Reliability of a novel wearable device to measure chewing frequency

Association Between Dietary Variety and Masticatory Behaviors Measured Using Wearable Device Among Community-Dwelling Older Adults in Japan: A Multilevel Meal-by-Meal Analysis

Background: Consuming a variety of foods is believed to promote thorough chewing; however, it remains unclear whether individuals who consume various foods actually chew them thoroughly. Therefore, this study aimed to examine the association between dietary variety and masticatory behaviors, measured using wearable devices, among community-dwelling older adults. Methods: Participants were from the Itabashi Longitudinal Study of Aging, meeting the eligibility criteria, including the ability to exchange messages via smartphone or computer. Masticatory behaviors (number of chews, chewing duration, and speed) and meal photo data were objectively measured using an ear-worn bite sensor and its application for two or three meals per day for at least three days at home. The "modified Dietary Variety Score (m-DVS)" (range 0-10, with higher values indicating greater dietary variety) was calculated by registered dietitians. Generalized linear mixed models assessed the association between m-DVS as the exposure variable and masticatory behaviors as the outcome variable. Covariates included sociodemographic status, health behavior, health status, oral health, and oral function. Results: Five hundred and eighty-seven mealtime data entries from 63 participants were included in the analysis. The m-DVS was significantly positively associated with the number of chews (cycles, unstandardized regression coefficient = 116.5, 95% confidence interval [CI] = 85.2 to 147.8) and chewing duration (min, unstandardized regression coefficient = 1.7, 95% CI = 1.3 to 2.2). Conclusions: Consuming more varied food groups was associated with more chews and longer chewing duration among community-dwelling older adults, potentially promoting thorough chewing.

Effects of Capsaicin on Masticatory and Swallowing Function

INTRODUCTION

Recent studies have shown that capsaicin improves the pharyngeal swallowing reflex. However, the mechanism by which capsaicin alters mastication and oesophageal function remains unclear. This study aimed to investigate the effects of capsaicin on masticatory and oesophageal function.

MATERIALS AND METHODS

Participants were 12 healthy individuals (7 men, 5 women: aged 31.5 ± 3.0 years). The participants ingested five rice cakes without capsaicin and then five rice cakes containing capsaicin. Total mastication frequency, total mastication time, and mastication rate were measured. Pharyngeal and upper oesophageal sphincter (UES) parameters were evaluated using high-resolution manometry (HRM). The masticatory and HRM parameters were compared between the ingestion of capsaicin-containing and non-capsaicin containing rice cakes.

RESULTS

The total mastication frequency and total mastication time(s) for capsaicin ingestion were significantly smaller (20.3 ± 9.4 vs. 22.4 ± 7.4; p = 0.011) and shorter (14.2 ± 7.0 vs. 15.4 ± 5.6; p = 0.038), respectively, than those for non-capsaicin ingestion. Comparison of the HRM parameters revealed significantly higher hypopharyngeal contractile integral (mmHg-s-cm) (56.6 ± 40.7 vs. 49.7 ± 43.6; p = 0.016) and proximal oesophageal contractile integral (mmHg-s-cm) (492.3 ± 292.64 vs. 381.2 ± 266; p < 0.001), significantly shorter UES basal pressure (mmHg) (93.6 ± 37.8 vs. 114.5 ± 43.4; p < 0.001), and significantly longer UES relaxation time (ms) (486.7 ± 90.7 vs. 431.2 ± 82.3; p < 0.001) for capsaicin ingestion than for non-capsaicin ingestion.

CONCLUSIONS

Decreased mastication frequency and time, increased hypopharyngeal and proximal oesophageal contractile integral, and prolonged UES opening time with capsaicin ingestion suggests that capsaicin improves oral, pharyngeal and oesophageal phases of swallowing.

The Association of Walking Ability with Oral Function and Masticatory Behaviors in Community-Dwelling Older People: A Cross-Sectional Study

Background/Objectives: An association between oral function and physical fitness, including walking capacity, has been reported. However, the association between masticatory behaviors and walking ability-both of which represent patterns of movement in daily life-has not been clarified. This study aimed to investigate the association between masticatory behaviors, oral function, and walking capacity in older people. Methods: One hundred community-dwelling older people (31 men, 69 women, mean age 75.7 ± 6.3 years) were selected to participate in this study. Age, sex, masticatory behaviors, oral functions (tongue pressure, tongue-lips motor function, occlusal force, and masticatory performance), and walking capacity were assessed. Masticatory behaviors were assessed during the consumption of one rice ball (100 g) using a wearable chewing counter, and the number of chews, chewing rate, the number of chews per bite, and meal time were recorded. Walking capacity was assessed using the timed up and go test (TUG). Spearman's rank correlation coefficients were calculated to assess the strength and direction of the association. Results: Moderate negative correlations were observed between TUG time and tongue pressure and between TUG time and tongue-lips motor function (/ta/ and /ka/) (rs = -0.33, -0.21, -0.28, respectively). In addition, moderate negative correlations between TUG time and chewing rate (rs = -0.22) and between TUG time and meal time (rs = 0.33) were observed, suggesting that lower walking capacity was associated with slower chewing rate and longer meal times. Conclusions: In community-dwelling older people, declines in mastication speed and dexterity and tongue strength are associated with lower walking capacity.

Factors Related to Masticatory Rhythm in Patients with Oral Tumors

Background: Older adults who have undergone surgery for oral tumors are at increased risk of impaired masticatory rhythm. This study investigated the correlations between masticatory rhythm, objective masticatory performance, and subjective masticatory performance as well as factors related to masticatory rhythm. Methods: The participants were 44 adults (24 men, 20 women; age range 42~90 years old) who had undergone maxillectomy, mandibulectomy, or glossectomy and were rehabilitated with a maxillofacial prosthesis. The number of functional contact teeth pairs was confirmed by intraoral examination. Chewing rate, cycle duration, coefficient of variation (CV) for cycle duration (reflecting the stability of masticatory rhythm), and mixing ability were measured simultaneously using a mastication movement rhythm tracking device during gum chewing. Maximum occlusal force was measured using the dental prescale system. Patients' perception of chewing ability was rated using a questionnaire. Results: The Spearman's rank correlation test revealed that mixing ability, patient-rated masticatory scores, cycle duration, CV for cycle duration, and maximum occlusal force showed significant correlations with chewing rate. Multiple linear regression analysis identified mixing ability and the CV for cycle duration as significant predictors of masticatory rhythm. Conclusions: Factors associated with a faster chewing rate were higher mixing ability and masticatory scores, greater maximum occlusal force, shorter cycle duration, and smaller CV for cycle duration. Stable masticatory rhythm and mixing ability are significant predictors of chewing rate. Poor masticatory performance and unstable masticatory rhythm can result in slower chewing and thus a higher risk of inadequate dietary intake.

Long-Term Soft-Food Rearing in Young Mice Alters Brain Function and Mood-Related Behavior

The relationship between caloric and nutrient intake and overall health has been extensively studied. However, little research has focused on the impact of the hardness of staple foods on health. In this study, we investigated the effects of a soft diet on brain function and behavior in mice from an early age. Mice fed a soft diet for six months exhibited increased body weight and total cholesterol levels, along with impaired cognitive and motor function, heightened nocturnal activity, and increased aggression. Interestingly, when these mice were switched back to a solid diet for three months, their weight gain ceased, total cholesterol levels stabilized, cognitive function improved, and aggression decreased, while their nocturnal activity remained high. These findings suggest that long-term consumption of a soft diet during early development can influence various behaviors associated with anxiety and mood regulation, including weight gain, cognitive decline, impaired motor coordination, increased nocturnal activity, and heightened aggression. Therefore, the hardness of food can impact brain function, mental well-being, and motor skills during the developmental stage. Early consumption of hard foods may be crucial for promoting and maintaining healthy brain function.

Effects of interferential current electrical stimulation (IFCS) on mastication and swallowing function in healthy young adults: A preliminary study

OBJECTIVES

This study aimed to investigate the effects of interferential current electrical stimulation (IFCS) on masticatory and swallowing function.

MATERIALS AND METHODS

Twenty healthy young adults were enrolled. The measurement items were spontaneous swallowing frequency (SSF), voluntary swallowing frequency (VSF), saliva secretion volume (SSV), glucose elution volume (GEV), and velocity of chew (VOC). All participants underwent both IFCS and sham stimulation (without stimulation, sham). Two sets of independent IFCS electrodes were placed on the bilateral neck. The precise location of the upper electrodes was just below the angle of the mandible, while the lower electrodes were placed at the anterior border of the sternocleidomastoid muscle. The intensity of IFCS was determined to be one level below the perceptual threshold that all participants felt discomfort. Statistical analysis was performed using a two-way repeated measures analysis of variance.

RESULTS

For IFCS, the results of each measurement before and during stimulation were SSF: 1.16 and 1.46, VSF: 8.05 and 8.45, SSV: 5.33 and 5.56 g, GEV: 171.75 and 208.60 mg/dL, and VOC: 87.20 and 95.20, respectively. SSF, GEV, and VOC during stimulation were significantly increased by IFCS (SSF, p = .009; GEV, p = .048; and VOC, p = .007). Following sham stimulation, the results were SSF: 1.24 and 1.34, VSF: 7.75 and 7.90, SSV: 5.65 and 6.04 g, GEV: 176.45 and 187.35 mg/dL, and VOC: 91.35 and 88.25, respectively.

CONCLUSION

While no significant differences were observed in the sham group, our findings suggest that IFCS of the superior laryngeal nerve may impact not only the swallowing function but also the masticatory function.

Masticatory Behavior Change with a Wearable Chewing Counter: A Randomized Controlled Trial

Because a relationship has been reported between masticatory behavior, obesity, and postprandial blood glucose, it is recommended to chew well and take a longer time to eat. The purpose of this study was to examine the possibility of changing masticatory behavior using a small ear-hung wearable chewing counter, which can monitor masticatory behavior without disturbing daily meals. In total, 235 healthy volunteers participated in a 4-wk randomized controlled trial and were divided into 3 groups. All participants were instructed about the importance of mastication at the first visit. During the intervention, group B used the chewing counter without an algorithm during each meal (notification of the number of chews after meal), and group C used the chewing counter with a masticatory behavior change algorithm (setting a target value and displaying the number of chews in real time). Group A was set as the control group. The number of chews and the meal time when consuming 1 rice ball (100 g) were measured before and after the intervention using the chewing counter, and the rate of change in these values was evaluated. Participants also provided a subjective evaluation of their changes in masticatory behavior. The number of chews and the meal time of 1 rice ball increased significantly in groups B and C compared with before the intervention, and the rate of change was significantly higher in group C than in group A and group B. In addition, the subjective evaluation of the change in the number of chews was highest in group C. Self-monitoring of masticatory behavior by providing a target value and the degree of achievement for the number of chews using a wearable chewing counter with a behavioral change algorithm could promote effective change in masticatory behavior and lead to an increased number of chews. (Trial ID: UMIN000034476).

Relationship between motor dysfunction and chewing movement in patients with Parkinson's disease: A transversal study

Objective

To assess the impact of chewing movement in patients with Parkinson's disease (PD), we examined the relation between chewing movement and motor dysfunction in association with PD progression.

Methods

Thirty patients with PD (mean age, 68.9 ± 9.0 years; mean Hoehn and Yahr stage, 3.0 ± 0.7) were recruited. The PD condition was assessed in each patient by using the score of Movement Disorder Society Unified PD Rating Scale (MDS-UPDRS) part III score, body mass index (BMI), serum albumin (Alb), and tongue pressure, number of chews, mealtime, and chewing speed were collected. The patients were divided into two groups (mild and moderate PD groups) based on an MDS-UPDRS part III cut-off value of 32.

Results

The chewing speed positively correlated with tongue pressure (rho = 0.69, p < 0.01) in the mild group, and with BMI (rho = 0.54, p = 0.03), serum Alb (rho = 0.63, p = 0.02), and number of chews (rho = 0.69, p < 0.01) in the moderate group. The MDS-UPDRS part III scores for all participants correlated negatively with chewing speed (rho = -0.48, p < 0.01), serum Alb (rho = -0.49, p < 0.01), and positively with mealtime (rho = 0.43, p = 0.01). Tongue pressure and serum Alb were identified to be as factors affecting the chewing speed (β= 0.560, p < 0.01; β= 0.457, p < 0.01, respectively).

Conclusions

These results indicated that the progression of motor dysfunction in patients with PD is likely to affect chewing speed and the nutritional status decline may be linked to the impairment of chewing movement in these patients.

Impact of Masticatory Behaviors Measured With Wearable Device on Metabolic Syndrome: Cross-sectional Study

Background

It has been widely recognized that mastication behaviors are related to the health of the whole body and to lifestyle-related diseases. However, many studies were based on subjective questionnaires or were limited to small-scale research in the laboratory due to the lack of a device for measuring mastication behaviors during the daily meal objectively. Recently, a small wearable masticatory counter device, called bitescan (Sharp Co), for measuring masticatory behavior was developed. This wearable device is designed to assess objective masticatory behavior by being worn on the ear in daily life.

Objective

This study aimed to investigate the relation between mastication behaviors in the laboratory and in daily meals and to clarify the difference in mastication behaviors between those with metabolic syndrome (MetS) and those without (non-MetS) measured using a wearable device.

Methods

A total of 99 healthy volunteers (50 men and 49 women, mean age 36.4 [SD 11.7] years) participated in this study. The mastication behaviors (ie, number of chews and bites, number of chews per bite, and chewing rate) were measured using a wearable ear-hung device. Mastication behaviors while eating a rice ball (100 g) in the laboratory and during usual meals for an entire day were monitored, and the daily energy intake was calculated. Participants’ abdominal circumference, fasting glucose concentration, blood pressure, and serum lipids were also measured. Mastication behaviors in the laboratory and during meals for 1 entire day were compared. The participants were divided into 2 groups using the Japanese criteria for MetS (positive/negative for MetS or each MetS component), and mastication behaviors were compared.

Results

Mastication behaviors in the laboratory and during daily meals were significantly correlated (number of chews r=0.36; P<.001; number of bites r=0.49; P<.001; number of chews per bite r=0.33; P=.001; and chewing rate r=0.51; P<.001). Although a positive correlation was observed between the number of chews during the 1-day meals and energy intake (r=0.26, P=.009), the number of chews per calorie ingested was negatively correlated with energy intake (r=–0.32, P=.002). Of the 99 participants, 8 fit the criteria for MetS and 14 for pre-MetS. The number of chews and bites for a rice ball in the pre-MetS(+) group was significantly lower than the pre-MetS(–) group (P=.02 and P=.04, respectively). Additionally, scores for the positive abdominal circumference and hypertension subgroups were also less than the counterpart groups (P=.004 and P=.01 for chews, P=.006 and P=.02 for bites, respectively). The number of chews and bites for an entire day in the hypertension subgroup were significantly lower than in the other groups (P=.02 and P=.006). Furthermore, the positive abdominal circumference and hypertension subgroups showed lower numbers of chews per calorie ingested for 1-day meals (P=.03 and P=.02, respectively).

Conclusions

These results suggest a relationship between masticatory behaviors in the laboratory and those during daily meals and that masticatory behaviors are associated with MetS and MetS components.

Trial Registration

University Hospital Medical Information Network Clinical Trials Registry R000034453; https://tinyurl.com/mwzrhrua

Relationship between body mass index and masticatory factors evaluated with a wearable device

Numerous studies have evaluated the relationship between eating behavior and obesity, however few studies have objectively assessed eating behavior. Additionally, the association of masticatory behaviors with masticatory performance remains unclear. This study aimed to verify the relationship between masticatory performance and behavior measured by a wearable masticatory counter, and BMI. 365 healthy adults participated. Mastication behaviors, i.e. number of chews and bites, chewing rate, and chewing time, were measured using wearable masticatory counter while consuming one rice ball (100 g). Masticatory performance was evaluated using testing gummy jelly. Lifestyle habits including exercise, walking, and breakfast, were surveyed by questionnaire. The correlation coefficients between masticatory behaviors and performance and BMI were analyzed. Furthermore, multiple regression analysis was performed. The number of chews showed positive correlation with chewing rate, number of bites and chewing time, but no correlation with masticatory performance. BMI had weak but significant negative correlation with number of chews, bites, chewing time, and masticatory performance, but had no correlation with chewing rate. Multiple regression analysis revealed that BMI was associated with sex, age, number of chews, bites, masticatory performance, and walking speed. In conclusion, masticatory behavior and performance were not interrelated, but both were independently associated with BMI weakly.