Levels Of Caffeine Intake Research Articles

Threshold effects between caffeine intake and urine flow rate: a population-based cross-sectional study.

The potential benefits of caffeine intake are currently receiving much attention and exploration. Urine flow rate (UFR) is an objective index to comprehensively reflect bladder function. The aim of this study was to investigate the association between caffeine intake and UFR using the National Health and Nutrition Examination Survey (NHANES) database. 14,142 participants were enrolled in this study. Weighted multivariate adjusted regression models were used to explore the relationship between caffeine intake and UFR. The dose-response relationships were explored using a restricted cubic spline (RCS) and a threshold effect analysis was conducted based on the inflection points identified by the two-segment linear regression model. In addition, subgroup analysis and sensitivity analysis were applied. The findings suggested that the intake of caffeine was correlated with improved UFR [Model 3: 0.091 (0.057, 0.126), P value < 0.001]. In addition, the RCS supported a nonlinear relationship between them. The analysis of threshold effect further revealed a specific level of caffeine intake (34.51mg/day) that exhibited a significant enhancement in UFR. Finally, through re-analyzing the data set obtained after multiple imputation (MI), we obtained similar results. This study found a nonlinear beneficial relationship between caffeine intake and UFR, and revealed the recommended intake of caffeine. The values varied by gender, race, education, and smoking status.

Repeated caffeine intake suppresses cerebral grey matter responses to chronic sleep restriction in an A1 adenosine receptor-dependent manner: a double-blind randomized controlled study with PET-MRI

Evidence has shown that both sleep loss and daily caffeine intake can induce changes in grey matter (GM). Caffeine is frequently used to combat sleepiness and impaired performance caused by insufficient sleep. It is unclear (1) whether daily use of caffeine could prevent or exacerbate the GM alterations induced by 5-day sleep restriction (i.e. chronic sleep restriction, CSR), and (2) whether the potential impact on GM plasticity depends on individual differences in the availability of adenosine receptors, which are involved in mediating effects of caffeine on sleep and waking function. Thirty-six healthy adults participated in this double-blind, randomized, controlled study (age = 28.9 ± 5.2 y/; F:M = 15:21; habitual level of caffeine intake < 450 mg; 29 homozygous C/C allele carriers of rs5751876 of ADORA2A, an A2A adenosine receptor gene variant). Each participant underwent a 9-day laboratory visit consisting of one adaptation day, 2 baseline days (BL), 5-day sleep restriction (5 h time-in-bed), and a recovery day (REC) after an 8-h sleep opportunity. Nineteen participants received 300 mg caffeine in coffee through the 5 days of CSR (CAFF group), while 17 matched participants received decaffeinated coffee (DECAF group). We examined GM changes on the 2nd BL Day, 5th CSR Day, and REC Day using magnetic resonance imaging and voxel-based morphometry. Moreover, we used positron emission tomography with [18F]-CPFPX to quantify the baseline availability of A1 adenosine receptors (A1R) and its relation to the GM plasticity. The results from the voxel-wise multimodal whole-brain analysis on the Jacobian-modulated T1-weighted images controlled for variances of cerebral blood flow indicated a significant interaction effect between caffeine and CSR in four brain regions: (a) right temporal-occipital region, (b) right dorsomedial prefrontal cortex (DmPFC), (c) left dorsolateral prefrontal cortex (DLPFC), and (d) right thalamus. The post-hoc analyses on the signal intensity of these GM clusters indicated that, compared to BL, GM on the CSR day was increased in the DECAF group in all clusters but decreased in the thalamus, DmPFC, and DLPFC in the CAFF group. Furthermore, lower baseline subcortical A1R availability predicted a larger GM reduction in the CAFF group after CSR of all brain regions except for the thalamus. In conclusion, our data suggest an adaptive GM upregulation after 5-day CSR, while concomitant use of caffeine instead leads to a GM reduction. The lack of consistent association with individual A1R availability may suggest that CSR and caffeine affect thalamic GM plasticity predominantly by a different mechanism. Future studies on the role of adenosine A2A receptors in CSR-induced GM plasticity are warranted.

The relationship between caffeine consumption and colon cancer prevalence in a nationally representative population.

This study examines the correlation between caffeine consumption and the prevalence of colon cancer. Utilizing data from the National Health and Nutrition Examination Survey (NHANES) for the years 2001 to 2014, we applied weighted logistic regression to evaluate the association between caffeine consumption and the prevalence of colon cancer. This analysis accounted for variables including age, gender, race, education, poverty income ratio, smoking status, alcohol consumption, and diabetes. The findings were expressed as weighted odds ratios (ORs) with accompanying 95% confidence intervals (CIs). The restricted cubic spline analysis was performed to exam the dose-dependent relationship. The study included 27,637 participants, of which 144 were diagnosed with colon cancer and 27,493 served as controls. Individuals in the highest quartile (Q4) of caffeine consumption (Q4) displayed a significantly increased risk of colon cancer compared to those in the lowest quartile (Q1), with a weighted OR of 2.00 (95% CI: 1.11-3.59; p = 0.022). Additionally, restricted cubic spline analysis indicated a significant correlation between higher caffeine intake and increased colon cancer risk, with an overall association p-value of 0.007. These findings suggest a potential relationship between higher levels of caffeine consumption and an increased risk of colon cancer. The dose-response relationship suggests a notable correlation at higher caffeine intake levels. Further investigations are warranted to confirm these results and elucidate potential underlying mechanisms.

The role of caffeine in headache disorders.

Caffeine is known to have both beneficial and adverse effects in individuals with headache disorders. This review describes recent findings regarding caffeine that are relevant to headache disorders and puts these findings into the context of clinical management. Preclinical studies show that caffeine has complex effects on sleep, brain blood flow, and intracranial pressure that may depend on the timing of caffeine intake relative to the sleep-wake cycle. Caffeine metabolism may have significant inter-individual variation that influences its therapeutic and/or adverse effects. Caffeine has acute therapeutic benefit for some primary headache disorders. For migraine, this benefit is predominantly in milder headache without cutaneous allodynia. High levels of caffeine intake may contribute to progression of headache disorders. Caffeine-containing combination analgesics commonly cause medication overuse headache. Abrupt reduction in caffeine consumption is a trigger for migraine that may be important in situations including the hospital setting, religious and cultural fasting, and pregnancy. There is not sufficient evidence to support universal guidelines for the use of dietary and medicinal caffeine in headache disorders. A sensible approach based upon available evidence is to limit dietary caffeine intake to moderate amounts with consistent timing before noon, and to use caffeine-containing combination analgesics infrequently for milder headache.

Caffeine’s complex influence on the attraction effect: a mixed bag of outcomes

Psychological state alterations induced by substance-related physiological mechanisms affect consumer decision-making. We examine the influence of caffeine—the world’s most popular psychostimulant—on the attraction effect. In three double-blinded experiments, we show that caffeine intake via coffee influences consumers’ preference for product options that asymmetrically dominate a decoy option in choice sets (i.e., the attraction effect). Using real products in consequential choice tasks, we show that high caffeine intake (200 mg) is associated with a larger attraction effect both on between-subjects and within-subjects levels and in free-choice as well as forced-choice decision tasks. On the contrary, we do not find support for caffeine’s influence on the attraction effect when considering intermediate levels of caffeine intake (125 mg) and hypothetical decisions. We discuss theoretical implications for context effect research and practical implications for marketers.

Assessment of caffeine intake in groups of pregnant and breastfeeding women: A cross-sectional analysis

Caffeine is commonly consumed by pregnant and breastfeeding women. The maximum safe dose of caffeine in their diet is 200mg per day, according to the European Food Safety Authority. The purpose of this study was to assess the consumption of caffeinated products by pregnant and breastfeeding women, as well as to estimate their caffeine intake. The number of subjects who qualified for the study was 1112 women, of whom 401 were pregnant and 711 were breastfeeding. The research was conducted with the use of a questionnaire, which included information about food frequency and history of consumption of caffeinated products during the past 3 days. The median (interquartile range) daily caffeine intake among pregnant women was 114.5 (57.6-202.8) mg, and the level of caffeine intake increased with the duration of pregnancy (p<0.001). For breastfeeding women it was 193.7 (100.5-324.8) mg/d. The majority of participants (58.9%) were not able to correctly identify the safe amount of caffeine in their diets. It was observed that the intake of 73.8% of pregnant women and 51.9% of breastfeeding women fit within the safe range (0-200mg/d). The main sources of caffeine were ground coffee, black tea, and instant coffee. For 63,6% of women knowledge about nutrition and supplementation came most often from blogs and social media run by medical professionals. Pleasure was the main reason for drinking coffee and tea. Most pregnant women did not exceed the recommended maximum daily dose of caffeine, while breastfeeding women often did.

Quantitative probabilistic assessment of caffeine intake from tea in Chinese adult consumers based on nationwide caffeine content determination and tea consumption survey

Caffeine has known effects on the central nervous and cardiovascular systems. An intake up to 400 mg/day does not give rise to health concerns. Tea, a major source of caffeine, is highly consumed in China. However, the potential health risk of caffeine from tea has not been well evaluated. The present study assessed caffeine intake levels from tea for Chinese adult consumers. We collected 1,398 samples of green, black, dark, jasmine, oolong, white, and yellow tea from 17 provinces. The caffeine content was determined by HPLC. The average contents were 27 (oolong tea) – 43 (yellow tea) mg/g. The leaching rate of caffeine into the water was about 100%. Tea consumption data were from the National Beverage Consumption Survey 2013–2014. Monte Carlo simulations were applied to estimate the distribution of caffeine intake. The average caffeine intake from tea was 180 mg/day of all consumers. Green, dark, and black tea were the primary sources. Males (197 mg/day) consumed more caffeine than females (136 mg/day) on average, but females older than 71 years had the highest intake level (259 mg/day) among all subgroups. Over 90% of Chinese adult tea drinkers have caffeine intake under 400 mg/day.

The Relation between Caffeine Consumption and Endometriosis: An Updated Systematic Review and Meta-Analysis.

While the contributing factors leading to endometriosis remain unclear, its clinical heterogeneity suggests a multifactorial causal background. Amongst others, caffeine has been studied extensively during the last decade as a putative contributing factor. In this systematic review and meta-analysis, we provide an overview/critical appraisal of studies that report on the association between caffeine consumption and the presence of endometriosis. In our search strategy, we screened PubMed and Scopus for human studies examining the above association. The main outcome was the relative risk of endometriosis in caffeine users versus women consuming little or no caffeine (<100 mg/day). Subgroup analyses were conducted for different levels of caffeine intake: high (>300 mg/day) or moderate (100–300 mg/day). Ten studies were included in the meta-analysis (five cohort and five case-control studies). No statistically significant association was observed between overall caffeine consumption and risk for endometriosis (RR 1.12, 95% confidence interval (CI) 0.97–1.28, I2 = 70%) when compared to little or no (<100 mg/day) caffeine intake. When stratified according to level of consumption, high intake was associated with increased risk of endometriosis (RR 1.30, 95%CI 1.04–1.63, I2 = 56%), whereas moderate intake did not reach nominal statistical significance (RR 1.18, 95%CI 0.99–1.40, I2 = 37%). In conclusion, caffeine consumption does not appear to be associated with increased risk for endometriosis. However, further research is needed to elucidate the potential dose-dependent link between caffeine and endometriosis or the probable role of caffeine intake as a measurement of other unidentified biases.

Does caffeine matter for arousal? Affective and autonomic responses induced by caffeine in coffee intake: evidence from a double-blind tasting task

Coffee is consumed worldwide, but there are different types of espresso blends, each with its unique concentration of caffeine, which can have different effects on the human being. The aim of this study was to understand the effect of the impact of caffeine on the autonomic nervous system, evaluating the physiological changes and subjective responses due to different levels of caffeine intake. A double-blind tasting task consisting of one within-subject factor design (caffeine level: high / double caffeine mixture (blend A) vs single-charge caffeine mixture (blend B) vs low-caffeine mixture (blend c) allowed us to assess participants’ autonomic responses using Heart Rate Variability (HRV) and Pupillary Reactivity (PR). Arousal was also assessed through the Self-Assessment Manikin (SAM). Results revealed statistically significant differences in HRV and PR between coffee blends, showing the blend A,a more pronounced autonomic response that blend C. However, no significant differences were found in arousal level among coffee blends. These results are similar to previous research that pointed out to a discordance between subjective and objective measures when caffeine is consumed.

Association of maternal caffeine intake during pregnancy with low birth weight, childhood overweight, and obesity: a meta-analysis of cohort studies.

Epidemiological studies reported inconsistent results on the associations between maternal caffeine intake during pregnancy and risk of low birth weight (LBW) and childhood overweight and obesity in their offspring. We conducted a meta-analysis of cohort studies to quantitatively assess these associations. Pertinent studies were identified by searching PubMed and Embase through June 2019. Study-specifics risk estimates were combined using fixed effects models, or random-effects models when significant heterogeneity was detected. Dose-response analysis was modeled by using restricted cubic splines. A total of 15 cohort studies, with 102,347 pregnancy women, was included in the meta-analysis. The pooled relative risk (RR) for LBW was 1.33 (95% CI: 1.12, 1.57) for mothers with the highest compared with the lowest level of caffeine intake during pregnancy, with significant heterogeneity across studies (I2 = 49.3%, P = 0.032). The pooled RR was 1.07 (95% CI: 1.02, 1.11) for each 100 mg/day increase of caffeine intake. The pooled RR for childhood overweight and obesity was 1.39 (95% CI: 1.15, 1.69) for mothers with the highest compared with the lowest level of caffeine intake during pregnancy. No significant heterogeneity across studies was detected (I2 = 38.9%, P = 0.179). The pooled RR was 1.31 (95% CI: 1.11, 1.55) for each 100 mg/day increase of caffeine intake. No evidence of publication bias was indicated. Maternal caffeine intake during pregnancy is associated with higher risk of LBW and childhood overweight and obesity. Further studies may focus on investigating the potential mechanisms before the recommendation of complete avoidance of caffeine intake during pregnancy.

Assessment of caffeine intake in children and adolescents aged 6-17 years in Beijing City

To assess the intake of caffeine from snacks among children and adolescents aged 6-17 years in Beijing City. A multi-stage stratified cluster random sampling method was adopted to obtain the consumption status of caffeine-containing snacks among 881 school-age children and adolescents in Chaoyang, Changping and Yanqing Districts through a 3 d 24 h continuous questionnaire survey between October 2016 and February 2017, and the caffeine content in snacks was obtained through literature retrieval and laboratory detection. The proportion of caffeinated snacks consumers among children and adolescents aged 6-17 years in Beijing was 42. 45%(374/881). The average daily caffeine intake of the whole population was 9. 19 mg, with a median of 0 and a P95 of 41. 38 mg. The average daily caffeine intake of consumers was 21. 66 mg, with a median of 11. 03 mg and 76. 99 mg of P95. About 1. 60%(6/374) of individuals exceeded the daily safe intake level and there were statistically significant differences in caffeine intake between different ages, genders, grades and groups with and without tea drinking habits after weight was taken into account. Among the top three contributors, 12. 13 mg of caffeine was derived from tea, milk tea and tea beverages(including solid drinks), with a contribution rate which reached 56. 01%, 4. 35 mg of caffeine was derived from coffee, with a contribution rate of 20. 09%, and 3. 31 mg of caffeine was derived from cola and energy drinks, with a contribution rate of 15. 30%, and there existed slightly difference of the top three contribution foods among 6-11 and 12-17 years old children and adolescents. Children and adolescents aged 6-17 years in Beijing City had low caffeine intake levels from snacks and there was little risk of overconsumption. Tea, milk tea and tea beverages(including solid drinks) was the major contributor to its caffeine exposure.

Dietary natural methylxanthines and colorectal cancer: a systematic review and meta-analysis.

Some evidence suggests that caffeine, theophylline, and theobromine, as natural methylxanthines (MTXs), possess anti-cancer effects. We systematically reviewed the animal and human studies investigating the effect of (or association between) dietary natural MTXs on (and) colorectal cancer (CRC) and performed a meta-analysis of epidemiological studies. Relevant studies were identified by searching MEDLINE, Embase, Scopus, and Web of Knowledge through September 2020. The overall relative risk (RR) and confidence interval (CI) were determined using a random-effects model. Eight animal and eight epidemiological investigations met our inclusion criteria. Animal studies indicated detrimental effects of high levels of caffeine intake on the initiation and promotion of CRC, while showing beneficial or non-significant effects at lower doses. The meta-analysis of six epidemiological studies found no association between dietary caffeine intake and the risk of CRC (RR = 0.98 (95% CI = 0.88-1.10)). Subgroup analysis revealed a direct association between caffeine intake and risk of CRC only in the studies with a moderate risk of bias and a lack of adjustment for smoking. The results of the only epidemiological study investigating the association between the serum levels of MTXs and the risk of CRC showed an inverse association. In conclusion, some animal studies underlined the beneficial effects of caffeine, at regular doses consumed by humans, on CRC. However, current epidemiological evidence does not support an association between caffeine intake and the risk of CRC.

Facile Fabrication of Graphene-Supported Pt Electrochemical Sensor for Determination of Caffeine.

Because elevated levels of caffeine intake can cause many health complications, it is necessary to develop an accurate, simple, rapid, and cost-effective methodology to quantify caffeine in commonly consumed products. This article discusses electrochemical methods to synthesize platinum-graphene hybrid nanosheets (Pt-GR), and how these methods can be utilized to create a new modified electrode, the platinum-graphene nanohybrid glass carbon electrode (Pt-GR/GCE). The electrochemical behavior of caffeine on Pt-GR/GCE was studied by differential pulse voltammetry (DPV). The results showed that a sensitive oxidation peak was observed at 1.336 V in 0.01 mol L-1 H2SO4 buffer solution, indicating that the Pt-GR/GCE exhibited a good electrooxidation activity towards caffeine. The detection limit is 1.129 × 10-7 mol L-1. The modified electrode was applied to the determination of caffeine in real samples with satisfactory electrocatalytic results.

Study on relationship between caffeine intake level and metabolic syndrome and related diseases in Korean adults: 2013 ~ 2016 Korea National Health and Nutrition Examination Survey

본 연구는 2013 ~ 2016년 국민건강영양조사 자료를 활용하여 19세 이상 성인의 카페인 섭취 수준이 대사증후군발생에 미치는 영향을 규명하기 위해 실시하였다. 카페인섭취 수준을 평가하기 위해 2014년 식품의약품안전평가원에서 수행한 주요급원식품의 카페인 함량 분석자료를 활용하여 1인당 카페인 섭취량과 주요급원식품을 통한 카페인 섭취량을 산출한 후 대사증후군 발생의 위험에 미치는 영향을 분석한 결과는 다음과 같다. 만 19세 이상 성인의 하루 평균 카페인 섭취량은 41.97 ㎎ 이었고, 각 군별 평균 카페인 섭취량은 Q1 0 ㎎, Q2 1.42 ㎎ (0 ~ 3.66 ㎎), Q3 6.94 ㎎ (3.99 ~ 12.31 ㎎), Q4 21.65 ㎎ (12.31 ~ 45.81 ㎎), Q5군 154.41 ㎎ (≥ 45.81 ㎎)으로 나타나 상위 20%에 해당하는 대상자들만이 하루 45.81 ㎎ 이상의 카페인을 섭취하였다. 카페인 섭취의 주요 급원식품은 커피, 탄산음료 및 기타음료, 차류의 순이었으며, 이들 식품을 통한 카페인 섭취량은 97% 정도 이었다. 카페인 섭취 수준에 따라 대사적 지표 및 대사증후군에 미치는 영향을 분석한 결과 성, 연령 이외 이들 대사적 지표 발생에 영향을 미칠수 있는 교육수준, 음주, 흡연, 신체활동, 에너지 및 당 섭취량에 보정 후 카페인 섭취량은 대사증후군, 고혈압, 저 HDL-콜레스테롤혈증 및 복부비만에 영향을 미치지 않았으나, 당뇨병과 고중성지방혈증의 경우 Q1군에 비해 Q3군에서 각각 0.76 (95% CI: 0.63 ~ 0.93), 0.87 (95% CI: 0.77 ~ 0.98)를 보였고, Q4군에서는 각각 0.66 (95% CI: 0.53 ~ 0.82), 0.83 (95% CI: 0.73 ~ 0.94)로 나타나 하루 3.66 ~ 45.81 ㎎ 정도의 카페인 섭취는 당뇨병 및 고중성지방혈증의 낮은 유병률과 관련이 있었다. 본 연구결과 적 정수준의 카페인 섭취는 당뇨병과 고중성지방혈증의 낮은 유병률과 관련이 있으므로 건강 유지에 도움이 되는 적정수준의 카페인 섭취량 선정 시 가이드라인으로 활용 될 수 있을 것으로 사료된다.

Health Related Nutritional Knowledge and Dietary Behavior Regarding Caffeine Intake among High School Students in Yongin Region.

ObjectivesWe aimed to examine health-related nutritional knowledge and dietary behavior related to caffeine intake among high school students (n = 310) in the Yongin region of Korea.MethodsData were collected using a face-to-face survey, and analyzed using chi-square test, t- test, and logistic regression analysis.ResultsThe level of caffeine intake in respondents was divided into low (< 30 mg/d; n = 208) and high caffeine intake groups (> 30 mg/d; n = 102). Total nutritional knowledge related to bone disease was higher in the low intake group (score 2.75) than the high intake group (score 2.39; p < 0.05). The high intake group had lower scores for nutritional knowledge (score 0.70; p < 0.05) related to how caffeinated beverages affect sleep and for dietary behavior (score 3.25; p < 0.001), based on “I avoid caffeinated foods before sleep,” than the low intake group (nutritional knowledge score, 0.80; dietary behavior score, 3.76).ConclusionIn the overall analysis, the low caffeine intake group had better nutritional knowledge related to bone and sleep health, and healthier dietary behavior related to sleep health compared with the high intake group.

Hourly and daily intake patterns among U.S. caffeinated beverage consumers based on the National Health and Nutrition Examination Survey (NHANES, 2013–2016)

Characterization of 'hour-of-day' or 'day-of-week' caffeine intake for the National Health and Nutrition Examination Survey (NHANES) population is limited. No study has focused on patterns from an individual perspective. The NHANES 2013–2016 survey respondents' dietary recalls were analyzed to gain a better understanding of caffeine intake patterns for different caffeinated beverage consumer types - defined by beverage type consumed and daily caffeine intake levels. Dominant caffeinated beverage consumers (≥143 mg) were identified by a reported daily caffeine intake level greater than or equal to the 50th percentile among those 1–80 y. Dominant caffeinated beverage consumers - irrespective of age groups investigated - typically reported the greatest caffeine intake early in the day from coffee. Analyses by consumer type, relevant age brackets and 'hour-of-day' or 'day-of-week' indicated that caffeinated beverage consumers generally do not cluster multiple caffeine intake events over short periods of time (i.e., less than fours). Dominant caffeinated beverage consumers appear to maintain a relatively stable daily caffeine intake by substitution of secondary sources of caffeine. Only a small fraction (4.1%) of individuals within 13–29 y respondents consumed caffeine at levels in excess of 400 mg/day, compared to 14% within the 30–80 y old survey respondent group.

용인지역 고등학생의 카페인 섭취수준에 따른 카페인에 대한 인식도, 지식도 및 구매행동

This study examined the awareness, knowledge, and purchasing behavior of caffeine according to the caffeine intake level (〈30 mg, 30∼60 mg, 60∼90 mg, and 〉90 mg) of high school students (171 males and 139 females) in the Yongin region. The awareness of low doses of caffeine was higher in the 〈30 mg group (70.7%) and awareness of high doses of caffeine was higher in the 〉90 mg group (30.0%) (p〈0.001). Withdrawal symptoms included ‘sleep disorder’ in all groups and ‘fatigue’ was higher in the 〉90 mg group (30.0%) compared to the other groups (p〈0.01). The knowledge score of ‘coffees’ and ‘energy drinks’ was higher, whereas ‘chocolate ice cream’, ‘carbonated soft drinks’, and ‘confectionaries with chocolate’ was lower regardless of the caffeine intake level (p〉0.05). The main purpose of purchasing ‘energy drinks’ was ‘sleepy’ except for the 30∼60 mg group (p〈0.05). The percentage of those checking the food labelling related to caffeine when buying caffeinated foods was low in all groups (〈30 mg, 13.0%; 30∼60 mg, 13.5%; 60∼90 mg, 15.0%; 〉90 mg, 26.7%) (p〉0.05). The results of factors affecting whether the students checked the food labelling related to caffeine showed that the participants having awareness of ‘don’t know caffeinated foods’ checked the labels 6.50 times more than those reporting ‘know caffeinated foods’ (p〈0.05). In conclusion, the degree of knowledge and checking food labelling for caffeine was low regardless of the caffeine intake level. Therefore, providing better nutrition education programs on the functionality and adverse effects of caffeine to high school students is recommended.

Adolescent habitual caffeine consumption and hemodynamic reactivity during rest, psychosocial stress, and recovery

ObjectiveMost adolescents regularly consume caffeine. Whereas observational studies have suggested that coffee may be cardio-protective, pharmacological experimentation with adults shows that caffeine at dietary doses increases blood pressure, thereby implicating regular caffeine consumption as a potential source of harm for cardiovascular health. The present study was in response to the dearth of caffeine research among younger consumers. It was hypothesised that compared to the consumption of little or no caffeine, adolescents who habitually consume caffeine have overall higher blood pressure and increased vascular resistance. MethodUsing a quasi-experimental design, continuous measurements of blood pressure, cardiac output, and total peripheral resistance were taken non-invasively from adolescents (n = 333) aged 14–15 years and 18–19 years who reported “low”, “moderate”, or “high” levels of caffeine intake. Measurements were conducted when participants generally had negligible or low systematic caffeine levels while at rest, during stress, and during recovery from stress. ResultsWhereas habitual caffeine consumption did not predict blood pressure level, higher caffeine intake was associated with modestly increased vascular resistance during all phases of the experiment (i.e., at rest, during stress, and during recovery from stress). ConclusionsPresent findings are important because they suggest that early exposure to caffeine may lead to persistent increases in vascular resistance, which in turn is an acknowledged risk factor for the development of hypertension. These results highlight the need for further studies of adolescents to determine the robustness of any persistent caffeine-related hemodynamic effects, and the implications such effects could have for long-term cardiovascular health.

Caffeine intake is not associated with serum testosterone levels in adult men: cross-sectional findings from the NHANES 1999–2004 and 2011–2012

Objective: The association of caffeine intake with testosterone remains unclear. We evaluated the association of caffeine intake with serum testosterone among American men and determined whether this association varied by race/ethnicity and measurements of adiposity.Methods: Data were analyzed for 2581 men (≥20 years old) who participated in the cycles of the NHANES 1999–2004 and 2011–2012, a cross-sectional study. Testosterone (ng/mL) was measured by immunoassay among men who participated in the morning examination session. We analyzed 24-h dietary recall data to estimate caffeine intake (mg/day). Multivariable weighted linear regression models were conducted.Results: We identified no linear relationship between caffeine intake and testosterone levels in the total population, but there was a non-linear association (pnonlinearity < .01). Similarly, stratified analysis showed nonlinear associations among Mexican-American and Non-Hispanic White men (pnonlinearity ≤ .03 both) and only among men with waist circumference <102 cm and body mass index <25 kg/m2 (pnonlinearity < .01, both).Conclusion: No linear association was identified between levels of caffeine intake and testosterone in US men, but we observed a non-linear association, including among racial/ethnic groups and measurements of adiposity in this cross-sectional study. These associations are warranted to be investigated in larger prospective studies.

Patterns of Blood Pressure and Stress: A Descriptive Report among Anesthesiology Residents Institution

There has been an increase in health problems among physicians due to low primary care maintenance, noncompliance with recommendations for physical activity and balanced eating practices, high levels of caffeine intake, and reduced amount of sleep. We hypothesize that physical health, specifically blood pressure (BP) control, is suboptimal among anesthesiology residents. The purpose of this study is to investigate the prevalence of hypertension and stress among an anesthesiology resident population, and attempt to correlate possible hypertension and increased stress among residents with life and work environment factors. All University of Miami anesthesiology residents in the year 2016 were invited to participate. Blood pressures were taken and anonymous surveys, including demographic and lifestyle questions, were administered. Of 85 invited residents, 80 (92%) participated. 18 (22.50%) residents had blood pressures within the normal range. Twenty (25.00%) residents were hypertensive and 42 (52.50%) were pre-hypertensive. Males exhibited higher systolic blood pressures than females (p<0.0001). The mean Perceived Stress Scale (PSS) for all residents was 17.16 ± 7.2. Fifty-four (67.50%) residents scored a PSS above 13, indicating stress levels greater than the national average. Thirty-three (41.25%) residents scored above 20, indicating the presence of severe stress. Females were more likely than males to have stress (p=0.0314). Residents sleeping less than 6 hours per night were more likely to have stress (p=0.0158). Residents reporting more than one overnight call per week were also more likely to have stress (p=0.013). Our study showed 75% of residents have hypertensive disease and 68% of residents exhibit clinically significant stress. These findings emphasize the need for greater attention to personal health and well-being.