The Association between Salt Taste Perception, Mediterranean Diet and Metabolic Syndrome: A Cross-Sectional Study

The Mediterranean diet and periodontitis: A systematic review and meta-analysis

Periodontitis is a severe oral health condition that affects the soft tissue and bone supporting the teeth. The Mediterranean diet has been proposed as a potential contributor to reducing the risk of periodontitis. This systematic review and meta-analysis aims to explore the association between adherence to the Mediterranean diet and periodontitis. A comprehensive literature search from 1992 to January 2024 was conducted across multiple databases, including PubMed, Scopus, Web of Science, and Google Scholar. The included studies were clinical trials, randomized controlled trials, and observational studies that evaluated the impact of the Mediterranean diet on periodontitis. Data extraction and quality assessment of the included studies were performed using standardized protocols. A meta-analysis was conducted to combine effect sizes from multiple studies. This review included seven studies, comprising one cohort study, five cross-sectional studies, and one randomized controlled trial. While some studies reported a potential link between Mediterranean diet adherence and periodontitis, the overall analysis did not demonstrate a significant association. The meta-analysis revealed an Odds Ratio (95 % Confidence Interval) of 0.77 (0.58, 1.03) for the association between adherence to the Mediterranean diet and periodontitis (p = 0.08). This systematic review and meta-analysis found no statistically significant association between periodontitis and Mediterranean diet adherence. Future research should prioritize the implementation of rigorous clinical studies with longer follow-up periods to better understand the causal association between the Mediterranean diet and periodontitis. Observational studies with larger sample sizes are needed to establish more conclusive evidence regarding the impact of dietary patterns on periodontal health.

The Obese Taste Bud study: Objectives and study design

AIMS

Taste modifies eating behaviour, impacting body weight and potentially obesity development. The Obese Taste Bud (OTB) Study is a prospective cohort study launched in 2020 at the University of Leipzig Obesity Centre in cooperation with the HI-MAG Institute. OTB will test the hypothesis that taste cell homeostasis and taste perception are linked to obesity. Here, we provide the study design, data collection process and baseline characteristics.

MATERIALS AND METHODS

Participants presenting overweight, obesity or normal weight undergo taste and smell tests, anthropometric, and taste bud density (TBD) assessment on Day 1. Information on physical and mental health, eating behaviour, physical activity, and dental hygiene are obtained, while biomaterial (saliva, tongue swap, blood) is collected in the fasted state. Further blood samples are taken during a glucose tolerance test. A stool sample is collected at home prior to Day 2, on which a taste bud biopsy follows dental examination. A subsample undergoes functional magnetic resonance imaging while exposed to eating-related cognitive tasks. Follow-up investigations after conventional weight loss interventions and bariatric surgery will be included.

RESULTS

Initial results show that glycated haemoglobin levels and age are negatively associated with TBD, while an unfavourable metabolic profile, current dieting, and vegan diet are related to taste perception. Olfactory function negatively correlates with age and high-density lipoprotein cholesterol.

CONCLUSION

Initial findings suggest that metabolic alterations are relevant for taste and smell function and TBD. By combining omics data from collected biomaterial with physiological, metabolic and psychological data related to taste perception and eating behaviour, the OTB study aims to strengthen our understanding of taste perception in obesity.

Impact of 4-week of a restricted Mediterranean diet on taste perception, anthropometric, and blood parameters in subjects with severe obesity

Introduction

The study of taste functionality and its relation to human health is receiving growing attention. Obesity has been reported to cause alterations in sensory perception regarding system functionality and preferences. However, a small body of research addresses tastes perception and its modification with the achievement of body mass reduction through surgical intervention. Much fewer efforts have been made to evaluate the impact of mild restrictive nutritional intervention on gustatory functions. Thus, the objectives of this study were to determine if a dietary intervention of 4 weeks following a restricted balanced Mediterranean diet would affect the sweet and salty taste thresholds of subjects with severe obesity and could influence their anthropometric and blood parameters.

Methods

Fifty-one patients with severe obesity (F: 31; age: 43.7 ± 12.5; BMI = 47.6 ± 1.0) were enrolled in the study. The recognition threshold for sweet and salty taste and anthropometric and blood parameters were assessed before and after the 4-week weight loss program.

Results and Discussion

The Mediterranean diet has proven to be an effective treatment, significantly improving all anthropometric and blood parameters (p < 0.05) after 4 weeks of intervention. Moreover, the hypo-sodium treatment associated with the diet significantly improved the salty threshold (p < 0.001). No changes were detected for the sweet threshold. Collectively, these data highlight that dietary treatment might impact taste perception differently. Therefore, a taste-oriented nutritional intervention could represent a novel approach to developing more individualized, taste-oriented follow-up interventions to maintain sustainable and long-term weight loss.

The Effects of Acute Sleep Curtailment on Salt Taste Measures and Relationships with Energy-Corrected Sodium Intake: A Randomized Cross-Over Trial with Methodology Validation

(1) Background: Sleep may be a factor that influences the taste-dietary intake relationship. The effect of sleep on salt taste measures has not been adequately studied, and no standardized methodology has been developed for measuring salt taste preference. (2) Methods: A sweet taste forced-choice paired-comparison test was adapted and validated to determine salt taste preference. In a randomized cross-over trial, participants slept a curtailed night (33% reduction in sleep duration) and a habitual night, confirmed by a single-channel electroencephalograph. Salt taste tests were conducted the day after each sleep condition using five aqueous NaCl solutions. One 24-h dietary recall was obtained after each taste test. (3) Results: The adapted forced-choice paired-comparison tracking test reliably determined salt taste preference. No changes in salt taste function (intensity slopes: p = 0.844) or hedonic measures (liking slopes: p = 0.074; preferred NaCl concentrations: p = 0.092) were observed after the curtailed sleep condition compared to habitual sleep. However, sleep curtailment disrupted the association between liking slope and energy-corrected Na intake (p < 0.001). (4) Conclusions: The present study serves as the first step toward more standardized taste assessments to facilitate comparison between studies and suggests accounting for sleep when exploring taste-diet relationships.

Oral Exposure to Sodium Chloride without Subsequent Consumption Does Not Alter Salt Taste Function in Adults: A Cross-Over Intervention Study

BACKGROUND

Reduction in dietary sodium increases salt taste sensitivity; however, non-oral sodium supplementation does not, suggesting that oral exposure is more important for modulating taste perception than consumption without tasting.

OBJECTIVE

Using psychophysical methods, we assessed the effect of a two-week intervention involving oral exposure to a tastant without consumption on modulating taste function.

METHODS

In a cross-over intervention study, n = 42 adults (age, mean ± SD: 29.7 ± 8.0 years) completed 4 intervention treatments requiring participants to rinse their mouths with 30 mL of a tastant, 3 times daily for 2 weeks. Treatments included oral exposure to 400 mM sodium chloride (NaCl), monosodium glutamate (MSG), monopotassium glutamate, and sucrose. Participants' taste function for salty, umami, and sweet [detection threshold (DT), recognition threshold (RT), and suprathreshold (ST)], and the glutamate-sodium discrimination status was evaluated before and after the tastant treatments. Effects of the interventions on taste function were assessed by using linear mixed models including treatment, time, and treatment x time interactions as fixed effects; significance was set at P > 0.05.

RESULTS

There was no treatment × time interaction on DT and RT for all tastes assessed (P > 0.05). The only change in ST was following the NaCl intervention, participants' salt ST decreased at the highest concentration (400 mM) compared with the pre-NaCl treatment taste assessment (mean difference (MD): -0.052 [95% CI: -0.093, -0.010] labeled magnitude scale, P = 0.016). Compared with the pre-MSG treatment taste assessment, participants improved their ability to perform the glutamate-sodium discrimination task after the MSG intervention (MD:1.64 [95% CI: 0.395, 2.878] correct discrimination tasks, P = 0.010).

CONCLUSION

Saltiness of an adult's free-living diet is unlikely to influence salt taste function, as oral exposure without consumption to a salt concentration greater than normally found in food, only attenuated taste responses to highly salty stimuli. This provides preliminary evidence that regulating salt taste function may require a coordinated response between oral activation and consumption of sodium.

Adherence to the Mediterranean Diet Association with Serum Inflammatory Factors Stress Oxidative and Appetite in COVID-19 Patients

Background and Objectives: The Mediterranean diet's bioactive components are suggested to strengthen the immune system and to exert anti-inflammatory actions. This study investigated the association between adherence to the Mediterranean diet with serum inflammatory factors, total antioxidant capacity, appetite, and symptoms of COVID-19 patients. Materials and Methods: This cross-sectional study was conducted among 600 Iranian COVID-19 patients selected by a simple random method. The ten-item Mediterranean diet adherence questionnaire was used to assess diet adherence. At the beginning of the study, 5 cc of blood was taken from all patients for measurement of serum interleukin 1β) IL-1β), tumor necrosis factor (TNF-α), malondialdehyde (MDA), high sensitivity C-reactive protein (hs-CRP) and total antioxidant capacity (TAC). A human ELISA kit with serial number 950.090.096 produced by the Diaclone Company was used to test this cytokine using the sandwich ELISA method. Results: One hundred and five patients presented a high adherence and 495 patients presented a low adherence to the Mediterranean diet. The incidence of fever, cough, diarrhea, taste changes, and pneumonia severity index were significantly lower in patients who adhered to the Mediterranean diet more than other patients. Serum levels of tumor necrosis factor (5.7 ± 2.1 vs. 6.9 ± 2.8 p = 0.02), interleukin 1 beta (3.2 ± 0.02 vs. 4.9 ± 0.01 p = 0.02), high-sensitivity C-reactive protein (17.08 ± 4.2 vs. 19.8 ± 2.5 p = 0.03), and malondialdehyde (5.7 ± 0.2 vs. 6.2 ± 0.3 p = 0.02) were significantly lower in patients who adhered more to the Mediterranean diet than other patients. Conclusion: The Mediterranean diet can improve the symptoms and elevated serum inflammatory factors in COVID-19 patients, so clinical trial studies are suggested to confirm this effect.

The impact of injury of the chorda tympani nerve during primary stapes surgery or cochlear implantation on taste function, quality of life and food preferences: A study protocol for a double-blind prospective prognostic association study

BACKGROUND

The chorda tympani nerve (CTN) is a mixed nerve, which carries sensory and parasympathetic fibres. The sensory component supplies the taste sensation of the anterior two-thirds of the ipsilateral side of the tongue. During middle ear surgery the CTN is exposed and frequently stretched or sacrificed, because it lacks a bony covering as it passes through the middle ear. Injury may cause hypogeusia, ageusia or altered taste sensation of the ipsilateral side of the tongue. To date, there is no consensus regarding which type of CTN injury (sacrificing or stretching), during middle ear surgery, leads to the least burden for the patient.

METHODS

A double-blind prospective prognostic association study was designed in a single medical centre in the Netherlands to determine the effect of CTN injury on postoperative taste disturbance and quality of life. 154 patients, who will undergo primary stapes surgery or cochlear implantation will be included. The taste sensation, food preferences and quality of life of these patients will be evaluated preoperatively and at one week, six weeks and six months postoperatively using the Taste Strip Test, Electrogustometry, supplementary questionnaire on taste disturbance, Macronutrient and Taste Preference Ranking Task, Appetite, Hunger and Sensory Perception questionnaire and Questionnaire of Olfactory Disorders to assess the association of these outcomes with CTN injury. Evaluation of olfactory function will only take place preoperatively and at one week postoperatively using the Sniffin' Sticks. The patient and outcome assessor are blinded to the presence or absence of CTN injury.

DISCUSSION

This study is the first to validate and quantify the effect of chorda tympani nerve injury on taste function. The findings of this study may lead to evidence-based proof of the effect of chorda tympani injury on taste function with consequences for surgical strategies.

TRIAL REGISTRATION

Netherlands Trial Register NL9791. Registered on 10 October 2021.

Inter-individual characteristics on basic taste recognition thresholds in a college-aged cohort: potential predictive factors

Studying nutritional status from the perspective of taste sensitivity, rather than only dietary patterns, may provide new insights into the role of taste receptor signaling in the development of metabolic-associated diseases. In this cross-sectional study, we investigated the possible influence of sociodemographic (sex and smoking habit) and clinical variables (dental cavities, missing teeth, sinusitis, rhinitis, body mass index and metabolic high prevalence family antecedent diseases) on tastant (sucrose, monosodium glutamate, sodium chloride, citric acid, quinine, sinigrin, phenylthiocarbamide) recognition thresholds (RTs) in a college-aged cohort (n = 397). Predictive models for the tastant RTs were generated and a higher sucrose RT was found in females than in males, while sinusitis and rhinitis explained sucrose and sodium chloride RTs. Smoking habit was not an important predictive factor of taste sensitivity, although its long-term influence on RTs remains unclear. Additionally, a positive correlation was found between all the tastant RTs studied. Although results did not show a clear pattern, the statistical approach employed should prove useful in future studies of predictors of taste sensitivity.

Umami detection threshold among children of different ethnicities and its correlation with various indices of obesity and blood pressure

Sensitivity to savory taste has been linked to high consumption of savory foods and increased risks of obesity and hypertension. However, there are limited studies that investigate whether obesity indices are correlated with the differences in umami taste perception, particularly in children. This study aimed to investigate the umami detection threshold among children of different ethnicities and the threshold's correlation with obesity indices and blood pressure. A total of 140 subjects were recruited and consisted of a nearly equal distribution of children from three main ethnicities (37.2% Malays, 31.4% Chinese, 31.4% Indians). Umami detection threshold was measured using the two-alternative, forced-choice staircase procedure. Body weight, height, waist circumference and blood pressure of children were measured. Body composition was assessed using bioelectrical impedance analysis (BIA). Mean umami detection threshold was 1.22 ± 1.04 mM and there were no observable differences attributable to the subjects' ethnicities. Body fat percentage was negatively correlated (r = −0.171, p < 0.05), while lean body mass percentage was positively correlated (r = 0.171, p < 0.05) with umami detection threshold. These findings revealed that umami taste perception correlated with children's body composition, but not other anthropometric indicators and blood pressure. Future studies should explore the correlation between umami taste perception and children's total dietary intake.

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The average umami detection threshold of Malaysian children was 1.22 ± 1.04 mM.

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No gender or ethnic differences in umami detection thresholds were observed.

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Umami taste perception was correlated only with children's body composition.

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It is worth to consider umami taste threshold in designing low-sodium food products.

Glutamate-Sodium Discrimination Status in Adults Is Associated with Salt Recognition Threshold and Habitual Intake of Discretionary Food and Meat: A Cross-Sectional Study

Umami non-discriminators (NDs) are a sub-group of the population with a reduced ability to discriminate between monosodium glutamate (MSG) and sodium chloride (NaCl) compared to umami discriminators (UDs). No research has investigated umami and salty taste perception associations across detection threshold (DT), recognition threshold (RT), and suprathreshold intensity perception (ST) or the habitual dietary intake of ND. Adults (n = 61, mean age of 30 ± 8 years, n = 40 females) completed taste assessments measuring their DT, RT, and ST for salty, umami (MSG and monopotassium glutamate (MPG)), and sweet tastes. To determine the umami discrimination status, participants completed 24 triangle tests containing 29 mM NaCl and 29 mM MSG, and those with ≥13 correct identifications were considered UDs. Habitual dietary intake was recorded via a food frequency questionnaire. NDs made up 14.8% (n = 9) of the study population, and UDs made up 85.2% (n = 52). NDs were less sensitive to salt at RT (mean step difference: -1.58, p = 0.03), and they consumed more servings of meat and poultry daily (1.3 vs. 0.6 serves, p = 0.006); fewer servings of discretionary food (1.6 vs. 2.4, p = 0.001); and, of these, fewer salty discretionary foods (0.9 vs. 1.3, p = 0.003) than NDs. Identifying these NDs may provide insight into a population at risk of the overconsumption of discretionary foods and reduced intake of protein-rich meat foods.

Vegans, vegetarians and omnivores differ in nutrient hedonics, salt and sweet preference and flavouring

BACKGROUND

Dietary content can influence taste responses. Therefore, we compared nutrient hedonics (liking foods by nutrient content), and seasoning, including taste responses to the prime flavours salt and sweet in 30 vegan, 37 vegetarian and 56 omnivore men and women.

METHODOLOGY

Questionnaires and taste tests examined macronutrient and electrolyte intake and hedonics, seasoning, salt and sweet preferences and psychophysical taste responses.

RESULTS

Compared to omnivores, vegans had lower protein, Ca⁺⁺, Na⁺ intake, and increased carbohydrate (CHO) intake. Independently of intake, hedonics for protein Ca⁺⁺ and Na⁺ were reduced and increased for CHO. Psychophysical responses to NaCl and sucrose also differed slightly, vegans and vegetarians scoring high concentrations of sucrose as more intense, Vegans reported more sweetening and less salting of food, added more sucrose to a test tea, less salt to a test soup, but did not differ in seasoning with oil or hot spice.

PRINCIPAL CONCLUSIONS

Habitual vegan, vegetarian and omnivore diets may alter taste responses to nutrient content and salt and sweet, the latter more pronounced in vegan and vegetarian women. Recognising diet-dependent changes in taste hedonics can inform diets and products.

Characterizing Adolescents' Dietary Intake by Taste: Results From the UK National Diet and Nutrition Survey

The taste of foods is a key factor for adolescents' food choices and intakes, yet, exploring taste characteristics of adolescents' diet is limited. Using food records for 284 adolescents (10–19 years old) from the National Diet and Nutrition Survey (NDNS), year 9 (2016–2017), we classified diets according to taste. Tastes for each food consumed were generated from a previous survey that asked participants to allocate one main taste to each food. Responses from that survey were processed and included in a Hierarchical Cluster Analysis (HCA) to identify taste clusters. The resulting tastes were then applied to the adolescents' food records in the NDNS. For each individual, the total weight of food per day for each taste was calculated. A linear regression model was used to explore dietary intakes from each taste. Findings reveal that adolescents' daily energy intake was highest (34%) from foods that taste sweet. Sweet foods were the main calorie contributors at breakfast and daytime snacking, while energy intake from neutral-tasting foods was higher at lunch and dinner. Sweet food intake was significantly positively associated with higher energy, sugar, and fat intakes. For each percentage increase in sweet foods, energy increased by 10 kcal/d (95% CI 6, 15; P &lt; 0.01). Savory food intake was lower in carbohydrates and sugars; with neutral food consumption inversely associated with energy, carbohydrate, sugars, saturated and total fat. Higher salty food intake was linked to higher saturated fat as well as sodium consumption. Sweet and neutral foods dominate the UK adolescent diet, followed by savory tastes. Balancing the contributions of different tasting foods could assist in improving adolescent diet quality.

Association between age-related sensory impairment with sarcopenia and its related components in older adults: a systematic review

Sensory impairments and sarcopenia are both highly prevalent age-related conditions, with the former having been postulated to contribute to the pathogenesis of the latter condition. Confirming this hypothesis may therefore help to better inform strategies for early treatment and intervention of sarcopenia. We performed a systematic review of the current literature examining the relationships between four major sensory impairments [vision (VI), hearing (HI), smell (SI), and taste (TI)] with (i) sarcopenia; and (ii) its associated components (low handgrip strength, slow gait speed, and low muscle mass). PubMed, EMBASE, CINAHL, and Cochrane Library databases were searched for observational studies investigating the relationship of VI, HI, SI, and TI with sarcopenia, low handgrip strength, slow gait speed, and low muscle mass, in adults aged 50 years or older, from inception until 24 May 2021. The risk of bias of the included studies was assessed using the Newcastle-Ottawa Scale. This study was registered with PROSPERO, reference CRD42021247967. Ten cross-sectional and three longitudinal population-based studies of community-dwelling adults (N = 68 235) were included, with five studies investigating more than one sensory impairment. In total, 8, 6, 3, and 1 studies investigated the relationship between VI, HI, SI, and TI and sarcopenia and its related components, respectively. Follow-up duration for the longitudinal studies ranged from 4 to 11 years. All studies had a low or moderate risk of bias. We found that the presence of VI and SI, but not TI, independently increased the odds of sarcopenia. In addition, VI and SI were each independently associated with low muscle mass; and VI, HI, and SI were each independently associated with slow gait speed. However, we found inconclusive evidence for the associations between VI, HI and SI, and low handgrip strength. Our systematic review suggests a potential association between the presence of single or multiple sensory impairments and a greater likelihood of sarcopenia and/or deficits in its associated components, especially for VI, HI, and SI. Prospective studies are needed to untangle the relationship between sensory impairment and sarcopenia to better inform clinical guidelines for disease prevention and management.

Associations between Taste Perception Profiles and Empirically Derived Dietary Patterns: An Exploratory Analysis among Older Adults with Metabolic Syndrome

Taste perception is a primary driver of food choices; however, little is known about how perception of all five tastes (sweet, salt, sour, bitter, umami) collectively inform dietary patterns. Our aim was to examine the associations between a multivariable measure of taste perception—taste perception profiles—and empirically derived dietary patterns. The cohort included 367 community-dwelling adults (55–75 years; 55% female; BMI = 32.2 ± 3.6 kg/m²) with metabolic syndrome from PREDIMED-Plus, Valencia. Six taste perception profiles were previously derived via data-driven clustering (Low All, High Bitter, High Umami, Low Bitter and Umami, High All But Bitter, High All But Umami); three dietary patterns were derived via principal component analysis (% variance explained = 20.2). Cross-sectional associations between profiles and tertials of dietary pattern adherence were examined by multinomial logistic regression. Overall, there were several significant differences in dietary pattern adherence between profiles: the vegetables, fruits, and whole grains pattern was significantly more common for the High All But Umami profile (OR range for high vs. low adherence relative to other profiles (1.45–1.99; 95% CI minimum lower, maximum upper bounds: 1.05, 2.74), the non-extra virgin olive oils, sweets, and refined grains pattern tended to be less common for Low All or High Bitter profiles (OR range: 0.54–0.82), while the alcohol, salty foods, and animal fats pattern tended to be less common for Low Bitter and Umami and more common for High All But Bitter profiles (OR range: 0.55–0.75 and 1.11–1.81, respectively). In conclusion, among older adults with metabolic syndrome, taste perception profiles were differentially associated with dietary patterns, suggesting the benefit of integrating taste perception into personalized nutrition guidance.

Comparing Taste Detection Thresholds across Individuals Following Vegan, Vegetarian, or Omnivore Diets

Taste perception plays an undisputed role in food choice, preference, and intake. Recent literature suggests that individual diet and taste sensitivity may have a reciprocal relationship, with evidence highlighting that specific diets can alter taste sensitivities. Commensurate with an increase in the prevalence of plant-based diets is the importance of investigating if following a vegetarian or vegan diet is associated with altered taste sensitivities. In this study, the taste detection thresholds for six compounds (i.e., sweet-sucrose, salty-sodium chloride, sour-citric acid, umami-monosodium glutamate, MSG, bitter-caffeine, and metallic-iron II sulphate heptahydrate) were measured for a total of 80 healthy, New Zealand European females aged 18-45 years old, who were categorised as 22 vegans, 23 vegetarians, and 35 omnivores. Each participant's detection thresholds to these compounds were measured across two sessions, using an ascending Method of Limits with two-alternative-forced-choice presentations. The threshold data were analysed using both multivariate (i.e., principal component analysis) and univariate (i.e., ANCOVA) techniques to assess differences across the three types of diet. Multivariate analysis suggested that the omnivore group had distinct taste sensitivity patterns across the six compounds compared to the vegetarian or vegan group, which were characterised by relatively heightened sensitivity to metallic and lowered sensitivity to sweetness. Furthermore, the vegetarian group was shown to have a significantly lower detection threshold to bitterness (i.e., caffeine) relative to the other two groups (p < 0.001). While future study is required to investigate the cause-effect relationship between individual diet and taste sensitivities, the present study provides a systematic evaluation of taste sensitivities of individuals following distinct diets. This information may be valuable to future gustatory research as well as to food manufacturers.

Data-Driven Clustering Approach to Derive Taste Perception Profiles from Sweet, Salt, Sour, Bitter, and Umami Perception Scores: An Illustration among Older Adults with Metabolic Syndrome

BACKGROUND

Current approaches to studying relations between taste perception and diet quality typically consider each taste-sweet, salt, sour, bitter, umami-separately or aggregately, as total taste scores. Consistent with studying dietary patterns rather than single foods or total energy, an additional approach may be to study all 5 tastes collectively as "taste perception profiles."

OBJECTIVE

We developed a data-driven clustering approach to derive taste perception profiles from taste perception scores and examined whether profiles outperformed total taste scores for capturing individual variability in taste perception.

METHODS

The cohort included 367 community-dwelling adults [55-75 y; 55% female; BMI (kg/m2): 32.2 ± 3.6] with metabolic syndrome from PREDIMED-Plus, Valencia. Cluster analysis identified subgroups of individuals with similar patterns in taste perception (taste perception profiles); quantitative criteria were used to select the cluster algorithm, determine the optimal number of clusters, and assess the profiles' validity and stability. Goodness-of-fit parameters from adjusted linear regression evaluated the individual variability captured by each approach.

RESULTS

A k-means algorithm with 6 clusters best fit the data and identified the following taste perception profiles: Low All, High Bitter, High Umami, Low Bitter & Umami, High All But Bitter and High All But Umami. All profiles were valid and stable. Compared with total taste scores, taste perception profiles explained more variability in bitter and umami perception (adjusted R2: 0.19 vs. 0.63, respectively; 0.40 vs. 0.65, respectively) and were comparable for sweet, salt, and sour. In addition, taste perception profiles captured differential perceptions of each taste within individuals, whereas these patterns were lost with total taste scores.

CONCLUSIONS

Among older adults with metabolic syndrome, taste perception profiles derived via data-driven clustering may provide a valuable approach to capture individual variability in perception of all 5 tastes and their collective influence on diet quality. This trial was registered at https://www.isrctn.com/ as ISRCTN89898870.

Obesity-induced taste dysfunction, and its implications for dietary intake

The incidence of obesity has dramatically increased in recent years, and poses a public health challenge for which an effective and scalable intervention strategy is yet to be found. Our food choices are one of the primary drivers of obesity, where the overconsumption of energy from foods high in fat and sugar can be particularly problematic. Unfortunately, these same foods also tend to be highly palatable. We select foods more on their sensory properties than on any other factor, such as price, convenience, or healthfulness. Previous evidence from human sensory studies has suggested a depressed sense of taste in panelists with obesity. Evidence from animal models also demonstrates a clear deficiency in taste buds occurring with obesity, suggesting that damage to the taste system may result from an obese state. In this review only taste, as opposed to smell, will be examined. Here we seek to bring together evidence from a diverse array of human and animal studies into taste response, dietary intake, and physiology, to better understand changes in taste with obesity, with the goal of understanding whether taste may provide a novel target for intervention in the treatment of obesity.

Does Each Menstrual Cycle Elicit a Distinct Effect on Olfactory and Gustatory Perception?

The obesity pandemic has brought forth a scientific interest in food intake and sensory perception interactions. Olfactory perception and gustatory perception are very complex and under the influence of many factors, including the menstrual cycle. This study aims to clarify conflicting findings on the influence of the menstrual cycle on olfactory and gustatory perception. Women were assessed during four consecutive phases of one complete cycle (mid-follicular, ovulatory, mid-luteal, and late luteal phases (N = 21)), in contrast to women measured across the same phases belonging to two menstrual cycles (N = 29). Additional control groups were men (N = 17), postmenopausal women (N = 14), oral contraceptive users (N = 10), and women with an anovulatory cycle (N = 8). Olfactory threshold, odor discrimination, and identification were tested using the "Sniffin Sticks" test kit. Suprathreshold intensity and hedonic ratings for sweet, salty, sour, and bitter solutions were assessed. One-way ANOVA and ANOVA for repeated measurements was applied in the analysis, along with linear and trigonometric data fitting and linear mixed models. Linear increases in olfactory discrimination, identification, and overall olfactory performance were observed only in women followed across a complete menstrual cycle. Compared to other groups, these women displayed a cyclic pattern characterized by a predilection for sweet solution; reduced distaste for salty and sour solutions; and increased intensity perception of salty, sour, and bitter solutions towards the end of the cycle. These results suggest that a distinct hormonal milieu of a complete menstrual cycle may be affecting both olfactory and gustatory perception.

Have Lifestyle Habits and Psychological Well-Being Changed among Adolescents and Medical Students Due to COVID-19 Lockdown in Croatia?

OBJECTIVE

To investigate dietary habits, sleep and psychological well-being of adolescents and medical students during COVID-19 lockdown in Split, Croatia.

METHODS

We surveyed 1326 students during 2018 and 2019, and compared their responses with 531 students enrolled in May 2020. Perceived stress, quality of life (QoL), happiness, anxiety, and optimism were assessed as proxies of psychological well-being, using general linear modelling.

RESULTS

We found no substantial differences in dietary pattern between pre-lockdown and lockdown periods, including the overall Mediterranean diet (MD) adherence. However, the MD pattern changed, showing increased adherence to the MD pyramid for fruit, legumes, fish, and sweets, while cereals, nuts, and dairy intake decreased during COVID-19 lockdown. A third of students reported weight loss during lockdown, 19% reported weight gain, while physical activity remained rather stable. The most prominent change was feeling refreshed after a night's sleep, reported by 31.5% of students during lockdown vs. 8.5% before; median length of sleep duration increased by 1.5 h. Lockdown significantly affected QoL, happiness, optimism (all p < 0.001), and perceived stress in students (p = 0.005). MD adherence was positively correlated with QoL and study time, and negatively with TV and mobile phone use in pre-lockdown period (all p < 0.001). Interestingly, higher MD adherence was correlated with less perceived hardship and greater happiness and QoL during lockdown.

CONCLUSION

These insights provide valuable information for tailored interventions aimed at maintaining healthy lifestyle in young population. Given the numerous beneficial effects associated with MD adherence, modification of lifestyle through application of lifestyle medicine deserves a priority approach.