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Journal ArticleDOI

Obese women have lower monosodium glutamate taste sensitivity and prefer higher concentrations than do normal-weight women.

01 May 2010-Obesity (NIH Public Access)-Vol. 18, Iss: 5, pp 959-965
TL;DR: Surprisingly, it was found that, relative to discriminators, nondiscriminators perceived less savoriness when tasting suprathreshold MSG concentrations and less sweetness from suPRathreshold sucrose concentrations but had similar MSG and sucrose detection thresholds.
Abstract: The goal of this study was to determine whether obese women exhibit altered umami and sweet taste perception compared to normal-weight women. A total of 57 subjects (23 obese and 34 normal weight) participated in a 2-day study separated by 1 week. Half of the women in each group were evaluated using monosodium glutamate (MSG; prototypical umami stimulus) on the first test day and sucrose on the second test day; the order was reversed for the remaining women. We used two-alternative forced-choice staircase procedures to measure taste detection thresholds, forced-choice tracking technique to measure preferences, the general Labeled Magnitude Scale (gLMS) to measure perceived intensity of suprathreshold concentrations, and a triangle test to measure discrimination between 29 mmol/l MSG and 29 mmol/l NaCl. Obese women required higher MSG concentrations to detect a taste and preferred significantly higher MSG concentrations in a soup-like vehicle. However, their perception of MSG at suprathreshold concentrations, their ability to discriminate MSG from salt, and their preference for sucrose were similar to that observed in normal-weight women. Regardless of their body weight category, 28% of the women did not discriminate 29 mmol/l MSG from 29 mmol/l NaCl (nondiscriminators). Surprisingly, we found that, relative to discriminators, nondiscriminators perceived less savoriness when tasting suprathreshold MSG concentrations and less sweetness from suprathreshold sucrose concentrations but had similar MSG and sucrose detection thresholds. Taken together, these data suggest that body weight is related to some components of umami taste and that different mechanisms are involved in the perception of threshold and suprathreshold MSG concentrations.
Citations
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Journal ArticleDOI
TL;DR: The view that CD36 and FA signaling coordinate fat utilization is presented, a view that is based on newly identified CD36 actions that involve oral fat perception, intestinal fat absorption, secretion of the peptides cholecystokinin and secretin, regulation of hepatic lipoprotein output, activation of beta oxidation by muscle, and regulation of the production of the FA-derived bioactive eicosanoids.
Abstract: CD36 (cluster of differentiation 36) is a scavenger receptor that functions in high-affinity tissue uptake of long-chain fatty acids (FAs) and contributes under excessive fat supply to lipid accumulation and metabolic dysfunction. This review describes recent evidence regarding the CD36 FA binding site and a potential mechanism for FA transfer. It also presents the view that CD36 and FA signaling coordinate fat utilization, a view that is based on newly identified CD36 actions that involve oral fat perception, intestinal fat absorption, secretion of the peptides cholecystokinin and secretin, regulation of hepatic lipoprotein output, activation of beta oxidation by muscle, and regulation of the production of the FA-derived bioactive eicosanoids. Thus abnormalities of fat metabolism and the associated pathology might involve dysfunction of CD36-mediated signal transduction in addition to the changes in FA uptake.

394 citations


Cites background from "Obese women have lower monosodium g..."

  • ...For example, earlier findings suggested that different pathways might be potentially involved in perceiving threshold versus suprathreshold concentrations of tastants (6, 72)....

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  • ...In addition, it is worth noting that the relationship of taste detection thresholds as measured in the first study to fat perception at above-threshold levels in real-world settings as measured in the second study is often not a direct one (6, 72)....

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Journal ArticleDOI
TL;DR: Recent scientific evidence supporting potential mechanisms that explain how "metabolically inactive" NNSs, which have few, if any, calories, might promote metabolic dysregulation is reviewed.

188 citations


Cites methods from "Obese women have lower monosodium g..."

  • ...subjects' taste sensitivity to detect sucralose and sucrose by using a twoalternative, forced-choice staircase procedure [84,85] in 16 of the 17...

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Book ChapterDOI
TL;DR: Understanding the exact genes and genetic differences that affect food intake may provide important clues in obesity treatment by allowing caregivers to tailor dietary recommendations to the chemosensory landscape of each person.
Abstract: Eating is dangerous. While food contains nutrients and calories that animals need to produce heat and energy, it may also contain harmful parasites, bacteria, or chemicals. To guide food selection, the senses of taste and smell have evolved to alert us to the bitter taste of poisons and the sour taste and off-putting smell of spoiled foods. These sensory systems help people and animals to eat defensively, and they provide the brake that helps them avoid ingesting foods that are harmful. But choices about which foods to eat are motivated by more than avoiding the bad; they are also motivated by seeking the good, such as fat and sugar. However, just as not everyone is equally capable of sensing toxins in food, not everyone is equally enthusiastic about consuming high-fat, high-sugar foods. Genetic studies in humans and experimental animals strongly suggest that the liking of sugar and fat is influenced by genotype; likewise, the abilities to detect bitterness and the malodors of rotting food are highly variable among individuals. Understanding the exact genes and genetic differences that affect food intake may provide important clues in obesity treatment by allowing caregivers to tailor dietary recommendations to the chemosensory landscape of each person.

186 citations

Journal ArticleDOI
TL;DR: Alterations in the fat content of the diet modulated taste sensitivity to C18:1 among lean subjects, which was increased following a 4-week period of fat restriction and attenuated following the high-fat diet.
Abstract: To evaluate the effects of a high-fat and low-fat diet on taste sensitivity to oleic acid (C18:1) in lean and overweight/obese (OW/OB) subjects. Randomized cross-over dietary intervention involving the consumption of a high-fat (>45% fat) and low-fat (<20% fat) diet, both consumed over a 4-week period. A total of 19 lean, mean age 33±13 years, mean body mass index (BMI) 23.2±2.2 kg m–2 and 12 OW/OB, mean age 39.5±3 years, mean BMI 28±2.6 kg m–2, subjects participated in the study, which measured taste thresholds for C18:1, fat perception and hedonic ratings for regular (RF) and lowered-fat (LF) foods before, and following consumption of a high- and low-fat diet. Consumption of the low-fat diet increased taste sensitivity to C18:1 among lean and OW/OB subjects (P<0.05) and increased the subjects ability to perceive small differences in the fat content of custard (P=0.05). Consumption of the high-fat diet significantly decreased taste sensitivity to C18:1 among lean subjects (P<0.05), with no change in sensitivity among OW/OB persons (P=0.609). The hedonic ratings for several RF and LF foods differed following the diets. Alterations in the fat content of the diet modulated taste sensitivity to C18:1 among lean subjects, which was increased following a 4-week period of fat restriction and attenuated following the high-fat diet. The failure of the high-fat diet to alter fatty acid taste thresholds among OW/OB subjects suggests that these individuals were ‘adapted’ to high-fat exposure, perhaps because of differences in habitual fat consumption. Taken together, these data suggest that excessive dietary fat attenuates nutrient sensing epithelia response in the oral cavity, which could be associated with changes in diet and weight status.

160 citations

Journal ArticleDOI
TL;DR: The ability to detect oleic acid both orally and within the gastrointestinal tract is compromised in obese men, and oral and gastrointestinal responses to oleoic acid are related.

153 citations


Cites result from "Obese women have lower monosodium g..."

  • ...Nevertheless, our data are in line with recent observations of attenuated taste sensitivity to monosodium glutamate in obese women (37) and may suggest a more generalized impairment of nutrient-sensing mechanisms in obesity....

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References
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Journal ArticleDOI
14 Mar 2002-Nature
TL;DR: This work identifies and characterize a mammalian amino-acid taste receptor and shows that sequence differences in T1R receptors within and between species (human and mouse) can significantly influence the selectivity and specificity of taste responses.
Abstract: The sense of taste provides animals with valuable information about the nature and quality of food. Mammals can recognize and respond to a diverse repertoire of chemical entities, including sugars, salts, acids and a wide range of toxic substances. Several amino acids taste sweet or delicious (umami) to humans, and are attractive to rodents and other animals. This is noteworthy because L-amino acids function as the building blocks of proteins, as biosynthetic precursors of many biologically relevant small molecules, and as metabolic fuel. Thus, having a taste pathway dedicated to their detection probably had significant evolutionary implications. Here we identify and characterize a mammalian amino-acid taste receptor. This receptor, T1R1+3, is a heteromer of the taste-specific T1R1 and T1R3 G-protein-coupled receptors. We demonstrate that T1R1 and T1R3 combine to function as a broadly tuned L-amino-acid sensor responding to most of the 20 standard amino acids, but not to their D-enantiomers or other compounds. We also show that sequence differences in T1R receptors within and between species (human and mouse) can significantly influence the selectivity and specificity of taste responses.

1,357 citations

Journal ArticleDOI
TL;DR: It is shown that human T1R2/T1R3 recognizes diverse natural and synthetic sweeteners, and this response is enhanced by 5′-ribonucleotides, a hallmark of umami taste, which implicate the T1Rs inUmami taste and suggest that sweet and Umami taste receptors share a common subunit.
Abstract: The three members of the T1R class of taste-specific G protein-coupled receptors have been hypothesized to function in combination as heterodimeric sweet taste receptors. Here we show that human T1R2/T1R3 recognizes diverse natural and synthetic sweeteners. In contrast, human T1R1/T1R3 responds to the umami taste stimulus l-glutamate, and this response is enhanced by 5′-ribonucleotides, a hallmark of umami taste. The ligand specificities of rat T1R2/T1R3 and T1R1/T1R3 correspond to those of their human counterparts. These findings implicate the T1Rs in umami taste and suggest that sweet and umami taste receptors share a common subunit.

1,316 citations


"Obese women have lower monosodium g..." refers background in this paper

  • ..., both employ the taste receptor T1R3 in the dimer that is responsible for recognizing (in part) sweeteners (T1R2+T1R3) and umami (T1R1+T1R3) compounds (12)), this study, using validated psychophysical methodology, examined the perception and preferences of these two taste qualities in obese and normal-weight women....

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Journal ArticleDOI
TL;DR: The Labeled Magnitude Scale can be used to scale sensations of taste and smell when they are broadly defined, but that it should be modified for use in scaling specific taste qualities.
Abstract: The Labeled Magnitude Scale (LMS) is a semantic scale of perceptual intensity characterized by a quasi-logarithmic spacing of its verbal labels. The LMS had previously been shown to yield psychophysical functions equivalent to magnitude estimation (ME) when gustatory, thermal and nociceptive stimuli were presented and rated together, and the upper bound of the LMS was defined as the 'strongest imaginable oral sensation'. The present study compared the LMS to ME within the more limited contexts of taste and smell. In Experiment 1, subjects used both methods to rate either taste intensity produced by sucrose and NaC1 or odor intensity produced by acetic acid and phenyl ethyl alcohol, with the upper bound of the LMS defined as either the 'strongest imaginable taste' or the 'strongest imaginable odor'. The LMS produced psychophysical functions equivalent to those produced by ME. In, Experiment 2 a new group of subjects used both methods to rate the intensity of three different taste qualities, with the upper bound of the LMS defined as the 'strongest imaginable [sweetness, saltiness, or bitterness]'. In all three cases the LMS produced steeper functions than did ME. Experiment 3 tested the hypothesis that the LMS yields data comparable to ME only when the perceptual domain under study includes painful sensations. This hypothesis was supported when the LMS again produced steeper functions that ME after subjects had been explicitly instructed to omit painful sensations (e.g. the 'burn' of hot peppers) from the concept of 'strongest imaginable taste'. We conclude that the LMS can be used to scale sensations of taste and smell when they are broadly defined, but that it should be modified for use in scaling specific taste (and probably odor) qualities. The implications of these results for theoretical issues related to ME, category-ratio scales and the size of the perceptual range in different sensory modalities are discussed.

689 citations


"Obese women have lower monosodium g..." refers background or methods in this paper

  • ...The gLMS is a computerized psychophysical tool that requires subjects to rate the perceived intensity along a vertical axis lined with adjectives that are spaced semilogarithmically, based upon experimentally determined intervals to yield ratio-quality data (18)....

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  • ...Before suprathreshold intensity testing, each subject was first familiarized with use of the general Labeled Magnitude Scale (gLMS) (18) with the top of the scale described as the “strongest imaginable” sensation of any kind (1) by rating the intensity of 10 oral and nonoral sensations (e....

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Journal ArticleDOI
TL;DR: A GPCR cloned from rat taste buds and functionally expressed in CHO cells is described, which shows an unusual concentration–response relationship and the similarity of its properties to MSG taste suggests that this receptor is a taste receptor for glutamate.
Abstract: Sensory transduction for many taste stimuli such as sugars, some bitter compounds and amino acids is thought to be mediated via G protein-coupled receptors (GPCRs), although no such receptors that respond to taste stimuli are yet identified. Monosodium L-glutamate (L-MSG), a natural component of many foods, is an important gustatory stimulus believed to signal dietary protein. We describe a GPCR cloned from rat taste buds and functionally expressed in CHO cells. The receptor couples negatively to a cAMP cascade and shows an unusual concentration-response relationship. The similarity of its properties to MSG taste suggests that this receptor is a taste receptor for glutamate.

577 citations


"Obese women have lower monosodium g..." refers background in this paper

  • ...Several G-protein-coupled receptors, including truncated type 1 and 4 metabotropic glutamate receptors (MGluRs) (37) and the heterodimer T1R1+T1R3 (refs....

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Journal ArticleDOI
TL;DR: In this article, the authors found that the older men were less sensitive than the young men and women for acetic acid, sucrose, citric acid, sodium and potassium chloride and IMP.
Abstract: Detection thresholds for NaCl, KCl, sucrose, aspartame, acetic acid, citric acid, caffeine, quinine HCl, monosodium glutamate (MSG) and inosine 5'-monophosphate (IMP) were assessed in 21 young (19-33 years) and 21 elderly (60-75 years) persons by taking the average of six ascending two-alternative forced choice tests. A significant overall effect was found for age, but not for gender. However, an interaction effect of age and gender was found. The older men were less sensitive than the young men and women for acetic acid, sucrose, citric acid, sodium and potassium chloride and IMP. To detect the compound dissolved in water they needed a 1.32 (aspartame) to 5.70 times (IMP) higher concentration than the younger subjects. A significant decline in thresholds with replication was shown. The age effect found could be attributed predominantly to a generic taste loss.

355 citations