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PubMed1995

Detection thresholds of potassium salts are related to the molar conductivity of the anion.

In a previous study, we found that human taste detection thresholds for Na+ salts were linearly correlated with molar conductivity values at infinite dilution of their anions. In the present study, detection threshold concentrations for potassium salts were also found to be linearly correlated (r = -0.92) with the molar conductivity of the anion of the salt. Detection thresholds were determined here for nine potassium salts with the same anions as the sodium salts previously tested. The mean detection thresholds for these potassium salts were found to be: K Acetate (0.00311 M), K Carbonate (0.00286 M), K Chloride (0.00242 M), K Citrate (0.000300 M), K Phosphate (0.00196 M), K Sulfate (0.00090 M), K Tartrate (0.00164 M), K Glutamate (0.00153 M), and K Ascorbate (0.00375 M). The rank order correlation between the detection threshold values for sodium and potassium salts was 0.88. This finding suggests that detection thresholds for both Na+ and K+ salts are determined by the charge mobility of the anion.

Adolescent↗
PubMedDate not supplied

Olfactory thresholds are associated with degree of dementia in Alzheimer's disease.

Recent neuroanatomical studies have noted that regions of the olfactory pathways contain high levels of neuritic plaques and neurofibrillary tangles, pathological hallmarks of Alzheimer's disease; and that the olfactory epithelium, the most peripheral level of the system, exhibits anatomical and biochemical changes in Alzheimer's disease. The present experiments investigated thresholds for olfactory and taste stimuli in patients with Probable Alzheimer's disease. Olfactory thresholds of Alzheimer's patients were significantly elevated relative to controls and were significantly correlated with scores on dementia scales. Taste thresholds of Alzheimer's patients were within normal limits and unrelated to scores on dementia scales. These results suggest that increased olfactory thresholds in patients with Alzheimer's disease reflect the effects of the disease process and, thus, may aid in the diagnosis and in the understanding of Alzheimer's disease.

Aged↗
PubMed2002

Sensitivity of three loci on the tongue and soft palate to four basic tastes in smokers and non-smokers.

The filter paper disk method was used to determine the map of the 4 tastes (sweet, salty, sour and bitter) on the tongue and soft palate in 69 healthy individuals. The equipment used for testing included filter paper disks 8 mm in diameter and taste solutions, which were sequentially diluted (in 13 stages from 80% sucrose, 12 stages from 20% NaCl, 12 stages from 8% tartaric acid and 14 stages from 4% quinine hydrochloride). The threshold at which each taste was recognized in three locations (center of the tongue tip, foliate papillae on the left side and center of the soft palate) was determined by testing increasing concentrations of each solution. We found no difference by sex for sweet taste but women were more sensitive to sour taste on the tongue tip and to salty and bitter tastes on the soft palate. No difference in taste threshold was noted at the different locations for sweet, salty or bitter tastes, but both sexes were less sensitive to sour taste on the soft palate than on the tongue tip, and in men the soft palate was even less sensitive to sour taste than the tongue root. Smoking was associated with increased (worse) taste thresholds for all four tastes, for both men and women.

Adolescent↗
PubMed1994

Taste Acuity of the Morbidly Obese before and after Gastric Bypass Surgery.

Obese individuals have an increased preference for high caloric foods, such as sweets and fats. However, following gastric bypass (GBP) surgery, morbidly obese patients tend to avoid these foods. We hypothesize that this aversion may occur, in part, from permutations in taste acuity. To test this hypothesis, taste detection and recognition thresholds for the four basic tastes (salt, sweet, sour, and bitter) were assessed using a modification of the Henkin forced choice three stimulus technique. Taste acuity measurements were obtained at baseline and at 30, 60, and 90 days post-operative for six morbidly obese GBP women and ten non-surgical, lean female controls. We found nonsignificant differences in taste detection and recognition thresholds between morbidly obese and lean control study subjects at baseline, and no significant correlation between taste acuity and body size. Furthermore, in our study population of lean and obese women, ages 26 to 52, there were no significant interrelationships between baseline taste thresholds and known effectors of taste acuity, i.e., zinc levels, glycemic status, liver and kidney function, or age. Following GBP surgery, a significant up-regulation in taste acuity for bitter and sour was observed along with a trend toward a reduction in salt and sweet detection and recognition thresholds. These findings would suggest the following: (1) taste acuity does not influence taste preferences of the obese individual who has not had bariatric surgery; (2) taste effectors such as zinc, when within the range of normal values, do not alter thresholds of the 4 basic tastes; and (3) weight loss following gastric bypass surgery is associated with an up-regulation in taste acuity in the morbidly obese. Studies are currently under investigation at our center to identify the specific etiology of taste acuity upregulation in the morbidly obese following GBP surgery.

Journal Article↗
PubMed1997

Responses to glutamate in rat taste cells.

We studied taste transduction in sensory receptor cells. Specifically, we examined the actions of glutamate, a significant taste stimulus, on the membrane properties of taste cells by applying whole cell patch-clamp techniques to cells in rat taste buds isolated from foliate and vallate papillae. In 55 of 91 taste cells, bath-applied glutamate, at concentrations that elicit taste responses in the intact animal (10-20 mM), produced one of two different responses when the cell membrane was held near its presumed resting potential, -85 mV. "Sustained" glutamate responses were observed in the majority of taste cells (51 of 55) and consisted of an outward current (reduction of the maintained inward current). Sustained glutamate responses were voltage dependent, were decreased by membrane depolarization, and were accompanied by a reduction in membrane conductance. An analysis of the reversal potential of sustained responses in different ionic conditions and the effect of ion substitutions suggested that the currents were carried by cations. The data suggest that sustained responses are mediated by the closure of nonselective cation channels. Other taste cells (4 of 55) responded to glutamate with a transient inward current--so-called "transient" responses. Transient glutamate responses were voltage dependent and Na+ dependent, and appeared to be generated by nonspecific cation channels activated by glutamate. L(+)-2-amino-4-phosphonobutyric acid (L-AP4), a specific agonist of a metabotropic glutamate receptor (mGluR4) recently identified in rat taste cells and believed to be involved in taste transduction, mimicked the sustained glutamate responses. These findings indicate that glutamate, at concentrations at or slightly above threshold for taste in rats, produces two different membrane currents. The properties of these two responses suggest that there may be two different sets of nonspecific cation channels in taste cells, one closed by glutamate (sustained response) and the other opened (transient response). Our findings on the effect of L-AP4 suggest that the sustained response is the membrane mechanism mediating, at least in part, taste transduction for glutamate.

Animals↗
PubMed1988

Taste acuity in institutionalized and noninstitutionalized elderly men.

Taste detection thresholds were determined in young men (18 to 25 years of age, n = 15), noninstitutionalized elderly men (63 to 88 years of age, n = 17), and institutionalized elderly men (61 to 92 years of age, n = 15). The technical procedure utilized a single blind format. The tastants were presented to the subjects in a multiple forced-choice sample presentation with an ascending series. Additional testing conditions included adequate oral hygiene, 10 ml of tastant, timed intervals, and deionized water rinses. The major findings were that sour, salt, and bitter thresholds increased with age. Sweet threshold did not change with age. The institutionalized elderly men had significantly higher sour detection thresholds when compared with the noninstitutionalized elderly men. The use of salt and tobacco had no apparent effect on detection thresholds for sweet, salt and bitter, but medication ingestion elevated the sour thresholds. Elderly subjects on antihypertensive medications had significantly higher salt detection thresholds.

Adolescent↗
PubMed1993

Taste intensity performance in patients irradiated to the head and neck.

Decrements in taste-detection thresholds during radiotherapy and subsequent recovery in the months after therapy are well documented. However, few studies have explored suprathreshold taste intensity perception in radiation patients. This cross-sectional study compared taste function in 15 men postradiation with a group of 23 healthy, nonirradiated male volunteers. A direct-scaling procedure was used to assess taste intensity perception of the four basic taste qualities. Patients performed nearly as well as control subjects on objective measures of suprathreshold functioning. Postradiation intensity judgments of salty (sodium chloride), sweet (sucrose), and bitter (quinine sulfate) solutions were not significantly reduced. Subtle, age-related taste impairments were identified for sour perception (citric acid) postradiotherapy. Younger patients judged citric acid to be more intense than did age-appropriate control subjects, whereas older patients judged it to be less intense. Moreover, younger patients were likely to be midly dysgeusic, whereas older patients appeared to be hypogeusic for citric acid. This study provides evidence for near normal suprathreshold taste intensity perception in patients who have received head and neck irradiation.

Adult↗
PubMed2004

Detection and recognition thresholds to the 4 basic tastes in Mexican patients with primary Sjögren's syndrome.

BACKGROUND: Primary Sjögren's syndrome (pSS) is a chronic autoimmune disease characterized by inflammatory lymphocytic infiltration of the salivary glands, leading to dryness of the mouth (xerostomia). It has been postulated that xerostomia is the preceding stage for the development of alterations in taste acuity (dysgeusia) in this type of patients. OBJECTIVES: To determine detection and recognition thresholds to the 4 basic tastes (sweet, salty, sour and bitter) in pSS patients and compare them to a control group. To determine if the long-term consumption of chile peppers and spicy Mexican diets had an effect on the taste perception and acuity of the pSS patients. SETTING: This study was done in the Department of Food Science and Technology of the Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán (INCMNSZ), a third-level hospital in Mexico City. SUBJECTS: The patient group consisted of 21 Mexican females (mean +/- s.d., age: 53.1 +/- 9.8 y) diagnosed with pSS (time of duration of the disease, 8.6 +/- 6.6 y, median 7 y, range 1-25 y) who were recruited at the outpatient service of the Department of Immunology and Rheumatology of the INCMNSZ. The control group consisted of 20 healthy nonsmokers age-matched Mexican women (50.3 +/- 11.9 y) most of them personnel of the INCMNSZ, and some friends and nonblood relatives to the patients (sisters-in-law) who volunteered to participate in the study. INTERVENTIONS: Detection and recognition thresholds were determined by the method of least noticeable differences on three occasions during three nonconsecutive days. Saliva production was determined by Saxon's test on two separate occasions. RESULTS: Although saliva production was severely reduced in pSS patients (1.35 +/- 0.55 ml/2 min, P<0.001) compared to controls (6.26 +/- 2.41 ml/2 min), all subjects recognized the 4 basic tastes when these were tested at suprathreshold concentrations. The detection thresholds for the sweet, sour and bitter tastes were higher in pSS patients, as well as the recognition thresholds for the salty, sour and bitter tastes. A relationship between time of evolution of the disease and saliva production with individual thresholds could not be established. CONCLUSIONS: pSS patients exhibited different degrees of dysgeusia depending on the taste being studied, that is, they were mildly dysgeusic for the sweet and salty tastes and clearly dysgeusic for the sour and bitter tastes. Although both pSS patients and controls had consumed 'typical Mexican diets' their entire lives, our results showed that the consumption of chile peppers and spicy foods did not have any effect on the taste perception and acuity of the pSS patients.

Capsicum↗
PubMed2005

Genetic and environmental determinants of bitter perception and sweet preferences.

OBJECTIVE: Flavor is the primary dimension by which young children determine food acceptance. However, children are not merely miniature adults because sensory systems mature postnatally and their responses to certain tastes differ markedly from adults. Among these differences are heightened preferences for sweet-tasting and greater rejection of bitter-tasting foods. The present study tests the hypothesis that genetic variations in the newly discovered TAS2R38 taste gene as well as cultural differences are associated with differences in sensitivity to the bitter taste of propylthiouracil (PROP) and preferences for sucrose and sweet-tasting foods and beverages in children and adults. DESIGN: Genomic DNA was extracted from cheek cells of a racially and ethnically diverse sample of 143 children and their mothers. Alleles of the gene TAS2R38 were genotyped. Participants were grouped by the first variant site, denoted A49P, because the allele predicts a change from the amino acid alanine (A) to proline (P) at position 49. Henceforth, individuals who were homozygous for the bitter-insensitive allele are referred to as AA, those who were heterozygous for the bitter-insensitive allele are referred to as AP, and those who were homozygous for the bitter-sensitive allele are referred to as PP. Using identical procedures for children and mothers, PROP sensitivity and sucrose preferences were assessed by using forced-choice procedures that were embedded in the context of games that minimized the impact of language development and were sensitive to the cognitive limitations of pediatric populations. Participants were also asked about their preferences in cereals and beverages, and mothers completed a standardized questionnaire that measured various dimensions of their children's temperament. RESULTS: Genetic variation of the A49P allele influenced bitter perception in children and adults. However, the phenotype-genotype relationship was modified by age such that 64% of heterozygous children, but only 43% of the heterozygous mothers, were sensitive to the lowest concentration (56 micromoles/liter) of PROP. Genotypes at the TAS2R38 locus were significantly related to preferences for sucrose and for sweet-tasting beverages and foods such as cereals in children. AP and PP children preferred significantly higher concentrations of sucrose solutions than did AA children. They were also significantly less likely to include milk or water as 1 of their 2 favorite beverages (18.6% vs 40%) and were more likely to include carbonated beverages as 1 of their most preferred beverages (46.4% vs 28.9%). PP children liked cereals and beverages with a significantly higher sugar content. There were also significant main effects of race/ethnicity on preferences and food habits. As a group, black children liked cereals with a significantly higher sugar content than did white children, and they were also significantly more likely to report that they added sugar to their cereals. Unlike children, there was no correspondence between TAS2R38 genotypes and sweet preference in adults. Here, the effects of race/ethnicity were the strongest determinants, thus suggesting that cultural forces and experience may override this genotype effect on sweet preferences. Differences in taste experiences also affected mother-child interaction, especially when the 2 resided in different sensory worlds. That is, children who had 1 or 2 bitter-sensitive alleles, but whose mothers had none, were perceived by their mothers as being more emotional than children who had no bitter-sensitive alleles. CONCLUSION: Variations in a taste receptor gene accounted for a major portion of individual differences in PROP bitterness perception in both children and adults, as well as a portion of individual differences in preferences for sweet flavors in children but not in adults. These findings underscore the advantages of studying genotype effects on behavioral outcomes in children, especially as they relate to taste preferences because cultural forces may sometimes override the A49P genotypic effects in adults. New knowledge about the molecular basis of food likes and dislikes in children, a generation that will struggle with obesity and diabetes, may suggest strategies to overcome diet-induced diseases.

Adult↗
PubMed2001

Determination of saltiness from the laws of thermodynamics--estimating the gas constant from psychophysical experiments.

One can relate the saltiness of a solution of a given substance to the concentration of the solution by means of one of the well-known psychophysical laws. One can also compare the saltiness of solutions of different solutes which have the same concentration, since different substances are intrinsically more salty or less salty. We develop here an equation that relates saltiness both to the concentration of the substance (psychophysical) and to a distinguishing physical property of the salt (intrinsic). For a fixed standard molar entropy of the salt being tasted, the equation simplifies to Fechner's law. When one allows for the intrinsic 'noise' in the chemoreceptor, the equation generalizes to include Stevens's law, with corresponding decrease in the threshold for taste. This threshold reduction exemplifies the principle of stochastic resonance. The theory is validated with reference to experimental data.

Animals↗
PubMed1997

A comparison of the ability of 8-9-year-old children and adults to detect taste stimuli.

Conflicting data exist in the literature regarding the maturity of the human sense of taste during childhood and if gender influences gustatory development. To investigate these 2 questions, taste detection thresholds for the 4 common tastants sucrose, sodium chloride, citric acid, and caffeine were established for 61 young adults and 68 children aged 8-9 years old, using a paired-comparison forced-choice procedure. No significant differences were found between the mean thresholds of women and men, or between those of female children and adults. In contrast, male children had significantly higher thresholds for all 4 tastants than adult females, for all tastants except caffeine than adult men, and for sucrose and sodium chloride than female children. It is concluded that the taste sensitivity of 8-9-year-old males, although well developed, has not fully matured, and that taste sensitivity is not affected by gender in young adults.

Adult↗
PubMed2003

(+)-(S)-alapyridaine--a general taste enhancer?

N-(1-Carboxyethyl)-6-hydroxymethyl-pyridinium-3-ol inner salt (alapyridaine), recently identified in heated sugar/amino acid mixtures as well as in beef bouillon, has been shown to exhibit general taste-enhancing activities, although tasteless on its own. Differing from other taste enhancers reported so far, racemic (R/S)-alapyridaine and, to an even greater extent (+)-(S)-alapyridaine, the physiologically active enantiomer, are able to enhance more than one basic taste quality. The threshold concentrations for the sweet taste of glucose and sucrose, for the umami taste of monosodium L-glutamate (MSG) and guanosine-5'-monophosphate (GMP), as well as the salty taste of NaCl, were significantly decreased when alapyridaine was present. In contrast, perception of the bitter tastes of caffeine and L-phenylalanine, as well as of sour-tasting citric acid, was unaffected. Furthermore, alapyridaine was shown to intensify known taste synergies such as, for example, the enhancing effect of L-arginine on the salty taste of NaCl, as well as that of GMP on the umami taste of MSG. The activity of (+)-(S)-alapyridaine could be observed not only in solutions of single taste compounds, but also in more complex tastant mixtures; for example, the umami, sweet and salty taste of a solution containing MSG, sucrose, NaCl and caffeine was significantly modulated, thus indicating that alapyridaine is a general taste enhancer.

Adult↗
PubMed2001

Functional recovery of taste sensitivity to sodium chloride depends on regeneration of the chorda tympani nerve after transection in the rat.

Chorda tympani nerve (CT) transection (CTX) raises sodium chloride (NaCl) taste detection threshold, but the effect of CT regeneration on NaCl threshold is unknown. This experiment examined whether CT regeneration supports normal NaCl threshold in the rat. Thresholds were measured with a 2-lever operant procedure. Thresholds increased more than 1 order of magnitude after CTX regardless of recovery period length. Postsurgical thresholds in rats with regenerated CTs did not differ from presurgical values. Stimulus adulteration with amiloride raised thresholds in rats with intact or regenerated CTs by about 1 order of magnitude but did not raise thresholds beyond postsurgical levels in rats with transected CTs. Thus, the regenerated CT supports normal NaCl threshold, which is raised by amiloride. Because thresholds remained elevated 62 days after CTX when regeneration was prevented, compensatory processes alone cannot support normal NaCl threshold.

Animals↗
PubMed1980

Improvement of uremic hypogeusia by zinc: a double-blind study.

Diminished taste acuity may account for the persistence of protein and caloric malnutrition observed in a majority of hemodialysis patients inspite of liberalization of the prescribed amount of dietary protein. Twenty-two patients undergoing thrice weekly hemodialysis for more than 6 months were tested for taste acuity and plasma zinc concentration, after which a double-blind study was instituted using a zinc supplement (50 mg of elemental zinc as zinc acetate per day) or a placebo. The threshold of taste detection and recognition for salt (NaCl), sweet (sucrose), and bitter (urea) but not for sour (HCl) improved significantly in all patients on zinc supplementation. None of these parameters improved in those taking placebo. During the study period, the mean plasma zinc level increased from 75 +/- 8 to 97 +/- 10 microgram/dl (P less than 0.001) in patients receiving zinc acetate. There was not significant change in plasma zinc level in the placebo group (75 +/- 15 to 80 +/- 15). The results of this study show that uremic hypogeusia improved in association with zinc supplementation and elevation of plasma zinc concentration.

Clinical Trials as Topic↗
PubMed1980

[Psychophysics of sweet taste. I. Goals and methods of investigation].

With a view to the solution of problems concerned with the consumer's acceptance of foods in which saccharose had been substituted, a discussion is opened on psychologic and physiologic aspects of the measurability of sensory stimulus-sensation relations. The classic method for measuring taste is the determination of the taste discrimination threshold which is also termed least discernible difference. In the lat years, the discrimination threshold has been determined and calculated mainly as the mean concentration (stimulus) difference resulting from the distribution of the tasters according to their efficiency (probit analysis). In contrast, the new method, which is described in detail, is based on the dependence of the probability of a perception of difference upon the intensity which is linear and represents the initial course of a stimulus-response curve. Differences in efficiency in the group of tasters, which is assumed to be homogeneous, are included in the variance of difference frequencies found. The control of the course of the test by sequential analysis and the binomial weighting of the probabilities obtained allow to perform calculations of the discrimination threshold which are largely free from systematic errors; this discrimination threshold is defined as the concentration difference that engenders the arbitrarily defined alternative probability of Pa = 0.75. To minimize the risk of overrating the measurement result, it is suggested to calculate in addition, on the basis of the binomial distribution, the confidence limits of the discrimination threshold. Furthermore, the constant stimulus method for determining the perception of two stimulus intensities of different sweetening agents is adapted, as to performance and calculation, to the new aspects in discrimination threshold determination.

Consumer Behavior↗
PubMed1987

Salt consumption and nutritional state especially dietary protein level.

To examine the background of excessive salt intake by the people who live in the northeastern district of the mainland of Japan, statistical analysis was carried out on salt consumption with nutritional status with data from the National Nutrition Survey of Japan and prefectural reports. We found that the dietary protein level (using the index animal-protein calorie intake:total calorie intake) was inversely proportional to the salt intake. To clarify the relationship between taste preference and nutritional status, the effects of dietary protein levels on the preference for salt were studied in spontaneously hypertensive rats (SHR), Wistar-Slc rats, and Sprague-Dawley (SD) rats. We found that the appetite or preference for sodium chloride depends not only on a genetic factor but also on the nutritional status, ie, dietary protein levels. We also observed that the preference for the monosodium glutamate solution was not induced in animals fed a low-protein diet. From these observations we speculated that the threshold of taste sensation is increased in rats fed a low-protein diet. To determine the threshold of taste sensation for NaCl, we calculated the turnover time of taste buds, which was lengthened in rats fed a low-protein diet. The findings from statistical analysis and the results from animal experiments suggest that taste preference is influenced not only by genetic factors but also by the nutritional status. Our hypothesis is that dietary protein level is one of the important factors affecting the taste preference for sodium chloride.

Animals↗
PubMed2000

Effect of tricyclic antidepressants on taste responses in humans and gerbils.

One of the side effects of antidepressant pharmacotherapy reported clinically is impairment of the sense of taste. In this study, the taste effects of four tricyclic antidepressant compounds (clomipramine HCl, desipramine HCl, doxepin HCl, and imipramine HCl) were evaluated experimentally by topical application of the drugs to the tongue. Taste detection threshold concentrations for all four medications ranged from 0.1 mM to 0.2 mM in young persons but were elevated by as much as 7.71 times that in elderly individuals who were taking no concurrent medications. Each compound had a predominantly bitter taste with other qualities including metallic, sour, and sharp-pungent. In addition, each tricyclic antidepressant at concentrations from 1 mM to 5 mM blocked responses to a wide range of taste stimuli in both humans and gerbils. The differential suppression of other tastes by tricyclic antidepressants at the level of the taste receptors may contribute to the clinical reports of dysgeusia and hypogeusia.

Adult↗
PubMed1992

Taste alterations in liver cirrhosis: are they related to zinc deficiency?

Patients with chronic liver disease may have taste impairment and altered zinc metabolism. We evaluated Taste Detection Thresholds (TDTs) in 60 patients with liver cirrhosis and correlated the findings with disease severity and alcoholic etiology. Plasma zinc levels and urinary output were also measured. A placebo-controlled treatment trial with zinc sulphate was made in 15 patients with compensated cirrhosis in order to ascertain whether zinc deficiency caused taste alterations. Taste detection of salty, sweet and acid tastants was significantly impaired in all cirrhotic patients in comparison with normal subjects. TDTs were not influenced either by the etiology or the severity of the disease. All groups of patients had low plasma zinc levels and decompensated cirrhosis had a significantly increased urinary output of zinc. No correlation was found between taste acuity and plasma zinc levels when only cirrhotic patients were considered. The effect of zinc supplementation on TDTs did not appear to be inferior to that of the placebo. Our results indicate that taste impairment in cirrhotics is due to the disease process per se and not to zinc deficiency.

Adult↗