The A allele of cluster of differentiation 36 (CD36) SNP 1761667 associates with decreased lipid taste perception in obese Tunisian women. Br J Nutr. 2015;113:1330-1337. [PMID: 25822988 DOI: 10.1017/s0007114515000343]

Genotypic and Allelic Distribution of the CD36 rs1761667 Polymorphism in High-Level Moroccan Athletes: A Pilot Study

Previous studies have shown that variations in the CD36 gene may affect phenotypes associated with fat metabolism as the CD36 protein facilitates the transport of fatty acids to the mitochondria for oxidation. However, no previous study has tested whether variations in the CD36 gene are associated with sports performance. We investigated the genotypic and allelic distribution of the single-nucleotide polymorphism (SNP) rs1761667 in the CD36 gene in elite Moroccan athletes (cyclists and hockey players) in comparison with healthy non-athletes of the same ethnic origin. Forty-three Moroccan elite male athletes (nineteen cyclists and twenty-four field hockey players) belonging to the national teams of their respective sports (athlete group) were compared to twenty-eight healthy, active, male university students (control group). Genotyping of the CD36 rs1761667 (G>A) SNP was performed via polymerase chain reaction (PCR) and Sanger sequencing. A chi-square (χ2) test was used to assess the Hardy-Weinberg equilibrium (HWE) and to compare allele and genotype frequencies in the "athlete" and "control" groups. The genotypic distribution of the CD36 rs1761667 polymorphism was similar in elite athletes (AA: 23.81, AG: 59.52, and GG: 16.67%) and controls (AA: 19.23, AG: 69.23, and GG: 11.54%; χ2 = 0.67, p = 0.71). However, the genotypic distribution of the CD36 rs1761667 polymorphism was different between cyclists (AA: 0.00, AG: 72.22, and GG: 27.78%) and hockey players (AA: 41.67, AG: 50.00, and GG: 8.33%; χ2 = 10.69, p = 0.004). Specifically, the frequency of the AA genotype was significantly lower in cyclists than in hockey players (p = 0.02). In terms of allele frequency, a significant difference was found between cyclists versus field hockey players (χ2 = 7.72, p = 0.005). Additionally, there was a predominance of the recessive model in cyclists over field hockey players (OR: 0.00, 95% CI: 0.00-0.35, p = 0.002). Our study shows a significant difference between cyclists and field hockey players in terms of the genotypic and allelic frequency of the SNP rs1761667 of the CD36 gene. This divergence suggests a probable association between genetic variations in the CD36 gene and the type of sport in elite Moroccan athletes.

Genetic determinants of food preferences: a systematic review of observational studies

BACKGROUND

Over the last decade, the results of several studies have indicated that adults' food preferences, consumption, and dietary choices vary depending on their genotype characteristics. However, the results of studies related to genes and polymorphisms involved in this phenomenon are contradictory. This study is a systematic review designed to evaluate the genetic determinants of food preferences.

METHODS

This study was conducted following the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Searches were conducted to identify articles testing the impact of genotypes on food choices, preferences, and intake in healthy adults. The search included all relevant keywords, and studies published between 1/1/1994 and October 2022 were considered. We assessed the quality of included studies and evaluated the risk of bias using the Newcastle-Ottawa Scale (NOS) for observational studies.

RESULTS

A total of 8,510 records were identified through our search method, and finally, 50 studies were included in this study. The majority of the studies evaluated the association of genetic variants with preferences for macronutrients, sweet, bitter, and fatty foods. The results of our study suggest a significant correlation between TAS2R38 variants (rs713598, rs1726866, rs10246939) and bitter and sweet taste preferences. Additionally, we found a considerable association between the T102C polymorphism of the 5-HT2A receptor gene and a higher intake of protein, and rs1761667 (CD36) was associated with fat preference.

CONCLUSION

In conclusion, this study revealed a significant association between certain genetic variants and food preferences among adults.

[Genetic variants in CD36: emerging role in oral fat perception and food preferences]

Introduction

CD36 is a receptor involved in physiologic, metabolic and pathologic processes. Due to its affinity for long-chain fatty acids, it has been postulated as a taste receptor of fatty taste. In this review, the emerging genetic evidence linking CD36 to oral fat perception is analyzed. A systematic literature search was conducted in PubMed, published articles from 2000 to 2022 were considered. Multiple studies have shown an association of some genetic variants in CD36 with fat foods preferences and it has been suggested that these variants can modify oral fat perception thresholds however the evidence is still heterogeneous; this can be explained by the genetic diversity of populations, the nutritional status and participant's characteristics, as well as other methodological aspects. Other factors involved in oral fat perception were and identified and discussed including the interaction with other flavors, hormones, and epigenetic factors. The conclusion is that the evidence supporting the role of CD36 as a dietary lipid receptor, the role of its genetic variants in fat acids oral perception thresholds and food preferences is intermediate level and more investigations are necessary in other populations with large number of participants as well as considering the interaction between different hormones and the expression of CD36.

Genetic Variants in CD36 Involved in Fat Taste Perception: Association with Anthropometric and Clinical Parameters in Overweight and Obese Subjects Affected by Type 2 Diabetes or Dysglycemia-A Pilot Study

Obesity and overweight represent a growing health problem worldwide. Genes regulating the intake and metabolism of different nutrients can positively or negatively influence the efficacy of nutritional interventions against obesity and its complications. The aim of this study was to assess changes in anthropometric and clinical parameters and the adherence to a Mediterranean diet (MedDiet) over time in relation to nutrigenetic variants in overweight or obese subjects affected by Type 2 Diabetes (T2D) or dysglycemia, who were included in a nutritional program. A total of 23 subjects were included in this study. Clinical parameters, physical activity levels, and the adherence to a MedDiet were evaluated at baseline, at 6 (T6), and at 12 months (T12) during and after a diet/lifestyle intervention. In a single blood sample from each subject, rs1984112 (A>G) and rs1761667 (G>A) in CD36; rs7950226 (G>A) in BMAL1; and rs1801260 (A>G), rs4864548 (A>G), and rs3736544 (G>A) in CLOCK were genotyped with Real-Time PCR. Significant associations were observed between CD36 rs1761667 and weight (p = 0.025), hip circumference (p = 0.042), triglycerides (p = 0.047), and HbA1c (p = 0.012) at baseline. Moreover, the genotype AA in CD36 rs1761667 was significantly associated with a lower BMI when compared to G carriers at baseline, at T6, and also at T12. In addition, subjects with the AA genotype at CD36 rs1984112 had significantly lower levels of HbA1c (p = 0.027) than the GG and AG genotypes at baseline. These results show that variants in CD36 can have an impact on anthropometric and clinical parameters in overweight or obese subjects affected by T2D or dysglycemia, and that it might influence the success of the diet/lifestyle intervention.

Novel Fat Taste Receptor Agonists Curtail Progressive Weight Gain in Obese Male Mice

BACKGROUND & AIMS

The spontaneous preference for dietary lipids is principally regulated by 2 lingual fat taste receptors, CD36 and GPR120. Obese animals and most of human subjects exhibit low orosensory perception of dietary fat because of malfunctioning of these taste receptors. Our aim was to target the 2 fat taste receptors by newly synthesized high affinity fatty acid agonists to decrease fat-rich food intake and obesity.

METHODS

We synthesized 2 fat taste receptor agonists (FTA), NKS-3 (CD36 agonist) and NKS-5 (CD36 and GPR120 agonist). We determined their molecular dynamic interactions with fat taste receptors and the effect on Ca²⁺ signaling in mouse and human taste bud cells (TBC). In C57Bl/6 male mice, we assessed their gustatory perception and effects of their lingual application on activation of tongue-gut loop. We elucidated their effects on obesity and its related parameters in male mice fed a high-fat diet.

RESULTS

The two FTA, NKS-3 and NKS-5, triggered higher Ca²⁺ signaling than a dietary long-chain fatty acid in human and mouse TBC. Mice exhibited a gustatory attraction for these compounds. In conscious mice, the application of FTA onto the tongue papillae induced activation of tongue-gut loop, marked by the release of pancreato-bile juice into collecting duct and cholecystokinin and peptide YY into blood stream. Daily intake of NKS-3 or NKS-5 via feeding bottles decreased food intake and progressive weight gain in obese mice but not in control mice.

CONCLUSIONS

Our results show that targeting fat sensors in the tongue by novel chemical fat taste agonists might represent a new strategy to reduce obesity.

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.

Six genetically linked mutations in the CD36 gene significantly delay the onset of Alzheimer's disease

The risk of Alzheimer’s disease (AD) has a strong genetic component, also in the case of late-onset AD (LOAD). Attempts to sequence whole genome in large populations of subjects have identified only a few mutations common to most of the patients with AD. Targeting smaller well-characterized groups of subjects where specific genetic variations in selected genes could be related to precisely defined psychological traits typical of dementia is needed to better understand the heritability of AD. More than one thousand participants, categorized according to cognitive deficits, were assessed using 14 psychometric tests evaluating performance in five cognitive domains (attention/working memory, memory, language, executive functions, visuospatial functions). CD36 was selected as a gene previously shown to be implicated in the etiology of AD. A total of 174 polymorphisms were tested for associations with cognition-related traits and other AD-relevant data using the next generation sequencing. Several associations between single nucleotide polymorphisms (SNP’s) and the cognitive deficits have been found (rs12667404 with language performance, rs3211827 and rs41272372 with executive functions, rs137984792 with visuospatial performance). The most prominent association was found between a group of genotypes in six genetically linked and the age at which the AD patients presented with, or developed, a full-blown dementia. The identified alleles appear to be associated with a delay in the onset of LOAD. In silico studies suggested that the SNP’s alter the expression of CD36 thus potentially affecting CD36-related neuroinflammation and other molecular and cellular mechanisms known to be involved in the neuronal loss leading to AD. The main outcome of the study is an identification of a set of six new mutations apparently conferring a distinct protection against AD and delaying the onset by about 8 years. Additional mutations in CD36 associated with certain traits characteristic of the cognitive decline in AD have also been found.

Is fat taste associated with diet quality? A cross-sectional study conducted among Tunisian adults

The Tunisian population has experienced a nutrition transition with an increase in the incidence of obesity. As obesity has been associated with a poor orosensory detection of fat. We hypothesized that poor fat detection could be a driver of poor diet quality. This study examined the association between linoleic acid (LA) detection and adherence to a healthy diet among adult participants. A total of 104 LA taster participants were recruited for this study. Dietary assessment was conducted using the 24 h dietary recall method. Diet quality was assessed by determining the Mediterranean diet (MD) score and Health diet indicator (HDI). The relationship between diet quality and log LA detection threshold was done using adjusted linear regression for age, sex, and daily energy intake (only in the fully adjusted model). The predictive margins model (interaction: anthropometric status x LA threshold) was used to assess the difference between non-obese and subjects with obesity adherence to MD across LA detection values. We have observed that the increase in the concentration of linoleic acid detection by 1 log(mmol/L) is associated with an increase of HDI score by 0.12-point [95% CI: 0.02-0.21] and a decrease of the MD score by -0.14-point [-0.25 to -0.03] in the partially adjusted model. However, only the MD score remained negatively associated with LA detection threshold in the fully adjusted model. The subjects with obesity adherence to the Mediterranean diet was lower than subjects with normal weight for LA concentration less than 0 log(mmol/L). The present study suggests that poor orosensory detection of dietary lipids might be a driver for worsening diet quality. Hence, These subjects might be at risk for obesity and, consequently, exposed cumulatively to the harmful effects of excess adiposity and an unhealthy diet.

A systematic review and meta-analysis on the association between CD36 rs1761667 polymorphism and cardiometabolic risk factors in adults

The cluster of differentiation 36 (CD36) is one of the main receptors implicated in the pathogenesis of the cardiovascular disease. This study aimed to assess the association between CD36 rs1761667 polymorphism and cardiometabolic risk factors including body mass index (BMI), waist circumference (WC), total cholesterol (TC), triglyceride, HDL-C, LDL-C, blood pressure and fasting blood glucose (FBG). PubMed, EMBASE, Scopus, web of science, and Google Scholar were searched up to December 2021. Subgroup and meta-regression analyses were conducted to explore sources of heterogeneity. Eighteen eligible studies (6317 participants) were included in the study. In the overall analysis, a significant association was found between rs1761667 polymorphism of CD36 and TG in allelic (p < 0.001), recessive (p = 0.001) and homozygous (p = 0.006) models. A relationship between this polymorphism and HDL-C and FBG level was observed in the recessive genetic model. In the subgroup analysis, the A allele was associated with impaired lipid profiles (TC, LDL-C and HDL-C) in the Asian population. The influences of health status, design of the study, confounders, and other sources of heterogeneity should be considered when interpreting present findings. Cohort studies with large sample size and in different ethnicities are needed to confirm the relationship between rs1761667 SNP and cardiometabolic risk factors.

Cellular and Molecular Mechanisms of Fat Taste Perception

During the last couples of years, a number of studies have increasingly accumulated on the gustatory perception of dietary fatty acids in rodent models and human beings in health and disease. There is still a debate to coin a specific term for the gustatory perception of dietary fatty acids either as the sixth basic taste quality or as an alimentary taste. Indeed, the psycho-physical cues of orosensory detection of dietary lipids are not as distinctly perceived as other taste qualities like sweet or bitter. The cellular and molecular pharmacological mechanisms, triggered by the binding of dietary long-chain fatty acids (LCFAs) to tongue taste bud lipid receptors like CD36 and GPR120, involve Ca²⁺ signaling as other five basic taste qualities. We have not only elucidated the role of Ca²⁺ signaling but also identified different components of the second messenger cascade like STIM1 and MAP kinases, implicated in fat taste perception. We have also demonstrated the implication of Calhm1 voltage-gated channels and store-operated Ca²⁺ (SOC) channels like Orai1, Orai1/3, and TRPC3 in gustatory perception of dietary fatty acids. We have not only employed siRNA technology in vitro and ex vivo on tissues but also used animal models of genetic invalidation of STIM1, ERK1, Orai1, Calhm1 genes to explore their implications in fat taste signal transduction. Moreover, our laboratory has also demonstrated the importance of LCFAs detection dysfunction in obesity in animal models and human beings.

Obesity-induced taste dysfunction, and its implications for dietary intake

The incidence of obesity has dramatically increased in recent years, and poses a public health challenge for which an effective and scalable intervention strategy is yet to be found. Our food choices are one of the primary drivers of obesity, where the overconsumption of energy from foods high in fat and sugar can be particularly problematic. Unfortunately, these same foods also tend to be highly palatable. We select foods more on their sensory properties than on any other factor, such as price, convenience, or healthfulness. Previous evidence from human sensory studies has suggested a depressed sense of taste in panelists with obesity. Evidence from animal models also demonstrates a clear deficiency in taste buds occurring with obesity, suggesting that damage to the taste system may result from an obese state. In this review only taste, as opposed to smell, will be examined. Here we seek to bring together evidence from a diverse array of human and animal studies into taste response, dietary intake, and physiology, to better understand changes in taste with obesity, with the goal of understanding whether taste may provide a novel target for intervention in the treatment of obesity.

Genetic variation in CD36 is associated with dietary intake in Korean males

Fat is one of the six types of taste. Perceived taste intensity could affect the preference for a food and whether or not it is consumed. Cluster of differentiation 36 (CD36) translocates fatty acids on the cellular membrane and is involved in the oral fat-sensing mechanism. Therefore, genetic variation rs1761667 in CD36 is known to be associated with the perception of fat taste and, hence, its dietary intake. This study examined whether CD36 rs1527479 T>C, a proxy of rs1761667, is associated with fat intake and related dietary behaviour in Koreans. Using the data of the Ansan/Ansung Study, a part of the Korean Genome Epidemiology Study, the association of rs1527479 with the intake of macronutrients, including fat and selected foods, and fat-related dietary behaviours were investigated in 3194 males and 3425 females grouped by their degree of obesity. The findings suggested that rs1527479 did not have a meaningful effect on the intake of fat or other macronutrients or on the selection of food among non-obese females and males. However, in males with obesity, the genetic variation showed a significant association with vegetable intake. Obese males with the mutant CC genotype had substantially lower cruciferous vegetable consumption (adjusted P = 0·0015) than individuals with the TT and CT genotypes. Rs1527479 had no significant effect on the frequency of consuming fried foods or commonly used types of seasoning and cooking oils. In conclusion, CD36 genetic variation was associated with the intake of cruciferous vegetables but not fat intake in obese Korean males.

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.

Transection of Gustatory Nerves Differentially Affects Dietary Fat Intake in Obesity-Prone and Obesity-Resistant Rats

The current prevalence of obesity has been linked to the consumption of highly palatable foods and may be mediated by a dysregulated or hyposensitive orosensory perception of dietary fat, thereby contributing to the susceptibility to develop obesity. The goal of the current study was to investigate the role of lingual taste input in obesity-prone (OP, Osborne-Mendel) and obesity-resistant (OR, S5B/Pl) rats on the consumption of a high-fat diet (HFD). Density of fungiform papillae was assessed as a marker of general orosensory input. To determine if orosensory afferent input mediates dietary fat intake, surgical transection of the chorda tympani and glossopharyngeal nerves (GLX/CTX) was performed in OP and OR rats and HFD caloric intake and body weight were measured. Fungiform papillae density was lower in OP rats, compared with OR rats. GLX/CTX decreased orosensory input in both OP and OR rats, as measured by an increase in the intake of a bitter, quinine solution. Consumption of low-fat diet was not altered by GLX/CTX in OP and OR rats; however, GLX/CTX decreased HFD intake in OR, without altering HFD intake in OP rats. Overall, these data suggest that inhibition of orosensory input in OP rats do not decrease fat intake, thereby supporting that idea that hyposensitive and/or dysregulated orosensory perception of highly palatable foods contribute to the susceptibility to develop obesity.

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.

Single nucleotide polymorphism in CD36: Correlation to peptide YY levels in obese and non-obese adults

BACKGROUND & AIMS

Human beings are often driven to exhibit dietary preference according to their hedonic characteristics. Though previous studies proposed that the fat taste preference of an obese individual was associated with BMI, the perception of fat taste differs for every individual. The genetic variation among populations in taste receptor genes such as CD36 may be a contributing factor for this difference. Satiety peptides can also play a role in the regulation of fat taste perception. Generally, this hormone helps us to feel the sense of satiety.

METHODS

We have analysed the relationship among oro-gustatory perception of dietary lipids, salivary peptide-YY and genetic polymorphism in CD36. Oral fatty acid sensitivity analysis was performed by alternative forced choice method. Salivary peptide-YY concentration was analysed by ELISA and single nucleotide polymorphism (SNP) in CD36 gene was determined by Real-Time PCR experiments.

RESULTS

We observed that the SNP at rs1761667 of CD36 and oral detection threshold for linoleic acid (LA) are associated with choice of food, lipid profiles, peptide-YY as well as adiposity parameters in obese population. Obese peoples had significantly low levels of peptide YY than people with BMI less than 25. These factors possibly play a role in preference for energy rich diets, development of obesity and associated complications.

CONCLUSION

This study provides a solid foundation for understanding the alterations in the dietary fat intake and levels of peptide-YY, which are associated with polymorphism in fat taste receptor. This is the first report that shows a significant relationship between the satiety hormone level, SNP in CD36 gene and oral fat detection threshold in human subjects.

Changes of Taste, Smell and Eating Behavior in Patients Undergoing Bariatric Surgery: Associations with PROP Phenotypes and Polymorphisms in the Odorant-Binding Protein OBPIIa and CD36 Receptor Genes

Bariatric surgery is the most effective long-term treatment for severe obesity and related comorbidities. Although patients who underwent bariatric surgery report changes of taste and smell perception, results from sensory studies are discrepant and limited. Here, we assessed taste and smell functions in 51 patients before, one month, and six months after undergoing bariatric surgery. We used taste strip tests to assess gustatory function (including sweetness, saltiness, sourness, umaminess, bitterness and oleic acid, a fatty stimulus), the “Sniffin’ Sticks” test to assess olfactory identification and the 3-Factor Eating Questionnaire to assess eating behavior. We also explored associations between these phenotypes and flavor-related genes. Results showed an overall improvement in taste function (including increased sensitivity to oleic acid and the bitterness of 6-n-propylthiouracil (PROP)) and in olfactory function (which could be related to the increase in PROP and oleic acid sensitivity), an increase in cognitive restraint, and a decrease in disinhibition and hunger after bariatric surgery. These findings indicate that bariatric surgery can have a positive impact on olfactory and gustatory functions and eating behavior (with an important role of genetic factors, such PROP tasting), which in turn might contribute to the success of the intervention.

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

BACKGROUND

The determinants of the intake of high-fat products are not well understood.

OBJECTIVE

The aim of this study was to examine the relations between fat perception, intake of high-fat food, and body-weight status, taking into account the polymorphism of the genes that encode the proteins involved in oral fat perception.

METHODS

A total of 421 participants aged 20-40 y were enrolled in Poznań, Poland, from 2016 to 2018. An ascending forced-choice triangle procedure was applied to determine fat discrimination ability. Salad dressings with varying concentrations of canola oil were used as stimuli. Genotyping of rs1761667 (CD36) rs1573611 [free fatty acid receptor 1 (FFAR1)], rs17108973 [free fatty acid receptor 4 (FFAR4)], and rs2274333 (CA6) was performed using TaqMan probes. The frequency of consumption of high-fat foods was measured using an application for mobile devices that uses the ecological momentary assessment approach. The associations were analyzed using linear regression or logistic regression, as appropriate.

RESULTS

Individuals with the GG CD36 genotype were twice as likely to be fat discriminators, compared with the A allele carriers (P < 0.05). The mean total consumption of high-fat food was 45.8 (44.6, 47.0) times/wk and was not associated with fat discrimination or body-weight status. Obese and overweight subjects ate healthy high-fat food less frequently than did participants with normal body weight, at 4.53 (3.83, 5.23) versus 6.68 (5.82, 7.55) times/wk, respectively (P < 0.001). Men ate sweet high-fat food and snacks 15% less frequently than did women (P < 0.001 and P < 0.05) but consumed high-fat meat and fast food almost 40% more often than did women (P < 0.001 for both associations).

CONCLUSIONS

In individuals aged 20-40 y, fat discrimination ability is associated with polymorphism of CD36 but not with the choice of high-fat food. The frequency of consumption of different types of high-fat foods varies by sex and body-weight status.

Single-nucleotide polymorphism rs1761667 in the CD36 gene is associated with orosensory perception of a fatty acid in obese and normal-weight Moroccan subjects

Obese subjects have shown a preference for dietary lipids. A recent collection of evidence has proposed that a variant in the CD36 gene plays a significant role in this pathway. We assessed the association between the orosensory detection of a long-chain fatty acid, i.e. oleic acid (OA), and genetic polymorphism of the lipid taste sensor CD36 in obese and normal-weight subjects. Adult participants were recruited in the fasting condition. They were invited to fat taste perception sessions, using emulsions containing OA and according to the three-alternative forced-choice (3-AFC) method. Genomic DNA was used to determine the polymorphism (SNP rs 1761667) of the CD36 gene. Obese (n 50; BMI 34⋅97 (sd 4⋅02) kg/m²) exhibited a significantly higher oral detection threshold for OA (3⋅056 (sd 3⋅53) mmol/l) than did the normal-weight (n 50; BMI 22⋅16 (sd 1⋅81) kg/m²) participants (1⋅20 (sd 3⋅23) mmol/l; P = 0⋅007). There was a positive correlation between OA detection thresholds and BMI in all subjects; evenly with body fat percentage (BF%). AA genotype was more frequent in the obese group than normal-weight group. OA detection thresholds were much higher for AA and AG genotypes in obese subjects compared with normal-weight participants. Higher oral detection thresholds for fatty acid taste are related to BMI, BF% and not always to CD36 genotype.

CD36 and GPR120 Methylation Associates with Orosensory Detection Thresholds for Fat and Bitter in Algerian Young Obese Children

Background: The spontaneous preference for dietary fat is regulated by two lingual lipid sensors (CD36 and GPR120) in humans and rodents. Our objective was to investigate whether obesity in children is associated with methylation of lipid sensor genes, and whether this alteration was implicated in altered gustatory perception of fat and bitter and increased preference of palatable foods. Methods: School children were recruited and classified according to their body mass index (BMI) z-score into two groups: obese and lean children. The detection of orosensory perception for oleic acid and 6-n-propylthiouracil was assessed by using a 3-alternative forced-choice test. After blood DNA extraction, methylation patterns were investigated by methylation-specific PCR. The children were also subjected to a food habit questionnaire. Results: Obese children showed higher lipid and bitter detection thresholds than lean children. Besides, more obese children presented higher methylation level of the CpG sites than lean participants. Interestingly, CD36 and GPR120 gene methylation was associated with high lipid detection thresholds in obese participants. The obese participants preferred highly palatable fat-rich food items, associated with CD36 and GPR120 gene methylation. Conclusion: Epigenetic changes in CD36 and GPR120 genes might contribute to low orosensory perception of fat and bitter taste, and might be, consequently, critically involved in obesity in children

Studies of human twins reveal genetic variation that affects dietary fat perception

To learn more about the mechanisms of human dietary fat perception, 398 human twins rated fattiness and liking for six types of potato chips that differed in triglyceride content (2.5, 5, 10, and 15% corn oil); reliability estimates were obtained from a subset (n = 50) who did the task twice. Some chips also had a saturated long-chain fatty acid (hexadecanoic acid, 16:0) added (0.2%) to evaluate its effect on fattiness and liking. We computed the heritability of these measures and conducted a genome-wide association study (GWAS) to identify regions of the genome that co-segregate with fattiness and liking. Perceived fattiness and liking for the potato chips were reliable (r = 0.31-0.62, p < 0.05) and heritable (up to h2 = 0.29, p < 0.001, for liking). Adding hexadecanoic acid to the potato chips significantly increased ratings of fattiness but decreased liking. Twins with the G allele of rs263429 near GATA3-AS1 or the G allele of rs8103990 within ZNF729 reported more liking for potato chips than did twins with the other allele (multivariate GWAS, p < 1×10-5), with results reaching genome-wide suggestive but not significance criteria. Person-to-person variation in the perception and liking of dietary fat was (a) negatively affected by the addition of a saturated fatty acid and (b) related to inborn genetic variants. These data suggest liking for dietary fat is not due solely to fatty acid content and highlight new candidate genes and proteins within this sensory pathway.

CD36 gene polymorphism -31118 G > A (rs1761667) is associated with overweight and obesity but not with fat preferences in Mexican children

CD36 glycoprotein is a candidate receptor involved in the gustatory detection of lipids and emerging evidence has suggested that genetic variations in CD36 may modulate the oral perception threshold to fatty acids. Here, we analyzed the association of -31118 G > A polymorphism in CD36 gene with nutritional status and preferences for fatty foods in Mexican children. Genotyping of SNP rs1761667 was performed in school-age children (n = 63) in addition to sensory tests evaluating the preference and satisfaction score assigned to oil-based sauces of different fatty acid composition. The G allele was associated with high BMI z-score in children (OR = 2.43, 95% (CI 1.02-5.99); p = 0.02) but CD36 genotypes (AA, GA, and GG) did not show significant association with the preference and satisfaction scores assigned to oil-based sauces. The BMI z-score showed no association with the preference to oil-based sauces; however, children with normal weight gave higher satisfaction scores to sauces with a high content of unsaturated fatty acids than to sauces rich in saturated fatty acids (0.56 ± 1.26 vs. 0.06 ± 1.22; p = 0.02). Therefore, the G allele of -31118 G > A SNP in CD36 gene is associated with overweight and obesity in Mexican children but do not appear to modulate the preferences and satisfaction scores to fat.

Preference for dietary fat: From detection to disease

Recent advances in the field of taste physiology have clarified the role of different basic taste modalities and their implications in health and disease and proposed emphatically that there might be a distinct cue for oro-sensory detection of dietary long-chain fatty acids (LCFAs). Hence, fat taste can be categorized as a taste modality. During mastication, LCFAs activate tongue lipid sensors like CD36 and GPR120 triggering identical signaling pathways as the basic taste qualities do; however, the physico-chemical perception of fat is not as distinct as sweet or bitter or other taste sensations. The question arises whether "fat taste" is a basic or "alimentary" taste. There is compelling evidence that fat-rich dietary intervention modulates fat taste perception where an increase or a decrease in lipid contents in the diet results, respectively, in downregulation or upregulation of fat taste sensitivity. Evidently, a decrease in oro-sensory detection of LCFAs leads to high fat intake and, consequently, to obesity. In this article, we discuss recent relevant advances made in the field of fat taste physiology with regard to dietary fat preference and lipid sensors that can be the target of anti-obesity strategies.

A Fatty Acid Mouth Rinse Decreases Self-Reported Hunger and Increases Self-Reported Fullness in Healthy Australian Adults: A Randomized Cross-Over Trial

Fatty acid (FA) chemoreception in the oral cavity, known as fat taste, may trigger a satiety response that is homologous to FA chemoreception in the gastrointestinal tract. In addition, individuals with an impaired fat taste sensitivity are more likely to have an impaired satiety response. This study aimed to assess the effect of an FA mouth rinse on self-reported appetite, and to determine if the effect is modified by fat taste sensitivity. Thirty-one participants (age, 32.0 ± 8.4 y; body mass index (BMI), 26.1 ± 8.1 kg/m²) were studied on four separate days to evaluate the effect of a 20 mM oleic acid (OA) mouth rinse (in duplicate) compared to a control (in duplicate) on self-reported appetite by using a visual analogue scale (VAS) every 30 min for three hours following a standardized low-fat breakfast. The area under the curve ratings for fullness were greater (p = 0.003), and those for hunger were lower (p = 0.002) following the OA rinse compared to the control. The effect of the OA rinse was greater in individuals who were hypersensitive to fat taste compared to moderately sensitive and hyposensitive individuals for fullness (p < 0.010) and hunger (p < 0.010) ratings. In summary, an OA mouth rinse decreases self-reported hunger and increases self-reported fullness, particularly in those who are more sensitive to fat taste. FA receptors in the oral cavity may be potential targets to regulate appetite.

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.

Novel GPR120 agonist TUG891 modulates fat taste perception and preference and activates tongue-brain-gut axis in mice

GPR120 is implicated as a lipid receptor in the oro-sensory detection of dietary fatty acids. However, the effects of GPR120 activation on dietary fat intake or obesity are not clearly understood. We investigated to determine whether the binding of TUG891, a novel GPR120 agonist, to lingual GPR120 modulates fat preference in mice. We explored the effects of TUG891 on obesity-related hormones and conducted behavioral choice tests on mice to better understand the physiologic relevance of the action of TUG891. In cultured mouse and human taste bud cells (TBCs), TUG891 induced a rapid increase in Ca²⁺ by acting on GPR120. A long-chain dietary fatty acid, linoleic acid (LA), also recruited Ca²⁺ via GPR120 in human and mouse TBCs. Both TUG891 and LA induced ERK1/2 phosphorylation and enhanced in vitro release of glucagon-like peptide-1 from cultured human and mouse TBCs. In situ application of TUG891 onto the tongue of anesthetized mice triggered the secretion of pancreatobiliary juice, probably via the tongue-brain-gut axis. Furthermore, lingual application of TUG891 altered circulating concentrations of cholecystokinin and adipokines, associated with decreased circulating LDL, in conscious mice. In behavioral tests, mice exhibited a spontaneous preference for solutions containing either TUG891 or LA instead of a control. However, addition of TUG891 to a solution containing LA significantly curtailed fatty acid preference. Our study demonstrates that TUG891 binds to lingual GPR120 receptors, activates the tongue-brain-gut axis, and modulates fat preference. These findings may support the development of new fat taste analogs that can change the approach to obesity prevention and treatment.

Bile acid receptor TGR5 is critically involved in preference for dietary lipids and obesity

We investigated the implication of Takeda G protein-coupled receptor 5 (TGR5) in fat preference and fat sensing in taste bud cells (TBC) in C57BL/6 wild-type (WT) and TGR5 knock out (TGR5^-/^-) male mice maintained for 20 weeks on a high-fat diet (HFD). We also assessed the implication of TGR5 single nucleotide polymorphism (SNP) in young obese humans. The high-fat diet (HFD)-fed TGR5^-/^- mice were more obese, marked with higher liver weight, lipidemia and steatosis than WT obese mice. The TGR5^-/^- obese mice exhibited high daily food/energy intake, fat mass and inflammatory status. WT obese mice lost the preference for dietary fat, but the TGR5^-/^- obese mice exhibited no loss towards the attraction for lipids. In lingual TBC, the fatty acid-triggered Ca²⁺ signaling was decreased in WT obese mice; however, it was increased in TBC from TGR5^-/^- obese mice. Fatty acid-induced in vitro release of GLP-1 was higher, but PYY concentrations were lower, in TBC from TGR5^-/^- obese mice than those in WT obese mice. We noticed an association between obesity and variations in TGR5 rs11554825 SNP. Finally, we can state that TGR5 modulates fat eating behavior and obesity.

Fat Addiction: Psychological and Physiological Trajectory

Obesity has become a major public health concern worldwide due to its high social and economic burden, caused by its related comorbidities, impacting physical and mental health. Dietary fat is an important source of energy along with its rewarding and reinforcing properties. The nutritional recommendations for dietary fat vary from one country to another; however, the dietary reference intake (DRI) recommends not consuming more than 35% of total calories as fat. Food rich in fat is hyperpalatable, and is liable to be consumed in excess amounts. Food addiction as a concept has gained traction in recent years, as some aspects of addiction have been demonstrated for certain varieties of food. Fat addiction can be a diagnosable condition, which has similarities with the construct of addictive disorders, and is distinct from eating disorders or normal eating behaviors. Psychological vulnerabilities like attentional biases have been identified in individuals described to be having such addiction. Animal models have provided an opportunity to explore this concept in an experimental setting. This discussion sheds light on fat addiction, and explores its physiological and psychological implications. The discussion attempts to collate the emerging literature on addiction to fat rich diets as a prominent subset of food addiction. It aims at addressing the clinical relevance at the community level, the psychological correlates of such fat addiction, and the current physiological research directions.

Review: Chemosensing of nutrients and non-nutrients in the human and porcine gastrointestinal tract

The gastrointestinal tract (GIT) is an interface between the external and internal milieus that requires continuous monitoring for nutrients or pathogens and toxic chemicals. The study of the physiological/molecular mechanisms, mediating the responses to the monitoring of the GIT contents, has been referred to as chemosensory science. While most of the progress in this area of research has been obtained in laboratory rodents and humans, significant steps forward have also been reported in pigs. The objective of this review was to update the current knowledge on nutrient chemosensing in pigs in light of recent advances in humans and laboratory rodents. A second objective relates to informing the existence of nutrient sensors with their functionality, particularly linked to the gut peptides relevant to the onset/offset of appetite. Several cell types of the intestinal epithelium such as Paneth, goblet, tuft and enteroendocrine cells (EECs) contain subsets of chemosensory receptors also found on the tongue as part of the taste system. In particular, EECs show specific co-expression patterns between nutrient sensors and/or transceptors (transport proteins with sensing functions) and anorexigenic hormones such as cholecystokinin (CCK), peptide tyrosine tyrosine (PYY) or glucagon-like peptide-1 (GLP-1), amongst others. In addition, the administration of bitter compounds has an inhibitory effect on GIT motility and on appetite through GLP-1-, CCK-, ghrelin- and PYY-labelled EECs in the human small intestine and colon. Furthermore, the mammalian chemosensory system is the target of some bacterial metabolites. Recent studies on the human microbiome have discovered that commensal bacteria have developed strategies to stimulate chemosensory receptors and trigger host cellular functions. Finally, the study of gene polymorphisms related to nutrient sensors explains differences in food choices, food intake and appetite between individuals.

Cluster of differentiation 36 gene polymorphism (rs1761667) is associated with dietary MUFA intake and hypertension in a Japanese population

Cluster of differentiation 36 (CD36) is a membrane receptor expressed on a wide variety of human cells. CD36 polymorphisms are reportedly associated with oral fat perception, dietary intake and metabolic disorders. The present study examined associations of two CD36 polymorphisms (rs1761667 and rs1527483) and dietary fat intake, and metabolic phenotypes in a Japanese population. This cross-sectional study was conducted based on clinical information collected from health check-ups in Japan (n 495). Dietary nutrient intake was estimated from a validated short FFQ and adjusted for total energy intake using the residual method. Mean blood pressure was calculated from systolic blood pressure (SBP) and diastolic blood pressure (DBP). Hypertension was defined as SBP ≥ 130 mmHg and/or DBP ≥ 85 mmHg, or use of antihypertensive drugs. Genotyping was performed using PCR with confronting two-pair primers method. Mean age was 63·4 (sd 9·9) years. Individuals with the AA genotype showed higher total fat and MUFA intake (standardised β = 0·110 and 0·087, P = 0·01 and 0·05, respectively) compared with the GG and GA genotypes. For metabolic phenotypes, the AA genotype of rs1761667 had a lower blood pressure compared with the GG genotype (standardised β = -0·123, P = 0·02). Our results suggested that the AA genotype of rs1761667 in the CD36 gene was associated with higher intake of total fat and MUFA and lower risk of hypertension in a Japanese population.

Human Tongue Electrophysiological Response to Oleic Acid and Its Associations with PROP Taster Status and the CD36 Polymorphism (rs1761667)

The perception of fat varies among individuals and has also been associated with CD36 rs1761667 polymorphism and genetic ability to perceive oral marker 6-n-propylthiouracil (PROP). Nevertheless, data in the literature are controversial. We present direct measures for the activation of the peripheral taste system in response to oleic acid by electrophysiological recordings from the tongue of 35 volunteers classified for PROP taster status and genotyped for CD36. The waveform of biopotentials was analyzed and values of amplitude and rate of potential variation were measured. Oleic acid stimulations evoked positive monophasic potentials, which represent the summated voltage change consequent to the response of the stimulated taste cells. Bio-electrical measurements were fully consistent with the perceived intensity during stimulation, which was verbally reported by the volunteers. ANOVA revealed that the amplitude of signals was directly associated, mostly in the last part of the response, with the CD36 genotypes and PROP taster status (which was directly associated with the density of papillae). The rate of potential variation was associated only with CD36, primarily in the first part of the response. In conclusion, our results provide direct evidence of the relationship between fat perception and rs1761667 polymorphism of the CD36 gene and PROP phenotype.

CD36 - a plausible modifier of disease phenotype in familial adenomatous polyposis

Background

Familial adenomatous polyposis (FAP) is a well characterised genetic predisposition to early onset colorectal cancer (CRC) that is characterised by polyposis of the colon and rectum. Animal models have consistently suggested the role of modifier genes in determining disease phenotype, yet none have been substantiated in the human population. The mouse homologue of cluster of differentiation 36 (CD36) has been proposed as a modifier of disease in the MIN mouse model of FAP.

Methods

Three single nucleotide polymorphisms (SNPs); rs1049673, rs1761667 and rs1984112 in CD36, have been investigated in 275 FAP patients to determine if they were associated with age of polyposis or risk of developing disease.

Results

The results revealed a substantially lower age of polyposis diagnosis for patients belonging to the severe FAP group (harbouring adenomatous polyposis coli (APC) variants in the mutation cluster region (MCR)) and high age for patients in the attenuated familial adenomatous polyposis (AFAP) group for SNPs rs1761667 and rs1984112.

Conclusions

This study provides evidence for patients belonging to the MCR and AFAP groups harbouring specific genotypes for SNPs in CD36 to initiate screening/treatment for FAP at much earlier (MCR) and much later (AFAP) ages than the norm in today’s clinical practice. The findings need to be verified in an independent FAP patient cohort.

Oleanolic acid improves diet-induced obesity by modulating fat preference and inflammation in mice

Obesity, triggered by high-fat diet (HFD), is associated to altered gustatory perception of dietary lipids. Oleanolic acid (OLA), a triterpene, has been reported to exert anti-obesity effects in animal models. Hence, we investigated the role of OLA in the modulation of oro-sensory perception of lipids in control and HFD-induced obese mice. As expected, OLA-treated obese mice exhibited a decrease in body, liver, and visceral adipose tissue weights. OLA treatment improved glucose tolerance, insulin level, plasma lipopolysaccharide (LPS), and hepatic cholesterol and triglyceride concentrations. OLA-treated obese mice exhibited higher fat preference compared to untreated obese mice, probably due to the increase in mRNA encoding CD36, a fat taste receptor, in mouse taste bud cells (mTBC). This phenomenon was associated with fatty-acid induced increases in free intracellular calcium concentrations, [Ca²⁺]i, induced in mTBC from OLA-treated obese mice. OLA also influenced the expression of mRNA encoding pro-inflammatory cytokines (IL-1β and IL-6) and some lipogenic genes (PPARα, SREBP1, FAS, ChREBP, and G6Pase) in liver and adipose tissue. These findings reveal that OLA improves gustatory perception of lipids and exerts protective effects in obesity.

Expression of the candidate fat taste receptors in human fungiform papillae and the association with fat taste function

Significant experimental evidence supports fat as a taste modality; however, the associated peripheral mechanisms are not well established. Several candidate taste receptors have been identified, but their expression pattern and potential functions in human fungiform papillae remain unknown. The aim of this study is to identify the fat taste candidate receptors and ion channels that were expressed in human fungiform taste buds and their association with oral sensory of fatty acids. For the expression analysis, quantitative RT-PCR (qRT-PCR) from RNA extracted from human fungiform papillae samples was used to determine the expression of candidate fatty acid receptors and ion channels. Western blotting analysis was used to confirm the presence of the proteins in fungiform papillae. Immunohistochemistry analysis was used to localise the expressed receptors or ion channels in the taste buds of fungiform papillae. The correlation study was analysed between the expression level of the expressed fat taste receptors or ion channels indicated by qRT-PCR and fat taste threshold, liking of fatty food and fat intake. As a result, qRT-PCR and western blotting indicated that mRNA and protein of CD36, FFAR4, FFAR2, GPR84 and delayed rectifying K+ channels are expressed in human fungiform taste buds. The expression level of CD36 was associated with the liking difference score (R −0·567, β=−0·04, P=0·04) between high-fat and low-fat food and FFAR2 was associated with total fat intake (ρ=−0·535, β=−0·01, P=0·003) and saturated fat intake (ρ=−0·641, β=−0·02, P=0·008).

Effects of CD36 Genotype on Oral Perception of Oleic Acid Supplemented Safflower Oil Emulsions in Two Ethnic Groups: A Preliminary Study

Previous studies demonstrate humans can detect fatty acids via specialized sensors on the tongue, such as the CD36 receptor. Genetic variation at the common single nucleotide polymorphism rs1761667 of CD36 has been shown to differentially impact the perception of fatty acids, but comparative data among different ethnic groups are lacking. In a small cohort of Caucasian and East Asian young adults, we investigated if: (1) participants could detect oleic acid (C18:1) added to safflower oil emulsions at a constant ratio of 3% (w/v); (2) supplementation of oleic acid to safflower oil emulsions enhanced perception of fattiness and creaminess; and (3) variation at rs1761667 influenced oleic acid detection and fat taste perception. In a 3-alternate forced choice test, 62% of participants detected 2.9 ± 0.7 mM oleic acid (or 0.08% w/v) in a 2.8% safflower oil emulsion. Supplementation of oleic acid did not enhance fattiness and creaminess perception for the cohort as a whole, though East Asians carrying the GG genotype perceived more overall fattiness and creaminess than their AA genotype counterparts (P < 0.001). No differences were observed for the Caucasians. These preliminary findings indicate that free oleic acid can be detected in an oil-in-water emulsion at concentrations found in commercial oils, but it does not increase fattiness or creaminess perception. Additionally, variation at rs1761667 may have ethnic-specific effects on fat taste perception.

The rs1527483, but not rs3212018, CD36 polymorphism associates with linoleic acid detection and obesity in Czech young adults

Recent evidence has raised the possibility of the existence of a sixth taste modality – that is, taste for fat – which is mediated by lingual CD36 and plays a role in obesity. Consequently, the genetic polymorphism of CD36 has been shown to be associated with altered oro-sensory detection of dietary lipids. In the present study, we investigated the relationship between oro-sensory perception of linoleic acid (LA), two CD36 polymorphisms (rs1527483 and rs3212018), obesity parameters and craving habits for dietary lipids in young Czech adults. We also sequenced 5 and 6 exons of CD36 to trace out any new mutation that might be responsible for the difference in taste perception. We observed that craving for dietary lipids was correlated with anthropometric parameters (P<0·05) and LA detection threshold (P=0·033). The participants with the CC genotype of the rs1527483 polymorphism had lower BMI (P=0·011), waist circumference (P=0·005), waist:height ratio (P=0·010) and higher sensitivity for LA (P=0·037) than the participants with the CT and TT genotypes. Interestingly, we did not observe any association between the rs3212018 polymorphism and the studied parameters. Moreover, we did not observe any mutation in exons 5 and 6 of the CD36 gene in these subjects. Finally, we can state that rs1527483, but not rs3212018, is associated with high body weight in young Czech subjects.

Orosensory detection of bitter in fat-taster healthy and obese participants: Genetic polymorphism of CD36 and TAS2R38

BACKGROUND & AIMS

We assessed orosensory detection of a long-chain fatty acid, linoleic acid (LA), and a bitter taste marker, 6-n-propylthiouracil (PROP), and correlated lipid-taster subjects with PROP detection and polymorphism in genes encoding bitter and lipid taste receptors, respectively, TAS2R38 and CD36, in normal weight and obese subjects.

DESIGN

The normal weight (n = 52, age = 35.3 ± 4.10 years, BMI = 23.22 ± 1.44 kg/m²) and obese (n = 52, age = 35.0 ± 5.43 years, BMI = 34.29 ± 5.31 kg/m²) participants were recruited to determine fat and bitter detection thresholds. The genomic DNA was used to determine single nucleotide polymorphism (SNP) of CD36 (rs1761667) and TAS2R38 (rs1726866 and rs10246939).

RESULTS

The study included the participants who could detect LA, i.e., lipid-tasters. There was a positive correlation between BMI and detection thresholds for fat and bitter taste in normal weight and obese subjects. Obese participants showed a positive correlation between LA and PROP detection thresholds. PROP detection thresholds were higher for CD36 SNP (rs1761667) and TAS2R38 SNPs (rs1726866 and rs10246939) in obese participants compared to normal weight subjects. LA detection thresholds were not high for CD36 SNP (rs1761667) or TAS2R38 SNP (rs1726866 and rs10246939) in obese participants.

CONCLUSIONS

Orosensory detection thresholds for fat and bitter taste are associated with BMI, and CD36 and TAS2R38 genotypes are not always associated with taste phenotypes.

Genetics of fat intake in the determination of body mass

Body mass and fat intake are multifactorial traits that have genetic and environmental components. The gene with the greatest effect on body mass is FTO (fat mass and obesity-associated), but several studies have shown that the effect of FTO (and of other genes) on body mass can be modified by the intake of nutrients. The so-called gene–environment interactions may also be important for the effectiveness of weight-loss strategies. Food choices, and thus fat intake, depend to some extent on individual preferences. The most important biological component of food preference is taste, and the role of fat sensitivity in fat intake has recently been pointed out. Relatively few studies have analysed the genetic components of fat intake or fatty acid sensitivity in terms of their relation to obesity. It has been proposed that decreased oral fatty acid sensitivity leads to increased fat intake and thus increased body mass. One of the genes that affect fatty acid sensitivity is CD36 (cluster of differentiation 36). However, little is known so far about the genetic component of fat sensing. We performed a literature review to identify the state of knowledge regarding the genetics of fat intake and its relation to body-mass determination, and to identify the priorities for further investigations.

Lingual CD36 and nutritional status differentially regulate fat preference in obesity-prone and obesity-resistant rats

Lingual fatty acid receptors (i.e. CD36) mediate the orosensory perception of fat/fatty acids and may contribute to the susceptibility to develop obesity. The current study tested the hypothesis that fat/fatty acid preference in obesity-prone (OP, Osborne-Mendel) and obesity-resistant (OR, S5B/Pl) rats is mediated by nutritional status and lingual CD36. To determine if nutritional status affected linoleic acid (LA) preference in OP and OR rats, rats were either fasted overnight or fed a high fat diet (60% kcal from fat). In OR rats, fasting increased the preference for higher concentrations of LA (1.0%), while consumption of a high fat diet decreased LA preference. In OP rats, fasting increased the preference for lower concentrations of LA (0.25%), however high fat diet consumption did not alter LA preference. To determine if lingual CD36 mediated the effects of an overnight fast on LA preference, the expression of lingual CD36 mRNA was assessed and the effect of lingual application of CD36 siRNA on LA preference was determined. Fasting increased lingual CD36 mRNA expression in OR rats, but failed to alter lingual CD36 mRNA in OP rats. Following an overnight fast, application of lingual CD36 siRNA led to a decrease in LA preference in OR, but not OP rats. Lingual application of CD36 siRNA was also used to determine if lingual CD36 mediated the intake and preference for a high fat diet in OP and OR rats. CD36 siRNA decreased the preference and intake of high fat diet in OR rats, but not OP rats. The results from this study suggest that the dysregulation of lingual CD36 in OP rats is a potential factor leading to increased fat intake and fat preference and an enhanced susceptibility to develop obesity.

Appetite control by the tongue-gut axis and evaluation of the role of CD36/SR-B2

Understanding the mechanisms governing food intake is a public health issue given the dramatic rise of obesity over the world. The overconsumption of tasty energy-dense foods rich in lipids is considered to be one of the nutritional causes of this epidemic. Over the last decade, the identification of fatty acid receptors in strategic places in the body (i.e. oro-intestinal tract and brain) has provided a major progress in the deciphering of regulatory networks involved in the control of dietary intake. Among these lipid sensors, CD36/SR-B2 appears to play a significant role since this membrane protein, known to bind long-chain fatty acid with a high affinity, was specifically found both in enterocytes and in a subset of taste bud cells and entero-endocrine cells. After a short overview on CD36/SR-B2 structure, function and regulation, this mini-review proposes to analyze the key findings about the role of CD36/SR-B2 along of the tongue-gut axis in relation to appetite control. In addition, we discuss whether obesogenic diets might impair lipid sensing mediated by CD36/SR-B2 along this axis.

CD36 gene polymorphism is associated with Alzheimer's disease

CD36 gene encodes a membrane glycoprotein (type B scavenger receptor) present on the surface of many types of cells and having multiple cellular functions ranging from angiogenesis to gustatory perception of fatty acids. Using a case control genetic association approach we have analyzed selected single nucleotide polymorphisms (SNP's) in a total of 859 patients with Alzheimer's disease (AD) and controls and have identified the allele A in rs3211892 polymorphism of CD36 gene as significantly increasing the risk of AD. Additionally we have investigated, in the same sample of control subjects and patients, SNP's in ApoE gene and confirmed that the previously identified AD-associated SNP's indeed increased the risk and decreased the age of onset of AD as reported by others earlier. Based on the current knowledge of CD36 biochemistry we propose that the AD risk-imparting variants of CD36 alter cholesterol homeostasis, oxidation stress or induce pathological inflammatory cascades. The SNP rs3211892 has previously been associated with heart disease and other conditions but the present study is the first to identify a significant association between variations in CD36 gene and the risk of Alzheimer's disease.