The importance of taste on swallowing function

The world's population is aging. Pneumonia is the leading cause of death among the older adults, with aspiration pneumonia being particularly common. Aspiration pneumonia is caused by a decline in swallowing function. Causes can include age-related sarcopenia of swallowing muscles, cognitive decline, cerebrovascular and other diseases or even changes in individual taste preference. Currently, the main treatment approach for dysphagia is resistance training of swallowing-related muscles. This approach has not been effective and establishment of novel methods are required. In this review, we introduce and discuss the relationship between taste, taste preference, carbonation and swallowing function. Taste and preference improve swallowing function. Recently, it has been shown that a carbonated beverage that combines the functionality of a thickening agent, the appeal of taste, and the stimulation of carbonation improves swallowing function. This may be very useful in the recovery of swallowing function. It is important to note that deliciousness is based not only on taste and preference, but also on visual information such as food form. Umami taste receptors are expressed not only in taste buds but also in skeletal muscle and small intestine. These receptors may be involved in homeostasis of the amino acid metabolic network, i.e., the process of amino acid ingestion, intestine absorption, and storage in skeletal muscle. Proper stimulation of umami receptors in organs other than taste buds may help maintain nutritional status and muscle mass. Umami receptors are therefore a potential therapeutic target for dysphagia.

Effect of storage on the levels of sodium benzoate in soft drinks sold in some Nigerian market with exposure and health risk assessment

Soft drinks consumption is still a controversial issue for public health and public policy, as the influence storage condition impacts taste, color and shelf life. In all, fifty (50) soft drinks samples, acquired from Enugu, Aba, Asaba, Onitsha and Owerri markets in Nigeria, were subjected to four different storage conditions namely: room temperature (RT), refrigerated (RF), 40 °C and 60 °C for 15 days after which they were analyzed for sodium benzoate concentration using HPLC - UV/Vis detector. The results showed on the average that at RT and RF, soft drinks from Aba had the highest concentration of sodium benzoate (98.7 mg/L and 112.9 mg/L) respectively while samples from Asaba had least concentration of 39.9 mg/L and 38.1 mg/L. At increased temperature of 40 °C, the concentration of sodium benzoate increased generally across the sample, while at 60 °C, the levels in all the samples analyzed were either reduced to less than 50% or below detection level, which suggest that degradation of sodium benzoate at this elevated temperature could result in benzene formation, which is a known carcinogen. Carcinogenic and non-carcinogenic risk assessment showed that children are at risk compared to adults due to higher sodium benzoate daily intake leading to high rate of hyperactivity in correlation to malaise.

Effects of Food and Liquid Properties on Swallowing Physiology and Function in Adults

Foods and liquids have properties that are often modified as part of clinical dysphagia management to promote safe and efficient swallowing. However, recent studies have questioned whether this practice is supported by the evidence. To address this, a scoping review was conducted to answer the question: "Can properties of food and liquids modify swallowing physiology and function in adults?" Online search in six databases yielded a set of 4235 non-duplicate articles. Using COVIDENCE software, two independent reviewers screened the articles by title and abstract, and 229 full-text articles were selected for full-text review. One-hundred eleven studies met the inclusion criteria for qualitative synthesis and assessment of risk of bias. Three randomized controlled trials and 108 non-randomized studies were analyzed. Large amounts of variability in instrumental assessment, properties of food and liquids, and swallowing measures were found across studies. Sour, sweet, and salty taste, odor, carbonation, capsaicin, viscosity, hardness, adhesiveness, and cohesiveness were reported to modify the oral and pharyngeal phase of swallowing in both healthy participants and patients with dysphagia. Main swallow measures modified by properties of food and liquids were penetration/aspiration, oral transit time, lingual pressures, submental muscle contraction, oral and pharyngeal residue, hyoid and laryngeal movement, pharyngeal and upper esophageal sphincter pressures, and total swallow duration. The evidence pooled in this review supports the clinical practice of food texture and liquid consistency modification in the management of dysphagia with the caveat that all clinical endeavors must be undertaken with a clear rationale and patient-specific evidence that modifying food or liquid benefits swallow safety and efficiency while maintaining quality of life.

Reversal of the effects of focal suppression on pharyngeal corticobulbar tracts by chemesthesis coupled with repeated swallowing

BACKGROUND

Previous reports suggested the potential benefit of chemesthesis in the form of carbonated water (CW) integrated within dysphagia rehabilitation protocols. Here, we examined the effects of CW within a repeated swallowing protocol following focal suppression to pharyngeal cortical representation as a prelude to its application in dysphagic patients.

METHODS

Fourteen healthy volunteers participated in a 3-arm study. Each participant underwent baseline corticobulbar pharyngeal and thenar motor-evoked potential (MEP) measurements with Transcranial Magnetic Stimulation (TMS). Subjects were then conditioned with 1Hz repetitive (r)TMS to induce focal unilateral suppression of the corticopharyngeal hotspot before randomization to each of three arms with 40 swallows of CW, non-CW and saliva swallowing on separate days. Corticobulbar and thenar MEPs were collected for up to 1 h and analyzed using repeated measures (rm)ANOVA.

RESULTS

A 2-way rmANOVA for Intervention x Time showed a significant effect of Intervention (F_(1,13)  = 7.519, p = 0.017) in both ipsi- and contra-lesional corticopharyngeal projections. Carbonation showed superiority in facilitating change by increasing pharyngeal cortical MEPs compared to non-CW (z = -3.05, p = 0.002) and saliva swallowing (z = -2.6, p = 0.008). No change in thenar representation (control) was observed nor in MEP latencies from both pharyngeal and thenar musculature.

CONCLUSIONS

We conclude that interventional paradigms with CW have the capacity to reverse the effects of a focal suppression with 1Hz rTMS more strongly than non-CW or saliva swallowing alone, producing site specific bi-hemispheric changes in corticopharyngeal excitability. Our data suggest that carbonation produces the effects through a mainly cortical mechanism.

Effects of Carbonation on Swallowing: Systematic Review and Meta-Analysis

OBJECTIVES

The effectiveness of the use of carbonation in preventing penetration/aspiration or enhancing swallowing function in adults remains unclear. This systematic review aimed to evaluate the effectiveness of carbonation on improving swallowing function in adult subjects.

METHODS

Literature published before March 2021 was inspected using MEDLINE, CINAHL, Web of Science Core Collection, The Cochrane Library, Cochrane Central Register of Controlled Trials, and Ichushi-web databases. We searched for intervention studies or randomized control trials considering the effects of carbonated liquids on swallowing function. The risk of bias was assessed using the Cochrane tool for assessing the risk of bias for randomized controlled trials and the Risk of Bias Assessment Tool for Nonrandomized Studies.

RESULTS

The systematic review identified 19 studies with a total of 586 participants. The effects of carbonation on swallowing function are diverse. Overall, most studies showed that carbonation promotes swallowing function compared to other liquids. Five studies were included in the quantitative synthesis. Meta-analysis showed that carbonated liquids prevent aspiration (risk difference [RD] -0.27%, 95% confidence interval [CI] -0.44 to -0.10; I²  = 0%; number needed to treat 3.8, 95% CI 2.2 to 15.0; moderate quality of evidence) when compared to noncarbonated thin liquids. Carbonated liquids also increased the duration of swallowing apnea than did noncarbonated liquids (standardized mean difference 0.25 (mean difference 0.36 seconds), 95% CI 0.03 to 0.47; I²  = 0%; low quality of evidence).

CONCLUSIONS

Carbonation had favorable effects on swallowing function. Further in-depth studies are needed to clarify the benefits of carbonation.

LEVEL OF EVIDENCE

NA Laryngoscope, 2022.

Effects of carbonation of liquids on penetration-aspiration and residue management

Objective

Carbonation as a sensory enhancement strategy for prevention of aspiration of thin liquids has not been thoroughly studied. The aim of our study was to examine the effect of carbonation on penetration–aspiration and pharyngeal residue in dysphagia patients using Fiber-Optic Endoscopic Evaluation of Swallowing (FEES) and to identify parameters associated with a response to carbonation.

Methods

A cross-sectional study of patients undergoing FEES in a dysphagia clinic. Patients were offered 100 cc of dyed water. Penetration–aspiration was scored using the penetration–aspiration scale (PAS). Residue was scored using the Yale Pharyngeal Residue Severity Rating Scale (YPR-SRS). Patients with a PAS ≥ 2 for water were subsequently offered 100 cc of carbonated water. PAS, YPR-SRS and residue clearance were compared between thin and carbonated liquids. Multivariate logistic regression analysis was used to identify predictors for good response to carbonation.

Results

84 patients were enrolled, 77.4% males, with diverse dysphagia etiologies (58.3% neurogenic, 11.9% radiation-induced, 23.8% deconditioning-induced, and 6% neck surgery induced). Median PAS was 7 (IQR 4–8) for thin liquids and 4.5 (IQR 2–8) for carbonated liquids (P = 0.0001). YPR-SRS was reduced for carbonated compared to thin liquids in the vallecula (1.58 ± 0.83 vs 1.76 ± 0.93, P = 0.001) and piriform sinuses (1.5 ± 0.87 vs 1.67 ± 0.9, P = 0.002). 31 patients had improvement in PAS with carbonation. Deconditioning as a dysphagia etiology was found to predict good response to carbonation on multivariate logistic regression analysis.

Conclusion

Carbonation may prevent aspiration and improve residue management for some patients with dysphagia for liquids.

Level of evidence

IV.

Targeting Chemosensory Ion Channels in Peripheral Swallowing-Related Regions for the Management of Oropharyngeal Dysphagia

Oropharyngeal dysphagia, or difficulty in swallowing, is a major health problem that can lead to serious complications, such as pulmonary aspiration, malnutrition, dehydration, and pneumonia. The current clinical management of oropharyngeal dysphagia mainly focuses on compensatory strategies and swallowing exercises/maneuvers; however, studies have suggested their limited effectiveness for recovering swallowing physiology and for promoting neuroplasticity in swallowing-related neuronal networks. Several new and innovative strategies based on neurostimulation in peripheral and cortical swallowing-related regions have been investigated, and appear promising for the management of oropharyngeal dysphagia. The peripheral chemical neurostimulation strategy is one of the innovative strategies, and targets chemosensory ion channels expressed in peripheral swallowing-related regions. A considerable number of animal and human studies, including randomized clinical trials in patients with oropharyngeal dysphagia, have reported improvements in the efficacy, safety, and physiology of swallowing using this strategy. There is also evidence that neuroplasticity is promoted in swallowing-related neuronal networks with this strategy. The targeting of chemosensory ion channels in peripheral swallowing-related regions may therefore be a promising pharmacological treatment strategy for the management of oropharyngeal dysphagia. In this review, we focus on this strategy, including its possible neurophysiological and molecular mechanisms.

Bubbles, Foam Formation, Stability and Consumer Perception of Carbonated Drinks: A Review of Current, New and Emerging Technologies for Rapid Assessment and Control

Quality control, mainly focused on the assessment of bubble and foam-related parameters, is critical in carbonated beverages, due to their relationship with the chemical components as well as their influence on sensory characteristics such as aroma release, mouthfeel, and perception of tastes and aromas. Consumer assessment and acceptability of carbonated beverages are mainly based on carbonation, foam, and bubbles, as a flat carbonated beverage is usually perceived as low quality. This review focuses on three beverages: beer, sparkling water, and sparkling wine. It explains the characteristics of foam and bubble formation, and the traditional methods, as well as emerging technologies based on robotics and computer vision, to assess bubble and foam-related parameters. Furthermore, it explores the most common methods and the use of advanced techniques using an artificial intelligence approach to assess sensory descriptors both for descriptive analysis and consumers' acceptability. Emerging technologies, based on the combination of robotics, computer vision, and machine learning as an approach to artificial intelligence, have been developed and applied for the assessment of beer and, to a lesser extent, sparkling wine. This, has the objective of assessing the final products quality using more reliable, accurate, affordable, and less time-consuming methods. However, despite carbonated water being an important product, due to its increasing consumption, more research needs to focus on exploring more efficient, repeatable, and accurate methods to assess carbonation and bubble size, distribution and dynamics.

Impact of carbonation on neurogenic dysphagia and an exploration of the clinical predictors of a response to carbonation

BACKGROUND

The need for effective compensatory strategies in neurogenic dysphagia management has led to the exploration of sensory enhancement strategies (SES), such as carbonated liquids. Despite some positive findings, evidence related to the efficacy of carbonation as an SES is limited.

AIMS

To determine if carbonated thin liquids reduced dysphagia symptoms and to explore clinical factors associated with response to carbonation.

METHODS & PROCEDURES

Participants (n = 29) with neurogenic dysphagia demonstrating deep penetration or aspiration on thin liquids during videofluoroscopic swallow studies (VFSS) completed a set protocol: discrete sips of non-carbonated thin fluids (DS-NC) followed by discrete sips of carbonated thin fluids (DS-C) and then consecutive sips of carbonated fluids (CS-C). The impact of carbonation was identified through changes to swallow physiology (videofluoroscopy dysphagia scale-VDS) and depth of airway compromise (penetration-aspiration scale-PAS). Demographic variables including genetic taste type, cranial nerve function and key results from the VDS were examined for association with carbonation response using both individual parameter analysis and exploratory cluster analysis.

OUTCOMES & RESULTS

Significant (p < 0.05) improvements in PAS scores were noted in DS-C and CS-C conditions compared with DS-NC. Total VDS score was also significantly (p < 0.05) reduced (i.e., improved function) in the DS-NC condition. Individual variability in response to carbonation was noted and no clear clinical factors associated with carbonation response in the current set of parameters were identified.

CONCLUSION & IMPLICATIONS

Findings support that carbonated thin fluids sometimes result in neurogenic dysphagia symptom reduction. However, identifying the clinical characteristics of patients who may benefit from trials of carbonation needs further investigation.

Effect of carrot puree in vegetable juice on linguapalatal swallowing pressure

This study aimed to ascertain the influence of various amounts (0-30%) of carrot puree (CP) in vegetable juice on linguapalatal swallowing pressure in healthy volunteers. Twenty healthy women (age range: 20-22 years) swallowed a 17-ml drink in a natural state, and linguapalatal swallowing pressure was measured using a special sensor sheet. Peak magnitude (maximum pressure of the tongue pushing on the hard palate), integrated values of linguapalatal swallowing pressure on the waveform, and duration of linguapalatal swallowing pressure were increased with increases in CP concentrations. The total integrated value for 30% CP vegetable juice was larger than that of vegetable juice with no CP. The apparent viscosity of the vegetable juice with a low CP concentration was smaller than that with a high CP concentration at the same shear rate. These results suggest that vegetable juice containing CP affects mechanoreceptor activity in the mouth and generates a neuromotor response.

PRACTICAL APPLICATIONS

This study aimed to ascertain the influence of various amounts of carrot puree (CP) in vegetable juice on linguapalatal swallowing pressure measured by using a special sensor sheet in healthy volunteers. Obtained results of this study clearly showed that vegetable juice containing CP affects the movement of the tongue in maneuvering the bolus. Moreover, the results demonstrated that this effect depended on the concentration of CP in the vegetable juice. These findings are expected to provide clinically valuable data on the effect of mechanical stimulation during the oral stage of swallowing.

Orosensory contributions to dysphagia: a link between perception of sweet and sour taste and pharyngeal delay time

Pharyngeal delay is a significant swallowing disorder often resulting in aspiration. It is suspected that pharyngeal delay originates from sensory impairment, but a direct demonstration of a link between oral sensation and pharyngeal delay is lacking. In this study involving six patients with complaints of dysphagia, taste sensation of the oral tongue was measured and subsequently related to swallowing kinematics. It was found that a response bias for sour taste was significantly correlated with pharyngeal delay time on paste, highlighting oral sensory contributions to swallow motor dysfunctions. Investigating the precise nature of such a link between oral sensation and dysphagia would constitute a basis for understanding the disorder. The results of this study highlight oral sensory contributions to pharyngeal swallow events and provide impetus to examine this link in larger samples of dysphagic patients.

Carbonation as a sensory enhancement strategy: a narrative synthesis of existing evidence

PURPOSE

Sensory enhancement techniques, like other compensatory strategies, aim to reduce dysphagia symptoms. The use of carbonated liquids has been proposed as a possible sensory technique, however to date, there is limited information of its efficacy or guidance for clinical implementation. A narrative synthesis was completed to determine the quality and strength of the evidence base for use of carbonation as a compensatory strategy in dysphagia rehabilitation.

METHODS

From 101 articles initially identified, 14 articles met the study criteria. Eleven papers described the effects of carbonation on swallowing in healthy participants whereas three described the impact of carbonation in dysphagic populations. A narrative synthesis of papers was undertaken given the diversity of identified studies.

RESULTS

Synthesis of findings was challenging given the exploratory phase of most research activity with diverse populations described and extensive differences in research methodologies. There is currently weak, but potentially positive evidence to support using carbonation as a compensatory technique in dysphagia rehabilitation.

CONCLUSION

Despite future potential, existing evidence fails to provide clear direction for the clinical implementation of carbonation. Validation of carbonation use with the dysphagic population requires further research with consistent, controlled methodologies, and larger cohorts of participants to inform potential for dysphagia rehabilitation. Implications for Rehabilitation The use of carbonated liquids has been proposed as a possible sensory enhancement technique which may facilitate changes to swallow physiology. However to date, there is limited information to direct clinical implementation. This paper provides a narrative synthesis of existing knowledge and highlights possible limitations of findings reported. Research to date has used disparate research methodologies in varied populations making synthesis of current findings challenging.