Polymorphism of CD36 Determines Fat Discrimination but Not Intake of High-Fat Food in 20- to 40-Year-Old Adults

T1R2/T1R3 polymorphism affects sweet and fat perception: Correlation between SNP and BMI in the context of obesity development

Genetic variations in taste receptors are associated with gustatory perception and obesity, which in turn affects dietary preferences. Given the increasing tendency of people with obesity choosing sweet, high-fat meals, the current study assessed the cross-regulation of two polymorphisms of the sweet taste receptor (T1R2/T1R3), rs35874116 and rs307355, on fat sensitivity in Indian adults. We investigated the association between taste sensitivity and BMI in the T1R2, T1R3, and CD36 polymorphic and non-polymorphic groups. The general labelled magnitude scale (gLMS) was used to assess the taste sensitivity of 249 participants in addition to anthropometric data. TaqMan Probe-based RT-PCR was employed to determine the polymorphisms. Additionally, the colorimetric method utilizing 3, 5-dinitro salicylic acid was used to evaluate the participants' salivary amylase activity. The mean detection thresholds for linoleic acid (LA) and sucrose were greater in individuals with obesity (i.e., 0.97 ± 0.08 mM and 0.22 ± 0.02 M, respectively) than in healthy adults (p < 0.0001), indicating lower sensitivity. Moreover, it was found that a greater proportion of persons with obesity fall into the polymorphic groups (i.e., 52% with genotype CD36 AA, 44% with genotype T1R2 CC, and 40% with genotype T1R3 TT). All three single nucleotide polymorphisms support the Hardy-Weinberg equilibrium (p = 0.78). The Pearson correlation analysis between LA and the sucrose detection threshold revealed a significant (p < 0.0001) positive relationship with an r value of 0.5299. Moreover, salivary amylase activity was significantly (p < 0.05) higher in the polymorphic sub-groups. The results of our study imply that genetic variations in T1R2/T1R3 receptors affect perception of both sweetness and fat, which may have an effect on obesity.

The gustin gene variation at rs2274333 and PROP taster status affect dietary fat perception: a stepwise multiple regression model study

Gustin, a trophic factor for taste bud development, and its polymorphism at rs2274333 influence taste perception of 6-n-propylthiouracil (PROP) and fungiform papillae (FP) density. The PROP taster status affects dietary fat sensing and body composition. However, there is a paucity of research on the gustin genotype with dietary fat perception, PROP tasting ability, and body mass index (BMI). Thus, taste sensitivity to fat and bitterness was evaluated in 178 healthy individuals. The general labeled magnitude scale was used to determine suprathreshold taste intensity ratings, whereas the alternative forced choice approach was used to estimate the taste-sensing ability. The FP density was assessed by applying blue-colored food dye over the anterior region of the tongue. Restriction fragment length polymorphism was used to detect the genetic polymorphism (rs2274333) in the carbonic anhydrase VI (CA-VI) gene. Fisher's chi-square analysis showed that the CA-VI genotype and allelic frequencies significantly correlated (p<0.001) with the PROP taster status and BMI. Healthy individuals with AA genotypes of the CA-VI polymorphism and PROP super-tasters demonstrated stronger gustatory sensitivity for linoleic acid (LA) with greater FP density in comparison to individuals with AG/GG genotypes and other PROP taster groups. Stepwise forward multiple regression analysis indicates that BMI and PROP taster status significantly influence the LA sensing ability. The suprathreshold intensity rating for LA was also significantly impacted by PROP taster status and CA-VI genotypes, with a variation of 73.3%. Overall, our findings show a relationship between the taste papillae environment and the CA-VI genetic mutation at rs2274333, which influenced the gustatory preference for dietary fat and bitter taste.

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.

Mitochondrial DNA and Epigenetics: Investigating Interactions with the One-Carbon Metabolism in Obesity

Mitochondrial DNA copy number (mtDNAcn) has been proposed for use as a surrogate biomarker of mitochondrial health, and evidence suggests that mtDNA might be methylated. Intermediates of the one-carbon cycle (1CC), which is duplicated in the cytoplasm and mitochondria, have a major role in modulating the impact of diet on the epigenome. Moreover, epigenetic pathways and the redox system are linked by the metabolism of glutathione (GSH). In a cohort of 101 normal-weight and 97 overweight/obese subjects, we evaluated mtDNAcn and methylation levels in both mitochondrial and nuclear areas to test the association of these marks with body weight, metabolic profile, and availability of 1CC intermediates associated with diet. Body composition was associated with 1CC intermediate availability. Reduced levels of GSH were measured in the overweight/obese group (p = 1.3∗10⁻⁵). A high BMI was associated with lower LINE-1 (p = 0.004) and nominally lower methylenetetrahydrofolate reductase (MTHFR) gene methylation (p = 0.047). mtDNAcn was lower in overweight/obese subjects (p = 0.004) and independently correlated with MTHFR methylation levels (p = 0.005) but not to LINE-1 methylation levels (p = 0.086). DNA methylation has been detected in the light strand but not in the heavy strand of the mtDNA. Although mtDNA methylation in the light strand did not differ between overweight/obese and normal-weight subjects, it was nominally correlated with homocysteine levels (p = 0.035) and MTHFR methylation (p = 0.033). This evidence suggests that increased body weight might perturb mitochondrial-nuclear homeostasis affecting the availability of nutrients acting as intermediates of the one-carbon cycle.

The Association between Fat Taste Sensitivity, Eating Habits, and Metabolic Health in Menopausal Women

The aim of our study was to evaluate the associations between sensitivity to fat taste, eating habits and BMI value in a sample of menopausal Polish women. In a population of 95 women, fat taste thresholds with oleic acid were determined, allowing us to classify each woman as a hypersensitive or hyposensitive taster. Eating habits were assessed using a validated KomPAN questionnaire for food frequency. Dietary intake was evaluated based on a food diary. Selected biochemical parameters were measured using a Konelab20i biochemical analyzer. Anthropometric parameters and blood pressure were also measured. Twenty-two menopausal women were classified as hyposensitive to fat taste and 73 as hypersensitive. The hyposensitive tasters were significantly older (p = 0.006), with the majority of them (92%) being postmenopausal (p < 0.001); this group had significantly higher BMI values (p < 0.001) and other adiposity indicators compared to their hypersensitive counterparts. The hyposensitive tasters had higher blood pressure (systolic blood pressure; SBP p = 0.030; diastolic blood pressure; DBP p = 0.003), glucose (p = 0.011) and triacylglycerols levels than the hypersensitive tasters (p = 0.031). Almost half of them had diagnosed metabolic syndrome. Daily eating occasions were associated with low oral fatty acid sensitivity, irrespective of age (p = 0.041) and BMI value (p = 0.028). There were also significant associations between frequency of consumption of meats and eggs, as well as snacks and fast foods and low oral fatty acid sensitivity before adjustment for potential confounders (both associations p < 0.05), which remained after adjustment for age (both associations p < 0.05), but not after adjustment for BMI. A multivariate logistic regression analysis showed that higher BMI value (p = 0.003), along with postmenopausal status (p = 0.003), were associated with low fat taste sensitivity irrespective of age and consumed percentage energy from fat. Postmenopausal status and BMI are associated with low fat taste sensitivity. Fat hyposensitivity may also play a role in eating habits, leading to increased eating occasions and favoring certain types of food. These eating habits may determine increased body weight and the occurrence of metabolic syndrome in mid-life women, especially those who have undergone menopause and have been exposed to the physiological changes which are conducive to these relationships.

Computational algorithmic and molecular dynamics study of functional and structural impacts of non-synonymous single nucleotide polymorphisms in human DHFR gene

Human dihydrofolate reductase (DHFR) is a conserved enzyme that is central to folate metabolism and is widely targeted in pathogenic diseases as well as cancers. Although studies have reported the fact that genetic mutations in DHFR leads to a rare autosomal recessive inborn error of folate metabolism and drug resistance, there is a lack of an extensive study on how the deleterious non-synonymous SNPs (nsSNPs) disrupt its phenotypic effects. In this study, we aim at discovering the structural and functional consequences of nsSNPs in DHFR by employing a combined computational approach consisting of ten recently developed in silico tools for identification of damaging nsSNPs and molecular dynamics (MD) simulation for getting deeper insights into the magnitudes of damaging effects. Our study revealed the presence of 12 most deleterious nsSNPs affecting the native phenotypic effects, with three (R71T, G118D, Y122D) identified in the co-factor and ligand binding active sites. MD simulations also suggested that these three SNPs particularly Y122D, alter the overall structural flexibility and dynamics of the native DHFR protein which can provide more understandings into the crucial roles of these mutants in influencing the loss of DHFR function.

The Associations Between Bitter and Fat Taste Sensitivity, and Dietary Fat Intake: Are They Impacted by Genetic Predisposition?

A relationship between bitter and fat taste sensitivity, CD36 rs1761667 and TAS2R38 has been demonstrated. However, research is scarce and does not take diet into account. This study aimed to explore associations between genetics, fat and bitter taste sensitivity and dietary fat intake in healthy UK adults. A cross-sectional study was carried out on 88 Caucasian participants (49 females and 39 males aged 35 ± 1 years; body mass index 24.9 ± 0.5 kg/m2). Bitter taste sensitivity was assessed using phenylthiocarbamide (PTC) impregnated strips and the general Labeled Magnitude Scale. Fat taste sensitivity was assessed by the Ascending Forced Choice Triangle Procedure and dietary intake with a semi-quantitative food frequency questionnaire. Genotyping for rs713598, rs1726866, rs10246939, and rs1761667 was performed. Participants with TAS2R38 PAV/PAV diplotype perceived PTC strips as more bitter than groups carrying AVI haplotypes (AVI/AVI, P = 1 × 10-6; AVI/AAV, P = 0.029). CD36 rs1761667 was associated with fat taste sensitivity (P = 0.008). A negative correlation between bitter taste sensitivity and saturated fat intake was observed (rs = -0.256, P = 0.016). When combining the CD36 genotypes and TAS2R38 diplotypes into one variable, participants carrying both TAS2R38 AVI haplotype and CD36 A allele had a higher intake of saturated fat compared to carriers of CD36 GG genotype or TAS2R38 PAV/PAV and PAV/AAV diplotypes (13.8 ± 0.3 vs. 12.6 ± 0.5%TEI, P = 0.047) warranting further exploration in a larger cohort.

Hedonic Hunger Is Associated with Intake of Certain High-Fat Food Types and BMI in 20- to 40-Year-Old Adults

BACKGROUND

Hedonic hunger occurs in response to a desire to consume food for pleasure. The μ-opioid system regulates the hedonic impact of food and the opioid receptor mu 1 gene (OPRM1) polymorphism has been associated with fat intake.

OBJECTIVES

The aim of this study was to determine whether the intake of high-fat food is associated with hedonic hunger and the OPRM1 polymorphism and whether these variables are related to BMI.

METHODS

Participants were 20- to 40-y-old women and men enrolled in Poznań, Poland in 2016-2018. The frequency of consumption of high-fat food was measured using a validated application for mobile devices. Hedonic hunger was assessed with the use of the Power of Food Scale (PFS). PFS1, PFS2, and PFS3 scores were generated for food available, food present, and food tasted, respectively. Genotyping of rs1799971 in the OPRM1 gene was performed using TaqMan probes. The associations were analyzed using linear regression or logistic regression, as appropriate.

RESULTS

Hedonic hunger scores were not associated with total high-fat food intake. Total PFS was associated with snack intake (β: 0.16, P = 0.0066). PFS1 was positively associated with healthy high-fat food intake (β: 0.27, P = 0.0001) and PFS2 with sweet high-fat food and fast-food intake (β: 0.27, P = 0.0030). OPRM1 genotype and hedonic hunger interacted on fast-food intake (β: -0.17; P < 0.0154). Total PFS and PFS2 increased the chance of having a BMI ≥ 25 kg/m2 (OR: 1.43; 95% CI: 1.03, 2.01; P = 0.0335 and OR: 1.89; 95% CI: 1.37, 2.61; P = 0.0001, respectively), whereas PFS3 decreased it (OR: 0.61; 95% CI: 0.41, 0.87; P = 0.0082).

CONCLUSIONS

Hedonic hunger is associated with the intake of selected types of high-fat food, but not with its total intake, in people aged 20-40 y. Associations between hedonic hunger and fast-food intake can be modified by OPRM1 genotype. Hedonic hunger is associated with BMI.

Greater self-reported preference for fat taste and lower fat restraint are associated with more frequent intake of high-fat food

The determinants of the intake of high-fat products are not well recognized, but fat preference may be one of them. The aim of this study was thus to determine whether intake of different types of high-fat food is associated with fat preference in people with normal and increased body weight. Participants aged 20-40 years [n = 421] were enrolled in Poznań, Poland in 2016-2018. Fat preference was measured using the Fat Preference Questionnaire. Self-reported preference for fat taste (TASTE) and fat restraint (DIFF) scores were calculated. The frequency of consuming high-fat food was measured with an application for mobile devices using ecological momentary assessment. TASTE was positively associated with calorie intake and total frequency of eating high-fat food in both the normal weight and the overweight/obese groups. Overweight and obese people had lower DIFF (p < 0.001) than normal weight people. DIFF was negatively associated with total calorie intake and total intake of high-fat food, but only in normal weight people (β = -0.16, p < 0.01 and β = -0.26, p < 0.001, respectively). DIFF was negatively associated with the frequency of eating sweet (β = -0.33, p < 0.000) and meat high-fat food (β = -0.25, p < 0.001) in the normal weight group. The frequency of consumption of high-fat food and calorie intake are positively associated with self-reported preference for fat taste. In normal weight subjects fat restraint is negatively associated with calorie intake and total frequency of high-fat food intake, as well as with intake of different types of fatty food. Fat preference measures are thus associated with high-fat food intake, but these associations differ by body weight status.

Low folate intake and serum levels are associated with higher body mass index and abdominal fat accumulation: a case control study

BACKGROUND

The link between folate metabolism and obesity has recently been underlined, suggesting that folate deficiency may lead to body weight gain and adiposity. We thus wished to determine whether the inefficiency in folate metabolism caused by genetic variation in the MTHFR and DHFR genes in folate metabolism, or inadequate folate intake, is associated with obesity.

METHODS

A case-control study including 421 healthy participants (aged 20-40) was performed in Poznań, Poland. The cases were 213 subjects with BMI > 25 kg/m2, while the controls were 208 subjects with BMI < 25 kg/m2. Genotyping of rs70991108 (DHFR) and rs1801133 (MTHFR) was performed using TaqMan probes. Serum folate concentrations were measured using an enzyme-linked immunosorbent assay and homocysteine was assessed with high performance liquid chromatography.

RESULTS

Subjects with overweight and obesity had 12% lower folate intake (p < 0.05) and 8.5% lower folate serum concentrations (p < 0.01) than the controls. Serum folate concentrations and folate intake were inversely associated with body fat percentage (p < 0.05) and waist circumference (p < 0.05 and p < 0.001, respectively). Serum folate concentration, though not folate intake, was negatively associated with WHR and BMI (p < 0.05, for both associations).

CONCLUSIONS

Lower folate intake and serum levels are weakly, but independently, associated with greater body weight and central adiposity in people aged 20-40. MTHFR and DHFR polymorphism seems not to have significant impact on body weight.