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1.
Intragastric administration of the bitter tastant quinine lowers the glycemic response to a nutrient drink without slowing gastric emptying in healthy men.
Bitarafan, V, Fitzgerald, PCE, Little, TJ, Meyerhof, W, Jones, KL, Wu, T, Horowitz, M, Feinle-Bisset, C
American journal of physiology. Regulatory, integrative and comparative physiology. 2020;(2):R263-R273
Abstract
The rate of gastric emptying and the release of gastrointestinal (GI) hormones are major determinants of postprandial blood-glucose concentrations and energy intake. Preclinical studies suggest that activation of GI bitter-taste receptors potently stimulates GI hormones, including glucagon-like peptide-1 (GLP-1), and thus may reduce postprandial glucose and energy intake. We evaluated the effects of intragastric quinine on the glycemic response to, and the gastric emptying of, a mixed-nutrient drink and the effects on subsequent energy intake in healthy men. The study consisted of 2 parts: part A included 15 lean men, and part B included 12 lean men (aged 26 ± 2 yr). In each part, participants received, on 3 separate occasions, in double-blind, randomized fashion, intragastric quinine (275 or 600 mg) or control, 30 min before a mixed-nutrient drink (part A) or before a buffet meal (part B). In part A, plasma glucose, insulin, glucagon, and GLP-1 concentrations were measured at baseline, after quinine alone, and for 2 h following the drink. Gastric emptying of the drink was also measured. In part B, energy intake at the buffet meal was quantified. Quinine in 600 mg (Q600) and 275 mg (Q275) doses alone stimulated insulin modestly (P < 0.05). After the drink, Q600 and Q275 reduced plasma glucose and stimulated insulin (P < 0.05), Q275 stimulated GLP-1 (P < 0.05), and Q600 tended to stimulate GLP-1 (P = 0.066) and glucagon (P = 0.073) compared with control. Quinine did not affect gastric emptying of the drink or energy intake. In conclusion, in healthy men, intragastric quinine reduces postprandial blood glucose and stimulates insulin and GLP-1 but does not slow gastric emptying or reduce energy intake under our experimental conditions.
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2.
The texture and taste of food in the brain.
Rolls, ET
Journal of texture studies. 2020;(1):23-44
Abstract
Oral texture is represented in the brain areas that represent taste, including the primary taste cortex, the orbitofrontal cortex, and the amygdala. Some neurons represent viscosity, and their responses correlate with the subjective thickness of a food. Other neurons represent fat in the mouth, and represent it by its texture not by its chemical composition, in that they also respond to paraffin oil and silicone in the mouth. The discovery has been made that these fat-responsive neurons encode the coefficient of sliding friction and not viscosity, and this opens the way for the development of new foods with the pleasant mouth feel of fat and with health-promoting designed nutritional properties. A few other neurons respond to free fatty acids (such as linoleic acid), do not respond to fat in the mouth, and may contribute to some "off" tastes in the mouth. Some other neurons code for astringency. Others neurons respond to other aspects of texture such as the crisp fresh texture of a slice of apple versus the same apple after blending. Different neurons respond to different combinations of these texture properties, oral temperature, taste, and in the orbitofrontal cortex to olfactory and visual properties of food. In the orbitofrontal cortex, the pleasantness and reward value of the food is represented, but the primary taste cortex represents taste and texture independently of value. These discoveries were made in macaques that have similar cortical brain areas for taste and texture processing as humans, and complementary human functional neuroimaging studies are described.
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3.
Effect of Physical Exercise on Taste Perceptions: A Systematic Review.
Gauthier, AC, Guimarães, RF, Namiranian, K, Drapeau, V, Mathieu, ME
Nutrients. 2020;(9)
Abstract
The effect of physical exercise on nutrition has gained substantial interest in the last decade. Meaningful results have been produced concerning the effect of physical exercise on different appetite hormones and food choice/preference. While it is well known that taste and nutrition are related, the relation between taste and physical activity has not yet been fully explored. This systematic review aims to provide a detailed view of the literature on physical exercise and its effect on taste perceptions. Five tastes were included in this review: sweet, salty, bitter, sour, and umami. Sweet taste intensity, sensitivity, and preference were increased by acute physical exercise, but sweet preference was reduced by chronic physical activity. Perceived intensity and sensitivity decreased overall for salty taste, but an increased preference was noted during/following exercise. Sour taste intensity ratings were decreased following exercise and preference was enhanced. Umami taste intensity and sensitivity increased following exercise and preference was decreased. No significant results were obtained for bitter taste. While evidence regarding the effect of exercise on taste has arisen from this review, the pre-testing nutrition, testing conditions, type of test, and exercise modality must be standardized in order to produce meaningful and reproducible results in the future.
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4.
Oral Microbiota Profile Associates with Sugar Intake and Taste Preference Genes.
Esberg, A, Haworth, S, Hasslöf, P, Lif Holgerson, P, Johansson, I
Nutrients. 2020;(3)
Abstract
Oral microbiota ecology is influenced by environmental and host conditions, but few studies have evaluated associations between untargeted measures of the entire oral microbiome and potentially relevant environmental and host factors. This study aimed to identify salivary microbiota cluster groups using hierarchical cluster analyses (Wards method) based on 16S rRNA gene amplicon sequencing, and identify lifestyle and host factors which were associated with these groups. Group members (n = 175) were distinctly separated by microbiota profiles and differed in reported sucrose intake and allelic variation in the taste-preference-associated genes TAS1R1 (rs731024) and GNAT3 (rs2074673). Groups with higher sucrose intake were either characterized by a wide panel of species or phylotypes with fewer aciduric species, or by a narrower profile that included documented aciduric- and caries-associated species. The inferred functional profiles of the latter type were dominated by metabolic pathways associated with the carbohydrate metabolism with enrichment of glycosidase functions. In conclusion, this study supported in vivo associations between sugar intake and oral microbiota ecology, but it also found evidence for a variable microbiota response to sugar, highlighting the importance of modifying host factors and microbes beyond the commonly targeted acidogenic and acid-tolerant species. The results should be confirmed under controlled settings with comprehensive phenotypic and genotypic data.
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5.
Rational design of agonists for bitter taste receptor TAS2R14: from modeling to bench and back.
Di Pizio, A, Waterloo, LAW, Brox, R, Löber, S, Weikert, D, Behrens, M, Gmeiner, P, Niv, MY
Cellular and molecular life sciences : CMLS. 2020;(3):531-542
Abstract
Human bitter taste receptors (TAS2Rs) are a subfamily of 25 G protein-coupled receptors that mediate bitter taste perception. TAS2R14 is the most broadly tuned bitter taste receptor, recognizing a range of chemically diverse agonists with micromolar-range potency. The receptor is expressed in several extra-oral tissues and is suggested to have physiological roles related to innate immune responses, male fertility, and cancer. Higher potency ligands are needed to investigate TAS2R14 function and to modulate it for future clinical applications. Here, a structure-based modeling approach is described for the design of TAS2R14 agonists beginning from flufenamic acid, an approved non-steroidal anti-inflammatory analgesic that activates TAS2R14 at sub-micromolar concentrations. Structure-based molecular modeling was integrated with experimental data to design new TAS2R14 agonists. Subsequent chemical synthesis and in vitro profiling resulted in new TAS2R14 agonists with improved potency compared to the lead. The integrated approach provides a validated and refined structural model of ligand-TAS2R14 interactions and a general framework for structure-based discovery in the absence of closely related experimental structures.
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6.
Relationship between sensory liking for fat, sweet or salt and cardiometabolic diseases: mediating effects of diet and weight status.
Lampuré, A, Adriouch, S, Castetbon, K, Deglaire, A, Schlich, P, Péneau, S, Fezeu, L, Hercberg, S, Méjean, C
European journal of nutrition. 2020;(1):249-261
Abstract
PURPOSE Previous works have been suggested that individual sensory liking is a predictor of dietary intake and weight status, and may consequently influence development of cardiometabolic diseases (CMDs). We investigated the association between sensory liking for fat-and-salt, fat-and-sweet, sweet or salt and the onset of hypertension, diabetes and cardiovascular diseases (CVDs) over 6 years in adults, and the mediating effects of dietary intake and body mass index (BMI). METHODS We examined the CMDs risk among 41,332 (for CVD and diabetes) and 37,936 (for hypertension) French adults (NutriNet-Santé cohort). Liking scores, individual characteristics, diet and anthropometry were assessed at baseline using questionnaires. Health events were collected during 6 years. Associations between sensory liking and CMDs risk, and the mediating effect of diet and BMI, were assessed using Cox proportional hazards models. RESULTS Sensory liking for fat-and-salt was associated with an increased risk of diabetes, hypertension and CVD [hazard ratios (HR) for 1-point increment of the sensory score: HR 1.30 (95% CI 1.18, 1.43), HR 1.08 (1.04, 1.13) and HR 1.10 (1.02, 1.19), respectively]. BMI and dietary intake both explained 93%, 98% and 70%, of the overall variation of liking for fat-and-salt liking in diabetes, hypertension and CVD, respectively. Liking for fat-and-sweet and liking for salt were also associated with an increased risk of diabetes [HR 1.09 (1.01, 1.17) and HR 1.09 (1.01, 1.18), respectively], whereas liking for sweet was associated with a decreased risk [HR 0.76 (0.69, 0.84)]. CONCLUSIONS Higher liking for fat-and-salt is significantly associated with CMDs risk, largely explained by dietary intake and BMI. Our findings may help to guide effective targeted measures in prevention.
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7.
Impact of Taste on Food Choices in Adolescence-Systematic Review and Meta-Analysis.
Bawajeeh, AO, Albar, SA, Zhang, H, Zulyniak, MA, Evans, CEL, Cade, JE
Nutrients. 2020;(7)
Abstract
Studies of adults report that perceived taste affects food choices and intake, which in turn may have an impact on health. However, corresponding evidence on adolescents is limited. Our aim was to summarize current evidence of the impact of taste perception on food choice preferences or dietary intakes among adolescents (mean age 10-19.9 years). Systematic searches identified 13 papers, 12 cross-sectional and one cohort study published between 1 January 2000 to 20 February 2020 assessing the impact of taste (using phenotypic and/or genotypic markers) on food choices in adolescents without any disease conditions. Qualitative assessment in the current review indicated that individuals sensitive to bitter tastes often have a lower preference of bitter-tasting food and higher preference for sweet-tasting food. A meta-analysis of three studies on bitter-taste sensitivity revealed no difference in preference for bitter-tasting vegetables between bitter tasters and non-tasters (standardized mean difference (SMD) = 0.04; 95% CI: -0.18, 0.26; p = 0.72). Overall, a limited number of studies were available for review. As a result, we report no clear relationship between taste perception and food choices or intake in adolescents. More studies are needed to evaluate the link between adolescents' taste perceptions and dietary intake.
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8.
Neuroimaging of smell and taste.
Olofsson, JK, Freiherr, J
Handbook of clinical neurology. 2019;:263-282
Abstract
The senses of taste and smell developed early in evolution and are of high ecological and clinical relevance in humans. Chemosensory systems function, in large part, as hazard avoidance systems, thereby ensuring survival. Moreover, they play a critical role in nutrition and in determining the flavor of foods and beverages. Their dysfunction has been shown to be a key element of early stages of a number of diseases, including Alzheimer's and Parkinson's diseases. Advanced neuroimaging methods provide a unique means for understanding, in vivo, neural and psychological processing of smell, taste, and flavor, and how diseases can impact such processing. This chapter provides, from a neuroimaging perspective, a comprehensive overview of the anatomy and physiology involved in the odor and taste processing in the central nervous system. Some methodological challenges associated with chemosensory neuroimaging research are discussed. Multisensory integration, the mechanisms that enable holistic sensory experiences, is emphasized.
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9.
Presence of carbohydrate binding modules in extracellular region of class C G-protein coupled receptors (C GPCR): An in silico investigation on sweet taste receptor.
Kashani-Amin, E, Sakhteman, A, Larijani, B, Ebrahim-Habibi, A
Journal of biosciences. 2019;(6)
Abstract
Sweet taste receptor (STR) is a C GPCR family member and a suggested drug target for metabolic disorders such as diabetes. Detailed characteristics of the molecule as well as its ligand interactions mode are yet considerably unclear due to experimental study limitations of transmembrane proteins. An in silico study was designed to find the putative carbohydrate binding sites on STR. To this end, α-D-glucose and its α-1,4-oligomers (degree of polymerization up to 14) were chosen as probes and docked into an ensemble of different conformations of the extracellular region of STR monomers (T1R2 and T1R3), using AutoDock Vina. Ensembles had been sampled from an MD simulation experiment. Best poses were further energy-minimized in the presence of water molecules with Amber14 forcefield. For each monomer, four distinct binding regions consisting of one or two binding pockets could be distinguished. These regions were further investigated with regard to hydrophobicity and hydrophilicity of the residues, as well as residue compositions and non-covalent interactions with ligands. Popular binding regions showed similar characteristics to carbohydrate binding modules (CBM). Observation of several conserved or semi-conserved residues in these binding regions suggests a possibility to extrapolate the results to other C GPCR family members. In conclusion, presence of CBM in STR and, by extrapolation, in other C GPCR family members is suggested, similar to previously proposed sites in gut fungal C GPCRs, through transcriptome analyses. STR modes of interaction with carbohydrates are also discussed and characteristics of non-covalent interactions in C GPCR family are highlighted.
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10.
Toxic exposures and the senses of taste and smell.
Genter, MB, Doty, RL
Handbook of clinical neurology. 2019;:389-408
Abstract
This review addresses the adverse influences of neurotoxic exposures on the ability to smell and taste. These chemical senses largely determine the flavor of foods and beverages, impact food intake, and ultimately nutrition, and provide a warning for spoiled or poisonous food, leaking natural gas, smoke, airborne pollutants, and other hazards. Hence, toxicants that damage these senses have a significant impact on everyday function. As noted in detail, a large number of toxicants encountered in urban and industrial air pollution, including smoke, solvents, metals, and particulate matter can alter the ability to smell. Their influence on taste, i.e., sweet, sour, bitter, salty, and savory (umami) sensations, is not well documented. Given the rather direct exposure of olfactory receptors to the outside environment, olfaction is particularly vulnerable to damage from toxicants. Some toxicants, such as nanoparticles, have the potential to damage not only the olfactory receptor cells, but also the central nervous system structures by their entrance into the brain through the olfactory mucosa.