Effect of chewing or compressing food on autonomic nervous activity in older adults

Influence of Chewing Gummy Jelly Containing Aroma Compound on Psychological Stress and Autonomic Nervous System Activity: A Randomized Crossover Trial

The aim of this randomized crossover trial was to clarify the effects of chewing gummy jelly containing a compound of decanoic acid, oligonol, methyl cellulose, and citral (DOMAC) on mental stress and autonomic nervous activity in facemask wearers. A placebo gummy jelly was used in conjunction with DOMAC. Eight healthy adults with no tooth loss (mean age: 35±5 yr) were included. The participants were required to chew one DOMAC or placebo gummy jelly for 5 min after wearing a facemask for 20 min in the laboratory, then the other gummy jelly after a washout period. Rate of change in salivary immunoglobulin A (IgA) as a marker of stress was compared between before and after chewing. Additionally, sympathetic and parasympathetic activity was compared at both time points. A significant difference was observed in the percentage change in salivary IgA from that at before wearing a facemask: 127±34% (mean±standard deviation) while wearing a facemask; 46±20% while chewing DOMAC gummies; and 47±26% while chewing placebo gummies (p<0.05). Parasympathetic nervous system activity was 971.2±1040.7 ms2 at 20 min after facemask wearing; 295.0±253.0 ms2 after DOMAC gummy chewing; and 1956.1±2798.0 ms2 after chewing a placebo gummy jelly; with significant differences only being found between 20 min after facemask wearing and after DOMAC gummy chewing (p<0.05). Sympathetic nervous system activity was 1.80±1.83 at 20 min after facemask wearing; 4.06±3.33 after DOMAC gummy chewing; and 4.95±7.02 after chewing a placebo gummy jelly; with significant differences only being found between 20 min after facemask wearing and after DOMAC gummy chewing. These results suggest that chewing gummy jellies containing DOMAC relieves stress caused by facemask wearing and activates sympathetic nervous system activity.

Effect of elastic oral appliance chewing on frontal lobe activity

OBJECTIVES

Chewing increases frontal lobe activity, resulting in improved memory, learning ability, and response reaction time. This study aimed to assess the effects of elastic oral appliance chewing on the activities and functions of the frontal lobe.

METHODS

The study participants were 15 healthy men with full dentulous (mean age, 27.4 ± 4.1 years). A prospective crossover design was used to assess frontal lobe activities and functions. Changes in frontal lobe activities were measured with near-infrared spectroscopy (NIRS). At baseline, the participants were assessed in the resting state. Changes in channels #7, representing right frontal lobe activities by NIRS, and #10, representing left frontal lobe activities, during the first and second chewing periods in a total of two periods were evaluated. Frontal lobe functions were measured using the Trail Making Test Part A (TMT-A) in the resting state and after elastic oral appliance or gum chewing. These values were compared with each period.

RESULTS

Elastic oral appliance chewing caused significant differences between the baseline and first chewing periods for channel #7 (p = .032) and significant differences between the baseline and second chewing periods for channels #7 and #10 (p < .001 and p < .001, respectively) using NIRS. Moreover, significant differences were found in the TMT-A results between the resting state and elastic oral appliance chewing (p = .04).

CONCLUSIONS

Elastic oral appliance chewing improves frontal lobe activities to a level similar to that obtained with gum chewing.

Effects of Gum Chewing on Recovery From Postoperative Ileus: A Randomized Clinical Trail

BACKGROUND

Sham feeding with products such as chewing gum has been theorized to decrease the incidence and time to resolution of postoperative ileus. The conflicting findings in the literature on this subject are because in part of the use of mixed study populations, which has led to difficulties in assessing the value of sham feeding in ameliorating this condition.

PURPOSE

The aim of this study was to evaluate the efficacy of postsurgical gum chewing in restoring normal bowel movement in patients with colorectal cancer who had undergone abdominal surgery for colon resection.

METHODS

A randomized controlled trial was used to examine the time to first postoperative flatus and defecation. The intervention group ( n = 30) received xylitol chewing gum on the first day after colon resection, one piece of gum for 15 minutes, 3 times daily, until the time to first flatus and defecation. Both the intervention and control groups ( n = 30) received standard postoperative care and were encouraged to walk as soon as possible after surgery. The time to first flatus was reported by patients.

RESULTS

The time to first flatus and defecation in the intervention group was significantly shorter than that in the control group (39.13 ± 15.66 vs. 52.92 ± 21.97 hours and 54.55 ± 18.90 vs. 77.98 ± 34.59 hours, respectively). However, after controlling for age and surgical duration, only time to first flatus was significantly shorter in the intervention group. Significantly positive correlations were found between time to first flatus and time to first defecation in both groups.

CONCLUSIONS/IMPLICATIONS FOR PRACTICE

In this study, gum chewing was shown to have a positive effect on the time to first postoperative flatus and defecation. This inexpensive and noninvasive intervention may be recommended to decrease the time to resolution of postsurgical ileus in middle-aged and older patients who have undergone open abdominal surgery for colorectal resection.

Decreased Frequency of Mental Workload-Induced Subjective Hot Flashes Through Gum Massage: An Open-Label, Self-Controlled Crossover Trial

Objective:

Hot flashes, a symptom of menopause, can decrease women's quality of life. Sympathetic nervous system activation has been identified as an important factor in the occurrence of hot flashes. Given that somatosensory stimulation of the oral cavity can affect autonomic nervous activity, we aimed to investigate the possibility that somatosensory stimulation of the gums (i.e., gum massage) could improve hot flashes.

Materials and Methods:

Nineteen women experiencing at least one hot flash per day were instructed to perform a gum massage on themselves before undertaking mental workload, using arithmetic task, and the frequency of hot flashes experienced during this task was measured. Changes in autonomic nervous activity were assessed based on heart rate variability.

Results:

Massage conditions promoted a significantly lower arithmetic task-induced hot flash frequency compared with nonmassage conditions (p < 0.05). During gum massage, the ratio between low and high frequency (LF/HF) values decreased significantly under massage conditions compared with nonmassage conditions (p < 0.01). During the arithmetic task, the gum massage-induced reduction in LF/HF, which changed from baseline, was significantly correlated with the gum massage-induced reduction in hot flash frequency.

Conclusions:

The results of this study indicate that gum massage can reduce the subjective frequency of hot flashes over a certain period under mental workload. Our study also indicates that gum massage can potentially decrease sympathetic nerve activity, which is known to be involved in the occurrence of hot flashes.

Clinical Trial Registration number 328 (the institutional review board of Lion Corporation).

Effect of tasteless calorie-free gum chewing before meal on postprandial plasma glucose, insulin, glucagon, and gastrointestinal hormones in Japanese men without diagnosed glucose metabolism disorder: a pilot randomized crossover trial

This pilot study aimed to examine the effect of pre-meal tasteless calorie-free gum chewing on post-meal blood levels of glucose, insulin, glucagon, and gastrointestinal hormones. This was an open-label, randomized, 2-sequence, 3-period, 2-treatment crossover trial with a 1:1 allocation. Sixteen Japanese adult male volunteers aged between 30 and 49 years without diagnosed glucose metabolism disorder were enrolled. Ingestion of 200-g cooked rice after 15-min tasteless calorie-free gum chewing (GUM+ treatment) was compared to that without preceding gum chewing (GUM- treatment). Cooked rice was divided into twelve equally sized portions and consumed by chewing each portion 30 times before swallowing. Treatment sessions were separated by an at least 1-week interval and attended after an overnight fast. Circulating levels of glucose, insulin, glucagon, active glucagon-like peptide (GLP)-1 and ghrelin were measured at baseline (before treatment) and 0, 15, 30, 60, and 120 min after completion of the meal ingestion, and the postprandial change from baseline was assessed. As a result, the change in glucose levels at 0 min was significantly lower in the GUM+ treatment than in the GUM- treatment (P = 0.004). Furthermore, the GUM+ treatment demonstrated higher incremental insulin levels at 15 min (P = 0.041) and higher incremental active GLP-1 levels at 30 and 60 min (P = 0.018 and 0.021, respectively); whereas, postprandial glucagon and ghrelin levels were not significantly different. In conclusion, the current pilot study demonstrated that tasteless calorie-free gum chewing before rice eating had a significant but limited impact on the increase of postprandial active GLP-1 levels in male individuals without diagnosed glucose metabolism disorder.

Differentiation of Feeding Behaviors Based on Masseter and Supra-Hyoid Muscle Activity

Older adults with disorders of mastication and swallowing are often fed soft foods such as jelly or puree. The texture of such semi-solid foods allows them to be squeezed between the tongue and palate rather than being chewed. However, it is difficult to visually identify such strategies for the oral processing of food. This study aimed to test the hypothesis that there is a difference in the sequential coordination between the masseter and supra-hyoid muscles, and to identify feeding behaviors such as chewing and squeezing using electromyography. Seventeen male subjects (mean age: 30.8 years) were recruited. Four kinds of gels were prepared (two kinds of fracture force and fracture strain) as test samples. Subjects were instructed to consume the gels in three ways: squeezing with the tongue, chewing with the teeth and eating freely until swallowing. The amount of squeezing/chewing and the consumption time was unlimited. The masseter and supra-hyoid muscle activity were recorded during the entire consumption time and videofluorography was simultaneously recorded during each ingestion. Lissajous figures were made from the electromyographic activity of the two groups of muscles during the first stroke, and a regression line was made to determine the gradient of each figure to compare squeezing and chewing using the Mann-Whitney U-test. The masseter and supra-hyoid muscles were active simultaneously during squeezing with the tongue. However, the masseter was active after the supra-hyoid during chewing. The gradient of the regression line from the Lissajous figures between the masseter and supra-hyoid muscle activity was positive during squeezing, but negative during chewing. Analysis of the ROC curve showed that the cutoff value of the gradient for differentiating feeding behaviors was 0.097, with a sensitivity of 95.3% and specificity of 98.4%. When we allocated 68 free intakes into squeezing and chewing according to this cutoff value, we could distinguish with good precision, and the accuracy, sensitivity, and specificity were 86.8, 91.1, and 66.7% respectively. These results suggest that certain aspects of muscle activity differed among oral processing methods. Lissajous analysis of muscle activity was useful for identifying ingestion behaviors.

Evaluation of Factors Associated with Tongue Coating Status in Elderly with Care Needs

The tongue surface in older people requiring nursing care is often coated with a layer believed to comprise, keratinized products of degeneration, food residue, bacteria, and leukocytes attached to the tongue papillae. Which factors affect the status of this tongue coating remain to be elucidated, however. The purpose of this study was to evaluate factors related to tongue coating status in older people requiring nursing care. The study participants comprised 41 individuals admitted to special nursing homes for the elderly. After undergoing tooth brushing and tongue cleaning by the facility staff, the participants were required to refrain from oral cleaning until evaluation of tongue coating status, which was performed just after lunch. The moisture level of the tongue surface was measured and total number of oral microbes determined. Food type, care level, and sex were determined by a questionnaire given by the attending nurses. Correlations between the tongue coating status and various factors were analyzed using Spearman's rank correlation coefficient. The participants were divided into 2 groups according to the median value of the tongue coating status. Factors related to tongue coating were analyzed using binomial logistic regression analysis (α=0.05). Tongue coating status showed a significant correlation with the total number of oral microbes on the tongue surface (r_S=0.449, p=0.003), type of food (r_S=0.388, p=0.012), and care level (r_S=-0.308, p=0.050). Logistic regression analysis revealed that the food type of the side dish significantly affected tongue coating status. These results showed a correlation between tongue coating status and type of food of the side dish in older people requiring nursing care.

Influence of chewing on expression level of human beta-defensin 2 and secretory immunoglobulin A in the epithelium

PURPOSE

This study aimed to clarify the influence of chewing on human β-defensin 2 (hBD-2) and secretory immunoglobulin A (SIgA) expression levels.

METHODS

We included 15 healthy males with no missing teeth (mean age, 25.5±2.5years). Subjects were instructed to chew a piece of gum for 30min. Saliva and skin-extraction samples were collected before and after chewing for 15 and 30min. hBD-2 and SIgA concentrations in the samples were determined using enzyme-linked immunosorbent assay (ELISA). hBD-2 and SIgA expression levels before and after chewing were analyzed using the Mann-Whitney U test, following the Friedman test. The significance level was 0.05.

RESULTS

The hBD-2 level in skin-extraction samples was significantly different before (99.4±17.3pg/mL) and after chewing for 30min (142±23.0pg/mL). The SIgA level in skin-extraction samples was also significantly different before (2.39±0.25μg/mL) and after chewing for 30min (3.61±0.33μg/mL). No significant difference was noted in either hBD-2 or SIgA secretion rate in saliva between before and after chewing.

CONCLUSIONS

Chewing gum for 30min increased hBD-2 and SIgA expression levels in skin. Moreover, chewing gum could influence the secretion pattern of these two biomolecules on skin, but not in saliva.

Change in Autonomic Nervous Activity during Ingestion of Soft Food in Older Nursing Home Residents

The deterioration in masticatory function often seen in older adults rules out the consumption of hard foods, while a common decline in autonomic nervous response often observed in older adults may result in maladjustment to environmental stresses. The purpose of this study was to investigate whether autonomic nervous activity in older adults increased during the mastication of soft foods compared to at rest. The participants comprised 9 volunteer nursing home residents aged 78 to 100 years. All consumed soft rice as a grain dish and coarsely chopped food as side dishes. The coefficient of variation of R-R intervals (CVRR) and high-frequency (HF) power on electrocardiograph (ECG) served as indices of parasympathetic nervous activity, while the low-frequency (LF)/HF ratio served as an index of sympathetic nervous activity. Total power, reflecting the level of autonomic nervous activity, was also measured. We measured autonomic nervous activity while nursing home residents were eating lunch. HF was 3,457.4±3,037.5 ms² at rest and 4,085.1±3,697.7 ms² during mastication. The CVRR was 26.8±16.9% at rest and 26.1±16.1% during mastication. No significant difference was observed in HF or CVRR. On the other hand, the LF/HF ratio was 0.77±0.24 ms² at rest and 31.0±3.77 ms² during mastication (p=0.011). A significant difference was observed in the LF/HF ratio between the resting and masticating conditions. Total power was 6,244.1±5,752.5 ms² at rest and 8,417.7±7,266.4 ms² during mastication (p=0.038). A significant difference was also observed in total power between resting and masticating conditions. These results suggest that mastication of soft foods stimulates autonomic nervous activity in older adults. In conclusion, autonomic nervous activity increased during chewing soft foods compared to that during the resting level in older adults.