Associations between taste and smell alterations and diabetes-related comorbidities among US adults: the National Health and Nutrition Examination Surveys 2011-2014

Association between olfactory dysfunction and gustatory dysfunction: evidence from the National Health and Nutrition Examination Survey

Background

Olfactory dysfunction (OD) and gustatory dysfunction (GD) are common among adults, with prevalence increasing significantly in older age groups. Both dysfunctions have negative effects on appetite, nutrition, social functioning and even environmental safety. OD and GD frequently coexist, indicating a possible close association between these conditions. At present, there is a lack of large-sample epidemiological studies on the relationship between OD and GD. Our study aims to investigate the relationship between OD and GD using both measurement and questionnaire data from the 2013-2014 NHANES for US adults aged 40 years and older.

Methods

This cross-sectional study utilized data from the National Health and Nutrition Examination Survey (NHANES). OD and GD were both assessed by measurements and questionnaires. The association between OD and GD was investigated with logistic regression models by adjusting for demographic characteristics, systemic diseases, and diseases of the nose and pharynx. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) are presented.

Results

Participants with complete olfactory and gustatory measurements and questionnaires (n = 2,582) were included. Using whole-mouth measurements, anosmia OD significantly increased the odds of hypogeusia and ageusia GD after adjusting for confounding factors. Similarly, the questionnaire data revealed that OD significantly increased the odds of GD. However, hyposmia OD decreased the odds of hypogeusia GD using the tongue-tip taste measurement.

Conclusion

Our findings highlighted that OD was closely associated with GD in a nationally representative sample of US adults.

Dysgeusia and Chronic Kidney Disease: A Scoping Review

Dysgeusia is a common altered taste perception in chronic kidney disease patients. The study aims to identify available treatments for educating, screening, and clinically managing dysgeusia in this population. A scoping review was conducted following the protocol of Arksey and O'Malley, incorporating the Joanna Briggs Institute methodology, and adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews guidelines. Among the 424 identified records, 13 studies were included. Screening methodologies, educational strategies, particularly a hospital-based program focusing on salt reduction, showed a significant improvement in dysgeusia (P < .001). The identified clinical treatments exclusively included oral zinc supplementation, with dosages ranging from 50 to 220 mg, reporting heterogeneous results not consistent across different studies. The personalized management of dysgeusia associated with chronic kidney disease is crucial, requiring targeted education and treatment protocols to prevent and address nutritional complications such as malnutrition.

The olfactory bulb: A neuroendocrine spotlight on feeding and metabolism

Olfaction is the most ancient sense and is needed for food-seeking, danger protection, mating and survival. It is often the first sensory modality to perceive changes in the external environment, before sight, taste or sound. Odour molecules activate olfactory sensory neurons that reside on the olfactory epithelium in the nasal cavity, which transmits this odour-specific information to the olfactory bulb (OB), where it is relayed to higher brain regions involved in olfactory perception and behaviour. Besides odour processing, recent studies suggest that the OB extends its function into the regulation of food intake and energy balance. Furthermore, numerous hormone receptors associated with appetite and metabolism are expressed within the OB, suggesting a neuroendocrine role outside the hypothalamus. Olfactory cues are important to promote food preparatory behaviours and consumption, such as enhancing appetite and salivation. In addition, altered metabolism or energy state (fasting, satiety and overnutrition) can change olfactory processing and perception. Similarly, various animal models and human pathologies indicate a strong link between olfactory impairment and metabolic dysfunction. Therefore, understanding the nature of this reciprocal relationship is critical to understand how olfactory or metabolic disorders arise. This present review elaborates on the connection between olfaction, feeding behaviour and metabolism and will shed light on the neuroendocrine role of the OB as an interface between the external and internal environments. Elucidating the specific mechanisms by which olfactory signals are integrated and translated into metabolic responses holds promise for the development of targeted therapeutic strategies and interventions aimed at modulating appetite and promoting metabolic health.