Sleep duration has a limited impact on the prevalence of menstrual irregularities in athletes: a cross-sectional study.

Background: This study aimed to investigate the relationship between the prevalence of menstrual irregularities, energy intake, and sleep deprivation among female athletes. Methods: A total of 128 female athletes, with an average age of 19.2 ± 1.2 years, participated in the study and tracked their food intake over a three-day period. Menstrual status and sleep duration were assessed using a questionnaire, and psychological anxiety was evaluated using the State and Trait Anxiety Inventory (STAI). These were measured once during the investigation. The impact of sleep status on state anxiety and daily energy intake was examined using the T-test. A generalized linear model (GLM) with a log link function was employed to investigate the effects of sleep deprivation on the presence of menstrual irregularities. Results: As the results of the present study, sleep deprivation significant increased both state and trait anxiety (p < 0.05), as well as affecting energy intake (p < 0.05), particularly protein and carbohydrate intakes (p < 0.05). However, GLM analysis indicated that while sleep deprivation did not directly influence the prevalence of menstrual irregularities (p > 0.05), state anxiety emerged as a significant factor impacting the prevalence of menstrual irregularities (p < 0.05). Conclusions: The results of the present study suggest a potential pathway wherein sleep deprivation might elevate state anxiety levels, consequently indirectly contributing to an increase the probability of menstrual irregularities. In conclusion, the results of the presents study provide novels insights suggesting that sleep deprivation might directly increase state anxiety and indirectly affect the prevalence of menstrual irregularities. Hence, decreased sleep duration might be related to mental health issues and the prevalence of menstrual irregularities both significant concerns among female athletes. Future studies will play a crucial role in further elucidating how sleep patterns impact the health and well-being of female athletes.

Association between awareness of limiting food intake and all-cause mortality: A cohort study in Japan.

BACKGROUND: Improving diets requires an awareness of the need to limit foods for which excessive consumption is a health problem. Since there are limited reports on the link between this awareness and mortality risk, we examined the association between awareness of limiting food intake (energy, fat, and sweets) and all-cause mortality in a Japanese cohort study. METHODS: Participants comprised 58,772 residents (27,294 men; 31,478 women) aged 35-69 years who completed baseline surveys of the Japan Multi-Institutional Collaborative Cohort Study from 2004 to 2014. Hazard ratios (HRs) for all-cause mortality and 95% confidence intervals (CIs) were estimated by sex using a Cox proportional hazard model, with adjustment for related factors. Mediation analysis with fat intake as a mediator was also conducted. RESULTS: The mean follow-up period was 11 years and 2,516 people died. Estimated energy and fat intakes according to the Food Frequency Questionnaire were lower in those with awareness of limiting food intake than in those without this awareness. Women with awareness of limiting fat intake showed a significant decrease in mortality risk (HR=0.73; 95% CI, 0.55 to 0.94). Mediation analysis revealed that this association was due to the direct effect of the awareness of limiting fat intake and that the total effect was not mediated by actual fat intake. Awareness of limiting energy or sweets intake was not related to mortality risk reduction. CONCLUSION: Awareness of limiting food intake had a limited effect on reducing all-cause mortality risk.

Exploring the relationship between nutritional intake and menstrual cycle in elite female athletes.

This study aimed to examine potential variations in nutritional intake among female athletes, including top-level, throughout the menstrual cycle. A total 122 female athletes participated in the study, documenting their food consumption over a 3-day period. The menstrual status of female athletes was also assessed, and using the survey results, the phase of the menstrual cycle (the follicular, early luteal, or late luteal) during which each meal was recorded was determined. Consequently, the meal records were categorized into the respective three phases. The findings of this study indicated that there were no notable disparities in nutritional intake, encompassing energy, protein, fat, carbohydrate, calcium, iron, and fiber, across the three phases of the menstrual cycle. The results imply that female athletes may experience comparatively smaller variations in nutrient intake related to the menstrual cycle. This could be attributed to the higher energy requirements of female athletes because of their rigorous training. This study underscores the significance of accounting for the population when examining nutrient intake changes associated with the menstrual cycle.

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.

GWAS of folate metabolism with gene-environment interaction analysis revealed the possible role of lifestyles in the control of blood folate metabolites in Japanese - the J-MICC Study.

BACKGROUND: The present genome-wide association study (GWAS) aimed to reveal the genetic loci associated with folate metabolites as well as to detect related gene-environment interactions in Japanese. METHODS: We conducted the GWAS of plasma homocysteine (Hcy), folic acid (FA), and vitamin B12 (VB12) levels in the Japan Multi-Institutional Collaborative Cohort (J-MICC) Study participants who joined from 2005 to 2012, and also estimated gene-environment interactions. In the replication phase, we used data from the Yakumo Study conducted in 2009. In the discovery phase, data of 2,263 participants from four independent study sites of the J-MICC Study were analyzed. In the replication phase, data of 573 participants from the Yakumo Study were analyzed. RESULTS: For Hcy, MTHFR locus on chr 1, NOX4 on chr 11, CHMP1A on chr 16, and DPEP1 on chr 16 reached genome-wide significance (P < 5×10-8). MTHFR also associated with FA, and FUT2 on chr 19 associated with VB12. We investigated gene-environment interactions in both studies and found significant interactions between MTHFR C677T and ever drinking, current drinking, and physical activity > 33% on Hcy (ß = 0.039, 0.038 and -0.054, P = 0.018, 0.021 and < 0.001, respectively) and the interaction of MTHFR C677T with ever drinking on FA (ß = 0.033, P = 0.048). CONCLUSIONS: The present GWAS revealed the folate metabolism-associated genetic loci and gene-environment interactions with drinking and physical activity in Japanese, suggesting the possibility of future personalized CVD prevention.

The effect of background music tempo on eating speed and food intake volume within in healthy women.

BACKGROUND: The effects of the different tempos of background music (BGM) on food intake and eating speed have not been fully studied. AIM: The study aimed to investigate the influence of changing the tempo of BGM during meals on food intake and to explore strategies to support appropriate eating behavior. METHODS: Twenty-six healthy young adult women participated in this study. In the experimental phase, each participant ate a meal under three separate conditions: fast (120% speed), moderate (original, 100% speed), and slow (80% speed) BGM. The same music was used for each condition, and appetite before and after eating, the amount of food consumed, and eating speed were recorded. RESULTS: The results showed that food intake (g, mean ± standard error (SE)) was slow: 317.9 ± 22.2, moderate: 400.7 ± 16.0, and fast: 342.9 ± 22.0. Eating speed (g/s, mean ± SE) was slow: 28.1 ± 2.8, moderate: 34.2 ± 2.7, and fast: 27.2 ± 2.4. The analysis showed that the moderate condition showed greater speed than the fast and slow conditions (slow-fast: p = .008; moderate-slow: p = .012; moderate-fast: p = .004). Moreover, the food intake in the moderate condition was significantly higher than that in the slow and fast conditions (moderate-slow: p < .001; moderate-fast: p < .001), and there was no significant difference between the slow and fast conditions in this regard (p = .077). CONCLUSION: These results suggest that original tempo BGM led to higher food intake compared to the faster and slower tempo conditions. These findings suggest that listening to music at an original tempo during meals may support appropriate eating behavior.

Cross-modal and subliminal effects of smell and color.

In the present study, we examined whether the cross-modal effect can be obtained between odors and colors, which has been confirmed under olfactory recognizable conditions and also occurs under unrecognizable conditions. We used two flavors of red fruits such as strawberries and tomatoes for this purpose. We also aimed to compare whether similar cross-modal effects could be achieved by setting the flavors at recognizable (liminal) and unrecognizable (subliminal) concentrations in the experiment. One flavor at a normal concentration (0.1%, Liminal condition) and one at a concentration below the subliminal threshold (0.015%, Subliminal condition), were presented, and the color that resembled the smell most closely from among the 10 colors, was selected by participants. Except for the subliminal tomato condition, each odor was significantly associated with at least one color (p < 0.01). Participants selected pink and red for liminal strawberry (0.1%) (p < 0.05), pink for subliminal strawberry (0.015%) (p < 0.05), and orange for liminal tomato (0.1%) (p < 0.05), but there was no color selected for subliminal tomato (0.015%) (p < 0.05). The results of this study suggest that the flavor of tomato produced a cross-modal effect in liminal conditions, but not in subliminal conditions. On the other hand, the results of the present study suggest that the flavor of strawberries produces a cross-modal effect even under subliminal conditions. This study showed that cross-modal effects might exist, even at unrecognizable levels of flavor.

Increased vitamin D intake may reduce psychological anxiety and the incidence of menstrual irregularities in female athletes.

Background: Vitamin D deficiency has been associated with major depression and premenstrual mood symptoms, and menstrual irregularity has been correlated with mental anxiety. However, the potential effect of increased vitamin D intake on reducing the risk of menstrual irregularities by decreasing psychological anxiety is yet to be fully elucidated. The existence of such a relationship in athletes with high levels of psychological anxiety and adequate dietary intake remains unknown. Therefore, this study aimed to examine the effects of vitamin D intake on psychological anxiety levels and the risk of menstrual irregularities in healthy college-and international-level female athletes. Methods: Female intercollege-level track and field and international-level rowing athletes (n = 107) aged 15-24 years were included in this study. Their nutritional intake, body mass, body fat, mental anxiety, and menstrual irregularities were investigated. A generalized linear mixed model (GLMM) was used to examine the effects of several parameters on menstrual irregularities. The independent variables introduced into the GLMM were determined based on Akaike's information criterion. Results: The GLMM identified a significant interaction effect of vitamin D intake and state anxiety on menstrual irregularities, with a p-value of 0.049 and an odds ratio of 0.423. The study results suggest that increased vitamin D intake in relatively young endurance athletes may reduce mental anxiety, consequently decreasing menstrual irregularities.

Irregular sleep and all-cause mortality: A large prospective cohort study.

OBJECTIVES: Previous studies using objective parameters have shown that irregular sleep is associated with the disease incidence, progression, or mortality. This study aimed to determine the association between subjective sleep duration and sleep regularity, with mortality in a large population. METHODS: Participants were from the Japan Multi-Institutional Collaborative Cohort study. We obtained information from each participant on sleep duration, sleep regularity, and demographics and overall lifestyle using self-administered questionnaires. We defined sleep regularity according to participants' subjective assessment of sleep/wake time regularity. Participants (n = 81,382, mean age: 58.1 ± 9.1years, males: 44.2%) were classified into 6 groups according to sleep duration and sleep regularity. Hazard ratios (HR) for time-to-event of death were calculated using the Cox proportional hazards model. RESULTS: The mean follow-up period was 9.1 years and the mean sleep duration was 6.6 h/day. Irregular sleep significantly increased the risk of all-cause mortality in all models compared with regular sleep (HR 1.30, 95% confidence interval; CI, 1.18-1.44), regardless of sleep duration. Multivariable analysis of the 6 groups by sleep pattern (sleep regularity and duration) showed irregular sleep and sleep durations of <6 h/day, 6 to <8 h/day, or ≥8 h/day were associated with a 1.2-1.5-fold increases in mortality, compared to regular sleep and sleep duration of 6 to <8 h/day. CONCLUSIONS: Our study shows an association between sleep irregularity and all-cause mortality in a large Japanese population. Our findings provide further confirmation of the need to consider not only sleep duration, but also the regularity aspect of sleep schedules.

Effects of Repetitive Peripheral Magnetic Stimulation through Hand Splint Materials on Induced Movement and Corticospinal Excitability in Healthy Participants.

Repetitive peripheral magnetic stimulation (rPMS) is a non-invasive neuromodulation technique. Magnetic fields induced by rPMS pass through almost all materials, and it has clinical applications for neurorehabilitation. However, the effects of rPMS through clothing and orthosis on induced movement and corticospinal excitability remain unclear. The aim of this study was to determine whether rPMS induces movement and enhances corticospinal excitability through hand splint materials. rPMS was applied directly to the skin (L0) and through one (L1) or two (L2) layers of splint material in 14 healthy participants at 25-Hz, 2-s train per 6 s for a total of 20 min. rPMS was delivered to the forearm with the stimulus intensity set to 1.5-times the train intensity-induced muscle contractions under the L0 condition. We recorded induced wrist movements during rPMS and motor-evoked potentials of the extensor carpi radialis pre- and post-application. The results showed that rPMS induced wrist movements in L0 and L1, and it facilitated corticospinal excitability in L0 but not in L1 and L2. This suggests that rPMS can make electromagnetic induction on periphery even when applied over clothing and orthosis and demonstrates the potential clinical applications of this technique for neurorehabilitation.

Time course changes in corticospinal excitability during repetitive peripheral magnetic stimulation combined with motor imagery.

Repetitive peripheral magnetic stimulation (rPMS) induces proprioceptive afferents and facilitates corticospinal excitability. Short-term sessions of rPMS combined with motor imagery (MI) enhance corticospinal excitability more than rPMS alone. However, it is not clear how long the intervention of rPMS combined with MI would be needed to facilitate corticospinal excitability. Therefore, we investigated the time course change in corticospinal excitability during the combination of rPMS and MI. Thirteen healthy volunteers participated in a 20-min intervention under the following three experimental conditions on different days: rPMS, MI, and rPMS combined with MI (rPMS + MI). In the rPMS and rPMS + MI, the participants were delivered rPMS, which was 25 Hz, 2 s/train at 1.5 × of the train intensity induced muscle contractions, through the wrist extensor muscles. In the MI and rPMS + MI, the participants repeatedly imagined wrist movements for 2 s. Motor evoked potentials (MEPs) were recorded from the extensor carpi radialis (ECR) and flexor carpi radialis (FCR) muscles every 5 min for each condition. The MEP amplitudes of the ECR after > 10 min of intermittent rPMS combined with MI were greater than baseline. The MEP amplitude of the ECR in rPMS + MI was greater than that in rPMS condition after 20 min of intervention. The present results suggest that over 10 min of intermittent rPMS combined with MI facilitates corticospinal excitability, and that the effect of rPMS combined with MI on corticospinal excitability might be greater than that of rPMS alone.

Relationship among Nutritional Intake, Anxiety, and Menstrual Irregularity in Elite Rowers.

There is evidence showing that excessive mental stress is detrimental to the menstrual period, and it is known that many elite athletes are highly susceptible to mental anxiety. This study investigated the nutritional intake and mental anxiety of 104 relatively young elite endurance athletes aged 16 to 23 years and used a multiple logistic model to examine the factors that might be related to menstrual irregularity. Calcium intake was marginally associated with the occurrence of menstrual irregularities (odds ratio = 1.004, p = 0.030), whereas there were strong associations between body mass or state anxiety and menstrual irregularities in elite athletes (odds ratio = 0.557, p = 0.035 for body mass; odds ratio = 1.094, p = 0.006 for state anxiety). These results suggested that state anxiety would be an important factor causing menstrual irregularity in elite endurance athletes. It is recommended that elite athletes are monitored for anxiety levels and develop a strategy for stress management.

A Proposal for Practical Diagnosis of Renal Hypouricemia: Evidenced from Genetic Studies of Nonfunctional Variants of URAT1/SLC22A12 among 30,685 Japanese Individuals.

BACKGROUND: Renal hypouricemia (RHUC) is characterized by a low serum uric acid (SUA) level and high fractional excretion of uric acid (FEUA). Further studies on FEUA in hypouricemic individuals are needed for a more accurate diagnosis of RHUC. METHODS: In 30,685 Japanese health-examination participants, we genotyped the two most common nonfunctional variants of URAT1 (NFV-URAT1), W258X (rs121907892) and R90H (rs121907896), in 1040 hypouricemic individuals (SUA ≤ 3.0 mg/dL) and 2240 individuals with FEUA data. The effects of NFV-URAT1 on FEUA and SUA were also investigated using linear and multiple regression analyses. RESULTS: Frequency of hypouricemic individuals (SUA ≤ 3.0 mg/dL) was 0.97% (male) and 6.94% (female) among 30,685 participants. High frequencies of those having at least one allele of NFV-URAT1 were observed in 1040 hypouricemic individuals. Furthermore, NFV-URAT1 significantly increased FEUA and decreased SUA, enabling FEUA and SUA levels to be estimated. Conversely, FEUA and SUA data of hypouricemic individuals are revealed to be useful to predict the number of NFV-URAT1. CONCLUSIONS: Our findings reveal that specific patterns of FEUA and SUA data assist with predicting the number of nonfunctional variants of causative genes for RHUC, and can also be useful for practical diagnosis of RHUC even before genetic tests.

Effect of repetitive peripheral magnetic stimulation combined with motor imagery on the corticospinal excitability of antagonist muscles.

OBJECTIVE: Repetitive peripheral magnetic stimulation (rPMS) combined with motor imagery facilitates the corticospinal excitability of the agonist muscles. However, the effects of rPMS combined with motor imagery on the corticospinal excitability of the antagonist muscles are unclear. This is an important aspect for applying rPMS in neurorehabilitation for sensorimotor dysfunction. Therefore, we investigated the real-time changes of corticospinal excitability of antagonist muscles during rPMS combined with motor imagery. METHODS: Fourteen healthy volunteers underwent four different experimental conditions: rest, rPMS, motor imagery, and rPMS combined with motor imagery (rPMS + motor imagery). In the rPMS and rPMS + motor imagery conditions, rPMS (25 Hz, 1600 ms/train, 1.5× of the motor threshold) was delivered to the dorsal side of the forearm. In motor imagery and rPMS + motor imagery, the participant imagined wrist extension movements. Transcranial magnetic stimulation was delivered to record motor-evoked potentials of the antagonist muscle during experimental interventions. RESULTS: The motor-evoked potential (normalized by rest condition) values indicated no difference between rPMS, motor imagery, and rPMS + motor imagery. CONCLUSION: These results suggest that rPMS combined with motor imagery has no effect on the corticospinal excitability of the antagonist muscles and highlight the importance of investigating the effects of rPMS combined with motor imagery at the spinal level.

Dietary intake and menstrual cycle changes in international level young athletes.

BACKGROUND: Few studies have examined the influence of nutritional status and mental stress on menstrual cycle characteristics. The purpose of this study was to describe the impact of low energy availability (EA) and mental health problems on the menstrual cycles of elite female rowing competitors during a survey period. METHODS: We enrolled sixteen subjects (16-18 years old) who were elite female rowing competitors preparing for an international competition. This study provides the first long-term assessment of dietary intake, body mass/composition, state of anxiety, and menstrual cycle in international level female athletes. RESULTS: Dietary energy intake increased significantly during the investigation period (P<0.001). CHO intake increased significantly during the investigation period (P<0.005). EA significantly increased during the investigation period (P<0.01). The percentage of athletes with menstrual dysfunction was 20.0% in April 2018 (2 of 10), but none of the athletes reported menstrual dysfunction in October 2019. The mental status measured by state anxiety index (STAI) did not change significantly during this survey period (P>0.05). CONCLUSIONS: There was no athlete who has menstrual disfunction after sufficient CHO intake during this survey period. These findings of this study suggest that adequate EA levels and sufficient CHO intake might lead to improved menstrual function. In addition, the impact of psychological factors on menstrual dysfunction at normal levels may be less than the effects of nutritional status.

The effect of an image of watchful eyes on the evaluation of the appearance of food.

It is known that an eye-like image promotes generosity. It is also known that the evaluation of the visual deliciousness of food is improved in the presence of an emotionally positive stimulus. The purpose of the present study was to examine whether the presence of open eyes (OPEN) causes generous behavior altering the evaluation of the visual deliciousness of food, and how the images of open and closed eyes (CLOSED) affect human emotions. Seventeen women participated in the present study. A picture of food was presented on a computer screen, and the participants predicted and evaluated its visual deliciousness. An image of OPEN or that of CLOSED was presented simultaneously with a picture of food. There was a significant difference between the OPEN and CLOSED conditions, as demonstrated by the scores on a nine-point Likert scale for visual deliciousness; the ratings in the OPEN condition were significantly higher than those in the CLOSED condition (p = 0.004). There was no significant difference in the image of watchful eyes for the perceived relaxation state; the ratings in the OPEN condition were not significantly higher than those in the CLOSED condition (p = 0.716). The results of the present study revealed that the evaluation of the visual deliciousness of food based on its appearance was likely due to the presence of an image of open watchful eyes, increasing the perceived visual deliciousness of the food without any changes in the participants' emotions.

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.

Short-term session of repetitive peripheral magnetic stimulation combined with motor imagery facilitates corticospinal excitability in healthy human participants.

The aim of the present study was to investigate the effects of repetitive peripheral magnetic stimulation (rPMS) combined with motor imagery (MI) on corticospinal excitability. Ten healthy individuals participated in two kinds of short-term sessions: rPMS combined with MI [magnetic stimulation motor imagery (MSMI)] and rPMS alone (magnetic stimulation) on different days. We measured the motor-evoked potentials before and after the session, and the MI ability of each participant using the Movement Imagery Questionnaire-Revised. The post-session/pre-session motor-evoked potential ratio was larger in the MSMI than in the magnetic stimulation condition, and the difference was correlated to the Movement Imagery Questionnaire-Revised score. This suggests that rPMS combined with MI induced greater corticospinal excitability than rPMS alone. This study highlights the possibility that short-term sessions of rPMS combined with MI could have clinical applications in improving the sensorimotor dysfunctions of stroke patients.

Effects of transcutaneous electrical nerve stimulation and visuotactile synchrony on the embodiment of an artificial hand.

The rubber hand illusion (RHI) is an experimental paradigm known to produce a bodily illusion. Transcutaneous electrical nerve stimulation (TENS) combined with the RHI induces a stronger illusion than the RHI alone. Visuotactile stimulus synchrony is an important aspect of the RHI. However, the effect of TENS and visuotactile stimulus synchrony in TENS combined with the RHI remains unknown. The purpose of this study was to investigate the effects of TENS and visuotactile stimulus synchrony on the embodiment of an artificial hand when using TENS combined with the RHI. The participants underwent four experimental conditions in random order: TENS/noTENS × Synchronous/Asynchronous. TENS was set at an intensity such that it generated a feeling of electrical paresthesia in the radial nerve area of the hand but did not cause pain, i.e., 100-Hz pulse frequency, 80-µs pulse duration, and a constant pulse pattern. A visuotactile stimulus, either temporally synchronous or asynchronous, was generated using paintbrush strokes. To evaluate the outcome measures, the participants completed a questionnaire report and proprioceptive drift assessments (motor response and perceptual response). There were significant main effects of TENS and visuotactile synchrony, but no interaction between these factors, on the results of the questionnaire and the perceptual response. In contrast, there was no significant effect on the result of the motor response. These findings indicate that TENS and visuotactile synchrony might affect differently the embodiment of an artificial hand when using TENS combined with the RHI.

The Response Time of the Stroop Test Is Delayed during Lemon-Flavored Gum Chewing.

In the present study, we examined the cognitive function during mastication of lemon-flavored gum, which is said to enhance cerebral blood flow. Nine healthy subjects (8 female and 1 male) participated in this study. Subjects chewed the gum for 3 min after fasting for 2 h and conducted a Stroop test while continuing to chew. At the end of all answers, gum chewing ended. The response time in the Stroop test was used as an indicator of cognitive function. We set the three conditions (lemon-flavored gum, mint-flavored gum, no gum chewing). There was no significant difference in reaction time between chewing mint-flavored gum and not chewing (p>0.05). However, the response time during chewing gum with a lemon flavor was significant slower than the conditions with mint-flavored gum and without gum chewing (p<0.05, in both). From the results of the present study, it was suggested that the response time delay of the Stroop test observed during the chewing of lemon-flavored gum revealed temporary decay of cognitive function during lemon-flavored gum chewing. It is suggested that lemon-flavored chewing gum forces a brain overload, resulting in a temporary decrease in cognitive function.