Substance and tongue-region specific loss in basic taste-quality identification in elderly adults

Does presbygeusia really exist? An updated narrative review

This review critically assessed the existence of presbygeusia, i.e., the impairment in taste perception occurring in the elderly, as a natural part of the aging process and its potential clinical implications. Several factors might contribute to age-related taste alterations (TAs), including structural changes in taste buds, alterations in saliva composition, central nervous system changes, and oral microbiota dysbiosis. A comprehensive literature review was conducted to disentangle the effects of age from those of the several age-related diseases or conditions promoting TAs. Most of the included studies reported TAs in healthy elderly people, suggesting that presbygeusia is a relatively frequent condition associated with age-related changes in the absence of pathological conditions. However, the impact of TAs on dietary preferences and food choices among the elderly seems to be less relevant when compared to other factors, such as cultural, psychological, and social influences. In conclusion, presbygeusia exists even in the absence of comorbidities or drug side effects, but its impact on dietary choices in the elderly is likely modest.

Time-frequency analysis of gustatory event related potentials (gERP) in taste disorders

In taste disorders, the key to a correct diagnosis and an adequate treatment is an objective assessment. Compared to psychophysical tests, EEG-derived gustatory event-related potentials (gERP) could be used as a less biased measure. However, the responses identified using conventional time-domain averaging show a low signal-to-noise ratio. This study included 44 patients with dysgeusia and 59 healthy participants, who underwent a comprehensive clinical examination of gustatory function. gERPs were recorded in response to stimulation with two concentrations of salty solutions, which were applied with a high precision gustometer. Group differences were examined using gERP analyzed in the canonical time domain and with Time-Frequency Analyses (TFA). Dysgeusic patients showed significantly lower scores for gustatory chemical and electrical stimuli. gERPs failed to show significant differences in amplitudes or latencies between groups. However, TFA showed that gustatory activations were characterized by a stronger power in controls than in patients in the low frequencies (0.1-4 Hz), and a higher desynchronization in the alpha-band (8-12 Hz). Hence, gERPs reflect the altered taste sensation in patients with dysgeusia. TFA appears to enhance the signal-to-noise ratio commonly present when using conventional time-domain averaging, and might be of assistance for the diagnosis of dysgeusia.

The Influence of Nutritional Status and Sleep Quality on Gustatory Function in Older Adults

Background and Objectives: Age-related declines in taste function are common. Taste acuity can be affected by nutritional status and sleep quality. This research aims to examine the effect of nutritional status and sleep quality on gustatory function in community-dwelling older adults. Materials and Methods: This cross-sectional study included 119 community-dwelling older adults (50.4% of whom were female). The gustatory function was evaluated using four liquid taste solutions (sweet, bitter, sour, and salty) each at four different concentrations and the Mini Nutritional Assessment (MNA) and Pittsburgh Sleep Quality Index (PSQI) was applied. Additionally, anthropometric measurements were taken. Results: The mean scores on the gustatory test for the sweet, bitter, sour, and salty tastes were 2.11 ± 1.27, 2.12 ± 1.03, 2.28 ± 1.03, and 1.98 ± 1.41, respectively. There were significant differences according to gender, polypharmacy, nutritional status, and sleep quality in identifying sweet tastes (all p < 0.05). It was also found that females and participants without polypharmacy had better scores for bitter tastes. When the gustatory functions were evaluated according to BMI classification, it was determined that underweight participants had a higher sour taste score than the obese ones. Multiple regression analysis revealed that age, MNA score, PSQI score, and gender accounted for a total of 20.4% of the variance in the sweet taste score. Conclusions: Determining the relationship between taste function, nutritional status, and sleep quality in older adults is important in terms of developing new strategies for older adults who have these problems.

Assessment of Taste Function

Taste disorders, impacting well-being and physical health, can be caused by many etiologies including the use of medication. Recently, taste disturbance is also considered as one of the predominant symptoms of COVID-19 although its pathogenesis requires further research. Localized taste disorders may be overlooked considering that whole-mouth taste perception is insured through several mechanisms. Individuals often fail to discern taste from flavor, and interviews/surveys are insufficient to properly assess taste function. Hence, various taste assessment methods have been developed. Among them, psychophysical methods are most widely applied in a clinical context. Less-biased electrophysiological, imaging, or morphological methods are used to a much lesser degree. Overall, more research is needed in the field of taste.

Taste Sensitivity of Elderly People Is Associated with Quality of Life and Inadequate Dietary Intake

Aging has been implicated in the alteration of taste acuity. Diet can affect taste sensitivity. We aimed to investigate the types of tastes altered in elderly Korean people and factors associated with taste alteration in relation to dietary intake and other factors. Elderly participants (≥65 years) and young adults were assessed to determine their recognition thresholds (RT) for sweet, salty, bitter, sour, and umami tastes. Elderly participants were further surveyed for dietary intake and non-nutritional factors. Five taste RTs were correlated with age, but only four taste RTs, except sweetness, differed between the elderly participants and young adults. Inadequate intake of iron, thiamin, folic acid, zinc, and phosphorus among the elderly participants was related to elevated taste RT levels, except for bitter taste. In both correlation and regression analyses, only salty and sour RTs were associated with energy, iron, thiamin, fiber, vitamin C, and riboflavin levels in the elderly participants. The elderly participants’ taste RTs exhibited strong associations with quality of life (QOL) but showed partial relationships with physical activity, number of medicine intakes, social gatherings, and education. Taste sensitivity may decrease with age, which is further influenced by insufficient dietary intake, especially iron and thiamin, and QOL.

Avaliação do paladar de idosos e sua relação com estado nutricional e hábitos alimentares

Objetivos: avaliar a prevalência de disgeusia (distorção ou diminuição do paladar) e a associação com o estado nutricional e as práticas alimentares em um grupo de idosos, assim como identificar os gostos mais afetados e preservados.Métodos: estudo transversal com amostra recrutada no Centro de Lazer para idosos no município de Porto Alegre, RS. Avaliou-se o paladar, através de tiras gustativas (“tastestrips”), e o estado nutricional, através do Índice de Massa Corporal. As práticas alimentares foram investigadas através de questionário. Para análise estatística utilizou-se os testes qui-quadrado e ANOVA, com nível de significância de p <0,05.Resultados: foram avaliados 62 idosos (84% feminino, média de 70±7,6 anos), prevalência de disgeusia foi 19,4% (n=12), detectou-se 58% de sobrepeso (n=36), 40,5% de eutrofia (n=25) e 1,5% de baixo peso (n=1), não sendo encontrada associação entre alteração de paladar e estado nutricional (p=0,397). Cerca de 55% dos idosos apresentaram consumo elevado de sódio. Não houve diferença na média de pontos para o gosto ácido entre os idosos que temperam a salada com limão ou vinagre e os que não o fazem (p=0,054 e p=0,935, respectivamente). A média de pontos para o gosto salgado não diferiu entre os que preparam as refeições com temperos ricos em sódio e os que não os utilizam (p=0,055). O doce foi o gosto mais preservado, enquanto o ácido mostrou-se mais reduzido.Conclusões: apesar de evidências contrárias, não se identificou impacto das alterações de paladar sobre o estado nutricional e as práticas alimentares. Ainda assim, novos estudos que incluam essas variáveis se fazem necessários.

Impact of the severity of dementia due to Alzheimer's disease on the gustatory sensitivity of older persons

OBJECTIVE

To evaluate the association between the severity of dementia and taste recognition abilities in older persons with Alzheimer's disease (AD).

METHODS

Anthropometric measurements were performed and body mass index was used to determine the nutritional status. The taste strips were used to test gustatory functions of the five basic tastes (sweet, salty, sour, bitter and umami).

RESULTS

A total of 30 healthy younger subjects, 30 healthy older subjects, 37 with mild stage AD and 23 with moderate stage AD were recruited. The older subjects with moderate AD showed a significant reduction of taste, less recognition of bitter and salty taste (score: 10.6 ± 2.6; 2.6 ± 0.9; 1.7 ± 1.5) when compared to older people without cognitive impairment (score: 13.3 ± 1.8; 3.4 ± 0.9; 3.2 ± 0.9), and less recognition of sweet taste (score: 2.9 ± 1.2) when compared to subjects with mild stage AD (score: 3.6 ± 0.8). Impaired recognition of salty taste was detected since the early stages of AD. Among the factors that possibly influence gustatory function, a significant correlation was detected between taste ability and age, medication intake, mini-mental state examination and the nutritional status.

CONCLUSION

The severity of dementia is directly associated with greater impairment of taste sensitivity, especially among older subjects with moderate stage disease.

Detection thresholds for quinine, PTC, and PROP measured using taste strips

PURPOSE

In clinical practice, when ability to perceive bitter taste is studied, quinine is preferred to phenylthiocarbamide (PTC) and 6-n-propylthiouracil (PROP) as taste stimulus, because many subjects are genetically non-tasters for PTC/PROP. However, it is poorly known how sensitive anterior (front) and posterior (back) parts of the tongue are to different bitter tastants that are detected by different bitter taste receptors (TAS2Rs). In the present study, we aimed to characterize sensitivity to bitter taste at front and back parts of tongue.

METHODS

We measured thresholds for quinine, PTC, and PROP using the "taste strips", employing seven concentrations of each stimulus both at front and back parts of tongue in 203 healthy participants (56% females, mean age 28 years).

RESULTS

Our data confirmed the hypothesis that the inability to perceive quinine was less frequent than the inability to perceive PTC and PROP: People can still perceive the bitter taste of quinine even if they are "non-tasters" for PROP/PTC. As expected, strong correlations between PTC and PROP thresholds were observed. Interestingly, correlations between thresholds for quinine and PTC/PROP also emerged. Overall, the detection thresholds were lower when measured at front part of the tongue.

CONCLUSIONS

Our data suggest that determining taster status for quinine using paper "taste strips", applied to front part of the tongue, represents a suitable method for the screening for ageusia for bitter taste.

Assessment of taste functions in allergic rhinitis patients undergoing allergen-specific immunotherapy

BACKGROUND

We evaluated taste functions of patients with perennial allergic rhinitis (AR) before and after allergen-specific immunotherapy (AIT).

METHODS

The study was designed as a prospective clinical study in our tertiary care hospital. Patients (n = 21) who were diagnosed with perennial AR on the basis of physical examination, skin prick test of at least 3* for HDM allergen and treated with AIT were enrolled in this study. A control group (n = 21) was selected from patients who were given intranasal steroids (INS) for perennial AR. Both groups had self-reported hyposmia and subjective loss of the sense of taste before treatment. Taste strips (Burghart, Wedel, Germany) were used for the taste identification scores before and after 6 months treatment.

RESULTS

A total of 42 subjects were included, with a mean age of 24.1 ± 7.9 years (range 15-43 years). Overall, the AIT group showed more of an improvement of taste function, observed in the total average test scores, compared to the INS group (p < 0.05), but no change was detected between the groups before treatment. No difference was found for the bitter taste scores between the study groups (p = 0.053).

CONCLUSION

Subcutaneous allergen immunotherapy resulted in more of an improvement in taste function than intranasal steroids. Further studies are needed.

Differences in the Density of Fungiform Papillae and Composition of Saliva in Patients With Taste Disorders Compared to Healthy Controls

This study investigated the relation of the fungiform taste papillae density and saliva composition with the taste perception of patients suffering from diagnosed taste disorders. For this purpose, 81 patients and 40 healthy subjects were included. Taste was measured by means of regional and whole mouth chemosensory tests, and electrogustometry. Olfaction was assessed using the Sniffin Sticks. Fungiform papillae were quantified using the "Denver Papillae Protocol for Objective Analysis of Fungiform Papillae". In addition, salivary parameters [flow rate, total proteins, catalase, total anti-oxidative capacity (TAC), carbonic anhydrase VI (caVI), and pH] were determined and the Beck Depression Inventory was administered. Patients showed less taste papillae compared to healthy subjects. The number of papillae correlated with total taste strip score and salivary flow rate. Regarding salivary parameters, the flow rate, protein concentration, and TAC of patients were higher compared to controls. In addition, salivary flow rate, protease, caVI, and catalase values correlated with the summed taste strip score. Regarding various taste disorders, salty-dysgeusia patients showed the lowest taste test scores compared to those with bitter or metal-dysgeusia. Olfactory function of patients was significantly worse compared to healthy controls. This difference was most pronounced for ageusia patients. Compared to controls, patients also exhibited higher depressive symptoms. The density of fungiform papillae seemed to be positively associated with taste perception. Furthermore, patients exhibited changes in saliva composition (higher salivary flow rate, increased protein concentration, proteolysis, and TAC) compared to controls indicating that assessment of saliva may be critical for the diagnostic procedure in taste disorders.

Taste loss in the elderly: Possible implications for dietary habits

Aging may coincide with a declining gustatory function that can affect dietary intake and ultimately have negative health consequences. Taste loss is caused by physiological changes and worsened by events often associated with aging, such as polypharmacy and chronic disease. The most pronounced increase in elderly people's detection threshold has been observed for sour and bitter tastes, but their perception of salty, sweet, and umami tastes also seems to decline with age. It has often been suggested that elderly people who lose their sense of taste may eat less food or choose stronger flavors, but the literature has revealed a more complicated picture: taste loss does not appear to make elderly people prefer stronger flavors, but nutrition surveys have pointed to a greater consumption of sweet and salty foods. Real-life eating habits thus seem to be more influenced by other, social and psychological factors. Elderly gustatory function is worth investigating to identify dietary strategies that can prevent the consequences of unhealthy eating habits in the elderly. This paper discusses age-related changes in taste perception, focusing on their consequences on food preferences, and pointing to some strategies for preserving appropriate dietary habits in elderly people.

Age-related changes of gustatory function depend on alteration of neuronal circuits

Studies on age-related gustatory function report a reduction of the taste function, but the degeneration of the peripheral papillae alone cannot explain this reduction. In the present study, we apply psychophysics and gustatory event-related potentials (gERPs) to explore age-related differences in the processing of gustatory information as indicated by the cerebral sources of the gERP. A total of 96 subjects (47 female), subdivided into four groups with increasing age, participated in the study. After olfactory and gustatory screening for normal function, the subjects were invited to two sessions of gERP acquisition. They received a randomized combination of five isointense basic tastants that were presented at a medium level. At the same time, we recorded scalp electroencephalography (EEG) from 128 scalp locations. Psychophysical testing for smell and taste function exhibited a significant decrease with age. Topographical analyses of the EEG delineated four basic topographical maps that explained the processing of taste in the pre-decline age range, with sources inside the relevant gustatory areas. The age-related change of gustatory processing was associated with the absence of a specific map with sources inside the cerebellum and posterior insula, and the temporal broadening of a map with sources in the bilateral inferior frontal gyrus. These results confirm the hypothesis that the reduction of taste function with aging is not only due to degradation of gustatory peripheral tissues but is also related to different neural signatures in the central nervous system.

Taste sensitivity of adults and elderly persons

Abstract Objective: To compare the taste sensitivity of adults and elderly people, considering nutritional status, smoking and alcohol consumption. Method: Forty-six volunteers participated in the research, thirteen of whom were adult employees of a company from the food industry and thirty-three of whom were elderly residents of three Long-Term Care Facilities for the Elderly from the Vale do Taquari (Taquari Valley). They responded to a structured questionnaire about their socioeconomic data and use of medication, smoking and alcohol consumption, and underwent a nutritional evaluation and a taste sensitivity test. The taste sensitivity test was applied at three different concentrations for every flavor, with 4 drops dripped on the tongue of the volunteer, who described the level of perceived palatability, giving a score of 0-5. Data was analyzed through statistical analysis using the Statistical Package SPSS 20.0, considering a value of significance of p<0.05. Result: a reduction in the taste sensitivity of the elderly persons was noted for the sweet and sour solutions, in comparison with adults, as the majority of the elderly people demonstrated lower sensitivity scale scores for the citric acid solution in concentration 1 (p=0.004) and concentration 2 (p=0.049) and sucrose in concentration 3 (p=0.026). Conclusion: Elderly people had a lower perception of the sweet and sour flavors than adults. Moreover, nutritional status, gender, alcohol consumption, smoking and medication use were not significantly associated with the taste perception of the individuals evaluated.

Decreased microbial diversity and Lactobacillus group in the intestine of geriatric giant pandas (Ailuropoda melanoleuca)

It has been established beyond doubt that giant panda genome lacks lignin-degrading related enzyme, gastrointestinal microbes may play a vital role in digestion of highly fibrous bamboo diet. However, there is not much information available about the intestinal bacteria composition in captive giant pandas with different ages. In this study, we compared the intestinal bacterial community of 12 captive giant pandas from three different age groups (subadults, adults, and geriatrics) through PCR-denaturing gradient gel electrophoresis (DGGE) and real-time PCR analysis. Results indicated that microbial diversity in the intestine of adults was significantly higher than that of the geriatrics (p < 0.05), but not significant compared to the subadults (p > 0.05). The predominant bands in DGGE patterns shared by the twelve pandas were related to Firmicutes and Proteobacteria. Additionally, in comparison to healthy individuals, antibiotic-treated animals showed partial microbial dysbiosis. Real-time PCR analyses confirmed a significantly higher abundance of the Lactobacillus in the fecal microbiota of adults (p < 0.05), while other bacterial groups and species detected did not significantly differ among the three age groups (p > 0.05). This study revealed that captive giant pandas with different ages showed different intestinal bacteria composition.

Association of Sodium Excretion With Metabolic Syndrome, Insulin Resistance, and Body Fat

Sodium intake was reported to be related to metabolic syndrome (MS). Although a strong association between sodium intake and blood pressure (BP) has been reported, the relationship between sodium intake and other components of MS is unknown. An observational study of 18,146 adults in the Korea National Health and Nutrition Examination Survey IV-V databases (2008-2011) was performed. Estimates of 24-h sodium excretion were made from a single fasting urine sample. A significant positive association was found between sodium excretion and systolic BP and between sodium excretion and diastolic BP in participants with and without hypertension after adjusting for multiple covariates (P < 0.001 for trend). The relationship between triglyceride or glucose levels and sodium excretion was linear (P < 0.005). In both men and women, a positive relationship between sodium excretion and waist circumference and an inverse relationship between sodium excretion and high-density lipoprotein were found (P ≤ 0.001). Body fat percentage, body fat mass, and insulin level were positively related to sodium excretion (P ≤ 0.001), and HOMA-IR was significantly associated with sodium excretion (P < 0.05). The risk of MS was elevated 1.279-fold in the second quartile of sodium excretion (95% CI, 1.088-1.504, P = 0.003), 1.479-fold in the third quartile (95% CI, 1.262-1.734; P < 0.001), and 1.929-fold in the highest quartile (95% CI 1.654-2.249, P <  .001) compared with the lowest quartile. Sodium intake is significantly associated with all components of MS, body fat, and insulin resistance. Therefore, a high-salt diet is a significant risk factor for MS.

Early influences on the development of food preferences

The ability to perceive flavors begins in utero with the development and early functioning of the gustatory and olfactory systems. Because both amniotic fluid and breast milk contain molecules derived from the mother's diet, learning about flavors in foods begins in the womb and during early infancy. This early experience serves as the foundation for the continuing development of food preferences across the lifespan, and is shaped by the interplay of biological, social, and environmental factors. Shortly after birth, young infants show characteristic taste preferences: sweet and umami elicit positive responses; bitter and sour elicit negative responses. These taste preferences may reflect a biological drive towards foods that are calorie- and protein-dense and an aversion to foods that are poisonous or toxic. Early likes and dislikes are influenced by these innate preferences, but are also modifiable. Repeated exposure to novel or disliked foods that occurs in a positive, supportive environment may promote the acceptance of and eventually a preference for those foods. Alternatively, children who are pressured to eat certain foods may show decreased preference for those foods later on. With increasing age, the influence of a number of factors, such as peers and food availability, continue to mold food preferences and eating behaviors.

Taste loss in hospitalized multimorbid elderly subjects

BACKGROUND

Loss of the sense of taste is common among older people. Morbidities and polypharmacy may contribute to the age-related decline in gustatory function. The aims of the present study were to investigate taste perception in elderly hospitalized patients by comparing their taste recognition thresholds with those of healthy, free-living elderly individuals and to identify potential determinants of taste loss.

METHODS

The participants in this observational study were 55 elderly patients hospitalized in the acute geriatric section of the Department of Medical and Surgical Sciences at Padova University and 41 free-living individuals aged older than 65 years, randomly recruited from elderly people attending mild fitness programs at public gymnasiums in Padova. Data were collected on nutrition, health, cognitive, and functional status for all participants. Gustatory capabilities were assessed using aqueous solutions of sucrose, sodium chloride, citric acid, and quinine hydrochloride (representing sweet, salty, sour, and bitter stimuli, respectively), and taste recognition thresholds were measured in both groups.

RESULTS

In comparison with the free-living elderly subjects, those in hospital were significantly less able to recognize the taste of citric acid (P < 0.05). Low citric acid sensitivity was independently associated with advanced age (≥75 years; odds ratio [OR] 3.01, 95% confidence interval [CI] 1.01-9.82), polypharmacy (number of prescribed drugs ≥ 4; OR 2.74, 95% CI 1.01-7.72), and poor nutritional status (as assessed by Mini Nutritional Assessment score < 23.5; OR 5.08, 95% CI 1.76-14.6).

CONCLUSION

Because gustatory impairment may reduce a person's appetite and lead to inadequate dietary intake, compensatory nutritional measures, such as the use of flavor-enhanced foods, should be strongly encouraged, particularly in the hospital setting.

Can age-related CNS taste differences be detected as early as middle age? Evidence from fMRI

Middle-aged Americans have higher obesity rates than any other age group, yet little is known about age-related changes in central taste function during this critical time. Research on taste and aging has primarily focused on psychophysical responses, and on older adults. Central taste processing in middle-age has not been investigated. In the current study, we compared functional magnetic resonance imaging (fMRI) activation of young and middle-aged adults during hedonic evaluation of a sweet and a bitter taste. A 2 (age group) by 2 (tastant) analysis of variance (ANOVA) on fMRI activation revealed: (1) a main effect of age (young adults>middle-aged adults) in the bilateral anterior cingulate, lentiform nucleus, putamen, caudate, and right precentral gyrus; (2) a main effect of taste (sweet>bitter) in the bilateral pre- and postcentral gyri, anterior cingulate and right middle frontal gyrus; qualified by (3) an age-by-taste interaction. Further inspection of the age-by-taste interaction revealed that there was a significant effect of age (greater activation in young adults) in sensory (insula) and reward (lentiform nucleus) regions during hedonic evaluation of the sweet taste; however, there was no age effect in the bitter taste condition. Further, young adults had greater responses during hedonic evaluation of sucrose than of caffeine in several sensory and motor processing regions (pre- and postcentral gyri, insula), but there were no taste-related differences in activation in the middle-aged adults. We speculate that these results might reflect early age-related differences in central taste processing that occur prior to deficits in gustatory function observed in old age, and this might have important implications for weight changes that occur during middle-age.

Gustatory and olfactory dysfunction in older adults: a national probability study

BACKGROUND

Olfactory and gustatory functions have not been well characterized in older adults in the US. Consequently, their relationships to sociodemographic characteristics, as well as physical and mental health, were studied in a large national probability sample using brief validated tests of chemosensory function.

METHODS

A five-odour identification test and taste-impregnated strips of filter paper (sweet, sour, bitter, and salty) assessed the ability to identify chemosensory stimuli.

RESULTS

Severe gustatory dysfunction was more prevalent than severe olfactory dysfunction. Age, education and sex were independently associated with performance on both the olfactory and gustatory identification tasks. Higher scores were associated with female sex, higher level of education, and lower age. Odour identification scores exhibited a positive, albeit weak, correlation with BMI, and food-related odours were better identified than non-food odours. In addition, odour identification performance was also negatively associated with depressive symptoms.

CONCLUSIONS

These data demonstrate a high prevalence of severe gustatory and, to a somewhat lesser extent, olfactory dysfunction in a population-based sample and demonstrate that even brief tests are capable of detecting correlations between both chemical senses and relevant health measures outside a clinical setting.

A study about the frequency of taste disorders

Although 5% of the general population exhibit a functional anosmia, little is known about the frequency of gustatory disorders. Whenever taste function has been tested within large sociodemographic studies, so far only short test versions were applied making the interpretation difficult. Using two psychophysical taste tests, the validated "taste strips" and suprathreshold taste solutions of the four basic tastes sweet, sour, salty and bitter we investigated 761 healthy subjects within the age range of 5-89 years. Prior to testing, all subjects rated their taste function. According to testing with the taste strips, 5.3% scored below the result considered as hypogeusia. All four taste sprays were correctly identified by 82.3% of all subjects. Results of the two taste tests correlated positively (r = 0.33, p < 0.001), and there was a significant negative correlation between age and test results. However, we never observed complete ageusia. Misinterpretations of tastes were surprisingly common. In summary, hypogeusia was present in 5% while complete ageusia seems to be very rare, in contrast to misinterpretations of tastes.

Normative data for a solution-based taste test

The aim of our study was to study gustatory function in a large portion of the general population using liquid tastants, extending previous research. Further, we investigated the test-retest reliability of the test used. Data from 944 healthy subjects were used (498 women and 446 men, mean age 45 years; age range 5-90 years). For lateralized assessment of gustatory function, liquid taste solutions were used with different concentrations of each tastant (sweet 0.03, 0.1, 0.4, 2 g/mL sucrose solution; sour 0.01, 0.05, 0.1, 0.15 mL citric acid; salty 0.025, 0.075, 0.15, 0.36 mL sodium chloride solution; bitter 0.0002, 0.0005, 0.001, 0.01 mL quinine hydrochloride). A drop (approximately 20 µL) of liquid tastant was applied on the right side or on the left side of the anterior/posterior third of the extended tongue. The taste test had a good test-retest reliability r (304) = 0.78 (P < 0.001) for the total score and r (304) = 0.77 (P < 0.001) for the right-sided measures and r (304) = 0.75 (P < 0.001) for the left-sided measures, respectively. Gustatory sensitivity was found to decrease with age; women were more sensitive to gustatory stimuli than men. Irrespective of the sex-related differences, the total score at the 10th percentile was 28 in subjects younger than 15 years, 26.1 for ages from 16 to 35 years, 25 for ages from 36 to 55 years, and 24 for subjects older than 56 years of age. In conclusion, this test is recommended for clinical assessment of the ability to taste. The test provides reliable data, which is easy to handle, inexpensive, timesaving and can be self-made.

Overview of the physiological changes and optimal diet in the golden age generation over 50

Basically, our lifespan is determined genetically. However, several other parameters such as the environment, lifestyle and diet have a high impact on living in the best of health. Many older persons suffer from various diseases, which often cannot be avoided; however, their development can be postponed and symptoms can be mitigated by a balanced diet, moderate physical activity as well as a healthy lifestyle. These diseases are, for example, sarcopenia (degenerative loss of muscle mass), osteoporosis (decomposition of bone structure), digestive restrictions, sensory impairment, water imbalance or a compromised immune system. Psychological modifications, obesity and loss of weight also commonly occur in older adults. To define an adequate diet for elderly between the ages 50 and 80 is difficult, even impossible, because the nutritional requirements differ between the dynamic quinquagenarian and the frailer eighty-year-old. However, several studies have shown that sufficient consumption of high-quality proteins, calcium, vitamin D, anti-oxidative food compounds, water as well as adapted energy values and nourishment with high-nutrient density in combination with physical activity especially help one to remain healthy to a great age. The cornerstone of healthy ageing is the maintenance of normal bodyweight in order to prevent the development of diseases such as osteoporosis, coronary heart disease or diabetes type 2. This publication will review the physiological changes that occur with advanced age and consequential nutritional recommendations for elderly persons.

Olfactory and gustatory function in irritable bowel syndrome

Irritable bowel syndrome (IBS) is the most common, functional disorder diagnosed by gastroenterologists. It is still unclear whether IBS has a central etiology, e.g., hyperreactivity of the brain, or a peripheral etiology, e.g., stimulation of olfactory/gustatory receptors on enterochromaffin cells, followed by serotonin release and changed gut motility. Testing the odor identification (ID), odor discrimination (DIS) and odor threshold (THR) as well as the total taste and the taste qualities "sweet", "sour", "salty" and "bitter" should be of help for determining the etiology. To our knowledge, this is the first study investigating the olfactory/gustatory function in IBS patients. The olfactory/gustatory function of 43 patients (32 women, 11 men) suffering from IBS as defined by the ROME III criteria was investigated by means of validated tests (Sniffin' Sticks and taste strips). Compared to normative data, scores of THR were decreased and scores of ID and DIS were increased in IBS patients. Additionally, when compared to normative data, there was no difference in the taste function of IBS patients. Assuming that THR reflects more the peripheral olfactory function, whereas ID and DIS are influenced by central activity, and that taste did not differ in IBS patients compared to normative data, this supports the idea of a central etiology of IBS.

Perspectives on population-based epidemiological studies of olfactory and taste impairment

Epidemiological studies of the senses of olfaction (smell) and gustation (taste) are needed since impairments in these senses have important implications for health. Only a few attempts have been made to measure the prevalence of olfactory and gustatory or taste dysfunction, and many methodological challenges remain to be addressed. These challenges differ from those faced in studies based in the clinic or research laboratory. Epidemiological studies of smell and taste represent translational research, because they can be used to understand how findings from laboratory or clinical studies apply to the general population. This paper briefly reviews existing methods for "how" to measure smell and taste dysfunction and then illustrates findings based on prior epidemiological studies to indicate "why" we wish to measure smell and taste functioning in population-based samples. Self-reported information collected on smell and taste loss in a national sample, the 1994-1995 Disability Sample (phase I screening) of the National Health Interview Survey, is contrasted with results provided by an exam-based measure of olfactory impairment in an epidemiological study conducted in Beaver Dam, WI. The comparison of self-reported and exam-based measures of smell or taste loss leads to the question of how to best define smell or taste impairment in population samples, since unlike other sensory domains (namely, vision and hearing), there are no internationally accepted standards of impairment for the chemosenses. In addition to highlighting existing epidemiological studies, the current development of an NIH Toolbox of brief exam measures is described. Through this symposium, we hope to advance the nascent field of olfactory and taste epidemiology.

Qualitative and Quantitative Assessment of Taste and Smell Changes in Patients Undergoing Chemotherapy for Breast Cancer or Gynecologic Malignancies

Purpose

Smell and taste changes during chemotherapy are significant complaints of cancer patients. Loss of olfactory/gustatory function can lead to malnutrition, weight loss, and possibly a prolonged morbidity of chemotherapy-induced adverse effects, decreased quality of life, poor compliance, and even decreased therapy response. This prospective study comprehensively investigated, to our knowledge for the first time, smell and taste changes in a cohort of 87 patients undergoing chemotherapy for breast cancer or gynecologic malignancies.

Patients and Methods

Olfactory function was tested using Sniffin' Sticks (Burghart; Wedel, Germany) and gustatory function was tested using taste strips before, during, and immediately and 3 months after chemotherapy.

Results

Olfactory and gustatory function significantly decreased during chemotherapy and recovered almost completely 3 months after chemotherapy. Scores of odor thresholds were affected more than those of discrimination or identification. The olfactory function of older patients was affected more than that of younger patients. There was no difference in the olfactory function during chemotherapy with respect to the chemotherapeutic agent or initial diagnosis (breast or ovarian cancer). Regarding taste, scores of salty taste were affected more than scores of sweet, sour, or bitter taste. The gustatory function did not differ significantly during chemotherapy with respect to age or diagnosis but did differ with respect to the chemotherapeutic agent. Taxane-based chemotherapy caused the most severe disorders.

Conclusion

Chemotherapy has a significant but transient effect on olfactory and gustatory function, possibly causing reduced appetite, a low energy intake, and weight loss. Additional spices and flavoring may compensate for this diminished chemosensory function, enhancing patient compliance and quality of life.