• Preventive Nutrition and Food Science
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• v.15 no.3
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• pp.229-232
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• 2010

Caffeine and catechins from the Yabukita, Yutakamidori, Saemidori, Okumidori, and Fushun varieties of tea leaves picked during different harvesting seasons from April to October were evaluated using HPLC. Total content of catechins increased greatly with the later harvesting time of tea leaves (i.e., picking the leaves in September versus in April) and decreased slightly after September. Yabukita tea leaves picked in August contained 43.1 mg% catechins including EGC, EC, ECG, and EGCG, with the ECGC levels constituting greater than 50% of those four compounds. Yutakamidori and Okumidori varieties picked in September contained the highest catechin values, at 43.6 mg% and 31.0 mg%, respectively. Fushun and Saemidori varieties contained lower catechin concentrations of 14.5 mg% (July) and 11.7 mg% (August) compared to other varieties. The EGCG levels gradually decreased in the late harvesting season, while levels of the other catechins, EC, EGC, and ECG, gradually increased. All varieties of green tea showed a gradual decrease in caffeine content toward the end of our harvesting efforts in October, with levels of 58～68 mg% in April and 28～57 mg% in October. Yabukita, Saemidori, and Okumidori varieties reached their highest caffeine levels in late spring/early summer, with Yabukita and Okumidori varieties reaching a high of 73.4% and 63.5% caffeine, respectively, in May, and Saemidori at 64.0% in June. In particular, Fushun still contained high caffeine of 66.8 mg% (September) during the late harvesting season.

• Journal of Digital Convergence
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• v.12 no.5
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• pp.491-500
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• 2014

The purpose of this study was to suggest the basic information about functional taping applied caffeine which is to improve the fatigue and athletic performance during exercise by examining the effects of the functional taping applied caffeine on fatigue substance during high-intensity training. 10 male university students who are sprint runners were participated for this study and blood lipid components such as lactic acid, LDH, and phosphorous were analyzed. First, a group who used the functional taping applied caffeine showed lower rate of increase in lactic acid than other group who didn't use taping and also lactic acid showed lower rate of increase after the training than before the training. Second, a group who used the functional taping applied caffeine showed lower rate of increase in LDH than other group who didn't use taping and LDH also showed lower rate of increase after the training than before the training. Third, a group who used the functional taping applied caffeine showed lower rate of increase in phosphorous than other group who didn't use taping and phosphorous also showed lower rate of increase after the training than before the training. With this results, a group who used functional taping applied caffeine and perform high-intensity training can be a method which it can change the lactic acid, LDH, and phosphorous in positive way to sprint runners.

• Journal of Nutrition and Health
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• v.45 no.6
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• pp.522-530
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• 2012

This study was performed in order to investigate the relationship between attention deficit hyperactivity disorder (ADHD), dietary habit and caffeine intake in upper-grade elementary school children. The total number of the study subjects was 237 students (111 boys and 126 girls), where 30 students (12.7%) were diagnosed as ADHD. The dietary habit score of the ADHD group was significantly lower than that of the normal group. In particular, the ADHD group had lower dietary scores in consuming daily breakfast, diverse foods, fruit and milk than those in the normal group. Meanwhile, the daily intake frequency of instant noodle (ramyeon) was significantly higher in the ADHD group than that in the normal group. The mean caffeine intake of the students was 42.95 mg and the proportion of students consuming more than the ADI (acceptable daily intake) was 11.8%. The caffeine intake of ADHD group (63.63 mg) tended to be higher than that of the normal group (39.95 mg); however, it was not significantly different. The ADHD score of the students was negatively related with the dietary habit score (r = -0.279, p < 0.01) but positively related with caffeine intake (r = 0.164, p < 0.05). The dietary habit score had a negative relationship with caffeine intake (r = -0.180, p < 0.01) and a positive relationship with height (r = 0.195, p < 0.01). Caffeine intake had a negative relationship with the height of the students (r = -0.171, p < 0.05). In conclusion, ADHD in children was related to poor dietary habit and high caffeine intake.

• The Korean Journal of Zoology
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• v.14 no.2
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• pp.43-56
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• 1971

The Ca uptake by the fragmented sarcoplasmic reticulum of the rabbit skeletal muscle was measured under various concentrations of K, Mg, Caffeine, procaine and quinine. The ATPase activity of this reticular membrane was measured under the same conditions simultaneously. The saturation of Ca uptake was almost completed within 1 minute. The Ca uptake was inhibited by high concentrations of K (above 50 mM) and Mg (above 1 mM)in the absence of ATP. When ATP is present, however, the Ca uptake did not reflect the concentration of K, while it increased greatly as the concentration of Mg was increased. Caffeine and procaine caused the inhibition of Ca uptake in the presence of ATP, but quinine did not. The ATPase activity of the membrane was little affected by the concentration of K, while it was enhanced in the presence of Mg. Caffeine, procaine and quinine did not influence the ATPase activity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.9
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• pp.1128-1136
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• 2017

Previous studies of the caffeine consumption pattern were limited primarily to beverages containing caffeine. Therefore, this study examined the caffeine consumption patterns and levels in beverages and foods containing caffeine among high school students (n=310) in the Yongin region. The participants included 171 boys (55.2%) and 139 girls (44.8%). The daily mean caffeine intake of the respondents was 41.27 mg (0.651 mg/kg) and 36.47 mg (0.696 mg/kg) in boys and girls, respectively. Among the caffeinated food groups, coffee had the highest caffeine intake group in both boys (18.95 mg) and girls (26.28 mg). Girls consumed large amounts of caffeine in the form of Americano-style coffee (20.04 mg), whereas boys consumed more canned coffee (6.77 mg) than girls (2.43 mg, P<0.01). Carbonated soft drinks were the second most prevalent source of caffeine intake in both groups, even though boys (14.29 mg) consumed larger amounts of caffeine than girls (5.85 mg, P<0.001). Multiple regression analysis investigating the major contributing food group to daily total caffeine intake also showed that the highest standardized coefficient was in coffee regardless of gender (boys 0.492, P<0.001 and girls 0.944, P<0.001), followed by carbonated soft drinks and energy drinks. Approximately 95% of high school students consumed normal levels of caffeine, whereas 3.5% of boys and 5.8% of girls consumed excessive amounts based on the standard limit of Korea Food and Drug Administration (<2.5 mg/kg/d) for adolescents. The daily mean caffeine intake of the excess group was 5.38 mg/kg and 6.96 mg/kg in boys and girls, respectively. Consequently, safe daily caffeine intake needs to be determined throughout continuous national management guidelines and nutritional education.

• The Journal of Internal Korean Medicine
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• v.29 no.3
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• pp.778-786
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• 2008

Objectives : This study was to investigate the short time effect of caffeine on heart rate variability(HRV) and the effect of Neiguan(PC6) acupuncture stimulation on HRV. Methods : 27 healthy adult volunteers were randomly allocated to two groups: Neiguan group (N=13) or placebo group (N=14). The study was carried out under a randomized double-blinded placebo-controlled trial method. Each group orally received the same tablets with 200 mg caffeine. After 1 hour, acupuncture was applied to the Neiguan(PC6) points for the Neiguan group, and for the placebo group was applied to a non-acupuncture point. Both groups were estimated with HRV 3 times, before and after caffeine ingestion, 20 minutes after acupuncture stimulation. Results : After taking caffeine, pulse rate, mean-HRV, and pNN50(the proportion derived by dividing NN50 by the total number of NN intervals) decreased, SDNN(standard deviation of all normal-to-normal (NN) intervals), RMSSD (the root square of successive differences), TP log, HF(high frequency), and HRV index was increased. There were significant changes to the autonomic nervous system after taking caffeine. There were no significant differences between the two groups after acupuncture at Neiguan. Conclusion : Caffeine could induce general activation of the autonomic nervous system. Neiguan acupuncture stimulation may not have significant influence on the autonomic nervous system.

• Korean Journal of Veterinary Research
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• v.31 no.1
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• pp.123-130
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• 1991

The present study was performed to investigate the effect of Ca ion concentration on sperm viability and acrosome reaction rate and to evaluate the effect of treatments using caffeine and Ca-ionophore A23187 on acrosome reaction rate in frozen-thawed bull spermatozoa. Viabilities of in vitro capacitated bull spermatozoa at 0, 2.25 and 4.5 mM Ca ion concenrations were 21.00, 26.00 and 22.59%, respectively and significantly higher in Ca ion 2.25mM added group than Ca ion free group (p<0.05) and acrosome reaction rates of in vitro capacitated bull spermatozoa were 17.09, 52.15 and 47.92%, respectively and significantly high in Ca ion added groups(p<0.05). Viabilities in vitro capacitation by caffeine and Ca-ionophore A23187 in control, caffeine treated group, Ca-ionophore A23187 treated group and caffeine+Ca-ionophore A23187 treated group were 37.91, 27.67, 22.33 and 25.59%, respectively and significantly higher in control than treated groups(p<0.05), there were no significant differences among the treated groups, and acrosome reaction rates were 10.33, 37.92, 48.09 and 57.17%, respectively and there were significant differences among the groups(p<0.05), especially higher in caffeine+Ca-ionophore A23187 treated group than others.

• The Korean Journal of Pharmacology
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• v.24 no.2
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• pp.197-201
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• 1988

Effects of high concentration of KC1 and caffeine on cytosolic $Ca^{2+}$ level $([Ca^{2+}]_{cyt})$, measured simultaneously with muscle tension using a fluorescent intracellular $Ca^{2+}$ indicator fura 2, were examined in isolated smooth muscle of rat aorta. High $K^+$ (72.7 mM) solution induced sustained increase in both $([Ca^{2+}]_{cyt})$ and tension. In contrast to this, caffeine (20 mM) induced a rapid increase in $([Ca^{2+}]_{cyt})$ followed by a decrease to a level which was higher than the resting level. However, muscle tension showed only a transient increase followed by a decrease below the resting level. In a $Ca^{2+}-free$ solution, high $K^+-induced$ neither $([Ca^{2+}]_{cyt})$ nor tension, whereas caffeine induced a transient increase in both $([Ca^{2+}]_{cyt})$ and muscle tension. These results suggest that high $K^+-induced$ contraction in vascular smooth muscle of rat aorta is due to $Ca^{2+}$ influx whereas caffeine-induced contraction is due to $Ca^{2+}$ release from cellular store. Further, caffeine seems to have an additional effect to decrease the sensitivity of the contractile elements to $Ca^{2+}$.

• Journal of Food Hygiene and Safety
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• v.29 no.2
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• pp.105-116
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• 2014

Surveys on the consumption of caffeinated beverages by high school students (n=886) were performed. Of the students, 97.0% consumed a variety of caffeinated beverages, including carbonated drinks (90.0%), processed milk and cocoa (79.0%), coffee (63.0), teas (52.1), energy drinks (16.4%) and nourishment drinks (15.5%). The frequency of intake per student was 8.2 times per week. Caffeine intake through the caffeinated beverages was 41.53 mg/day, which was accounted for by coffee (51.5%), carbonated drinks (19.6%), processed milk and cocoa (11.5%), teas (11.4%), energy drinks (5.0%) and nourishment drinks (1.1%). Students with high levels of stress, those who consumed snacks twice a day, and those who used a computer (or smart phone) for more than 3 hours per day showed significantly higher caffeine intake. The groups with high caffeine intake experienced heart palpitations, insomnia and pollakiuria. Students indicated that they consumed the caffeinated beverages for the taste (57.9%), waking up (18.0%), thirst (13.2%), etc. (10.9%). They tended to consume drinks with a high content of caffeine to sleep less. In addition, they rarely checked the label, and showed a lack of awareness of the caffeine contents in the beverages, which calls for education.

• Journal of the Korean Society of School Health
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• v.29 no.2
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• pp.71-80
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• 2016

Purpose: The purpose of this study is to examine the association between consuming high-caffeine energy drinks and suicidal ideation in Korean adolescents. Methods: This study used data drawn from the 2015 Korea Youth Risk Behavior Web_Based Survey. The data of 66,068 students in total (33,374 middle school students and 32,694 high school students) were included in the analysis. The $x^2$ test, univariate and multivariate logistic regressions were conducted with the use of SAS 9.3. Results: Adjusted for the variables associated with suicidal ideation, multivariate logistic regression revealed that consuming highly caffeinated energy drinks had a significant effect on suicidal ideation (middle school students, 1~2 times per week: OR=1.24, 3~4 times per week: OR=1.88, 5~6 times per week: OR=2.20, everyday: OR=2.66, high school students, 1~2 times per week: OR=1.26, 3~4 times per week: OR=1.84, 5~6 times per week: OR=2.42, everyday: OR=3.89). Conclusion: This study strongly suggests adolescents be provided with health education and information about consuming an adequate amount of high-caffeine energy drink and the drink's side effects. In addition, regulations and polices on high-caffeine drink intake should be implemented.