Chewing Duration Research Articles

Effect of vitamin C supplementation on serum Cotinine, MDA and vitamin C levels in smokeless Tobacco chewers

Smokeless tobacco is a commonly used drug in the world. Tobacco use in any form is a rising crisis for the population in developing countries. Tobacco contributes significantly to oxidative stress induced morbidity and mortality. The study was aimed to evaluate the effect of vitamin C supplementation on serum cotinine, malondialdehyde (MDA) and serum vitamin C level in smokeless tobacco (ST) chewers. In addition, the study was aimed to evaluate the effect of duration of tobacco chewing on above-said parameters. A total number of 338 healthy participants of aged between 31 to 60 years were classified into two groups comprising of tobacco chewers and tobacco non-chewers. Tobacco chewers group further divided into three subgroups with respect to tobacco chewing duration. Participants were asked to take 1000 mg of vitamin C daily for 45 days. Serum cotinine, MDA and serum vitamin C were measured in all the participants before and after supplementation of vitamin C. Serum cotinine (p<0.001) and MDA (p<0.001) were significantly increased whereas serum vitamin C level (p<0.001) was significantly decreased in smokeless tobacco chewers as than to controls. However, serum cotinine (p<0.001) and MDA (p<0.001) were significantly decreased whereas vitamin C (p<0.001) level was significantly increased in both the groups after supplementation of vitamin C as compared to before. It was observed that the changes become more prominent with increased smokeless tobacco consumption duration. Daily intake of vitamin C may be beneficial to restore the oxidant-antioxidant balance in tobacco chewers.

Effect of attention on chewing and swallowing behaviors in healthy humans

We examined how attention alters chewing and swallowing behaviors. Twenty-one healthy volunteers were asked to freely eat 8 g of steamed rice in three separate trials, and we obtained the average number of chewing cycles (N) and chewing duration (T) prior to the first swallow in each trial. We also conducted an N-limited test, in which participants chewed the food while independently counting the number of chewing cycles and swallowed the food when they reached N, and a T-limited test, in which they chewed the food for T sec and then swallowed. We recorded electromyograms (EMGs) from masseter and suprahyoid muscles and collected videoendoscopic images. In the N-limited test, chewing speed decreased, masseter muscle activity (area under the curve of the rectified EMG burst) per cycle increased, and suprahyoid muscle activity per cycle decreased. In the T-limited test, the chewing speed increased, muscle activities per cycle decreased, and the number of cycles increased. The occurrence frequency of bolus propulsion into the pharynx before swallowing was smaller in the N- and T-limited tests than in the free chewing test. Further, the whiteout time was longer in the T-limited test than in the free chewing test. Attentional chewing changes not only chewing but also swallowing behavior.

Exacting Responses: Lack of Endocrine Cephalic Phase Responses Upon Oro-Sensory Exposure.

Oro-sensory exposure (OSE) to food plays an important role in the regulation of food intake. One proposed underlying mechanism is the occurrence of cephalic phase responses (CPRs). CPRs include the pre-digestive endocrine responses induced by food-related sensory input. Yet, whether OSE duration or sweetness intensity affects CPRs is unknown. The objective of this study was to determine the independent and interactive effects of oro-sensory duration (chewing) and stimulation intensity (sweetness) on endocrine CPRs and satiation. Eighteen males (22 ± 2 years, BMI 22 ± 2 kg/m2) participated in a 2 × 2 randomized study with a control condition. Each session participants performed modified sham feeding (MSF) with one of the four gel-based model foods. During the control session no MSF was performed. Model foods differed in chewing duration (hard or soft texture) and sweetness (low or high intensity). During each session, eight blood samples were collected up till 25 min after MSF onset. Subsequently, food intake from an ad libitum lunch was measured. No typical CPR was found for insulin, pancreatic polypeptide (PP), and ghrelin. However, the overall PP response was 1.1 times greater for the hard sweet MSF condition compared to control (p = 0.02). Overall ghrelin responses were 1.1 times greater for the hard model food compared to the soft model food conditions (p = 0.003). These differences in endocrine response were not associated with differences in food intake at the subsequent meal. Exploratory sub-analysis of the responsive insulin curves showed that after 2.5 min of MSF the hard texture model foods insulin concentrations were 1.2 greater compared to the soft texture. These findings indicate that texture hardness and sweetness increase the overall PP response and that MSF on hard texture increases the overall ghrelin response compared to soft texture model foods. However, MSF on model foods does not lead to a typical CPR. This study, among others, shows that there are major dissimilarities in the endocrine responses to food stimulation between individuals. This emphasizes the importance of considering cephalic responders and non-responders. More research is needed to understand CPRs in relation to food texture and taste properties.

Dough and bread making from high- and low-protein flours by vacuum mixing: Part 3. Oral processing of bread

This study aimed to understand the impact of vacuum mixing induced changes in the structural and physical characteristics of bread, which had extensively been investigated in the first two parts of the series of study, on human oral processing of baked bread and steamed bread. The chewing behaviour, dynamic texture perception and swallowing thresholds of twelve healthy panellists were characterised using surface electromyography (EMG), temporal dominance of sensation (TDS) and bolus characterization, respectively. There was no difference in the swallowing thresholds between the vacuum mixed bread and control bread, for either baked bread or steamed bread. Nevertheless, baked bread made from vacuum mixed dough required slightly longer chewing duration and greater muscle activities than the control baked bread, which was attributed to its denser structure and harder texture. On the other hand, steamed bread made from vacuum mixed dough required smaller muscle activities compared to the control steamed bread. Significance difference in texture perception was only observed between baked and steamed bread but not among the same type of bread made between vacuum and atmospheric mixing. Results indicated that vacuum mixing might be used as a technique to change bread structure that affects consumer's eating behaviour but not texture perception.

Relationships of oral comfort perception and bolus properties in the elderly with salivary flow rate and oral health status for two soft cereal foods

The aim of this study was to investigate food oral processing and bolus formation in the elderly population, and their relationship with the perception of oral comfort, for two soft cereal products of different composition: sponge-cake and brioche. Twenty subjects aged 65 and over participated in the study. They were classified in two groups according to dental status (poor vs. satisfactory) and presented various stimulated salivary flow rate (SSF) in each group. Food bolus properties (hydration ratio and apparent viscosity) were characterized after three chewing stages for both groups. Results showed that chewing duration did not depend on food product but rather on physiology: subjects with a poor dental status had a shorter chewing duration. For each chewing stage, sponge-cake boli showed a higher hydration ratio than brioche boli, which showed higher apparent viscosity. For sponge-cake, perception of oral comfort was primarily driven by SSF rate, irrespective of the dental status. In the case of brioche, oral comfort was also partially explained by SSF in the case of subjects with poor dental status. This result suggests that perception of oral comfort in brioche could be driven by product related attributes rather than oral health. For both foods, a phenomenological model of bolus viscosity as a function of stimulated salivary flow and chewing duration was proposed.

Effect of body posture on chewing behaviours in healthy volunteers.

Mastication is essential to the eating process and forms an important part of feeding behaviour. Many factors related to the food bolus, such as bolus texture and size, are known to influence mastication. The aim of this study was to determine the effects of body posture on (i) chewing duration prior to the first swallow and (ii) patterns of mastication-related EMG activity. We asked 10 healthy adults to chew 8g of steamed rice with barium sulphate while we recorded masseter, suprahyoid and infrahyoid muscle activity and simultaneously collected videofluorographic images. Participants chewed in either an upright or reclining position. Chewing duration, which was defined as the time from the start of mastication to the first swallow, was not different between the positions. However, the variability of chewing duration was larger in the upright versus reclining position, and the chewing duration in the reclining position was distributed around 15s. Masseter activity gradually decreased in a time-dependent manner and was significantly larger at the early versus late stage of mastication. Suprahyoid activity was significantly larger at the early versus middle stage of mastication in the upright position only. Finally, masseter activity per second was negatively correlated with changes in chewing duration, that is, the larger the increase in chewing duration in the reclining position, the more the decrease in masseter activity per second. These results suggest that position-dependent changes in chewing behaviours, as described by chewing duration and EMG activity, may vary among participants.

The Effects of Both Chewing Rate and Chewing Duration on Temporal Flavor Perception

Previous research showed that the number of chews has been shown to influence flavor perception in crispy potato chips. This study aimed to further determine how the number of chews modulates the temporal dynamics of flavor perception (i.e., flavor development) in potato chips. The number of chews was manipulated not only by changing chewing rate (40, 80, and 120 chews/min) for a fixed swallowing time (at 25 s after the onset of the first bite; experiment 1), but also by changing the time to swallow (10, 20, and 30 s after the onset of the first bite) for a constant chewing rate (80 chews/min; experiment 2). In experiment 1, the time-intensity (TI) analysis showed that the maximum flavor intensity (Imax) and the area under the curve (AUC) were significantly higher for the medium (80 chews/min) and fast (120 chews/min) chewing rates than for the slow (40 chews/min) chewing rate in both plain and spicy flavored chips. In experiment 2, the temporal flavor perception was altered by the interaction between the chewing duration before swallowing and the flavor type of the potato chips. More specifically, in the natural chewing rate, while the Imax and AUC of spicy flavored chips were the greatest when the bolus was swallowed after the natural chewing-duration (for 20 s), the AUC of plain flavored chips was significantly greater in the longer chewing-duration (for 30 s) than the natural chewing-duration. This study supports and extends the notion that the number of chews, and corresponding parameters such as chewing rate and duration, affect temporal flavor perception in the plain and spicy flavored potato chips. Our findings show that flavor intensity of plain and spicy potato chips can be reduced when people chew the chips slowly and/or swallow quickly.

Chewing Duration Time Of Various Food Textures In Young Adults

OBJECTIVE: To obtain reference values of chewing time of several food textures in young adults. 
 METHOD: descriptive study with a quantitative approach that was developed in a clinical reference, being the population composed of 40 young adults between 18-30 years of age, of both genres. As exclusion criteria: those with neuromuscular and / or degenerative diseases or consequences thereof, as well as subjects who were making use of any orthodontic / orthopedic resource. We conducted a dental evaluation, followed by a clinical assessment. One at a time, the following foods were offered: French bread, wafer biscuit, roasted cashews, for voluntary chewing. To measure the food chewing time, we used a stopwatch, and this collection procedure was filmed. Data analysis was performed by means of the SPSS statistics 20.0 (IBM®) program. 
 RESULTS: There was a statistically significant difference (p < 0.05) between the medians of chewing time of French bread, wafer biscuit and cashew nuts, which were 33.0s (interquartile amplitude 29.0 - 40.0), 10.0s (interquartile amplitude 8.25-12.0) and 18.5s (interquartile amplitude 15.0-23.75), respectively. 
 CONCLUSION: The texture of foods influences the length of mastication. The more rigid is the food, the more cycles and mandibular movements, and therefore the longer the duration of chewing.

Chewing bread: impact on alpha-amylase secretion and oral digestion.

During chewing, saliva helps in preparing the food bolus by agglomerating the formed particles, and it initiates enzymatic food breakdown. However, limited information is actually available on the adaptation of saliva composition during the oral processing of complex foods, especially for foods that are sensitive to salivary enzymes. We addressed this question in the context of starch-based products and salivary alpha-amylase. The objectives were two-fold: (1) to determine if salivary alpha-amylase secretion can be modulated by the bread type and (2) to evaluate the contribution of the oral phase in bread enzymatic breakdown. Mouthfuls of three different wheat breads (industrial, artisan and whole-meal breads) were chewed by twelve subjects. Saliva samples were collected at rest and at different times corresponding to 33, 66 and 100% of the individual's chewing sequence. Alpha-amylase activity and total protein content were determined for all saliva samples that were collected. Additionally, the salivary maltose concentration was measured as a marker of bread enzymatic digestion. Boluses were collected at the swallowing time to evaluate the saliva uptake. Chewing industrial bread induced higher saliva uptake than the other breads despite a similar chewing duration. The evolution of salivary amylase activity tended to depend on the type of bread and was highly influenced by a large degree of inter- and intra-subject variability. The protein and maltose concentration steadily increased during chewing as a result of bread breakdown. The salivary protein concentration was mainly affected by the release of the water-soluble proteins of the bread. The salivary maltose concentration was found to be significantly lower for the whole-meal bread. When considering the weight of the mouthful, enzymatic breakdown was found to be most efficient for the breads ranking from industrial > artisan > whole-meal.

An innovative masticatory efficiency test using odour intensity in the mouth as a target marker: a feasibility study

A large number of studies have reported the findings for masticatory efficiency tests; however, some objective masticatory efficiency tests have a drawback, in that subjects are required to spit out the test material. This study examined the possibility of a masticatory efficiency test that evaluates the intensity of odours released when chewing an odour compound-containing material. A total of 20 volunteers were used in this study. The odour intensity in the breath after chewing a gum was measured by portable odour sensor device. The odour intensity after chewing the gum was measured over four chewing durations and at four intervals between spitting out and measurement of the odour intensity. The volume of stimulated saliva was measured by calculating the difference in the weight of the gauze before and after chewing to examine the effect of saliva flow. With an increase in chewing duration, odour intensity reduced. The odour intensity was the highest immediately after chewing. There was a positive correlation between odour intensity and gummy jelly-related masticatory efficiency test value (G-METV), which was significant for 10-s chewing. The regression equation was calculated from three objective variables of odour intensity and G-METV as dependent variable. Pearson's correlation coefficient between G-METV and the odour intensity-related masticatory efficiency value (O-METV) was 0·68. The coefficient of variation of O-METV was significantly lower than that of G-METV. These results suggest that the masticatory performance can be estimated by measuring the odour intensity immediately after chewing food containing odour compounds for 10 s.

Preparation of double‐network tofu with mechanical and sensory toughness

SummaryIn this study, sugar beet pectin and soy protein were used to prepare the double‐network (DN) modified‐tofu by sequential laccase and microbial transglutaminase treatments. The mechanical properties of modified‐tofu were analysed by uniaxial compression test and texture profile analysis. The DN modified‐tofu exhibited greater mechanical toughness than the corresponding single‐network modified‐tofu, while the ratio of soy glycinin to soy protein isolate reached and exceeded 50%. The enhancement of mechanical toughness may be mainly ascribed to the hierarchical microstructure which is observed in DN modified‐tofu by scanning electron microscopy. DN modified‐tofu provided a distinctive mechanical and sensory tough texture as compared to other tofu samples. In addition, the oral processing measurements indicated that DN modified‐tofu required higher jaw‐closing muscle activities, a greater number of chews and longer chewing duration to be processed. Furthermore, the chewing pattern of DN modified‐tofu was different from other tofu samples.

Chewed out: an experimental link between food material properties and repetitive loading of the masticatory apparatus in mammals.

Using a model organism (rabbits) that resembles a number of mammalian herbivores in key aspects of its chewing behaviors, we examined how variation in dietary mechanical properties affects food breakdown during mastication. Such data have implications for understanding phenotypic variation in the mammalian feeding apparatus, particularly with respect to linking jaw form to diet-induced repetitive loading. Results indicate that chewing frequency (chews/s) is independent of food properties, whereas chewing investment (chews/g) and chewing duration(s), which are proportional to repetitive loading of the jaws, are positively related to food stiffness and toughness. In comparisons of displacement-limited and stress-limited fragmentation indices, which respectively characterize the intraoral breakdown of tough and stiff foods, increases in chewing investment and duration are linked solely to stiffness. This suggests that stiffer foods engender higher peak loads and increased cyclical loading. Our findings challenge conventional wisdom by demonstrating that toughness does not, by itself, underlie increases in cyclical loading and loading duration. Instead, tough foods may be associated with such jaw-loading patterns because they must be processed in greater volumes owing to their lower nutritive quality and for longer periods of time to increase oral exposure to salivary chemicals.

Changes in jaw muscle activity and the physical properties of foods with different textures during chewing behaviors

This study aimed to investigate how the activity of the masseter (Mas) and suprahyoid (Hyoid) muscles is influenced by the physical properties of food, how changes in the rheological properties of food differ between different foods during the process of food reduction, and how different salivary flow rates affect bolus-making capability during masticatory behavior in healthy humans. Ten healthy adults participated in this study. Electromyographic (EMG) recordings were obtained from the Mas and Hyoid muscles, and 15g of steamed rice and rice cake was prepared as test foods. In the ingestion test, the subjects were asked to eat each food in their usual manner. The chewing duration, number of chewing cycles before the first swallow, Mas and Hyoid EMG activity, and chewing cycle time were compared between the foods. Total chewing duration was divided into three substages: early, middle, and late; chewing cycle time and EMG activity per chewing cycle of each substage were compared between the foods and among the substages. In the spitting test, the rheological properties of the bolus at the end of each substage were compared between the foods and among the substages. Finally, stimulated salivary flow rates were measured and the relationships between salivary flow rate and chewing duration, EMG activity, and changes in physical food characteristics were investigated. There were significant differences in total chewing duration and the number of chewing cycles, but not in chewing cycle time, between the foods, which had similar hardness values. The EMG activity levels of the Mas and Hyoid per chewing cycle for the rice cake were significantly greater than for the steamed rice throughout the recording periods. While Mas activity did not change among the substages during chewing, Hyoid EMG activity decreased as chewing progressed. Chewing cycle time also gradually decreased as chewing progressed. The hardness of both foods initially increased, then gradually decreased back to baseline. The adhesiveness of the rice cake initially increased, and did not fall throughout the recording period; the adhesiveness of the steamed rice did not significantly change. Cohesiveness barely changed in either of the two foods during chewing, but was significantly greater for the rice cake than for the steamed rice. Finally, a correlation between the stimulated salivary flow rate and chewing performance was evident only in a change in Mas EMG activity. The current results demonstrate that the activities of the Mas and Hyoid muscles changed as chewing progressed, and were affected by hardness, adhesiveness, and cohesiveness. Salivary flow rate may affect the changes in Mas activity during the process of bolus formation.

Differences in chewing behaviors between healthy fully dentate young and older adults assessed by electromyographic recordings

To characterize changes in chewing behaviors associated with healthy aging, 10 young and 10 older fully dentate healthy participants were enrolled in this study. They chewed carrot samples that differed in hardness until their normal swallowing threshold. Their chewing behaviors were assessed using an electromyographic recording device. Adjusting for gender and body mass index, older adults had a higher number of chewing cycles (p = 0.020), a longer chewing duration (p < 0.001), a slower chewing rate (p = 0.002), a greater maximal electromyographic voltage (p = 0.003) and a greater muscle activity (p = 0.002) before they could comfortably swallow the food bolus. A statistically significant main effect of food hardness on the number of chewing cycles, chewing duration, chewing rate and muscle activity was also observed (p < 0.001 for all). These results suggest that reduced mastication efficiency is associated with healthy aging in fully dentate adults. This ingestive behavior may contribute to aging-related reduction in appetite in older adults.

Relationship between chewing behavior and body weight status in fully dentate healthy adults

Recent research indicates that chewing behavior may influence energy intake and energy expenditure. However, little is known about the relationship between chewing behavior and body weight status. In the present study, 64 fully dentate normal-weight or overweight/obese adults were asked to consume five portions of a test food and the number of chewing cycles, chewing duration before swallowing and chewing rate were measured. Adjusting for age and gender, normal-weight participants used a higher number of chewing cycles (p = 0.003) and a longer chewing duration (p < 0.001) to consume each portion of the food, compared to overweight/obese participants. However, there was no significant difference in their chewing rate (p = 0.597). A statistically significant negative correlation between body mass index and the number of chewing cycles (r = −0.296, p = 0.020) and chewing duration (r = −0.354, p = 0.005) was observed. In conclusion, these results suggest that chewing behavior is associated with body weight status in fully dentate healthy adults.

Assessment of mastication in healthy children and children with cerebral palsy: a validity and consistency study

The aim of this study was to develop the Mastication Observation and Evaluation instrument for observing and assessing the chewing ability of children eating solid and lumpy foods. This study describes the process of item definition and item selection and reports the content validity, reproducibility and consistency of the instrument. In the developmental phase, 15 experienced speech therapists assessed item relevance and descriptions over three Delphi rounds. Potential items were selected based on the results from a literature review. At the initial Delphi round, 17 potential items were included. After three Delphi rounds, 14 items that regarded as providing distinctive value in assessment of mastication (consensus >75%) were included in the Mastication Observation and Evaluation instrument. To test item reproducibility and consistency, two experts and five students evaluated video recordings of 20 children (10 children with cerebral palsy aged 29-65 months and 10 healthy children aged 11-42 months) eating bread and a biscuit. Reproducibility was estimated by means of the intraclass correlation coefficient (ICC). With the exception of one item concerning chewing duration, all items showed good to excellent intra-observer agreement (ICC students: 0.73-1.0). With the exception of chewing duration and number of swallows, inter-observer agreement was fair to excellent for all items (ICC experts: 0.68-1.0 and ICC students: 0.42-1.0). Results indicate that this tool is a feasible instrument and could be used in clinical practice after further research is completed on the reliability of the tool.

History of Frequent Gum Chewing Is Associated with Higher Unstimulated Salivary Flow Rate and Lower Caries Severity in Healthy Chinese Adults

This was a single-center, prospective, cross-sectional study stratified by age and gender with the objective of determining the relationship between gum chewing history, salivary flow, and dental caries severity in adults. We enrolled 191 subjects aged 18–65 years who underwent assessments for gum chewing history, unstimulated salivary flow rate, salivary pH, and caries severity. Unstimulated salivary flow rate tended to decline with increasing age (p = 0.04), and significant differences in unstimulated salivary flow rate were also found for males (0.58 ± 0.32 ml/min) versus females (0.48 ± 0.30 ml/min) (p = 0.02). Weekly gum chewing frequency was greater in younger subjects (p = 0.001) while no age group differences were noted in pieces per day or chewing duration. Gum chewing habits were similar in males and females. A multivariate model demonstrated that only days per week chewing gum (p < 0.001) and gender (p = 0.007) were predictive of unstimulated salivary flow rate (R² = 0.40). Mean caries severity scores, assessed via ICDAS II and DMFT, increased with age. In multivariate analysis, age was positively associated with ICDAS (p = 0.001) and days per week chewing gum was negatively associated with ICDAS (p = 0.004), indicating that caries severity increased with age, and that days of chewing provided an inverse effect, with increased days of chewing being associated with decreased severity of caries. Overall, a history of frequent gum chewing is associated with higher unstimulated salivary flow rate and lower caries severity.

Gender difference in masticatory performance in dentate adults

PurposeTo clarify whether there might be a gender difference in masticatory performance in dentate adults. MethodsThirty male subjects and thirty female subjects were asked to chew gummy jelly on their habitual chewing side for 10, 15 and 20s and the amounts of glucose extraction were measured. The changes of both glucose extraction and standardized glucose extraction from 10 to 20s were investigated differently for males and females. The amount of glucose extraction was compared between males and females for each chewing duration. In addition, in order to confirm a gender difference in occlusal force, the maximum occlusal force was compared between males and females. ResultsFor both males and females, the amount of glucose extraction was lowest for 10-s chewing and increased significantly for 15-s and 20-s chewing. The mean standardized glucose extraction values increased in proportion with the duration of chewing. The standard deviations of the standardized glucose extraction were very small (below 0.02) for all chewing durations in both males and females. With regard to comparison of the glucose extraction between males and females, the amount of glucose extraction was significantly larger for males than for females for all chewing durations. The maximum occlusal force was significantly larger for males. ConclusionIt was suggested that it might be important to take into consideration gender-related differences while analyzing masticatory performance in dentate adults.

Prevalences of betel nut chewing and cigarette smoking among male prisoners before their imprisonment in Taiwan

Background/purposeSubstance abuse is considered prevalent in incarcerated populations; however, consumption of betel nut in this group has not been adequately studied. In the present study, we attempted to elucidate the prevalences of betel nut chewing and cigarette smoking, and determine the relationship between use of the two substances among prisoners before imprisonment in order to increase our understanding of this phenomenon. Materials and methodsIn 2000, a self-administered anonymous questionnaire was given to 976 male prisoners who were over 18 years of age and had been sentenced to imprisonment for a total incarnation period of more than 10 years in Kaohsiung Prison, Kaohsiung, Taiwan. ResultsThe response rate was 60.3% (589/976). Respective prevalences of betel nut chewing and smoking before imprisonment were 73.2% and 90.7%. Results of a cross-sectional analysis showed that dual-substance (betel nut and cigarette) users made up the majority (71.6%) of the study sample, whereas simple smokers and simple chewers comprised 19.0% and 1.5%, respectively. Only 7.8% of participants used neither substance. Smoking generally began 5.07 years before betel nut use. The duration of betel nut chewing was significantly associated with the daily quantity chewed (r=0.212; P<0.01), and a significant relationship was also found between the daily quantity chewed and smoking (r=0.314; P<0.01). Moreover, the daily quantity chewed increased concomitant with the chewing duration and daily quantity smoked. ConclusionsPrevalences of betel nut chewing and smoking are high among male Taiwanese prisoners before imprisonment. The association of use of these two substances among Taiwanese inmates was significant in a time-dependent manner.

Increasing the number of masticatory cycles reduces food intake in healthy young adults

To investigate if the number of masticatory cycles made during ingestion affects satiation, 47 healthy participants (16 lean, 16 overweight and 15 obese) were recruited for this present study. Pizza rolls were used as the test food and their habitual mastication parameters were measured before they were randomized to a treatment order. Participants were asked to consume the same breakfast and reported to the laboratory for lunch, once a week for three weeks. After baseline appetite measures were made they were asked to eat until they were comfortably full, by chewing each portion of the food at their habitual number of chews, 150% or 200% of their habitual number of chews. Subjective appetite was measured regularly for 60 minutes and upon meal termination. There was no effect of body mass index (BMI) on habitual number of chews, chewing rate and chewing duration. Adjusting for BMI, increased number of masticatory cycles resulted in increased meal duration (P&lt;0.0001) and reduced food intake (P=0.0026). 200% of the habitual number of chews reduced the food intake by 15% (P=0.0007) whereas 150% of the habitual number of chews reduced the food intake by 10% (P=0.0257). The number of chews did not affect hunger, fullness, desire to eat and palatability of the test food. The results suggest increasing the number of chews promotes satiation and could be a strategy for body weight management.Grant Funding Source : Iowa State University