Enhanced sweet taste perception in obesity: Joint analysis of gustatory data from multiple studies

Impact of obstructive sleep apnea syndrome on olfactory and gustatory capacity

Only a few studies have investigated olfactory function in patients with obstructive sleep apnea syndrome (OSAS) using psychophysical testing, and there is a scarcity of data regarding taste evaluation in the existing literature. The primary objectives of this study were to assess both smell and taste in patients with OSAS and to explore the correlation between the severity of symptoms and sensory perception. A total of 85 OSAS patients and a control group comprising 81 subjects were enrolled. Initial assessments included anamnesis, nasal endoscopy, and the completion of questionnaires (Epworth Sleepiness Scale, Visual Analogue Scale, Questionnaire of Olfactory Disorders, and the importance of olfaction questionnaire). The diagnosis of OSAS was confirmed by polysomnography, while nasal airflow was evaluated using rhinomanometry. Olfaction was assessed using the Sniffin' Sticks test, and the Threshold-Discrimination-Identification (TDI) score was calculated. Taste evaluation was conducted in a subgroup of participants (42 patients, 38 controls) using taste strips. The mean TDI score was 31 ± 5.6 for OSAS patients and 35 ± 4.6 for controls, indicating a significant difference (P < 0.001). Similarly, the taste score was 7 ± 3.0 for OSAS patients and 12.6 ± 3.2 for controls (P < 0.001). No correlations were observed between TDI and Apnea Hypopnea Index (AHI) (r = -0.12; P = 0.28), as well as between the taste score and AHI (r = -0.31; P = 0.22). However, a weak but significant correlation between TDI score and Epworth Sleepiness Scale was detected (r = -0.05; P = 0.002). The study revealed a significant decrease in sensory perception among patients with OSAS, though open questions persist about the pathophysiology.

Association between physical activity and taste-The advantage of increased intensity for some but not all individuals

INTRODUCTION

Taste is a key sensory modulator of energy intake, and while the effects of acute physical activity (PA) on taste have been recently confirmed, its chronic effects remain poorly documented.

METHODS

Data were extracted from the NHANES database, including salty and bitter taste tests, moderate PA (MPA) and vigorous PA (VPA) levels, and anthropometric data. Binary logistic regressions were conducted, and odds ratios (ORs) represent the association between physical activity level and successful taste tests.

RESULTS

3,114 participants (51.5% women, mean age 58.5±11.9 years, mean BMI 29.5±7.0 kg/m2) were analyzed. For the tongue tip test, the frequency of VPA was associated with a better score for the bitter and total taste test, while duration of VPA was associated with a better score for the bitter, salty, and total taste test (OR [1.01-1.06], p<0.05). For the whole mouth test, MPA frequency improved the bitter taste score (OR = 1.06, p = 0.01) while VPA frequency and duration were associated with better scores for bitter, salty, and total taste tests (OR [1.01-1.15], p<0.05). These findings were distinctively influenced by weight status and gender, with males and individuals without obesity mainly beneficiating from an active lifestyle.

PERSPECTIVES

This study underlines the link between PA, particularly its frequency and intensity, and improved taste preservation. These findings emphasize the potential benefits of regular VPA for optimizing taste perception, although questions remain regarding the advantages for individuals with obesity and the lack of association observed in women who might already have a preserved profile.

Striatal dopamine D2-like receptors availability in obesity and its modulation by bariatric surgery: a systematic review and meta-analysis

There is significant evidence linking a 'reward deficiency syndrome' (RDS), comprising decreased availability of striatal dopamine D2-like receptors (DD2lR) and addiction-like behaviors underlying substance use disorders and obesity. Regarding obesity, a systematic review of the literature with a meta-analysis of such data is lacking. Following a systematic review of the literature, we performed random-effects meta-analyses to determine group differences in case-control studies comparing DD2lR between individuals with obesity and non-obese controls and prospective studies of pre- to post-bariatric surgery DD2lR changes. Cohen's d was used to measure effect size. Additionally, we explored factors potentially associated with group differences in DD2lR availability, such as obesity severity, using univariate meta-regression. In a meta-analysis including positron emission tomography (PET) and single-photon emission computed tomography (SPECT) studies, striatal DD2lR availability did not significantly differ between obesity and controls. However, in studies comprising patients with class III obesity or higher, group differences were significant, favoring lower DD2lR availability in the obesity group. This effect of obesity severity was corroborated by meta-regressions showing inverse associations between the body mass index (BMI) of the obesity group and DD2lR availability. Post-bariatric changes in DD2lR availability were not found, although a limited number of studies were included in this meta-analysis. These results support lower DD2lR in higher classes of obesity which is a more targeted population to explore unanswered questions regarding the RDS.