Normal taste acuity and preference in female adolescents with impaired 6-n-propylthiouracil sensitivity.
TL;DR: This is the first study to demonstrate that 6-n-propylthiouracil nontasters have taste sensitivity for the four basic tastes similar to that in 6- n-Propylthaviouracil tasters, at least in female adolescents, as measured by the gustatory test using a filter-paper disc method.
Abstract: This study was conducted to determine the relationship between 6-n-propylthiouracil sensitivity and taste characteristics in female students at Nara Women's University. Participants (n=135) were screened for 6-npropylthiouracil sensitivity using a taste test with 0.56 mM 6-n-propylthiouracil solution, and the sensitivity was confirmed by an assay for the bitter-taste receptor gene, TAS2R38. Based on the screening results, 33 6-npropylthiouracil tasters and 21 non-tasters were enrolled. The basic characteristics that are thought to influence taste acuity, including body mass index, saliva volume and serum micronutrient concentrations (iron, zinc and copper), were similar between the two groups. In an analysis using a filter-paper disc method, there were no differences in the acuity for four basic tastes (sweet, salty, sour and bitter) between 6-n-propylthiouracil tasters and non-tasters. In addition, the taste preference for the four basic tastes as measured by a visual analogue scale was also comparable between the two groups. This is the first study to demonstrate that 6-n-propylthiouracil nontasters have taste sensitivity for the four basic tastes similar to that in 6-n-propylthiouracil tasters, at least in female adolescents, as measured by the gustatory test using a filter-paper disc method.
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TL;DR: These are the first data showing an association between sweet taste and saliva proteome, and some differences were sex-dependent, with higher levels of α-amylase and CA-VI in low-sensitivity individuals and higher levels in sensitive ones for both sexes.
Abstract: Sweet taste plays a critical role in determining food preferences and choices. Similar to what happens for other oral sensations, individuals differ in their sensitivity for sweet taste and these inter-individual differences may be responsible for variations in food acceptance. Despite evidence that saliva plays a role in taste perception, this fluid has been mainly studied in the context of bitterness or astringency. We investigated the possible relationship between sweet taste sensitivity and salivary composition in subjects with different sucrose detection thresholds. Saliva collected from 159 young adults was evaluated for pH, total protein concentration and glucose. One- and bi-dimensional electrophoresis (2-DE) were performed and protein profiles compared between sweet sensitivity groups, with proteins that were differently expressed being identified by MALDI-FTICR-MS. Moreover, Western blotting was performed for salivary carbonic anhydrase VI (CA-VI) and cystatins and salivary amylase enzymatic activity was assessed in order to compare groups. Females with low sensitivity to sweet taste had higher salivary concentrations of glucose compared to those with sensitivity. For protein profiles, some differences were sex-dependent, with higher levels of α-amylase and CA-VI in low-sensitivity individuals and higher levels of cystatins in sensitive ones for both sexes. Body mass index was not observed to affect the association between salivary proteome and taste sensitivity. To our knowledge, these are the first data showing an association between sweet taste and saliva proteome.
28 citations
Cites background from "Normal taste acuity and preference ..."
...However, such a relationship is questionable [13] and only a weak link between PROP taste sensitivity and sweet perception has been observed [14]....
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TL;DR: Subjective assessment of taste differs according to food composition and nationality, and it is important to consider taste preferences according to nationality when promoting oral nutritional support.
1 citations
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TL;DR: Bitterness and sweetness of sampled vegetables varied by taste genetic and taste function markers, which explained differences in preference for vegetables tasted in the laboratory as well as overall vegetable intake outside the laboratory.
369 citations
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...0 Serum Fe (μg/dL) 88 (28-216) 100 (23-168) 0....
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TL;DR: Men, women, elderly persons, children, negroes, Chinese, Germans and Italians were all shown to have in their ranks both tasters and non-tasters and it was established that this peculiar phenomenon was not connected with age, race or sex.
Abstract: Some time ago the author had occasion to prepare a quantity of phenyl thio carbamide, and while placing it in a bottle the dust flew around in the air. Another occupant of the laboratory, Dr. C. R. Noller, complained of the bitter taste of the dust, but the author, who was much closer, observed no taste and so stated. He even tasted some of the crystals and assured Dr. Noller they were tasteless but Dr. Noller was equally certain it was the dust he tasted. He tried some of the crystals and found them extremely bitter. With these two diverse observations as a starting point, a large number of people were investigated and it was established that this peculiarity was not connected with age, race or sex. Men, women, elderly persons, children, negroes, Chinese, Germans and Italians were all shown to have in their ranks both tasters and non-tasters. At first it was thought that this phenomenon was connected with the acidity or alkalinity of the mouth, but experiment soon showed there was no connection whatever. This peculiar phenomenon offered an interesting opportunity for a chemical study of related compounds. Phenyl thio carbamide has the structure 0-NHC-NH2 l11
347 citations
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...Tasters (n=33) Non-tasters (n=21) p value A) Tube number Sweet 6 (1-10) 8 (2-10) 0....
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TL;DR: These results support taste genetic effects on alcohol intake, and PROP bitterness serves as a marker of these effects.
Abstract: STRONG SUPPORT EXISTS for a familial component in the etiology of alcoholism and alcohol use [see Dick and Foroud (2003) for review]. Twin studies show that the heritability of alcoholism ranges from 50 to 60% (Heath et al., 1997) and that genetic influences can explain a 5-fold difference in alcohol use among adolescents in alcohol-predisposing environments (Dick et al., 2001). Genetic risk for alcoholism is complex; several different genes undoubtedly exert effects on the rewarding influence of drinking alcohol, on the metabolic tolerance of alcohol overconsumption, on brain systems that respond to reward, and on response to alcohol withdrawal (Crabbe, 2002). Specific gene mechanisms have been linked to, for example, the metabolism of alcohol via alcohol dehydrogenase (Mulligan et al., 2003; Osier et al., 1999) and aldehyde dehydrogenase (Oota et al., 2004), as well as dependence via γ-aminobutyric acid receptors (Song et al., 2003). The purpose of this study was to examine the association between genetic variation in taste and alcohol use in a group of reportedly healthy young adults.
Genetic variation in taste influences the sensations from alcoholic beverages and could be one of the genetic factors that interacts with environmental factors to determine the risk of alcohol overconsumption, as suggested by models of gene-environment interaction (Heath and Nelson, 2002). The ability to taste the bitterness of phenylthiocarbamide (PTC) and 6-n-propylthiouracil (PROP), which share an group, is a well documented phenotypic polymorphism. The distribution of thresholds for PTC or PROP tasting is bimodal: “nontasters” have increased thresholds (low sensitivity), and “tasters” have lower thresholds (higher sensitivity). Family studies have generally supported the model that tasting was a dominant trait and nontasting a recessive trait (Blakeslee, 1932; Snyder, 1931).
An important gene contributing to PTC perception has been identified (Kim et al., 2003). The gene (TAS2R38), located on chromosome 7q36, is a member of the bitter taste receptor family. There are two common molecular forms [proline-alanine-valine (PAV) and alanine-valine-isoleucine (AVI)] of this receptor defined by three nucleotide polymorphisms that result in three amino acid substitutions: Pro49Ala, Ala262Val, and Val296Ile. The ancestral human haplotype at these three amino acids—determined by sequencing DNA from several other ape species, an old world monkey, and a new world monkey—is PAV (Kim et al., 2003; Wooding et al., 2004). This molecular form is common in humans and is associated with tasting; the other common form, the triply derived molecular form, AVI, is associated with nontasting. Three other haplotypes have been observed: AAV, AAI, and PVI. The original report (Kim et al., 2003) studied 200 Europeans and 118 individuals from other regions.
Historically, researchers have used detection thresholds to classify individuals as nontasters or tasters of these bitter compounds (e.g., Fox, 1931; Harris and Kalmus, 1949). Fischer and Griffin (1964) replaced PTC with its chemical relative PROP, which lacks the sulfurous odor of PTC and may be less toxic (Barnicot et al., 1951; Lawless, 1980). Insensitivity to PTC or PROP is estimated at 30% in European populations, although the percentages vary with sex and among ethnic groups globally (Bartoshuk et al., 1994; Guo and Reed, 2001).
The taster group shows significant variability in the perceived bitterness of PROP. Although threshold measures may be used to separate individuals with low thresholds (tasters) from individuals with increased thresholds (nontasters), subsequent work by Bartoshuk et al. (1994) identified two distinct populations within the taster group. By comparing the perceived intensity of concentrated PROP, the taster group is subdivided into those who taste concentrated PROP (3.2 mM) as “strongly” bitter (medium tasters) and those who taste PROP as greater than “very strongly” bitter (supertasters) (Bartoshuk et al., 1994). Supertasters cannot be identified via thresholds, because the distributions between those who are sensitive and extremely sensitive to PROP overlap (Reed et al., 1995). Supertasters differ from medium tasters and nontasters in the number of taste papillae on the anterior tongue (fungiform papilla); PROP supertasters have, on average, the most fungiform papillae and taste buds as assessed with videomicroscopy (Bartoshuk et al., 1994). A positive relationship between PROP bitterness and fungiform papillae number is also observed by using lower magnification for papillae counting (Delwiche et al., 2001; Tepper and Nurse, 1997). Supertasting may result from an anatomical difference related to the density of fungiform papillae on the tongue, as well as an allelic variation of TAS2R38 that results in the presence or absence of a functional receptor, as proposed by Bartoshuk et al. (2001) and as supported by data shown in this article. The genetic control of fungiform papilla density is unknown.
The perceived bitterness of PROP is correlated with unpleasant and pleasant sensations from alcohol. Those who taste PROP as more bitter also report ethanol (Bartoshuk et al., 1993; Duffy et al., 2004; Prescott and Swain-Campbell, 2000), some types of beer (Intranuovo and Powers, 1998), scotch (Lanier et al., 2004), and red wines (Pickering et al., 2004) as more bitter or irritating. Nontasters not only perceive scotch as less bitter but also as more sweet than do supertasters (Lanier et al., 2005). The density of fungiform papillae can explain some of the oral sensory differences associated with PROP tasting, as first suggested by Miller and Reedy (1990). The taste buds are surrounded by fibers of the trigeminal nerve (cranial nerve V), which are believed to mediate oral burn (Finger et al., 1994; Whitehead et al., 1985; Whitehead and Kachele, 1994). It is interesting to note that sucrose and ethanol stimulate similar central brain centers in rats (Lemon et al., 2004) and that ethanol stimulates taste nerve fibers responsive to sucrose in primates (Hellekant et al., 1997).
Supertasters may have an inherent sensory aversion to consuming alcoholic beverages with high levels of ethanol and a pronounced alcohol flavor. Young adults who taste PROP as more bitter have been found to consume less beer (Guinard et al., 1996), including during their first year of drinking (Intranuovo and Powers, 1998). In young adults who were not college undergraduates, we found that PROP supertasters reported consuming alcoholic beverages less frequently than did nontasters (Duffy et al., 2004), a finding that was also seen in preliminary data in adults (primarily men) recruited through an industrial worksite wellness program (Hutchins et al., 2002). Not all studies, however, find associations between PROP bitterness and alcohol intake (e.g., Mattes and DiMeglio, 2001).
The literature is inconsistent with respect to a relationship between PROP tasting and risk of alcoholism. In studies with alcoholics compared with controls, some report an excess of nontasters among alcoholics (DiCarlo and Powers, 1998; Peeples, 1962; Spiegel, 1972), whereas other studies do not (Reid et al., 1968; Smith, 1972; Swinson, 1973). In studies examining family history of alcoholism, Pelchat and Danowski (1992) found significantly more PROP nontasters among children of alcoholics than among children of nonalcoholics, whether or not the children themselves were alcoholic. Kranzler and colleagues, however, were unable to show a significant relationship between PROP threshold and parental history of alcohol dependence in nonalcoholic young adults (Kranzler et al., 1998) or in those with alcohol dependency (Kranzler et al., 1996). One study found comorbidity between depression and alcoholism in college students who reported PROP as very bitter (DiCarlo and Powers, 1998).
Some of the inconsistencies in PROP effects on alcohol consumption behaviors could relate to the measurement of PROP tasting. A number of studies relating alcohol-ingestive behaviors to PROP have relied on a threshold procedure (Kranzler et al., 1996, 1998; Peeples, 1962; Pelchat and Danowski, 1992; Spiegel, 1972), which, because it cannot identify supertasters (Bartoshuk et al., 1994), has the potential to fail to find PROP effects. In fact, we reported positive and significant associations between the frequency of consuming alcoholic beverages and PROP bitterness, but not PROP threshold (Duffy et al., 2004). Distinguishing PROP supertasters from medium tasters and nontasters requires valid scaling methods, as reviewed previously (Bartoshuk et al., 2002b, 2004a,Bartoshuk et al., b).
Discovery of allelic variation in TAS2R38, the gene for the PTC receptor, presented the opportunity for examining its ability to predict the oral sensation from an ethanol probe and the frequency of consuming alcoholic beverages in a sample of healthy adults who were recruited into a study of taste genetics and dietary behaviors and who reported consuming alcoholic beverages. Analysis of these data showed that genotype predicts PROP bitterness and, because of its association with PROP bitterness, predicts alcohol intake. However, genotype fully accounts neither for supertasting nor for some of the oral sensations from alcohol.
338 citations
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...Tasters (n=33) Non-tasters (n=21) p value A) Tube number Sweet 6 (1-10) 8 (2-10) 0....
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TL;DR: The primary goal of this review is to assess the current understanding of the role of the PROP bitter taste phenotype in food selection and body weight in both children and adults.
Abstract: Genetic sensitivity to the bitter taste of phenylthiocarbamide and 6-n-propylthiouracil (PROP) is a well-studied human trait. It has been hypothesized that this phenotype is a marker for individual differences in taste perception that influence food preferences and dietary behavior with subsequent links to body weight and chronic disease risk. Steady progress has been made over the past several decades in defining the involvement of this phenotype and its underlying gene, TAS2R38, in this complex behavioral pathway. However, more work needs to be done to fully determine its overall nutritional and health significance. The primary goal of this review is to assess our current understanding of the role of the PROP bitter taste phenotype in food selection and body weight in both children and adults. A brief history of the field is included and controversies surrounding the use of different PROP screening methods are addressed. The contribution of other receptors (both bitter and nonbitter) to human taste variation is also discussed.
304 citations
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...Tasters (n=33) Non-tasters (n=21) p value A) Tube number Sweet 6 (1-10) 8 (2-10) 0....
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TL;DR: The data suggest that PROP taste sensitivity plays a role in acceptance of certain bitter cruciferous vegetables and cheese by young children, and suggest that gender-specific environmental factors might interact with genetics to influence fat preferences.
278 citations
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...Tasters (n=33) Non-tasters (n=21) p value A) Tube number Sweet 6 (1-10) 8 (2-10) 0....
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