The Safety of Ingested Caffeine: A Comprehensive Review

Secondary Headache: Current Update

PURPOSE

The purpose of this paper is to review some of the causes of secondary headache particularly focusing on the subcategories of secondary headache in the International Classification of Headache Disorders, 3rd edition, the clinical features of these headaches, and their associated features and management.

OVERVIEW

Headache attributed to trauma or injury to the head and/or neck, headache attributed to cranial or cervical vascular disorder, headache attributed to non-vascular intracranial disorder, headache attributed to a substance or its withdrawal, headache attributed to infection, headache attributed to disorder of homeostasis, and headache or facial pain attributed to disorder of the cranium, neck, eye, ears, nose, sinuses, teeth, mouth, or other facial or cervical structure are discussed in this paper.

DISCUSSION

Headache is a common symptom of multiple medical conditions. Although a minority of headache patients have a secondary basis for their headaches, it is important to identify clinical features of secondary headache disorders including both the headache and non-headache features of the condition, diagnose the secondary etiology correctly, and treat them appropriately.

Wide awake at bedtime? Effects of caffeine on sleep and circadian timing in male adolescents - A randomized crossover trial

Adolescents often suffer from short and mistimed sleep. To counteract the resulting daytime sleepiness they frequently consume caffeine. However, caffeine intake may exaggerate sleep problems by disturbing sleep and circadian timing. In a 28-hour double-blind randomized crossover study, we investigated to what extent caffeine disturbs slow-wave sleep (SWS) and delays circadian timing in teenagers. Following a 6-day ambulatory phase of caffeine abstinence and fixed sleep-wake cycles, 18 male teenagers (14-17 years old) ingested 80 mg caffeine vs. placebo in the laboratory four hours prior to an electro-encephalographically (EEG) recorded nighttime sleep episode. Data were analyzed using both frequentist and Bayesian statistics. The analyses suggest that subjective sleepiness is reduced after caffeine compared to placebo. However, we did not observe a strong caffeine-induced reduction in subjective sleep quality or SWS, but rather a high inter-individual variability in caffeine-induced SWS changes. Exploratory analyses suggest that particularly those individuals with a higher level of SWS during placebo reduced SWS in response to caffeine. Regarding salivary melatonin onsets, caffeine-induced delays were not evident at group level, and only observed in participants exposed to a higher caffeine dose relative to individual bodyweight (i.e., a dose > 1.3 mg/kg). Together, the results suggest that 80 mg caffeine are sufficient to induce alertness at a subjective level. However, particularly teenagers with a strong need for deep sleep might pay for these subjective benefits by a loss of SWS during the night. Thus, caffeine-induced sleep-disruptions might change along with the maturation of sleep need.

Anti-Cancer Effects of Green Tea Epigallocatchin-3-Gallate and Coffee Chlorogenic Acid

Tea and coffee are consumed worldwide and epidemiological and clinical studies have shown their health beneficial effects, including anti-cancer effects. Epigallocatechin gallate (EGCG) and chlorogenic acid (CGA) are the major components of green tea polyphenols and coffee polyphenols, respectively, and believed to be responsible for most of these effects. Although a large number of cell-based and animal experiments have provided convincing evidence to support the anti-cancer effects of green tea, coffee, EGCG, and CGA, human studies are still controversial and some studies have suggested even an increased risk for certain types of cancers such as esophageal and gynecological cancers with green tea consumption and bladder and lung cancers with coffee consumption. The reason for these inconsistent results may have been arisen from various confounding factors. Cell-based and animal studies have proposed several mechanisms whereby EGCG and CGA exert their anti-cancer effects. These components appear to share the common mechanisms, among which one related to reactive oxygen species is perhaps the most attractive. Meanwhile, EGCG and CGA have also different target molecules which might explain the site-specific differences of anti-cancer effects found in human studies. Further studies will be necessary to clarify what is the mechanism to cause such differences between green tea and coffee.

Massive β1-Adrenergic Receptor Reaction Explains Irreversible Acute Arrhythmia in a Fatal Case of Acute Pure Caffeine Intoxication

Caffeine, a naturally occurring purine-based alkaloid, is the most consumed psychostimulant worldwide. Since caffeine pharmacokinetics shows extreme interindividual variability, it is not easy to establish its toxic dose. Only a few cases of death due to acute caffeine intoxication have been described so far, the majority of which attributable to massive assumption of caffeine-based medications. We present a case of acute caffeine overdose due to ingestion of pure caffeine. The extremely high blood concentration of caffeine determined a strong cardiovascular response, leading to fatal arrhythmia, as supported by histological evidence of myocardial injury. Quantitation of catecholamines and their metabolites in urine samples was performed and showed level near the highest limit of normal ranges for norepinephrine and high level of epinephrine. Contraction band is a pathological modification of the myocell caused by the catecholaminergic action and can occur in conditions of alteration due to the interaction between calcium and catecholamines. We demonstrated the β1-adrenoceptor involvement in our fatal case by immunohistochemical analysis.

Cocoa-Rich Chocolate and Quality of Life in Postmenopausal Women: A Randomized Clinical Trial

Menopause has a negative impact on quality of life (QoL). The aim of the present study was to analyse the effect on QoL of adding 10 g per day of chocolate with a high concentration of cocoa (99%) to the habitual diet, for 6 months, in a sample of postmenopausal women. Postmenopausal women (n = 140) aged 50–64 years were randomised to either an addition of 10 g per day of cocoa-rich chocolate to their usual diet or no supplement addition. All variables were measured at baseline and after six months of intervention. QoL was evaluated using the 3-level version of EuroQol-5D (EuroQoL-5D-3L), the EuroQol Visual Analogue Scale (EQ-VAS) and the Cervantes scale. Analysis of covariance (ANCOVA) analyses adjusted for the main determinants of QoL considered in this study showed no changes in the global score of QoL evaluated with the EuroQoL-5D-3L. The intervention group showed an increase of 6.0 points (95% confidence interval (CI): 0.4, 11.7) in the EQ-VAS compared to the control group (p = 0.036). No significant changes were observed between groups in the global score of QoL nor in the dimensions and subdimensions measured with the Cervantes scale. The additional daily contribution of 10 g of cocoa-rich chocolate in postmenopausal women could have a slight impact on their perception toward their health state, although without modifying the health-related QoL or the dimensions that compose it.

Micro-NIR spectrometer for quality assessment of tea: Comparison of local and global models

Near-infrared (NIR) spectroscopy is an effective tool for analyzing components relevant to tea quality, especially catechins and caffeine. In this study, we predicted catechins and caffeine content in green and black tea, the main consumed tea types worldwide, by using a micro-NIR spectrometer connected to a smartphone. Local models were established separately for green and black tea samples, and these samples were combined to create global models. Different spectral preprocessing methods were combined with linear partial-least squares regression and nonlinear support vector machine regression (SVR) to obtain accurate models. Standard normal variate (SNV)-based SNV-SVR models exhibited accurate predictive performance for both catechins and caffeine. For the prediction of quality components of tea, the global models obtained results comparable to those of the local models. The optimal global models for catechins and caffeine were SNV-SVR and particle swarm optimization (PSO)-simplified SNV-PSO-SVR, which achieved the best predictive performance with correlation coefficients in prediction (Rp) of 0.98 and 0.93, root mean square errors in prediction of 9.83 and 2.71, and residual predictive deviations of 4.44 and 2.60, respectively. Therefore, the proposed low-price, compact, and portable micro-NIR spectrometer connected to smartphones is an effective tool for analyzing tea quality.

Migraine and Sleep in Children: A Bidirectional Relationship

Migraine and sleep disorders in children exhibit a bidirectional relationship. This relationship is based on shared pathophysiology. Migraine involves activation of the trigeminal vascular system. Nociceptive neurons that innervate the dura release various vasoactive peptides. Calcitonin gene-related peptide is the most active of these peptides. Neural pathways that are involved in sleep generation are divided into those responsible for circadian rhythm, wake promotion, non-rapid eye movement, and rapid eye movement sleep activation. Sleep state switches are a critical component of these systems. The cerebral structures, networks, and neurochemical systems that are involved in migraine align closely with those responsible for the regulation of sleep. Neurochemical systems that are involved with both the pathogenesis of migraine and regulation of sleep include adenosine, melatonin, orexin, and calcitonin gene-related peptide. Sleep disorders represent the most common comorbidity with migraine in childhood. The prevalence of parasomnias, obstructive sleep apnea, and sleep-related movement disorders is significantly greater in children migraineurs. Infantile colic is a precursor of childhood migraine. Treatment of comorbid sleep disorders is important for the appropriate management of children with migraine. Sleep-based behavioral interventions can be of substantial benefit. These interventions are particularly important in children due to limited evidence for effective migraine pharmacotherapy.

Calories, Caffeine and the Onset of Obesity in Young Children

OBJECTIVE

High calorie foods and beverages, which often contain caffeine, contribute to child overweight/obesity. We evaluated the results of an educational intervention to promote healthy growth in very young children. Secondarily, we used detailed diet data to explore the association of nutrient intake with the early development of overweight and obesity.

METHODS

Mothers were obese Latina women, enrolled prenatally, and their infants. Specially trained community health workers provided breastfeeding support and nutrition education during 10 home visits, birth to 24 months. At follow-up, age 18 to 36 months, we measured growth and completed detailed diet recalls (1-7 recall days/child).

RESULTS

Of 174 infants randomized, 106 children were followed for 24 to 36 months. The educational intervention did not prevent overweight/obesity. Forty-two percent of children became overweight or obese. Fifty-eight percent of children consumed caffeine on at least 1 recall day. Mean intake was 0.48 mg/kg/day. Caffeine correlated with higher consumption of calories, and added sugar and decreased intake of protein, fiber and dairy. Compared with days without caffeine, on days when caffeine was consumed, children ingested 121 more calories and 3.8 gm less protein. Children frequently consumed less than the recommended daily intake of key nutrients such as fiber, vegetables, whole fruit, and vitamins.

CONCLUSIONS

Caffeine was a marker for increased intake of calories and decreased intake of key nutrients. When discussing dietary intake in early childhood, practitioners should screen for nutrient deficiency in young children and recommend limiting the intake of caffeinated foods and beverages.

Chronic and Acute Oral Administration of Caffeine Enhance Performance of Olfactory Learning in Crickets

Crickets were arbitrarily fed a caffeine-containing diet during their lifetime or were orally administered caffeine in solution once during the conditioning session. These chronically or acutely treated crickets were used to test whether there were positive effects of caffeine on their learning performance. The effects of chronic exposure to caffeine on crickets' growth were also examined by measuring their body weight and counting the number of adults that emerged from larvae. Chronic treatment with relatively high concentrations of caffeine (5 mg/g and 0.5 mg/g in the diet) impaired the growth of crickets. Mortality was higher with 5 mg/g caffeine, and the survivors could not attain the final molt (eclosion). Body weight gain and eclosion rate were also negatively influenced in the group fed 0.5 mg/g caffeine. The olfactory learning paradigm was used to examine the effects of chronic caffeine treatment. Of the caffeine concentrations tested (0.5 µg/g to 0.5 mg/g), significant improvement in long-term memory (LTM) formation was observed only with 50 µg/g caffeine. Acute effects on olfactory learning were examined after oral administration of 0.1 nM to 10 µM caffeine solutions during the conditioning session. Administration of caffeine ≥ 1 nM consistently resulted in a significant improvement in LTM formation. These results suggest that chronic exposure to caffeine enhances learning performance in crickets at a specific dose (50 µg/g in the diet), although it inhibits their growth at higher doses (≥ 0.5 mg/g). In contrast, acute oral administration of caffeine in naive crickets may enhance their learning performance even at a very low (nanomolar) concentration.

Caffeine and Doping-What Have We Learned since 2004

Caffeine is a naturally occurring plant alkaloid and is found in plant constituents such as coffee and cocoa beans, tea leaves, guarana berries and the kola nut [...].

Alcohol, nicotine, and caffeine consumption on a public U.S. university campus determined by wastewater-based epidemiology

Alcohol, nicotine, and caffeine use in at-risk populations is a public health concern that claims over 550,000 lives annually. Self-reported surveys from college students often reveal overconsumption of these substances. Unfortunately, the costs of these surveys are high, and consequently, the results from few studies are often extrapolated across the entire target population. Here we employed wastewater-based epidemiology (WBE) to directly measure the levels of these three psychotropic substances and their metabolites in sewage from a large public Southwestern U.S. university campus during the 2017-2018 academic year. Results showed per person alcohol consumption was 11.3 ± 7.5 g d^-1 person^-1 or 0.8 ± 0.5 drinks d^-1 person^-1, similar to averages of nationwide estimates from self-reporting of this subpopulation aged 18-25 years (10.1 ± 0.8 g d^-1 person^-1 or 0.7 ± 0.06 drinks d^-1 person^-1). Caffeine and nicotine consumption determined by WBE were significantly lower (p < 0.05) than nationwide estimates from self-reporting (caffeine: 114 ± 49 vs. 178 ± 19 mg d^-1 person^-1; nicotine: 627 ± 219 vs. 927 ± 243 μg d^-1 person^-1). Strong positive correlations were found for consumption of alcohol and nicotine (Spearman r_s: 0.71; p < 0.01), and nicotine and caffeine (0.59, p < 0.01), but not alcohol and caffeine (0.17). Alcohol and nicotine consumption were significantly higher on weekends compared to weekdays (p < 0.01), while caffeine consumption was higher during the week (p < 0.05). This first U.S. WBE study on alcohol, nicotine, and caffeine use among U.S. college students demonstrated the feasibility and practicality of longitudinally tracking the behavior of an entire campus population of 60,000 students directly, repeatedly, and more inexpensively (US$0.58/person) compared to conventional questionnaires (US$127/person).

Health Decline Is Associated with Reports of No Coffee Consumption Years After Reporting Coffee Consumption Among Older Adults in Spain

BACKGROUND

Part of the health benefits of coffee reported in observational studies might be due to health status influencing coffee intake rather than the opposite.

OBJECTIVE

We examined whether changes in health influenced subsequent reports of no coffee consumption in older adults.

METHODS

Data came from 718 coffee drinkers aged ≥60 y recruited in the Seniors-Estudio de Nutrición y Salud Cardiovascular en España (ENRICA) cohort in 2008-2010 (wave 0) and followed-up in 2012 (wave 1), 2015 (wave 2), and 2017 (wave 3). Health status was measured with a 52-item deficit accumulation index (DAI) with 4 domains: functionality, self-rated health/vitality, mental health, and morbidity/health services use. Coffee intake was estimated with a validated diet history. We examined how changes in health status over a 3-y period (wave 0 to wave 1) influenced reports of no coffee consumption during the subsequent 5 y (wave 1 to wave 3) by using logistic regression models.

RESULTS

Health deterioration over 3 y was associated with a higher frequency of reports of no regular coffee consumption during the subsequent 5 y (fully adjusted OR: 1.48 per 1-SD increment in DAI; 95% CI: 1.17-1.87). Deteriorating function (OR: 1.38 per 1-SD increment; 95% CI: 1.06-1.81) and mental health (OR: 1.34 per 1-SD increment; 95% CI: 1.04-1.73) were the DAI domains associated with increased reports of no regular coffee consumption. Also, individuals with worsened perceived health or hypertension onset were more likely to report no regular coffee consumption. No associations were found for decaffeinated coffee.

CONCLUSIONS

Health deterioration was associated with reports of no regular coffee consumption years after reporting regular coffee consumption among older adults in Spain. A potential implication of this finding is that part of the beneficial effect of coffee consumption on health in observational studies might be due to reverse causation, which should be confirmed in future research.

Caffeine Use and Associations With Sleep in Adolescents With and Without ADHD

OBJECTIVE

The objective of this study was to compare caffeine consumption in the morning, afternoon, and evening in adolescents with and without attention-deficit/hyperactivity disorder (ADHD) and examine associations with sleep functioning.

METHODS

Participants were 302 adolescents (ages 12-14) with (N = 140) and without (N = 162) ADHD. Adolescents wore actigraph watches to assess total sleep time and wake after sleep onset and reported on sleep-wake problems and the number of caffeinated beverages consumed per day in the morning, afternoon, and evening. Parents reported on adolescents' difficulties initiating and maintaining sleep. Chi-square tests, odds ratios, and path analyses were conducted.

RESULTS

Analyses controlled for sex, medication status, and pubertal development. Adolescents with ADHD were 2.47 times more likely to consume caffeine in the afternoon and evening than adolescents without ADHD. Path analyses indicated significant associations between afternoon caffeine use and more self-reported sleep problems for adolescents with and without ADHD, and an association between evening caffeine use and self-reported sleep problems only in adolescents with ADHD. Afternoon caffeine use was associated with parent-reported sleep problems in adolescents with ADHD only. Caffeine use was not associated with actigraphy-assessed sleep.

CONCLUSION

This is the first study to show that adolescents with ADHD consume more caffeine than peers during later times of the day. Additionally, caffeine use is more consistently associated with poorer subjective sleep functioning in adolescents with ADHD. Pediatricians and mental health professionals should assess for caffeine use in adolescents with ADHD and co-occurring sleep problems.

Caffeine and Its Pharmacological Benefits in the Management of Androgenetic Alopecia: A Review

Caffeine, particularly after ingestion, is well known to exert various pharmacological effects. A growing body of evidence implicates the ingestion of caffeine with beneficial effects on several diseases. The easy penetration of caffeine across the skin barrier and into human skin makes caffeine an ideal compound for topical application. Hair loss is known to negatively affect the quality of life and predispose to depression and anxiety. Androgenetic alopecia (AGA) is the most common type of hair loss in both men and women. To date, only few approved drug-based treatments for AGA exist, and these are inevitably associated with side effects. Therefore, the development of topical treatments based on well-tolerated natural ingredients such as caffeine to alleviate hair loss may provide a much-needed alternative to drug-based approaches.

Mechanisms for the reduction of caffeine consumption: What, how and why

BACKGROUND

Anecdotal evidence suggests consumers of caffeine self-administer strategies to reduce consumption, but little is known of what these strategies are or how they are implemented. This study aimed to understand the lived experience of reducing caffeine consumption including specific techniques (what) and implementation strategies (how), harm and withdrawal symptoms (why).

METHODS

We developed a classification system through an inductive and deductive approach and applied it to a large dataset derived from online sources.

RESULTS

A total of 112 internet sources were identified, containing 2,682 different strategies. The classification system identified 22 categories of Behaviour Change Techniques (BCT): 10 categories were directly aligned with a BCT, one was split into two categories (substance and behavioural substitution), six represented a cluster of BCT's (e.g., withdrawal management and maintaining momentum) and four appeared to uniquely represent a consumer perspective (e.g., realisation of a problem). The most common techniques were substance substitution, seek knowledge and information, avoidance of caffeine and identify prompts for change. The most frequently perceived benefit was the stimulating effects of caffeine and a feeling of mental alertness. The most frequently cited harms were sleep problems including insomnia and concerns about dependence (or addiction) to caffeine. We found 16 categories of withdrawal symptoms. The most frequently endorsed symptom was headaches, followed by fatigue, exhaustion and low energy.

CONCLUSIONS

Consumers use a wide range of techniques when attempting to reduce caffeine consumption. Treatment approaches are focused on fading, but the current study found consumers most frequently focus on substance and behavioural substitution.

Effects of Multi-ingredient Preworkout Supplements on Physical Performance, Cognitive Performance, Mood State, and Hormone Concentrations in Recreationally Active Men and Women

Beckner, ME, Pihoker, AA, Darnell, ME, Beals, K, Lovalekar, M, Proessl, F, Flanagan, SD, Arciero, PJ, Nindl, BC, and Martin, BJ. Effects of multi-ingredient preworkout supplements on physical performance, cognitive performance, mood state, and hormone concentrations in recreationally active men and women. J Strength Cond Res XX(X): 000-000, 2020-Performance enhancement supplement research has primarily focused on the effectiveness of individual ingredients, rather than the combination. This study investigated the acute effects of 2 multi-ingredient preworkout supplements (MIPS), with beta-alanine and caffeine (BAC) and without (NBAC), compared with placebo (PLA) on anaerobic performance, endurance capacity, mood state, cognitive function, vascular function, and anabolic hormones. Thirty exercise-trained individuals (24.4 ± 4.9 years, 15 men and 15 women) completed a fatiguing exercise protocol on 3 separate occasions, 30 minutes after ingestion of BAC, NBAC, or PLA. Outcomes were analyzed using one-way or two-way repeated-measures analysis of variance, as appropriate (alpha = 0.05). Anaerobic power was greater when supplementing with NBAC (10.7 ± 1.2 W·kg) and BAC (10.8 ± 1.4 W·kg) compared with PLA (10.4 ± 1.2 W·kg) (p = 0.014 and p = 0.022, respectively). BAC improved V[Combining Dot Above]O2peak time to exhaustion (p = 0.006), accompanied by an increase in blood lactate accumulation (p < 0.001), compared with PLA. Both NBAC and BAC demonstrated improved brachial artery diameter after workout (p = 0.041 and p = 0.005, respectively), but PLA did not. L-arginine concentrations increased from baseline to postsupplement consumption of BAC (p = 0.017). Reaction time significantly decreased after exercise for all supplements. There was no effect of supplement on mood states. Exercise-trained individuals looking to achieve modest improvements in power and endurance may benefit from consuming MIPS before exercise.

Dietary Behaviors That Place Young Adults at Risk for Future Osteoporosis

Dietary behaviors during adolescence and emerging adulthood have important consequences for peak bone mass (PBM) attainment. This study aimed to examine dietary factors that are either beneficial or detrimental to bone health and determine the major sources of calcium in the diets of a sample of young adults. A cross-sectional survey was conducted among 189 Australians aged 18–30 years. Three-day dietary intakes were collected using consecutive 24 h recall interviews. Daily totals for energy and nutrients and serves for food groups were computed. The proportion contribution of calcium (mg) from different food groups as well as calcium (mg) per portion and per 100 g were calculated. Females and males failed to meet the recommendations for dairy (91%, 82%), fruit (89%, 94%) and vegetables (74%, 86%). Eighty percent were above the recommended daily intake range for sodium. For calcium, 53% of females and 48% of males had intakes below the estimated average requirement (EAR). Milk products and dishes made the highest mean calcium contribution per portion (mg) mean standard deviation (SD), 204 mg (212) and accounted for 30% of calcium intake in females and 35% in males. As young adulthood is the final chance for dietary manipulation before PBM is achieved, these dietary risk factors should be addressed.

Can caffeine intake combined with aerobic exercise lead to improvement in attentional and psychomotor performance in trained individuals?

•

Supplementation effect was found, suggesting distinct interaction mechanisms between attention and SRT (simple reaction time).

•

The change in the SRT magnitude increased after 60 min from caffeine intake, and even more after exercise.

•

The decrease in the SRT magnitude after caffeine intake and exercise suggests additional effects of caffeine on exercise.

To evaluate the acute effects of ingestion of 500 mg of caffeine in addition to aerobic exercise on the optimization of cognitive attention tasks and simple reaction time. Twenty men were randomly divided into two groups, caffeine (CAF) and placebo (PLA), and underwent cardiopulmonary exercise testing and cognitive testing (D2SLK, D2GZ, D2F% and TRS). Then, both ingested 500 mg of caffeine or placebo (double blind), and after 60 min performed a 30-minute continuous exercise session at 70 % VO2Max. Cognitive tests were repeated immediately after exercise, and after 30 min. D2SLK, D2GZ, D2F% and TRS scores were compared by repeated measures ANOVA. The magnitude of the effect was established, and it was considered meaningful p = 0.05. CAF is able to alter D2SLK and also reduce D2F% (0.001 - moderate effect, 0.82) and improve the task after 30 min of exercise (p = 0.014 - moderate effect 0.95). The TRS showed significant gains for the CAF group compared to PLA (0.000 - high effect 1.76). Caffeine induces significant effects in attention and reaction time domains independent of the effect of aerobic exercise.

Trait specific modulatory effects of caffeine exposure on compulsive-like behaviors in a spontaneous mouse model of obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a psychiatric disorder characterized by recurring intrusive thoughts and repetitive compulsive behaviors, ultimately interfering with their quality of life. The complex heterogeneity of symptom dimensions across OCD patient subgroups impedes diagnosis and treatment. The core and comorbid symptomologies of OCD are thought to be modulated by common environmental exposures such as consumption of the psychostimulant caffeine. The effect of caffeine on the expression of obsessions and compulsions are unexplored. The current study utilized mouse strains (HA) with a spontaneous, predictable, and stable compulsive-like phenotype that have face, predictive, and construct validity for OCD. We demonstrate that an acute high dose (25 mg/kg) of caffeine decreased compulsive-like nest-building behavior in the HA strains in the first hour after injection. However, nest-building scores increased in hours 3, 4, and 5 after administration finally decreasing over a 24 h period. In contrast, a high dose of chronic caffeine (25 mg/kg/d) increased nest-building behavior. Interestingly for compulsive-like digging behavior, acute exposure to a high dose of caffeine decreased the number of marbles buried, while chronic exposure had little effect. An acute high dose of caffeine decreased anxiety-like and motor activity in open field behaviors whereas chronic caffeine administration did not have any overall effect on open field activity. The results, therefore, suggest a complex role of caffeine on compulsive-like, anxiety-like, and locomotor behaviors that is dependent on the duration of exposure.

A Randomized Placebo Controlled Clinical Trial Demonstrating Safety & Efficacy of EnXtra® in Healthy Adults

Objective: The present randomized, placebo-controlled study aimed to assess the long-term safety and perceivable mental acuity benefits of EnXtra^® in healthy individuals.Methods: Study participants were administered EnXtra^® with or without caffeine for a period of 12 weeks. The cardiovascular safety was evaluated by assessing change in QT interval, blood pressure and heart rate. Further, other efficacy variables evaluated were change in perceived alertness and calmness by Bond and Lader mood scales, Sleep disturbance by Pittsburgh sleep quality Index and daytime sleepiness by Epworth sleepiness scale.Results: None of the study group showed any significant change in the ECG or haemodynamic parameters as compared to baseline (p > 0.05). Post consumption, alertness and calmness scores were significantly increased in the EnXtra^®, and EnXtra^® plus caffeine group (p < 0.001) as compared to placebo. Daytime sleep scores decreased in the EnXtra^® group however change was not significant. Sleep quality remained undisturbed in all three arms.Conclusion: The findings demonstrated the psychostimulant efficacy of EnXtra^® with no safety concerns on long-term usage.

Beneficial Impact of Semicarbazide-Sensitive Amine Oxidase Inhibition on the Potential Cytotoxicity of Creatine Supplementation in Type 2 Diabetes Mellitus

Creatine supplementation of the population with type 2 diabetes mellitus (T2DM) combined with an exercise program is known to be a possible therapy adjuvant with hypoglycemic effects. However, excessive administration of creatine leads to the production of methylamine which is deaminated by the enzyme semicarbazide-sensitive amine oxidase (SSAO) and as a result, cytotoxic compounds are produced. SSAO activity and reaction products are increased in the serum of T2DM patients. Creatine supplementation by diabetics will further augment the activity of SSAO. The current review aims to find a feasible way to ameliorate T2DM for patients who exercise and desire to consume creatine. Several natural agents present in food which are involved in the regulation of SSAO activity directly or indirectly are reviewed. Particularly, zinc-α2-glycoprotein (ZAG), zinc (Zn), copper (Cu), histamine/histidine, caffeine, iron (Fe), and vitamin D are discussed. Inhibiting SSAO activity by natural agents might reduce the potential adverse effects of creatine metabolism in population of T2DM.

The Association Between Coffee Consumption and Local Anesthesia Failure: Social Beliefs and Scientific Evidence

Introduction In our clinical practice, we have encountered patients who reported the failure of local anesthesia due to excessive coffee consumption and required higher-than-normal doses of local anesthesia. Therefore, our study aimed to assess the awareness and knowledge of coffee consumption, its effect on local anesthesia, and the available scientific evidence among the public, patients, and clinicians in dental practice.  Material and Methods A cross-sectional survey with two sets of questionnaires was designed based on the Likert scale. A 5-point scale was used to assess agreement and frequency. Yes/no and open-ended questions were used for the assessment. Questionnaires were distributed among the clinicians, patients, and the public. Data were analyzed with descriptive linear statistics. Results Of the 430 responses provided by patients and the general public, more than 40% believed that the local anesthetic failure was caused by excessive coffee consumption. Among the 235 responses provided by the clinicians, 65% of the clinicians reported encountering patients with local anesthesia failure and believed it could be due to excessive coffee consumption. However, only 9% of the clinicians were aware of scientific evidence regarding the effect of coffee consumption on local anesthesia failure.  Conclusion Surprisingly, the majority of clinicians believed that caffeine had an effect on the reduction of local anesthesia; however, only a few of them had scientific knowledge. The available scientific evidence relates that caffeine can influence cognitive performance by increasing alertness, as well as sleep deprivation causing stress and anxiety, which partially explains the local anesthetic failure among coffee consumers. Therefore, a stress reduction protocol should be a routine daily practice for a dentist to reduce the failure rate of local anesthesia.

Caffeine, a Risk Factor for Osteoarthritis and Longitudinal Bone Growth Inhibition

Osteoarthritis (OA), the most common chronic rheumatic disease, is mainly characterized by a progressive degradation of the hyaline articular cartilage, which is essential for correct joint function, lubrication, and resistance. Articular cartilage disturbances lead to joint failure, pain, and disability. Hyaline cartilage is also present in the growth plate and plays a key role in longitudinal bone growth. Alterations of this cartilage by diverse pathologies have been related to longitudinal bone growth inhibition (LBGI), which leads to growth retardation. Diet can play a crucial role in processes involved in the OA and LBGI's onset and evolution. Specifically, there is ample evidence pointing to the negative impacts of caffeine consumption on hyaline cartilage. However, its effects on these tissues have not been reviewed. Accordingly, in this review, we summarize all current knowledge in the PubMed database about caffeine catabolic effects on articular and growth plate cartilage. Specifically, we focus on the correlation between OA and LBGI with caffeine prenatal or direct exposure. Overall, there is ample evidence indicating that caffeine intake negatively affects the physiology of both articular and growth plate cartilage, increasing consumers predisposition to suffer OA and LBGI. As a result, caffeine consumption should be avoided for these pathologies.

Intake of Caffeine and Its Association with Physical and Mental Health Status among University Students in Bahrain

In Western populations, the caffeine intake of young adults has received significant attention in the research literature; our knowledge in other societies remained limited. The objective of this research is to quantify the amount of ingested caffeine and how this is related to measures of physical and mental health in a Bahraini population. A semi-quantitative food frequency questionnaire was used to estimate caffeine intake from coffee, tea, cocoa, soft drinks, energy drinks, chocolates, and over-the-counter medications. Associations between caffeine intake, demographic variables and 25 symptoms measured using the Hopkins Symptoms Checklist-25 were examined. A convenience sample of university students in Bahrain (n = 727) was surveyed. Caffeine, in any form, was consumed by 98% of students. Mean daily caffeine consumption was 268 mg/day, with males consuming more than females. Coffee was the main source of caffeine intake, followed by black tea and energy drinks. Participants consuming 400 mg/day or more showed a statistically and significantly twice as high risk for five symptoms, these were: headaches, spells of terror or panic, feeling trapped or caught, worrying too much about things, and having feelings of worthlessness. The prevalence of caffeine intake among university students in Bahrain is high. The overall mean intake of caffeine from all sources by university students was within levels considered to be acceptable by many dietary recommendations. High caffeine intake was associated with an anxiogenic effect in the surveyed students.

Chronic voluntary caffeine intake in male Wistar rats reveals individual differences in addiction-like behavior

Caffeine is the most widely consumed psychoactive substance in the world. However, there is controversy about whether becoming addicted to caffeine is possible and a lack of well-established animal models to examine caffeine consumption. The present study sought to establish a model of caffeine consumption in Wistar rats, identify different rat populations based on caffeine preference, and determine whether extended voluntary caffeine consumption produces compulsive-like caffeine intake and withdrawal symptoms. Male Wistar rats were used throughout the experiment. The optimal concentration of caffeine to maximize caffeine consumption and caffeine preference was determined. Rats were then given continuous access to caffeine, followed by intermittent access. Rats were tested for signs of withdrawal-like behavior by measuring mechanical nociception and irritability-like behavior. Rats were further examined for compulsive-like caffeine consumption using quinine adulteration. Dose-response testing indicated an optimal caffeine concentration of 0.3 mg/mL. During intermittent access to caffeine, the rats did not escalate their caffeine intake and instead exhibited a decrease in intake over sessions. Three groups of rats were identified based on caffeine preference (high, medium, and low) across continuous and intermittent access. These three groups of rats matched low (1 cup), medium (2 cups), and high (4 cups) levels of daily coffee consumption in humans. Caffeine-consuming rats did not exhibit differences in mechanical nociception or irritability-like behavior compared with controls. In high caffeine-preferring rats but not in medium or low caffeine-preferring rats, compulsive-like caffeine consumption was observed. The present study established a rodent model of caffeine consumption that resulted in large individual differences in caffeine intake, similar to humans. Compulsive-like caffeine consumption in high caffeine-preferring rats and differences in caffeine preference between groups suggest that caffeine may result in compulsive-like intake in a subpopulation of subjects. Further testing is necessary to determine the factors that contribute to differences in caffeine preference and compulsive-like intake.

The Influence of Caffeine Supplementation on Resistance Exercise: A Review

This paper aims to critically evaluate and thoroughly discuss the evidence on the topic of caffeine supplementation when performing resistance exercise, as well as provide practical guidelines for the ingestion of caffeine prior to resistance exercise. Based on the current evidence, it seems that caffeine increases both maximal strength and muscular endurance. Furthermore, power appears to be enhanced with caffeine supplementation, although this effect might, to a certain extent, be caffeine dose- and external load-dependent. A reduction in rating of perceived exertion (RPE) might contribute to the performance-enhancing effects of caffeine supplementation as some studies have observed decreases in RPE coupled with increases in performance following caffeine ingestion. However, the same does not seem to be the case for pain perception as there is evidence showing acute increases in resistance exercise performance without any significant effects of caffeine ingestion on pain perception. Some studies have reported that caffeine ingestion did not affect exercise-induced muscle damage, but that it might reduce perceived resistance exercise-induced delayed-onset muscle soreness; however, this needs to be explored further. There is some evidence that caffeine ingestion, compared with a placebo, may lead to greater increases in the production of testosterone and cortisol following resistance exercise. However, given that the acute changes in hormone levels seem to be weakly correlated with hallmark adaptations to resistance exercise, such as hypertrophy and increased muscular strength, these findings are likely of questionable practical significance. Although not without contrasting findings, the available evidence suggests that caffeine ingestion can lead to acute increases in blood pressure (primarily systolic), and thus caution is needed regarding caffeine supplementation among individuals with high blood pressure. In the vast majority of studies, caffeine was administered in capsule or powder forms, and therefore the effects of alternative forms of caffeine, such as chewing gums or mouth rinses, on resistance exercise performance remain unclear. The emerging evidence suggests that coffee might be at least equally ergogenic as caffeine alone when the caffeine dose is matched. Doses in the range of 3-9 mg·kg^-1 seem to be adequate for eliciting an ergogenic effect when administered 60 min pre-exercise. In general, caffeine seems to be safe when taken in the recommended doses. However, at doses as high as 9 mg·kg^-1 or higher, side effects such as insomnia might be more pronounced. It remains unclear whether habituation reduces the ergogenic benefits of caffeine on resistance exercise as no evidence exists for this type of exercise. Caution is needed when extrapolating these conclusions to females as the vast majority of studies involved only male participants.

Use of stimulants, over-the-counter and prescription drugs among Danish pregnant women

Using self-reports and blood samples from 225 unselected Danish first trimester pregnant women, the purpose of this study was to assess their use of stimulants, for example caffeine and nicotine as well as over-the-counter (OTC) and prescription drugs. According to self-reported information, 24% had used prescription drugs and 48% had used OTC drugs mainly acetaminophen (42%), 9.3% were habitual smokers, 44% stated a daily use of caffeinated beverages, and 1.3% used illegal drugs. Ultra-performance liquid chromatography with high-resolution time-of-flight mass spectrometry (UPLC-HR-TOFMS) analysis was performed on corresponding blood samples applying golden standards for use of UPLC-HR-TOFMS in forensic medicine. Traces of prescription drugs were detected in 5.3% of the samples and 8.9% contained OTC drugs (acetaminophen 7.1%). Traces of smoking were identified in 8.0%, caffeine in 83% and illegal drugs in 0.9%. These results indicate a substantial use of OTC drugs and caffeine among Danish pregnant women. Blood analysis indicated that many women could be unaware of their caffeine intake. As common substances may be associated with adverse pregnancy outcomes, healthcare professionals should inquire about such habits during pregnancy. The results also underline the need for more research into the molecular effects of such drugs on placental function and foetal development.

Prevalence and Correlates of Caffeine Use Disorder Symptoms Among a United States Sample

Background: The DSM-5 recognizes caffeine use disorder as a condition for further study, but there is a need to better understand its prevalence and clinical significance among the general population.

Methods: A survey was conducted among an online sample of 1006 caffeine-consuming adults using demographic quotas to reflect the U.S. population. Caffeine consumption, DSM-proposed criteria for caffeine use disorder, sleep, substance use, and psychological distress were assessed.

Results: Eight percent of the sample fulfilled DSM-proposed criteria for caffeine use disorder. These individuals consumed more caffeine, were younger, and were more likely to be cigarette smokers. Fulfilling caffeine use disorder criteria was associated with caffeine-related functional impairment, poorer sleep, some substance use, as well as greater depression, anxiety, and stress.

Conclusions: The prevalence of caffeine use disorder among the present sample suggests that the proposed diagnostic criteria would identify only a modest percentage of the general population, and that identified individuals experience significant caffeine-related distress.

Safety of Short-Term Supplementation with Methylliberine (Dynamine®) Alone and in Combination with TeaCrine® in Young Adults

Methylliberine (Dynamine^®; DYM) and theacrine (Teacrine^®; TCR) are purine alkaloids purported to have similar neuro-energetic effects as caffeine. There are no published human safety data on DYM, and research on TCR is limited. The purpose of this study was to examine the effect of four weeks of DYM supplementation with and without TCR on cardiovascular function and blood biomarkers. One-hundred twenty-five men and women (mean age 23.0 yrs, height 169.7 cm, body mass 72.1 kg; n = 25/group) were randomly assigned to one of five groups: low-dose DYM (100 mg), high-dose DYM (150 mg), low-dose DYM with TCR (100 mg + 50 mg), high-dose DYM with TCR (150 mg + 25 mg) , and placebo. Regardless of group and sex, significant main effects for time were noted for heart rate, systolic blood pressure, and QTc (p < 0.001), high-density lipoproteins (p = 0.002), mean corpuscular hemoglobin (p = 0.018), basophils (p = 0.006), absolute eosinophils (p = 0.010), creatinine (p = 0.004), estimated glomerular filtration rate (p = 0.037), chloride (p = 0.030), carbon dioxide (p = 0.023), bilirubin (p = 0.027), and alanine aminotransferase (p = 0.043), among others. While small changes were found in some cardiovascular and blood biomarkers, no clinically significant changes occurred. This suggests that DYM alone or in combination with TCR consumed at the dosages used in this study does not appear to negatively affect markers of health over four weeks of continuous use.

Metabolic Response of Adult Male Offspring Rats to Prenatal Caffeine Exposure

Caffeine is the most widely consumed psychoactive substance, with recommendations from health associations and regulatory bodies for limiting caffeine consumption during pregnancy being increasingly common. Prenatal exposure to caffeine has been shown to increase the risk of developing abnormalities in lipid metabolism in adult life. We further investigated the effect of prenatal caffeine exposure (PCE) (20 mg/kg of body weight) on the metabolic "reserve" of male Sprague Dawley offspring fed on a high fructose diet in adult life. Male adult PCE offspring were assigned to four groups; Nw and Nf: offspring of control mothers (N group of mothers), having received tap water or high fructose water respectively; Cw and Cf: offspring exposed to caffeine during gestation (C group of mothers) and receiving tap water or a high fructose water solution, respectively. Cf rats presented increased serum triglyceride level, as well as raised systolic and diastolic blood pressure levels, together with extensive renal tissue oedema in adulthood, compared to the other groups (p<0.05 for all comparisons). These findings show further evidence for potential detrimental metabolic effects of prenatal caffeine exposure during adulthood in this animal model.

Basolateral Amygdala Connectivity With Subgenual Anterior Cingulate Cortex Represents Enhanced Fear-Related Memory Encoding in Anxious Humans

BACKGROUND

The amygdala can enhance emotional memory encoding as well as anxiogenesis via corticotropin-releasing factor neurons. However, the amygdala's explicit role in emotional encoding remains unclarified in humans. We examined how functional connectivity (FC) of amygdala subnuclei affects emotional encoding, considering its mechanism in which anxiety, attention, and cortisol conceivably participate.

METHODS

A total of 65 healthy humans underwent resting-state functional magnetic resonance imaging scans and saliva collection at 10 points in time over 2 days. FC analysis was performed for basolateral amygdala subnucleus (BLA) and centromedial amygdala subnucleus. We assessed attentional control via an emotional Stroop task and assessed emotional encoding via a facial identification task that examines how strongly a neutral face is memorized when accompanied by an emotional face (fearful, sad, or happy). FC and task performance were compared between high-anxious and non-high-anxious groups classified by anxious personality scores.

RESULTS

BLA connected with subgenual anterior cingulate cortex (sgACC) in proportion to the strength of fear-related encoding, whereas centromedial subnucleus connected with caudate nucleus for happy-related encoding. The high-anxious group showed more enhanced fear-related encoding but impaired happy-related encoding compared with the non-high-anxious group. BLA-sgACC FC was more intensified in the high-anxious group than in the non-high-anxious group; however, centromedial-caudate FC did not differ between them. Although emotional encoding was uncorrelated with either attentional control or cortisol, BLA-sgACC was positively correlated with cortisol increase after awakening.

CONCLUSIONS

The study revealed that neural interactions of BLA, specifically with sgACC, might play a critical role in fear-related memory encoding, depending on the individual's level of anxiety. These findings aid in understanding the complicated mechanisms of emotional memory in anxiety disorders.

Attenuation of Weight Gain and Prevention of Associated Pathologies by Inhibiting SSAO

Obesity is a worldwide prevalent metabolic disorder that is associated with diabetes, among many other diseases. Bearing this in mind, prevention and treatment ways need to be improved. Notably, activity of the enzyme semicarbazide-sensitive amine oxidase (SSAO) is found to be elevated in overweight subjects. Moreover, SSAO inhibition has resulted in an increase of histamine activity in adipose tissue and the limitation of body fat. The current review aims to overview the risks of obesity, rationalize the molecular ways of SSAO activity, and outline the strategies of inhibiting upregulated enzyme levels. It describes the differences between SSAO inhibitors and advances the prospective agents. Based on evidence, caffeine is proposed as an effective, safe, and reliable choice to inhibit SSAO activity. Furthermore, the histamine in adipocytes has been associated with SSAO activity. Therefore, it is suggested as one of the key compounds to be studied for obesity management. To conclude, inhibiting SSAO may attenuate weight gain and prevent related diseases.

Associations Between Caffeine Consumption, Cognitive Decline, and Dementia: A Systematic Review

BACKGROUND

Epidemiologic studies have provided inconclusive evidence for a protective effect of caffeine consumption on risk of dementia and cognitive decline.

OBJECTIVE

To summarize literature on the association between caffeine and 1) the risk of dementia and/or cognitive decline, and 2) cognitive performance in individuals with mild cognitive impairment (MCI) or dementia, and 3) to examine the effect of study characteristics by categorizing studies based on caffeine source, quantity and other possible confounders.

METHODS

We performed a systematic review of caffeine effects by assessing overall study outcomes; positive, negative or no effect. Our literature search identified 61 eligible studies performed between 1990 and 2020.

RESULTS

For studies analyzing the association between caffeine and the risk of dementia and/or cognitive decline, 16/57 (28%) studies including a total of 40,707/153,070 (27%) subjects reported positive study outcomes, and 30/57 (53%) studies including 71,219/153,070 (47%) subjects showed positive results that were dependent on study characteristics. Caffeine effects were more often positive when consumed in moderate quantities (100-400 mg/d), consumed in coffee or green tea, and in women. Furthermore, four studies evaluated the relationship between caffeine consumption and cognitive function in cognitively impaired individuals and the majority (3/4 [75% ]) of studies including 272/289 subjects (94%) reported positive outcomes.

CONCLUSION

This review suggests that caffeine consumption, especially moderate quantities consumed through coffee or green tea and in women, may reduce the risk of dementia and cognitive decline, and may ameliorate cognitive decline in cognitively impaired individuals.

The effects of caffeine on olfactory function and mood: an exploratory study

Caffeine has been demonstrated to enhance olfactory function in rodents, but to date, the sparse research in humans has not shown any equivalent effects. However, due to the methodological nature of those human studies, a number of questions remain unanswered, which the present study aimed to investigate. Using a double-blind experimental design, participants (n = 40) completed baseline mood measures, standardised threshold and identification tests and were then randomly allocated to receive a capsule containing either 100 mg of caffeine or placebo, followed by the same olfactory tests and mood measures. Results revealed that despite a trend toward elevated arousal following caffeine for habitual caffeine consumers, there were no changes in odour function. In contrast, for non-caffeine consumers, caffeine acted to enhance odour (threshold) sensitivity but reduce odour identification. Overall, these findings demonstrate a complex profile of effects of caffeine on odour function and, given the evidence from the wider caffeine literature, it is proposed that the effects of caffeine might be limited to older populations.

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.

The Impact of Genetic Variations in ADORA2A in the Association between Caffeine Consumption and Sleep

ADORA2A has been shown to be responsible for the wakefulness-promoting effect of caffeine and the 1976T>C genotype (SNP rs5751876, formerly 1083T>C) to contribute to individual sensitivity to caffeine effects on sleep. We investigate the association between six single nucleotide polymorphisms (SNP) from ADORA2A and self-reported sleep characteristics and caffeine consumption in 1023 active workers of European ancestry aged 18-60 years. Three groups of caffeine consumers were delineated: low (0-50 mg/day, less than one expresso per day), moderate (51-300 mg/day), and high (>300 mg/day). We found that at caffeine levels higher than 300 mg/day, total sleep time (TST) decreased (F = 13.9, p < 0.01), with an increase of insomnia (ORa [95%CI] = 1.5 [1.1-1.9]) and sleep complaints (ORa [95%CI] = 1.9 [1.1-3.3]), whatever the ADORA2A polymorphism. Odds ratios were adjusted (ORa) for sex, age, and tobacco. However, in low caffeine consumers, lower TST was observed in the T allele compared to homozygote rs5751876 and rs3761422 C carriers. Conversely, higher TST was observed in rs2298383 T allele compared to C and in rs4822492G allele compared to the homozygote C (p < 0.05). These 4 SNPs are in strong linkage disequilibrium. Haplotype analysis confirmed the influence of multiple ADORA2a SNPs on TST. In addition, the rs2298383 T and rs4822492 G alleles were associated with higher risk of sleep complaints (Ora = 1.9 [1.2-3.1] and Ora = 1.5 [1.1-2.1]) and insomnia (Ora = 1.5 [1.3-2.5] and Ora = 1.9 [1.3-3.2). The rs5751876 T allele was associated with a decreased risk of sleep complaints (Ora = 0.7 [0.3-0.9]) and insomnia (Ora = 0.5 [0.3-0.9]). Our results identified ADORA2A polymorphism influences in the less-than-300-mg-per-day caffeine consumers. This opens perspectives on the diagnosis and pharmacology of sleep complaints and caffeine chronic consumption.

Effects of acute caffeine, theanine and tyrosine supplementation on mental and physical performance in athletes

BACKGROUND

A limited amount of research has demonstrated beneficial effects of caffeine and theanine supplementation for enhancement of mental performance. The purpose of this investigation was to determine whether the acute ingestion of a supplement containing caffeine, theanine and tyrosine improves mental and physical performance in athletes.

METHODS

Twenty current or former male collegiate athletes (age: 20.5 ± 1.4 y; height: 1.82 ± 0.08 m; weight: 83.9 ± 12.6 kg; body fat: 13.8 ± 5.6%) completed this randomized, double-blind, placebo-controlled crossover trial. After familiarization, each participant completed two identical testing sessions with provision of a proprietary dietary supplement (SUP) containing caffeine theanine and tyrosine or a placebo (PL). Within each testing session, participants completed assessments of mental and physical performance before and after provision of SUP or PL, as well as after two rounds of exercise. Assessments were performed using a performance testing device (Makoto Arena) that evaluated multiple aspects of mental and physical performance in response to auditory and visual stimuli. Testing was performed both with the body in a static position and during dynamic movement. General linear models were used to evaluate the effects of SUP and PL on performance.

RESULTS

Changes in movement accuracy during performance assessment were greater following SUP ingestion as compared to PL for both static and dynamic testing (SUP: + 0.4 to 7.5%; PL: - 1.4 to 1.4% on average; p < 0.05). For dynamic testing, the change in number of targets hit was higher and the change in average hit time was lower with SUP as compared to PL (p < 0.05). However, there were no differences between conditions for the changes in number of targets hit or average hit time during static testing. There were no differences in changes of subjective variables during either condition, and performance measures during the two rounds of exercise did not differ between conditions (p > 0.05).

DISCUSSION

The present results indicate that a combination of a low-dose of caffeine with theanine and tyrosine may improve athletes' movement accuracy surrounding bouts of exhaustive exercise without altering subjective variables. Based on this finding, supplementation with caffeine, theanine and tyrosine could potentially hold ergogenic value for athletes in sports requiring rapid and accurate movements.

TRIAL REGISTRATION

NCT03019523. Registered 24 January 2017.

Quantitative Analysis of Caffeine Levels in Local Coffee (Coffea sp) Powder on Dabo Island with UV-Vis Spectrophotometry

Coffee (Coffea sp) is the second-largest beverage consumed by people around the world whose process comes from the processing and extraction of coffee beans. Coffee has a chemical compound, one of which is caffeine. Caffeine is a crystal-shaped compound. Caffeine can be a tangible white powder or a shiny white needle-shaped, odorless caffeine, and caffeine has a bitter taste. The purpose of the study was to determine the caffeine levels of local ground coffee on the island of Dabo with the spectrophotometry UV-Vis method. Analysis of the ground coffee caffeine levels is quantitative determined using spectrophotometry UV-Vis. The equation of the calibration curve of caffeine is regression y = 0.1307x + 0.0112 with a correlation coefficient value (r) of 0.9993. Based on Indonesian National Standards (SNI) 01-7152-2006, The maximum limit of caffeine in foods and beverages is 150 mg/day and 50 mg/serving. The results of the analysis of caffeine levels from three samples of ground coffee circulating on Dabo Island each in 2 g were 0.3383 mg for Sample A; 0.3786 mg for Sample B; and 0.5803 mg for Sample C.

Impact of caffeine on metabolic activity and biofilm formation of Candida albicans on acrylic denture resin in the presence of nicotine

STATEMENT OF PROBLEM

Candida albicans has been implicated in denture stomatitis, and this effect is exacerbated by nicotine exposure. However, studies have also suggested that caffeine exposure inhibits the growth of C. albicans. The interaction effects of nicotine and caffeine are not yet clear on the growth of C. albicans.

PURPOSE

The purpose of this in vitro study was to determine the effect of caffeine on metabolic activity and biofilm formation of C. albicans growing on acrylic denture resin while simultaneously exposed to nicotine and, if an effect were to be identified, whether this effect would vary depending on the caffeine concentration.

MATERIAL AND METHODS

A total of 240 acrylic resin specimens were divided into 2 equal groups (120 each). Specimens in one group were processed to measure C. albicans metabolic activity, and those in the other group were processed to measure C. albicans biofilm attachment. Ten subgroups (n=12) were established within each group with different concentration combinations of nicotine and caffeine to test the interaction effect. The first subgroup was designed as a negative control, containing 0 mg/mL of nicotine and caffeine. The following subgroups all contained 8.00 mg/mL of nicotine, and the caffeine concentrations were prepared at the following 9 levels: 0, 0.25, 0.50, 1.00, 2.00, 4.00, 8.00, 16.00, and 32.00 mg/mL. Metabolic activity was measured by using a 2,3-bis (2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-carboxanilide (XTT) assay. Biofilm attachment was measured by using spiral plating and calculated in terms of the number of colony-forming units (CFUs)/mL. Descriptive statistics and a 2-way ANOVA were conducted to determine whether the concentrations of nicotine and caffeine used affected the biofilm attachment and metabolic activity of C. albicans (α=.05).

RESULTS

The presence of 8 mg/mL of nicotine increased the metabolic activity and biofilm formation of C. albicans. When compared with the 0 mg/mL of caffeine and 8.00 mg/mL of nicotine group, caffeine from 1.00 to 4.00 mg/mL significantly increased C. albicans biofilm metabolic activity. Caffeine at 16.00 and 32.00 mg/mL significantly decreased C. albicans biofilm metabolic activity in the presence of 8 mg/mL of nicotine. Caffeine from 1.00 to 32.00 mg/mL significantly decreased the biofilm formation of C. albicans in the presence of 8 mg/mL of nicotine.

CONCLUSIONS

The presence of 8 mg/mL of nicotine alone increased the metabolic activity and biofilm formation of C. albicans. In the presence of 8 mg/mL of nicotine with different caffeine concentrations, the results suggest that, overall, caffeine at higher concentrations (16 and 32 mg/mL) inhibited the metabolic activity and biofilm formation of C. albicans on acrylic denture resin most.

The Effect of Caffeine on the Velocity of Half-Squat Exercise during the Menstrual Cycle: A Randomized Controlled Trial

Recent literature confirms the ergogenic effect of acute caffeine intake to increase muscle strength and power in men. However, the information about the effect of caffeine on muscle performance in women is uncertain and it is unknown whether its ergogenicity is similar during the menstrual cycle. The goal of this investigation was to assess the effect of acute caffeine intake on mean and peak velocity of half-squat exercise during three different phases of the menstrual cycle. Thirteen trained eumenorrheic athletes (age = 31 ± 6 years; body mass = 58.6 ± 7.8 kg) participated in a double-blind, crossover and randomized experimental trial. In the early follicular (EFP), late follicular (LFP) and mid luteal phases (MLP), participants either ingested a placebo (cellulose) or 3 mg/kg/bm of caffeine in an opaque and unidentifiable capsule. In each trial, participants performed a half-squat exercise at maximal velocity with loads equivalent to 20%, 40% 60% and 80% of one repetition maximum (1RM). In each load, mean and peak velocity were measured during the concentric phase of the exercise using a rotatory encoder. In comparison to the placebo, a two-way ANOVA showed that the ingestion of 3 mg/kg/bm of caffeine increased mean velocity at 60% 1RM in EFP (Δ = 1.4 ± 2.7%, p = 0.04; ES: 0.2 ± 0.2) and LFP (Δ = 5.0 ± 10.4%, p = 0.04; ES: 0.3 ± 0.4). No other statistical differences were found for the caffeine-placebo comparison for mean velocity, but caffeine induced an ergogenic effect of small magnitude in all of the menstrual cycle phases. These results suggest that the acute intake of 3 mg/kg/bm of caffeine induces a small effect to increase movement velocity during resistance exercise in eumenorrheic female athletes. The positive effect of caffeine was of similar magnitude in all the three phases of the menstrual cycle.

Caffeine and Clinical Outcomes in Premature Neonates

Caffeine is the most widely used drug by both adults and children worldwide due to its ability to promote alertness and elevate moods. It is effective in the management of apnea of prematurity in premature infants. Caffeine for apnea of prematurity reduces the incidence of bronchopulmonary dysplasia in very-low-birth-weight infants and improves survival without neurodevelopmental disability at 18-21 months. Follow-up studies of the infants in the Caffeine for Apnea of Prematurity trial highlight the long-term safety of caffeine in these infants, especially relating to motor, behavioral, and intelligence skills. However, in animal models, exposure to caffeine during pregnancy and lactation adversely affects neuronal development and adult behavior of their offspring. Prenatal caffeine predisposes to intrauterine growth restriction and small growth for gestational age at birth. However, in-utero exposure to caffeine is also associated with excess growth, obesity, and cardio-metabolic changes in children. Caffeine therapy is a significant advance in newborn care, conferring immediate benefits in preterm neonates. Studies should help define the appropriate therapeutic window for caffeine treatment along with with the mechanisms relating to its beneficial effects on the brain and the lung. The long-term consequences of caffeine in adults born preterm are being studied and may depend on the ability of caffeine to modulate both the expression and the maturation of adenosine receptors in infants treated with caffeine.

Caffeine Consumption During Pregnancy Accelerates the Development of Cognitive Deficits in Offspring in a Model of Tauopathy

Psychoactive drugs used during pregnancy can affect the development of the brain of offspring, directly triggering neurological disorders or increasing the risk for their occurrence. Caffeine is the most widely consumed psychoactive drug, including during pregnancy. In Wild type mice, early life exposure to caffeine renders offspring more susceptible to seizures. Here, we tested the long-term consequences of early life exposure to caffeine in THY-Tau22 transgenic mice, a model of Alzheimer’s disease-like Tau pathology. Caffeine exposed mutant offspring developed cognitive earlier than water treated mutants. Electrophysiological recordings of hippocampal CA1 pyramidal cells in vitro revealed that early life exposure to caffeine changed the way the glutamatergic and GABAergic drives were modified by the Tau pathology. We conclude that early-life exposure to caffeine affects the Tau phenotype and we suggest that caffeine exposure during pregnancy may constitute a risk-factor for early onset of Alzheimer’s disease-like pathology.

Efficacy and safety of acetaminophen and caffeine for the management of acute dental pain: A systematic review

AIM

Because the use of non-steroidal anti-inflammatory drugs and opioids has several restrictions, this review evaluates the efficacy and safety of acetaminophen and caffeine for the management of dental pain.

METHODS

A search of the literature was carried out looking for randomized controlled trials on the use of acetaminophen and caffeine for the management of dental pain, performed on humans and written in English, Italian, French or Arabic languages. The following databases were searched: PubMed, The Cochrane Central Register of Controlled Trials (CENTRAL), Ovid Medline and Scopus.

RESULTS

Three controlled clinical trials were retrieved and evaluated by using the Study Quality Assessment Tool of the National Institute for Health and Clinical Excellence.

CONCLUSION

The use of acetaminophen and caffeine appears to be effective in achieving good control of acute dental pain compared to placebo and other analgesic medications, but clinical recommendations cannot be made for the limited number of studies assessed.

Caffeine regulates GABA transport via A1R blockade and cAMP signaling

Caffeine is the most consumed psychostimulant drug in the world, acting as a non-selective antagonist of adenosine receptors A₁R and A_2AR, which are widely expressed in retinal layers. We have previously shown that caffeine, when administered acutely, acts on A₁R to potentiate the NMDA receptor-induced GABA release. Now we asked if long-term caffeine exposure also modifies GABA uptake in the avian retina and which mechanisms are involved in this process. Chicken embryos aged E11 were injected with a single dose of caffeine (30 mg/kg) in the air chamber. Retinas were dissected on E15 for ex vivo neurochemical assays. Our results showed that [³H]-GABA uptake was dependent on Na⁺ and blocked at 4 °C or by NO-711 and caffeine. This decrease was observed after 60 min of [³H]-GABA uptake assay at E15, which is accompanied by an increase in [³H]-GABA release. Caffeine increased the protein levels of A₁R without altering ADORA1 mRNA and was devoid of effects on A_2AR density or ADORA2A mRNA levels. The decrease of GABA uptake promoted by caffeine was reverted by A₁R activation with N6-cyclohexyl adenosine (CHA) but not by A_2AR activation with CGS 21680. Caffeine exposure increased cAMP levels and GAT-1 protein levels, which was evenly expressed between E11-E15. As expected, we observed an increase of GABA containing amacrine cells and processes in the IPL, also, cAMP pathway blockage by H-89 decreased caffeine mediated [³H]-GABA uptake. Our data support the idea that chronic injection of caffeine alters GABA transport via A₁R during retinal development and that the cAMP/PKA pathway plays an important role in the regulation of GAT-1 function.