS2R38 mRNA, such as pancreas and small intestine, using autopsy data from the Genotype-Tissue Expression project (although people with high expression of TAS2R38 mRNA in colon also tended to have higher expression in the small intestine). Thus, taste tissue TAS2R38 mRNA expression among heterozygotes is unlikely to predict expression in other tissues, perhaps reflecting tissue-dependent function, and hence regulation, of this protein.

Correlation of Mother and Child's Taste Perception and their Caries Experience

AIM AND BACKGROUND

Nowadays, clinical assessment of caries susceptibility is evaluated by the individuals taste perception. As food habits of the child are mostly influenced by the parents (mothers), it would be beneficial to assess the relation between mother and child's taste status and their caries experience to predict the caries susceptibility of the child.

METHODOLOGY

A convenience sample of 310 mother-child dyads of both the sexes were selected. After obtaining the data on the taste preferences, dietary habits, and oral hygiene practices, caries experience of both the mother and child were recorded using the DMFT and defs indices, followed by the taste assessment using 6-n propylthiouracil (PROP) tester strips.

RESULTS

Irrespective of the taste status, the majority of the mother and child dyads showed preference to sweet foods. A statistically significant relationship between taste status and caries experience was noticed among mothers and children individually. However, there was no significant association between mother and child taste status. Whereas, a weak-positive correlation is observed between the mother and child's caries experience. The children of supertaster mothers have relatively less caries experience compared to children of moderate and nontaster mothers, which was not statistically significant.

CONCLUSION

Mother's taste perception or caries experience may not always be a risk predictor for their child's caries experience, but the PROP tester strips were very effective in predicting the caries risk of an individual.

The evolution of taste and perinatal programming of taste preferences

Taste is important for food intake. The fetus first experiences taste through amniotic fluid, and later via mother's milk. Early human experience with taste has a key importance for later acceptance of food. Dietary behavior is determined by the interaction of many different factors. The development of the olfactory and taste receptors begins at 7-8 weeks of gestation. An early sensitive period probably exists when flavor preference is established. Sweet taste is preferred in early childhood; this is the reason why children are at increased risk of over-consuming saccharides. Gustatory sensitivity declines with age. The threshold for the perception of each basic taste differs, and is established genetically. In this review, we summarize published data on taste preferences and its development and changes during life.

Association between genetic taste sensitivity, 2D:4D ratio, dental caries prevalence, and salivary flow rate in 6-14-year-old children: a cross-sectional study

Background. The aim of this study was to assess the relationship between genetic taste sensitivity, dietary preferences and salivary flow rate in 6‒14-year-old children for identification of individuals at higher risk of developing dental caries.

Methods. A total of 500 children 6‒14 years of age, of both genders, who reported to the Department of Oral Medicine and Radiology, were included. Propylthiouracil (PROP) sensitivity test was carried out and the subjects whose perception was bitter were grouped as tasters, whereas those who were unable to perceive any taste were grouped as non-tasters. The 2D:4D ratio was obtained by measuring the length ratio of index finger to ring finger with the help of a digital Vernier caliper. Evaluation of dietary preferences was carried out using a 24-hour dietary recall and accordingly they were categorized as sweet likers and dislikers. The salivary flow rate was estimated by collecting unstimulated saliva by spitting method. Data were analyzed with Student’s t-test and chi-squared test.

Results. The results suggested a positive relation between low digit ratio (2D:4D), non-tasters, sweet likers and high caries index among the participants with a highly significant statistical difference (P ≤ 0.000). Tasters had high mean of USSR (0.48) than non-tasters (0.29), which was statistically significant.

Conclusion. The present research revealed a positive correlation between all the parameters evaluated. Therefore an individual considered as non-taster by PROP was a sweet liker with low 2D:4D ratio, reduced salivary flow rate and high caries index.

Variation in the Ability to Taste Bitter Thiourea Compounds: Implications for Food Acceptance, Dietary Intake, and Obesity Risk in Children

The ability to taste bitter thiourea compounds, such as phenylthiocarbamide (PTC) and 6-n-propylthiouracil (PROP), is inherited. Polymorphisms in the bitter-taste receptor TAS2R38 explain the majority of phenotypic variation in the PROP phenotype. It has been hypothesized that the PROP phenotype is a marker for perception of a variety of chemosensory experiences. In this review, we discuss studies that have investigated the relationship between bitter-taste response and dietary behaviors and chronic health in children. Investigators have hypothesized that children who are PROP tasters have lower liking and consumption of bitter foods, such as cruciferous vegetables. Additionally, several studies suggest that children who are unable to taste PROP (i.e., nontasters) like and consume more dietary fat and are prone to obesity. The relationship between the PROP phenotype and obesity is influenced by multiple confounders, including sex, food access, ethnicity, and socioeconomic status. Future studies that adjust for these variables are needed.

Does Taste Perception Effect Body Mass Index in Preschool Children?

INTRODUCTION

Eating trends established early in life leads to chronic life style disorders such as obesity, which is hard to overcome as child comes of age. Energy expenditure is less but caloric intake is high leading to disparity of energy balance in turn leading to obesity. Obesity is the outcome of a disparity between energy expenditure and caloric intake. Genes play a role in establishing eating habits, which is termed as genetic sensitivity to taste.

AIM

To determine taste perception effect on body mass index (BMI) in preschool central Indian urban children.

MATERIALS AND METHODS

A total of 500 children of 3-6 years were selected and genetic taste perception was assessed using PROP sensitivity test. Anthropometric measurements were recorded to obtain BMI value. Categorical variables were analysed using Pearson's Chi square test.

RESULTS

Non tasters were mostly in overweight category i.e. 73.30% where as more number of tasters i.e. 59.70% were in underweight category. A significant correlation is seen between BMI and taste perception. No statistically significant correlation was seen between oral hygiene and taste perception. Females were predominant in both the tasters and non tasters categories.

CONCLUSION

Taste perception showed significant relationship with BMI of children between 3-6-year-old children.

Bitter taste genetics--the relationship to tasting, liking, consumption and health

Bitter is the most complex of human tastes, and is arguably the most important. Aversion to bitter taste is important for detecting toxic compounds in food; however, many beneficial nutrients also taste bitter and these may therefore also be avoided as a consequence of bitter taste. While many polymorphisms in TAS2R genes may result in phenotypic differences that influence the range and sensitivity of bitter compounds detected, the full extent to which individuals differ in their abilities to detect bitter compounds remains unknown. Simple logic suggests that taste phenotypes influence food preferences, intake and consequently health status. However, it is becoming clear that genetics only plays a partial role in predicting preference, intake and health outcomes, and the complex, pleiotropic relationships involved are yet to be fully elucidated.