Simultaneous analysis of caffeine and paraxanthine provides potentially useful indexes in the treatment of acute caffeine intoxication.

Caffeine (CFF) is efficiently absorbed after ingestion, and approximately 80% of ingested CFF is metabolized to paraxanthine (PXT). Although PXT has approximately twice the adenosine receptor antagonist activity of CFF, there are few reports measuring the metabolite concentrations during CFF intoxication. Furthermore, no studies have examined the efficacy of hemodialysis (HD) on PXT or the indicators that contribute to treatment strategies for patients with acute CFF intoxication. This study analyzed the association between CFF and PXT blood levels, the blood biochemical data, and the vital signs of 27 cases with information on CFF intake and elapsed time data. It was found that HD was not as effective as CFF against PXT in CFF intoxication; however, HD was effective in cases with relatively high PXT concentrations (>10 µg/mL). Simultaneous analysis of CFF and PXT would make it possible to estimate the time elapsed from CFF intake and the risk of hyperCKemia, which may develop in cases left untreated for a prolonged period after ingestion. Therefore, the measurement of PXT, in addition to CFF, is expected to provide useful information for understanding the pathogenesis of CFF intoxication and the development of treatment strategies of acute CFF intoxication.

Effects of coffee intake on skeletal muscle microvascular reactivity at rest and oxygen extraction during exercise: a randomized cross-over trial.

PURPOSE: The effects of coffee ingestion on skeletal muscle microvascular function are not well understood. This study aimed to investigate the acute effects of coffee intake with varying levels of caffeine on skeletal muscle microvascular reactivity at rest and oxygen extraction during maximal incremental exercise in physically active individuals. METHODS: Twenty healthy young male participants were administered coffee with low caffeine (3 mg/kg body weight; LC), high caffeine (6 mg/kg body weight; HC), and placebo (decaf) in different sessions. Skeletal muscle reactivity indexes, including tissue saturation index 10s slope (TSI10) and TSI half time recovery (TSI ½) following 5-minute ischemia were measured at rest and were measured at baseline and post-coffee consumption using near-infrared spectroscopy (NIRS). Post-coffee intake, NIRS was also used to measure microvascular oxygen extraction during exercise via maximal incremental exercise. Peak oxygen consumption and peak power output (Wpeak) were simultaneously evaluated. RESULTS: Post-coffee consumption, TSI10 was significantly higher in the LC condition compared to placebo (p = 0.001) and significantly higher in the HC condition compared to placebo (p < 0.001). However, no difference was detected between LC and HC conditions (p = 0.527). HC condition also showed significant less TSI ½ compared to placebo (p = 0.005). However, no difference was detected for microvascular oxygen extraction during exercise, despite the greater Wpeak found for HC condition (p < 0.001) compared to placebo. CONCLUSION: Coffee ingestion with high caffeine level (6 mg/kg body weight) significantly enhanced skeletal muscle reactivity at rest. However, the improvement of exercise performance with coffee intake is not accompanied by alterations in muscle oxygen extraction.

Patterns of caffeine consumption among medical undergraduates in Secunderabad, Telangana, India.

BACKGROUND: Caffeine products are increasingly found in a wide range of products that abuse of the substance may be unnoticed. Introduction of new energy drinks has led to an increase in consumption of caffeine in the last few decades. Caffeine is a cognitive booster and has physically enhancing effects, leading to its higher consumption across various age groups. The objective of this study was to determine patterns of caffeine consumption and to determine the knowledge and awareness of side effects and safety limits of caffeine consumption among medical undergraduate students. MATERIAL AND METHODS: A cross-sectional study was conducted from December 2021 to February 2022 in the Department of Community Medicine at a tertiary care institute, Secunderabad, Telangana, India, among 560 medical undergraduate students of all academic years. A predesigned, pretested, semistructured questionnaire was administered. RESULTS: The mean age of the study population was 19.09 years, and female preponderance (61.2%) was noted. The average self-reported caffeine consumption was 151.3 mg/day. The average caffeine consumption was found to be higher among males (174 mg/day) as compared to females (137 mg/day). The average consumption of caffeine during exam time was higher than the daily ceiling limit, >300 mg/day, in 38.1% of students, which was statistically significant (P = 0.015). CONCLUSIONS: Caffeine consumption during times of stress increased among medical students, which is an unfavorable sign as the majority of the times, medical students in future have to deal with physically and emotionally stressful situations during work hours.

The effect of caffeine chewing gum on muscle performance and fatigue after severe-intensity exercise: isometric vs. dynamic assessments in trained cyclists.

This study investigated the effect of caffeinated chewing gum (GUMCAF) on muscle fatigue (isometric vs. dynamic) after severe-intensity cycling bouts. Fifteen trained male cyclists participated in four visits. Each visit involved two severe-intensity cycling bouts (Δ1 and Δ2) lasting 6 min, separated by a 5-min recovery period. Muscle fatigue was assessed by isometric maximal voluntary knee extension contraction (IMVC) with twitch interpolation technique and dynamically by 7 s all-out cycling sprints. Assessments were performed before GUMCAF (Pre-GUM) and after the cycling bouts (Post-Exercise). GUMCAF and placebo gum (GUMPLA) were administered in a randomized double-blind procedure with participants receiving each gum type (GUMCAF and GUMPLA) during two separate visits. The results showed no significant interaction between gum types and time for the isometric and dynamic measurements (p > 0.05). The percentage change in performance from Pre-GUM to Post-Exercise showed no significant difference between GUMCAF and GUMPLA for either the dynamic-derived TMAX (~ -17.8% and -15.1%, respectively; p = 0.551) or isometric IMVC (~ -12.3% and -17.7%, respectively; p = 0.091) measurements. Moderate to large correlations (r = 0.31-0.51) were found between changes in sprint maximal torque and maximal power output measurements and isometric force, for both gum conditions. GUMCAF was not effective in attenuating muscle force decline triggered by severe-intensity cycling exercises, as measured by both isometric and dynamic methods. The correlations between IMVC and cycling maximal torque and power output suggest caution when interpreting isometric force as a direct measure of fatigue during dynamic cycling exercises.

Association between caffeine intake and erectile dysfunction: a meta-analysis of cohort studies.

BACKGROUND: Erectile dysfunction (ED) is a common condition with various contributing factors, including lifestyle and dietary habits. Caffeine, a widely consumed stimulant, has been linked to multiple physiological effects on vascular function and hormonal balance that might influence sexual function. This meta-analysis aims to evaluate the association between caffeine intake and the risk of ED by analyzing data from cohort studies. METHODS: A systematic search was conducted across PubMed, Web of Science, Scopus, and Embase databases, and a manual search was conducted on Google Scholar for studies on the relationship between caffeine intake and ED in adult men. The search included observational studies published up to April 1, 2024. Four cohort studies were included, and their data were extracted and analyzed by STATA version 18. RESULTS: Four included cohort studies comprised 51,665 cohort members. The study population included adult males, on average, aged 18 to 80. The results indicate that there was no significant relationship between coffee consumption and the risk of ED (relative risk [RR] = 0.94, 95% CI: 0.86-1.03; p = 0.999). CONCLUSIONS: The current evidence suggests no significant relationship between caffeine intake and ED, but limited studies limit conclusions. Future research should focus on larger sample sizes, standardized outcome assessments, and different dosages and forms of caffeine consumption.

Unraveling tea and coffee consumption effects on cardiovascular diseases risk factors: A narrative review.

Backgrounds and Aims: Daily lifestyle plays a vital role in modifying the risk for cardiovascular diseases (CVDs). Our daily life isn't inseparable from nutrition intake. As such, tea and coffee are often regarded as the most consumed beverages worldwide. There have been a lot of debates on the adverse effects and benefits of consuming these popular beverages. This comprehensive review explores the different types of tea and coffee and their mechanism of action. It delves deeper into their roles in reducing CVD risk, aiding CVD recovery, lowering CVD mortality, and their varying effects across populations and regions. Methods: An extensive literature search was conducted on PubMed. Relevant articles were identified through cross-referencing and manual searches. Excluded from the study were commentaries, case reports, clinical vignettes, and non-English articles. Results: Tea and coffee contain varying levels of caffeine and other bioactive compounds with cardioprotective effects against oxidative stress, inflammation, and more. Genetic factors further modulate their effects. Tea flavonoids benefit cholesterol, blood pressure, and endothelial function, while coffee constituents impact oxidative stress, metabolism, insulin sensitivity, and gut flora. Moderate consumption of both beverages may offer cardiovascular benefits, but outcomes vary depending on populations and conditions. Tea and coffee consumption may influence CVD recovery by reducing mortality and improving survival, however, it must be noted that it has the potential to be harmful to some individuals. Conclusion: Evidence suggests that moderate consumption of these beverages may be linked to reduced cardiovascular mortality, although individual characteristics and pre-existing conditions can influence outcomes. Excessive caffeine consumption, found in both beverages, may pose risks such as arrhythmias, hypertension, and cardiovascular mortality in CVD patients, with a dose-dependent nature. Future research should delve into mechanisms, genetic factors, and diverse cultural impacts of its use. Health care providers should consider individual characteristics when advising on tea and coffee consumption in the context of cardiovascular health.

Respiratory Responses to a Single Oral Dose of Caffeine in Male Sprague-Dawley Rats.

Caffeine is a key component of beverages such as coffee and tea and has effects on the cardiovascular and respiratory systems, prompting a variety of physiological changes. In our previous study, intravenously administered caffeine at high concentrations significantly influenced respiratory rates. However, comparative research on the potential adverse effects of caffeine consumption on the respiratory system is limited. To address this issue, in this study, we focused on evaluating the effects of orally administered caffeine (0, 2, 6, and 20 mg/kg) on the respiratory system of 6-week-old male Sprague-Dawley rats. We measured the respiratory rate, tidal volume, and minute volume following the guidelines set forth by the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use, specifically adhering to Harmonized Tripartite Guideline S7A for Safety Pharmacology Studies for Human Pharmaceuticals. Caffeine administration led to a notable increase in both the respiratory rate and the tidal volume. Conversely, a marked reduction in minute volume was recorded between 0.5 and 2 h following caffeine administration in doses exceeding 6 mg/kg.

Nutritional habits of professional team sport athletes: An insight into the carbohydrate, fluid, and caffeine habits of English Premier League football players during match play.

To better understand the in-match fuelling practices of elite football players and compare against current guidelines, we quantified the carbohydrate, fluid, and caffeine intake of players from an English Premier League club (n = 22) during 90 min of competitive match-play. Mean carbohydrate intake across match-play was 17 ± 11 g.h-1 with players demonstrating a preference towards CHO-containing fluids (58%) when compared with semi-solids (38%) and solids (14%), respectively. CHO intake was significantly lower than reported by players (17 ± 11 vs 24.8 ± 11 g.h-1, p < 0.001) during initial consultation. Fluid was ingested at a rate of 0.45 ± 0.14 L.h-1, with 54, 40 and 6% of ingested fluid coming from water, carbohydrate, and electrolyte-only solutions, respectively. The majority of players (91%) met the UEFA guidelines for fluid consumption. Of the players who consumed caffeine across match-play (55%) the average dose was 233 ± 148 mg (2.8 ± 1.1 mg.kg-1 body mass [BM]), which meets the UEFA consensus guidelines for caffeine intake. Caffeine capsules (42%) and caffeine containing fluids (30%) were the preferred format prior to the warm-up whilst caffeine gum was exclusively used prior to kick-off and during the half-time period (100%). We conclude that 81% of the total playing squad failed to meet the current UEFA CHO intake recommendations of 30-60 g.h-1, which may be attributed to the preference towards fluid-based CHOs as the chosen format of delivery.

Soccer players demonstrate sub-optimal in-match fuelling practices, with 81% of players failing to meet current UEFA CHO intake recommendations of 30-60 g.h⁻¹Players demonstrate a preference towards fluid as the primary mode of CHO delivery over the use of semi-solid and solid formats.These data highlight the need for future research to test the efficacy of lower doses of CHO on elements of both physical and technical soccer performance in a dose-response manner.Future research is also necessary to investigate the impact of traditional guidelines and recommendations within football-specific contexts to assess their effectiveness and relevance in practical applications.

Impact of Cold Atmospheric Plasma Pretreatment on the Recovery of Phenolic Antioxidants from Spent Coffee Grounds.

In the present study, cold atmospheric plasma (CAP) was employed as a pretreatment method for the extraction of phenolic compounds from spent coffee grounds (SCGs). The impact of CAP treatment conditions, i.e., thickness of the SCGs layer (mm), distance between the plasma source and the SCGs layer (mm) and duration of CAP treatment (min), on the total phenol content, in vitro antioxidant activity, as well as caffeine and chlorogenic acid content of SCGs, was investigated. The process parameters were optimized with the aid of response surface methodology (RSM). After optimizing the CAP pretreatment conditions, the CAP-treated SCGs were subjected to ultrasound-assisted extraction using ethanol as the extraction solvent. The optimum conditions for CAP treatment identified, i.e., thickness, 1 mm; distance, 16 mm; and duration, 15 min, led to a significant enhancement in the recovery of bioactive compounds from SCGs compared to those obtained from untreated SCGs. Total phenolic content and antioxidant activity significantly increased (i.e., TPC from 19.0 ± 0.7 to 24.9 ± 1.4 mg GAE/100 g dry SCGs, ADPPH from 106.7 ± 5.01 to 112.3 ± 4.3 µmol Trolox/100 g dry SCGs, AABTS from 106.7 ± 5.01 to 197.6 ± 5.8 µmol Trolox/100 g dry SCGs, ACUPRAC from 17938 ± 157 to 18299 ± 615 µmol Trolox/100 g dry SCGs). A significant increase in caffeine content from 799.1 ± 65.1 mg to 1064 ± 25 mg/100 g dry SCGs and chlorogenic acid content from 79.7 ± 15.3 mg to 111.3 ± 3.3 mg/100 g dry SCGs, was also observed. Overall, CAP pre-treatment can be used to enhance the recovery of bioactive compounds from SCGs.

Development and characterization of caffeine-loaded nanoliposomes decorated by cationic amylose and cationic amylose- menthol inclusion complex coatings; a novel oral co-delivery system.

Nanoliposomes (NLPs) have evolved as compelling carriers for loading bioactive compounds. To improve the phospholipid bilayer membrane stability, caffeine-loaded NLPs were coated with cationic amylose (CA) and CA-menthol inclusion complexes (CAMICs). The zeta potential results indicated an electrostatic attraction between CA and the negatively charged NLPs. Observations from dynamic light scattering, atomic force microscopy, and Fourier transform infrared spectroscopy demonstrated the efficient deposition of both CA and CAMICs onto the surface of NLPs without altering their spherical shape. Raman spectra and X-ray diffraction patterns indicated that both CA and CAMICs can decrease membrane fluidity and enhance lipid packing laterally. Additional assessment through thermogravimetric analysis revealed that the coating of NLPs, particularly with CAMICs, protected caffeine against thermal degradation. These coated NLPs show promise for formulation advancement, facilitating the simultaneous delivery of functional compounds.