Flavour-enhanced cortisol release during gum chewing

Effects of different food hardness on cognitive inhibitory control function

Mastication leads to an immediate enhancement in cognitive functions, including inhibitory control. Furthermore, the hardness of the food increases sympathetic nerve activity during and immediately after mastication. Hence, the cognitive function could be enhanced by increased sympathetic nerve activity. The present study aimed to investigate the effects of food hardness on cognitive inhibitory control function in humans. The participants were 23 healthy adults (19-22 years old). Experiments were conducted with two types of gummies (soft and hard). The participants ingested 13 g of gummies and performed a stop-signal task to measure cognitive inhibitory control function after they rested for 5 min. The reaction time for the stop-signal task after gummy consumption was significantly shorter in the hard gummy condition compared to the soft gummy condition (p < .05). Furthermore, the accuracy rate of the responses was also significantly higher in the hard gummy condition compared to the soft gummy condition (p < .05). The results of the present study suggest that food hardness enhances cognitive inhibitory control function in humans.

Emotional modulation of cortical activity during gum chewing: A functional near-infrared spectroscopy study

Distinct brain regions are known to be associated with various emotional states. Cortical activity may be modulated by emotional states that are triggered by flavors during food intake. We examined cortical activity during chewing with different flavors and assessed the emotional modulation of cortical activity using multichannel near-infrared spectroscopy. Thirty-six right-handed volunteers participated in this crossover trial. The participants experienced positive and negative emotions from chewing flavorful (palatable) or less flavorful (unpalatable) gums, respectively for 5 min. Participants rated the taste, odor, and deliciousness of each gum using a visual analog scale. Bilateral hemodynamic responses in the frontal and parietal lobes, bilateral masseter muscle activation, and heart rate were measured during gum chewing. Changes in all measured data during gum chewing were also evaluated. The ratings of the tastes and odors of each gum significantly differed among the participants (P &lt; 0.001). Hemodynamic response changes were significantly elevated in the bilateral primary sensorimotor cortex during gum-chewing, in comparison to resting. The difference in hemodynamic responses between palatable and unpalatable gum conditions was detected in the left frontopolar/dorsolateral prefrontal cortex. Muscle activation and heart rate were not significantly different between different gum types. Our findings indicate that differential processing in the left prefrontal cortex might be responsible for the emotional states caused by palatable and unpalatable foods.

Relationship between Psychological Stress Determined by Voice Analysis and Periodontal Status: A Cohort Study

In modern society, evaluation and management of psychological stress may be important for the prevention of periodontal disease. The purpose of this study was to examine the relationship between psychological stress (vitality and mental activity) evaluated by Mind Monitoring System (MIMOSYS) and periodontal status. Forty students of Okayama University underwent the oral examination and self-reported questionnaire on the first day (baseline) and the 14th day (follow-up). Voice recording was performed every day with the MIMOSYS app during the whole study period. The participants completed the Patient Health Questionnaire (PHQ)-9 and Beck Depression Inventory (BDI) at baseline and at follow-up. Spearman’s rank correlation coefficient was used to determine the significance of correlations among variables. The PHQ-9 and BDI scores were negatively correlated with vitality in the morning. Change in vitality in the morning was significantly correlated with changes in periodontal inflammation. Mental activity was significantly correlated with change in mean probing pocket depth. This result shows that measurement of psychological stress using a voice-based tool to assess mental health may contribute to the early detection of periodontal disease.

The Effects of Chewing Gum on Reducing Anxiety and Stress: A Meta-Analysis of Randomized Controlled Trials

There was currently no consensus on whether chewing gum should be widely instituted as a means to help reduce anxiety and stress. Chewing gum was also not included in guidelines for alleviating anxiety and stress. The purpose of this study was of two aspects: (1) to review the research progress of the relationship between gum chewing and anxiety and stress in recent years and (2) to make a meta-analysis of the effects of mastication on anxiety and stress. We conducted a meta-analysis of studies extracted from PubMed, the Cochrane Library, and Embase to identify randomized controlled trials (RCTs) evaluating the efficacy of chewing gum on anxiety, and stress was evaluated through screening, inclusion, data extraction, and quality assessment. The meta-analysis we performed was using Review Manager 5.3 software. We included a total of 8 RCTs, involving more than 400 adults over 18 years old. Compared with no chewing gum, chewing gum resulted in anxiety (MD = -0.26, 95% CI (-0.48, -0.04), p=0.02, I 2 = 11%), where the heterogeneity was low and statistically significant. While in stress (MD = -0.27, 95% CI (-0.79, -0.25), p=0.31, I 2 = 48%), the heterogeneity was high, and there was of no statistical significance. Based on current evidence, chewing gum is an inexpensive, well-tolerated, safe, and effective way to relieve anxiety and stress. To confirm the conclusion, we still need to conduct more randomized trials.

A double-blinded randomized clinical trial of pain perception during orthodontic treatment

Abstract Introduction Orthodontic movement can cause painful symptoms, especially in the early stages of treatment. Objective This study aimed to compare the performance of chewing gum and ibuprofen in pain control during the initial period of orthodontic treatment. Material and method A randomized blind clinical trial, with an allocation ratio of 1:1, was developed with patients aged ≥18 years old. The sample size was established considering a significance level of 5% and test power of 80%, resulting in a minimum of 30 volunteers per group (n=90). Participants were paired regarding sex, age, the severity of malocclusion, defined by the Dental Health Component (DHC) of the Index of Orthodontic Treatment Need (IOTN), and crowding, determined by Little’s irregularity index. The sample was randomly allocated to three groups: Group I (control) placebo; Group II chewing gum; and Group III Ibuprofen. Pain perception was evaluated by the Visual Analog Scale (VAS) in the first 24, 36, and 48 hours after activation of the orthodontic appliance. The data were analyzed by generalized linear models for repeated measures in time. Result No statistically significant difference (p>0.05) was observed among the groups for the methods of pain therapy evaluated in 24, 36, and 48 hours post-activation. Conclusion There was no difference among the method used for pain control during the orthodontic treatment.

Analysis of facial expressions in response to basic taste stimuli using artificial intelligence to predict perceived hedonic ratings

Taste stimuli can induce a variety of physiological reactions depending on the quality and/or hedonics (overall pleasure) of tastants, for which objective methods have long been desired. In this study, we used artificial intelligence (AI) technology to analyze facial expressions with the aim of assessing its utility as an objective method for the evaluation of food and beverage hedonics compared with conventional subjective (perceived) evaluation methods. The face of each participant (10 females; age range, 21–22 years) was photographed using a smartphone camera a few seconds after drinking 10 different solutions containing five basic tastes with different hedonic tones. Each image was then uploaded to an AI application to achieve outcomes for eight emotions (surprise, happiness, fear, neutral, disgust, sadness, anger, and embarrassment), with scores ranging from 0 to 100. For perceived evaluations, each participant also rated the hedonics of each solution from –10 (extremely unpleasant) to +10 (extremely pleasant). Based on these, we then conducted a multiple linear regression analysis to obtain a formula to predict perceived hedonic ratings. The applicability of the formula was examined by combining the emotion scores with another 11 taste solutions obtained from another 12 participants of both genders (age range, 22–59 years). The predicted hedonic ratings showed good correlation and concordance with the perceived ratings. To our knowledge, this is the first study to demonstrate a model that enables the prediction of hedonic ratings based on emotional facial expressions to food and beverage stimuli.

Effects of Chewing Gum Base on Oral Hygiene and Mental Health: A Pilot Study

The purpose of the present study was to clarify the long-term effects of frequent chewing of unflavored and odorless gum (hereafter, gum base) on oral hygiene and mental health. This single-arm study, which started with a 4-week control and ended with a 4-week intervention period, was conducted in two phases: one in 2017 and one in 2018. The participants comprised 36 dental hygiene students (17 in 2017, 19 in 2018). During the intervention period, all participants were required to chew a piece of gum base 7 times a day for 10 min each time. The unstimulated salivary flow rate and masticatory efficiency were measured and chewing number counted. Two questionnaires －the Profile of Mood States, second edition (POMS2) and the 30-item General Health Questionnaire (GHQ-30)－ were administered to assess mental health. In both phases, the unstimulated salivary flow rate showed a significant increase after the intervention period (p<0.05). In 2017, the GHQ-30 scores and masticatory efficiency showed a tendency toward a negative correlation after the intervention period (r=－0.4647, p=0.06). In 2018, a significant negative correlation was observed between chewing number and the POMS2 scores after the intervention period (r=－0.6296, p<0.01). These findings suggest that frequent chewing of gum base increases unstimulated salivary flow rate. However, no significant change was observed in the mental health.

Association between declines in objective masticatory performance and salivary stress markers: The Suita study

Dentists often encounter patients suffering from psychological and social stress due to declines in masticatory performance, making this a critical issue to manage. We aimed to clarify the relationships between salivary stress markers as objective indices of chronic stress and objective masticatory performance in a general urban Japanese population. Data from 880 participants (mean age, 65.8 years) in the Suita study were used. Salivary interleukin (IL)-6 and cortisol concentrations were measured by enzyme-linked immunosorbent assay. Objective masticatory performance was determined by measuring the increase in surface area test gummy jelly after 30 times chewing. Participants were divided into two groups based on masticatory performance: a decreased group (lowest quartile) and a non-decreased group (second to fourth quartiles). Odds ratios (ORs) of higher salivary levels of stress markers (highest quartile) according to masticatory performance were estimated using logistic regression analysis adjusting for age, sex, periodontal status, salivary flow rate and smoking habit. Salivary IL-6 level was significantly higher in the decreased group than in the non-decreased group. Logistic regression analysis showed the adjusted OR for higher salivary IL-6 was significantly higher in the decreased group than in the non-decreased group (OR = 1.92; 95% confidence interval = 1.33-2.76; P < .001). No significant associations were found between salivary cortisol and decreased masticatory performance in any analyses. Declines in objective masticatory performance may correlate with higher salivary IL-6 level as an objective index of chronic stress.

Mastication of Hard Gumi Decreases the Gustatory Threshold for Sodium Chloride

In recent years, there has been an increase in the number of hypertensive diseases and the various diseases associated with them. A major cause of these is excessive salt intake. The purpose of the present study was to examine whether chewing hard foods lowers the saltiness threshold. Fifteen subjects (fourteen women and one man) participated in the present study. Two types of gummies are available as ingredients: hard and soft gummies. The saltiness thresholds before and after chewing of each gummi were studied using 11 different NaCl solutions. Then, points of subjective equality (PSEs) were calculated to detect changes in the saltiness for each subject. In the soft Gumi condition, there was no significant difference in PSE for the saltiness between before and after ingesting Gumi (p>0.05), while in the hard Gumi condition, the PSE for the saltiness significantly decreased after ingesting Gumi compared with the value of before ingesting Gumi (p=0.001). From these results, we concluded that sensitivity to saltiness would increase after mastication of hard foods such as hard Gumi.