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Clinical and physiological investigations in patients with taste abnormality.

The cause of taste abnormality was investigated in 25 patients with decreased taste sensation (hypogeusia group) and 14 patients with abnormal taste sensation (dysgeusia group) by examining taste threshold, salivary flow rate, Candida cell culture, and laboratory examination of peripheral blood. The cause of hypogeusia was identified as iron deficiency in 7 patients, oral candidiasis in 6, hyposalivation (xerostomia) in 6, and psychiatric distress in 3, and could not be determined in 3 (idiopathic). Dysgeusia was associated with psychiatric distress in 8 patients, oral candidiasis in 3, drug medication in 2, and hyposalivation in 1. In the hypogeusia group, the decreased taste sensation generally corresponded with elevated taste thresholds, which decreased along with improvement of the decreased taste sensation in all except the 3 patients with psychiatric etiology and 2 of the 3 patients with idiopathic etiology. In contrast, no elevation or depression of taste thresholds were observed in the dysgeusia group, and the abnormal taste sensation did not disappear in most cases; however, drug-induced dysgeusia improved completely within 2 months after cessation of the drug administration. The serum copper and zinc levels were not decreased in any patient, but a decreased serum iron level was observed in 7 patients. Based on these results, it is concluded that abnormal taste sensation may be induced by many oral and systemic disturbances and that hypogeusia, which may be induced by deficiency of iron but not of zinc or copper, is usually accompanied by elevation of taste thresholds, while dysgeusia is not.

Adult↗

Basic properties of umami and effects on humans.

This is a review of the taste of umami substances, and some related findings. The data demonstrate that, though the taste of the common umami substances such as MSG and IMP is mainly caused by their anions, the effects of their cations, such as Na, should not be ignored. The effects of cations approach the taste thresholds of umami substances. Although the taste threshold of MSG was slightly lower than that of Na, the threshold of IMP was found to be controlled by Na. However, the degree of saltiness was less than 10% above the threshold of the equivalent weight of NaCl. It was also found that the taste of IMP was probably caused by glutamic acid in saliva, since IMP itself has no umami taste. That is, IMP enhances the umami taste of MSG. Finally, comparison of umami sensitivity of Japanese and Americans revealed no difference.

Cross-Cultural Comparison↗

Automated electrogustometry: a new paradigm for the estimation of taste detection thresholds.

Electrogustometery, first introduced in the 1950s for the clinical assessment of taste function, has returned to favour in recent years. This is due, in part, to the credence given to the procedure by an increased understanding of the mechanisms of taste transduction. The reliability and validity of electrogustometric assessments of taste function should increase with the use of automated testing. An automated computer-controlled testing paradigm was used to obtain threshold estimates simultaneously from the left and right sides of the tongue in 97 volunteers aged between 17 and 63 years. A small but statistically significant advantage was found for thresholds from the right side of the tongue (P<0.01). The range of thresholds, and of interside differences obtained with this procedure, are reported, and practical issues related to testing are discussed.

Adolescent↗

Chorda tympani nerve transection, but not amiloride, increases the KCl taste detection threshold in rats.

Water-restricted rats were trained to press one lever after KCl presentation and the other lever after distilled water. Water reinforcement was given after each correct response, and a time-out followed each incorrect response. Rats were trained and tested on KCl stimuli of varying concentrations. Threshold was defined as the KCl concentration corresponding to 1/2 the maximum asymptote of performance for each rat. The geometric mean KCl detection threshold for all rats was 0.033 M KCl. Rats that had the chorda tympani nerve (CT) bilaterally transected showed an average increase in KCl threshold of approximately 0.60 log10 units, whereas sham-operated rats showed no change. Control rats retested with 100 microM amiloride added to all KCl concentrations and water displayed no change in threshold. These results suggest that although the CT contributes significantly to the rat's sensitivity to KCl, amiloride-sensitive taste transduction pathways do not.

Amiloride↗

[Determination of the thresholds of taste sensitivity to table salt in a population study].

The study of an organized population has revealed three types of gustatory sensitivity to sodium chloride: low, medium and high. A certain dependence of salt sensitivity threshold on sex and age has been found. The examination of hypertensive patients in hospitals has revealed that patients with low gustatory sensitivity to salt are characterized by sodium and water retention. High gustatory sensitivity suggests sodium deficiency and corresponds to salt appetite. High salt sensitivity threshold may serve an indication for the administration of diuretics and for dietary salt restriction necessary for hypertension prevention and treatment.

Adolescent↗

Thresholds for sweet, salt, and sour taste stimuli in cockatiels (Nymphicus hollandicus).

Little is known about avian taste perception and how taste affects food choice. We designed a study to determine the concentrations of aqueous solutions of common chemical taste stimuli that result in altered consumption patterns. Using two-choice taste-preference tests, we studied the taste thresholds of caged cockatiels (Nymphicus hollandicus) for aqueous solutions of potassium chloride, a phosphate buffer (to test pH), fructose, and glucose. First, the preferred and nonpreferred bottle locations were determined for each bird. Then, depending on the compound, the test solutions were placed in bottles in either the preferred or the nonpreferred locations and water was placed in the opposite bottle. Four parameters were measured at the end of 3-day test periods (total consumption, consumption from water side, consumption from test solution side, and proportion of nonpreferred side consumption to total consumption). Experiments were repeated with increasing concentrations of test flavors until intake variables were significantly affected (P < 0.05). Cockatiels distinguished (P < 0.05) between purified water and 0.16 mol L(-1) potassium chloride, 0.40 mol L(-1) fructose, or 0.16 mol L(-1) glucose. The test birds did not distinguish between water and 0.05 mol L(-1) mono- and dibasic sodium phosphate buffer solution at any tested pH within the range of 4.9-7.7. When these findings are compared to previous experiments with the same birds, it becomes clear that the gustatory reactions of cockatiels for two different stimuli (e.g., NaCl and KCl) from the same general taste category (salt, sweet, sour) can vary widely. This variation in the responses to related stimuli could be the result of a number of factors including anion effects (for salts and acids) as well as nongustatory physiological processes (e.g., as renal control of blood osmolarity). Zoo Biol 20:1-13, 2001. Copyright 2001 Wiley-Liss, Inc.

Journal Article↗

[Variability of serum zinc concentration and taste acuity in denture wearers].

The zinc appears to play a significant roles in enzymatic activities as well as taste qualities, and it has been given considerable attention to the decreased serum zinc concentration patients who has been suffering from changes in taste acuity. There is, however, no report regarding the influence of the zinc concentration related to the denture wearers taste qualities. This study was undertaken to elucidate the correlation between serum zinc concentration and taste acuity in denture wearers. Total of 66 subjects were selected on 35 male and 31 female, aged 22 to 81 years. Within 66 subjects, 16 male and 18 female were denture wearers on aged 35 to 81 years. Serum zinc levels were made using atomic-absorption flame spectrophotometry, and taste thresholds were tested using electrogustometer on the anterior and posterior part of the tongue and on the soft palate. The results were as follows: 1. Significant decrease in serum zinc concentration with advancing age were obtained in both male and female subjects (Male: Y = 123.1-0.4 X, R = -0.67, p less than 0.01, Female: Y = 103.5-0.2 X, R = -0.37, p less than 0.05, where Y is serum zinc concentration in micrograms/dl and X is age in years). 2. Significant increase in taste-thresholds in every area with advancing age were obtained in both male and female subjects. 3. Denture wearers showed low value of serum zinc concentration (Male: 90.7 micrograms/dl, Female: 91.7 micrograms/dl) compared to young subjects (Male: 110.8 micrograms/dl, Female: 102.6 micrograms/dl). 4. Denture wearers showed high value of taste thresholds (Anterior part of the tongue: 18.8 dB, Posterior part of the tongue: 15.8 dB, Soft palate: 18.9 dB) compared to young subjects (Anterior part of the tongue: 6.6 dB, Posterior part of the tongue: 7.6 dB, Soft palate: 8.8 dB).

Adult↗

Temperature coefficients of the electrical thresholds of taste sensations.

Each papilla in an enlarged photograph of the tip of the tongue was identified electrically as belonging to one of the four basic taste sensations. The temperature coefficient of the threshold for electrical stimulation was observed for single papillae. The results seem to divide the four basic taste sensations into two different groups: sour-salty and sweet-bitter. This is the same division that has been reported with other methods.

Acids↗

Abnormalities of taste sensation in cancer patients.

In fifty patients with cancer, subjective and objective correlates of anorexia of malignancy were studied. Decreased taste was reported by 25 patients, and an aversion for meat was reported by 16 patients. The decreased taste symptom correlated with an elevated taste threshold for sweet (sucrose), and the symptom of meat aversion correlated with a lowered taste threshold for bitter (urea). The likelihood of having a taste abnormality increased with increasing extent of disease, but not with histologic type of neoplasm. Patients with an abnormality of taste had an increased incidence of weight loss compared with patients with normal taste, even though many in the latter group had other causes of weight loss. These observations suggest that an abnormality of taste may be one determinant of the anorexia of malignancy. Better understanding of the anorexia in the cancer patient may contribute to the care of the patient.

Adult↗

Amiloride increases sodium chloride taste detection threshold in rats.

The epithelial sodium-channel blocker amiloride has been shown to inhibit sodium responses in the 7th cranial nerve of the rat. In the signal detection task used in this study, amiloride (100 microM) treatment raised the NaCl threshold by approximately 1 log10 unit. The inhibition constant for amiloride was 1 microM at 0.013 M NaCl. Because the NaCl intake of adult rats has been shown to be related to the level of dietary NaCl exposure early in development, rats were exposed by way of maternal diet to 1 of 3 diets (0.1% NaCl, n = 8; 1.0% NaCl, n = 8; 3.0% NaCl, n = 9) from conception through weaning, to determine whether this treatment affects taste sensitivity. At Postnatal Day 30, rats were placed on 1.0% NaCl chow. This treatment did not affect NaCl detection or amiloride sensitivity in adulthood. The amiloride-induced shifts in NaCl sensitivity functions imply that the transcellular sodium transduction pathway is necessary for normal NaCl detection in the rat.

Amiloride↗

Changes in patients' taste acuity after Roux-en-Y gastric bypass for clinically severe obesity.

OBJECTIVE: Patients who have undergone Roux-en-Y gastric bypass (RYGB) for clinically severe obesity often report an aversion to sweet foods and meat. This study was designed to determine whether changes in taste acuity occur after RYGB. DESIGN: This prospective, repeated measures trial evaluated acuity for sweet (sucrose) and bitter (urea) tastes, zinc status, and reported changes in taste perceptions in patients undergoing RYGB for weight reduction. SUBJECTS: Taste acuity and serum zinc level were measured in 14 subjects, 6 men and 8 women (mean preoperative body mass index [calculated as kg/m2] = 60.8 +/- 11.8 and mean age = 38.4 +/- 6 years), before surgery and 6 and 12 weeks after surgery. Inquiries regarding taste preferences were made at each postoperative visit with specific reference to sweets and meat. Serum zinc level was measured at the same visit. A noncontrolled comparison group of 4 subjects who were consuming a very-low-calorie diet also underwent taste acuity testing at similar intervals. MAIN OUTCOME MEASURES: The main outcome measures were recognition taste thresholds, serum zinc levels, and taste preference changes. STATISTICAL ANALYSIS: Analysis of variance with repeated measures over time, Pearson correlation coefficients, and post hoc analysis of variance were used to analyze data. RESULTS: Mean recognition thresholds for sucrose were 0.047 +/- 0.03 mol/L preoperatively and fell significantly to 0.024 +/- 0.01 and 0.019 +/- 0.01 mol/L at 6 and 12 weeks postoperatively, respectively. Overall, there were no significant differences in taste thresholds for urea over time; a significant difference was noted, however, in the pattern of change for urea between patients who reported an aversion to meats and those who did not. Zinc concentrations did not change during the study. APPLICATION/CONCLUSIONS: At 6 weeks postoperatively, all patients reported that foods tasted sweeter, and they modified food selection accordingly. Six patients reported an aversion to meats associated with increased nausea and vomiting. Acuity for sweet and bitter tastes may need to be considered when planning dietary modifications for patients undergoing RYGB.

Adult↗

[Contribution of linoleic acid to the bitter taste of poppy seeds (Papaver somniferum)].

In lipids isolated from poppy seeds which tasted "burning-bitter" the off-taste was associated with the free fatty acids fraction. In this fraction linoleic acid predominates, while oxidized fatty acids were among the minor constituents. The taste threshold of linoleic acid emulsified in water with monolinolein lies in the range of 4.0-6.0 mumol/ml. On the basis of its high concentration and relatively low taste threshold we conclude that free linoleic acid contributes significantly to the "burning-bitter" off-taste in poppy seeds.

Chromatography, Gel↗

[Investigation about the taste of di, tri- and tetrahydroxy fatty acid].

Two diastereomeric 9, 10-dihydroxystearic acids, four diasteromeric 9,10,12-trishydroxystearic acids, a mixture of diastereomeric 9,10,12,13-tetrahydroxystearic acids, a mixture of 9.12,13,-trihydroxy-10 trans- and 9,10,13-trihydroxy-11-trans-octadecenoic acids (tri-OH-mixture from lipoxygenase catalysis) and the hydrogenated tri-OH mixture were tested for bitter taste. Only the tri - and tetrahydroxy acids are bitter. The taste thresholds of the saturated tri- and tetrahydroxy acids are in the range from 1.0--4.3 micron ol/ml. There are no significant differences in the taste thresholds between the four diastereomeric 9,- 10,12-trihydroxy acids. The double bond in the trihydroxy acids from the lipoxygenase catalysis enhances the bitter taste 3-fold.

Humans↗