The clinical toxicology of caffeine: A review and case study

Common questions and misconceptions about caffeine supplementation: what does the scientific evidence really show?

Caffeine is a popular ergogenic aid that has a plethora of evidence highlighting its positive effects. A Google Scholar search using the keywords "caffeine" and "exercise" yields over 200,000 results, emphasizing the extensive research on this topic. However, despite the vast amount of available data, it is intriguing that uncertainties persist regarding the effectiveness and safety of caffeine. These include but are not limited to: 1. Does caffeine dehydrate you at rest? 2. Does caffeine dehydrate you during exercise? 3. Does caffeine promote the loss of body fat? 4. Does habitual caffeine consumption influence the performance response to acute caffeine supplementation? 5. Does caffeine affect upper vs. lower body performance/strength differently? 6. Is there a relationship between caffeine and depression? 7. Can too much caffeine kill you? 8. Are there sex differences regarding caffeine's effects? 9. Does caffeine work for everyone? 10. Does caffeine cause heart problems? 11. Does caffeine promote the loss of bone mineral? 12. Should pregnant women avoid caffeine? 13. Is caffeine addictive? 14. Does waiting 1.5-2.0 hours after waking to consume caffeine help you avoid the afternoon "crash?" To answer these questions, we performed an evidence-based scientific evaluation of the literature regarding caffeine supplementation.

Risperidone suppresses caffeine-induced hyperthermia and hyperactivity in rats

Caffeine, a methylxanthine alkaloid, works as a nonselective adenosine receptor antagonist. It is the most widely used psychostimulant drug worldwide. However, caffeine overdose can lead to acute intoxication, posing a clinical problem. Hyperthermia and hyperactivity are associated issues with acute caffeine intoxication; however, no definitive treatment exists. This study aimed to assess the ability of risperidone to attenuate caffeine-induced hyperthermia and hyperactivity while elucidating the unknown mechanisms of caffeine intoxication. The rats received intraperitoneal injections of saline, risperidone (0.25 mg/kg, 0.5 mg/kg), WAY-100635, ketanserin, haloperidol, sulpiride, or SCH 23390, 5 min after the administration of caffeine (25 mg/kg). Subcutaneous temperature and activity counts were measured using nano tag ® for up to 90 min. In vivo microdialysis was used to determine the effect of risperidone on caffeine-induced elevation of dopamine (DA), serotonin (5-HT), and noradrenaline (NA) concentrations in the anterior hypothalamus. Rats were injected with caffeine (25 mg/kg), followed by saline or risperidone (0.5 mg/kg) 5 min later. The levels of DA, 5-HT, and noradrenaline were measured every 15 min for up to 90 min after caffeine administration. Risperidone and 5-HT2A receptor antagonist ketanserin attenuated caffeine-induced hyperthermia and hyperactivity. Haloperidol and dopamine D1 antagonist SCH-23390 exacerbated hyperthermia without any effect on the hyperactivity. In the microdialysis study, risperidone treatment further attenuated caffeine-induced 5-HT elevation, but not DA and NA. Our results indicate that risperidone attenuates caffeine-induced hyperthermia and hyperactivity by blocking 5-HT2A receptor activity and may be potentially useful for treating caffeine intoxication.

Potential Application of Plant-Derived Compounds in Multiple Sclerosis Management

Multiple sclerosis (MS) is a chronic autoimmune disorder characterized by inflammation, demyelination, and neurodegeneration, resulting in significant disability and reduced quality of life. Current therapeutic strategies primarily target immune dysregulation, but limitations in efficacy and tolerability highlight the need for alternative treatments. Plant-derived compounds, including alkaloids, phenylpropanoids, and terpenoids, have demonstrated anti-inflammatory effects in both preclinical and clinical studies. By modulating immune responses and promoting neuroregeneration, these compounds offer potential as novel adjunctive therapies for MS. This review provides insights into the molecular and cellular basis of MS pathogenesis, emphasizing the role of inflammation in disease progression. It critically evaluates emerging evidence supporting the use of plant-derived compounds to attenuate inflammation and MS symptomology. In addition, we provide a comprehensive source of information detailing the known mechanisms of action and assessing the clinical potential of plant-derived compounds in the context of MS pathogenesis, with a focus on their anti-inflammatory and neuroprotective properties.

Antagonistic interaction between caffeine and ketamine in zebrafish: Implications for aquatic toxicity

The coexistence of caffeine (CF) and ketamine (KET) in surface waters across Asia has been widely reported. Previous studies have implied that CF and KET may share a mechanism of action. However, the combined toxicity of these two chemicals on aquatic organisms remains unclear at environmental levels, and the underlying mechanisms are not well understood. Here we demonstrate that KET antagonizes the adverse effects of CF on zebrafish larvae by modulating the gamma-aminobutyric acid (GABA)ergic synapse pathway. Specifically, KET (10-250 ng L-1) ameliorates the locomotor hyperactivity and impaired circadian rhythms in zebrafish larvae induced by 2 mg L-1 of CF, showing a dose-dependent relationship. Additionally, the developmental abnormalities in zebrafish larvae exposed to CF are mitigated by KET, with an incidence rate reduced from 26.7% to 6.7%. The competition between CF and KET for binding sites on the GABA-A receptor (in situ and in silico) elucidates the antagonistic interactions between the two chemicals. Following a seven-day recovery period, the adverse outcomes of CF exposure persist in the fish, whereas the changes observed in the CF + KET groups are significantly alleviated, especially with KET at 10 ng L-1. Based on these results, it is imperative to further assess the environmental risks associated with CF and KET co-pollution. This pilot study underscores the utility of systems toxicology approaches in estimating the combined toxicity of environmental chemicals on aquatic organisms. Moreover, the nighttime behavioral functions of fish could serve as a sensitive biomarker for evaluating the toxicity of psychoactive substances.

Caffeine consumption of medical students in Korea: amount and symptoms based on a 2023 survey

PURPOSE

To investigate the form and level of daily caffeine intake recommended above 400 mg in medical students expected to consume caffeinated beverages to enhance their performance.

METHODS

From May to June 2023, freshman through senior medical students at a medical school in Korea were administered a seven-item questionnaire designed to measure the amount of caffeine-containing foods consumed, the weekly interval between consumption, the reason for consumption, and the level of caffeine-induced symptoms experienced.

RESULTS

Out of 443 students, 361 responded (81.5%). The most commonly consumed caffeine beverages were coffee (79.2%), followed by soda (33.2%), tea (27.4%), chocolate (25.2%), and energy drinks (20.5%). The estimated (average±standard deviation) daily intake was estimated to 274.6±276.5 mg, and they consumed caffeine on an average of 4.25±2.26 days per week. Students who consumed 400 mg or more of caffeine daily consumed 19.9%. The primary motivation for caffeine intake was "to improve academic performance" (60.9%) and "preferred food" (51.8%). Among the responders, 98% of them replied they had symptoms that could be caused by caffeine, in order of palpitations (47.4%), frequent urination (42.9%), anxiety (27.1%), indigestion (17.5%), and excitement (17.5%). A total of 45.7% reported two symptoms, and 24.7% reported three or more.

CONCLUSION

Caffeinated beverage consumption was routine among current medical students, with 20% consuming more than the recommended daily amount. Most students experienced at least one caffeine-induced symptom, with two symptoms in half, suggesting the need for policy measures and warnings about caffeine-containing foods.

Enjoy or quit: impact of coffee on cardiac and metabolic health

Coffee is one of the most consumed beverages worldwide. The effects of coffee on the body are primarily attributed to its key active ingredient, caffeine, a methylxanthine derivative with stimulant effects. However, coffee contains over one hundred bioactive compounds apart from caffeine, such as phenolic compounds, chlorogenic acids, tannin, thiamin, spermidine, quinides, trigonelline, lignins, and minerals like potassium and magnesium, all of which may contribute to its effects on the body. Each of these compounds may have beneficial effects. A common misconception is that coffee consumption should be avoided, especially by those with cardiovascular problems. However, recent data support the safety of moderate habitual consumption of two to three cups of coffee per day. Furthermore, this moderate regular consumption is associated with reduced cardiovascular mortality, lower blood pressure, and improved metabolic state. Many recent studies report additional medical benefits associated with coffee consumption. In this article, we review recent literature on the cardiometabolic effects of regular coffee drinking, including its impact on cardiac arrhythmia, blood pressure, and glucose and lipid metabolism. To sum up the medical evidence in the literature, individuals who drink modest amounts of coffee should feel comfortable continuing to enjoy it, provided they do not experience adverse effects.

Development of a simple estimation method of serum caffeine concentration using a point-of-care test kit for urinary caffeine

PURPOSE

Serum caffeine concentration is an indicator of caffeine intoxication; however, it is difficult to measure it in most emergency departments. We developed a simple estimation method using a point-of-care test kit for urinary caffeine.

METHODS

Caffeine-spiked human serum (100, 50, 25, and 10 µg/mL) was diluted 10-, 20-, 50-, and 100-fold with phosphate-buffered saline and applied to the kit. After 5 min incubation, the kit was scanned by a flatbed scanner and the membrane image was processed with ImageJ.

RESULTS

When the 20-fold diluted serum was applied, serum samples with initial caffeine concentration ≤ 25 and ≥ 50 µg/mL were caffeine-negative and -positive, respectively. When the 100-fold diluted serum was applied, none of the caffeine-spiked serum samples gave positive results. Therefore, we proposed the following test procedure: (i) 20-fold diluted serum was initially tested and (ii) 100-fold diluted serum was additionally tested when the initial result was caffeine positive. Using this procedure, caffeine concentration is expected to be classified into three levels: ≤ 25, > 25- ≤ 100, and > 100 µg/mL, which almost correspond to no or mild, severe, and potentially fatal intoxication, respectively. The test procedure was validated using postmortem heart blood from two cases of fatal caffeine intoxication (caffeine concentration: 276 and 175 µg/mL) and two cases of other intoxication.

CONCLUSIONS

Our developed method using point-of-care urinary caffeine test kits enabled simple estimation of serum caffeine concentration.

Caffeine induces alveolar bone loss in rats submitted to orthodontic movement via activation of receptor activator of nuclear factor ҡB, receptor activator of nuclear factor ҡB ligand, and osteoprotegerin pathway

INTRODUCTION

Caffeine is a widely consumed substance with several effects on bone metabolism. This study aimed to investigate the effect of caffeine on the bone tissue of rats submitted to orthodontic movement.

METHODS

Twenty-five male Wistar rats underwent orthodontic movement (21 days) of the first permanent maxillary molars on the left side. The experimental group (caffeine; n = 13) and control group (n = 12) received caffeine and water, respectively, by gavage. Microcomputed tomography was performed to analyze orthodontic movement. Histologic analysis of the inflammatory infiltrate and osteoclast count by tartrate-resistant acid phosphatase were conducted. Maxilla tissue was evaluated for receptor activator of nuclear factor ҡB (RANK), RANK ligand (RANKL), and osteoprotegerin by immunohistochemistry.

RESULTS

Caffeine exhibited a lower bone volume/tissue volume ratio (78.09% ± 5.83%) than the control (86.84% ± 4.89%; P <0.05). Inflammatory infiltrate was increased in the caffeine group compared with the control group (P <0.05). A higher number of tartrate-resistant acid phosphatase-positive cells was observed in the caffeine (9.67 ± 1.73) than in the control group (2.66 ± 0.76; P <0.01). Immunoexpression of RANK and RANKL in the caffeine group was greater than the control (P <0.05).

CONCLUSIONS

The use of caffeine thermogenic induces alveolar bone loss in rats submitted to orthodontic movement via activation of RANK, RANKL, and osteoprotegerin signaling pathways.

Motor improvement in Parkinson's disease patients receiving caffeine adjuvants: A double-blind randomized controlled trial in Indonesia

Parkinson's disease (PD) manifests as a movement and brain function disorder characterized by symptoms such as resting tremors, rigidity, bradykinesia, and postural instability, leading to disability among patients. The use of psychostimulants such as caffeine has been associated with the improvement of motor symptoms in PD patients; however, studies regarding the effect of caffeine adjuvant therapy on motor function among PD patients in the Indonesian population are lacking. The aim of this study was to evaluate motor improvement as measured by the change in scores of the Movement Disorder Society - Unified Parkinson's Disease Rating Scale Part III (MDS-UPDRS-III) among PD patients receiving caffeine adjuvant. A double-blind randomized controlled trial (RCT) was conducted among PD patients at Dr. Soetomo General Academic Hospital and Universitas Airlangga Hospital, Surabaya, Indonesia, from April to August 2023. A total of 27 patients were enrolled and randomly assigned to an intervention (receiving caffeine adjuvant, n=15) and control group (receiving placebo, n=12). Motor improvement was measured using the UPDRS III score prior to intervention and three weeks after. The Chi-squared test was used to analyze the difference in UPDRS III scores between the two groups. Motor improvement, as demonstrated by a reduction in the UPDRS III score, was observed in patients receiving caffeine adjuvant compared to those receiving placebo (80.0% vs 16.7%; p=0.004). Regarding the safety profile, only four out of 15 (26.6%) patients treated with caffeine reported minor adverse events. These conditions improved over time during the intervention. None of the 12 patients in the placebo reported adverse events. This study provides valuable insights into the initial dosage of caffeine that improves motor function in PD patients with minimum adverse effects.

Death Due to Caffeine and Methamphetamine Toxicity: A Case Report

Caffeine (1,3,7-trimethylxanthine) is an over-the-counter psychostimulant that, when used in appropriate amounts, is generally considered safe. However, excessive use can cause various symptoms and, in severe cases, can even be life-threatening. A 34-year-old man with a reported history of psychiatric disorders was found unresponsive at his girlfriend's house and transported to an emergency department. He was presumed to have taken several caffeine pills and was pronounced dead approximately six hours later. There was no evidence of trauma or natural diseases at autopsy. Toxicology testing on hospital blood samples revealed toxic levels of caffeine and methamphetamine. After investigation of the circumstances surrounding the death and accounting for the autopsy and toxicology findings, the cause and manner of death were certified as combined caffeine and methamphetamine toxicity and accident, respectively. Lethal levels of caffeine have been reported when blood concentration exceeds 80 mg/L. Caution is needed to avoid excessive caffeine intake, especially when consumed in concentrated forms like tablets or powders. Caffeine should be used with care not only in cases of cardiovascular disease or genetic vulnerability but also for those with psychiatric disorders. Although deaths from caffeine are rare, they are consistently reported, necessitating attention and caution in its use.

TRPA1, TRPV1, and Caffeine: Pain and Analgesia

Caffeine (1,3,7-trimethylxanthine) is a naturally occurring methylxanthine that acts as a potent central nervous system stimulant found in more than 60 different plants and fruits. Although caffeinated beverages are widely and casually consumed, the application of caffeine beyond dietary levels as pharmacologic therapy has been recognized since the beginning of its recorded use. The analgesic and vasoactive properties of caffeine are well known, but the extent of their molecular basis remains an area of active research. There is existing evidence in the literature as to caffeine's effect on TRP channels, the role of caffeine in pain management and analgesia, as well as the role of TRP in pain and analgesia; however, there has yet to be a review focused on the interaction between caffeine and TRP channels. Although the influence of caffeine on TRP has been demonstrated in the lab and in animal models, there is a scarcity of data collected on a large scale as to the clinical utility of caffeine as a regulator of TRP. This review aims to prompt further molecular research to elucidate the specific ligand-host interaction between caffeine and TRP by validating caffeine as a regulator of transient receptor potential (TRP) channels-focusing on the transient receptor potential vanilloid 1 (TRPV1) receptor and transient receptor potential ankyrin 1 (TRPA1) receptor subtypes-and its application in areas of pain.

Effects of Different Caffeine Dosages on Maximal Physical Performance and Potential Side Effects in Low-Consumer Female Athletes: Morning vs. Evening Administration

While previous studies have explored a range of factors governing the optimal use of caffeine (CAF) in athletes, limited research has explored how time of day (TOD) affects the ergogenic effects of various CAF dosages on physical performance. This study aimed to increase knowledge about how different recommended CAF doses (3 mg/kg vs. 6 mg/kg) ingested at different TODs affected maximal high-intensity physical performance and the perception of potential side effects in female athletes. In this double-blind, randomized, and counterbalanced study, 15 low CAF consumer athletes (aged 18.3 ± 0.5 y) underwent six trials, including three testing conditions assessed across two TODs: one in the morning (08:00 a.m.) and one in the evening (06:00 p.m.). During each condition, the participants ingested either a placebo, 3 mg/kg CAF (CAF (3 mg)), or 6 mg/kg CAF (CAF (6 mg)) capsules 60 min before each test with an in-between washout period of at least 72 h. In each trial, the participants performed a countermovement jumps test (CMJ), a modified agility t test (MATT), a repeated sprint ability (RSA), a rating of perceived exertion (RPE), and finally, a CAF side effects questionnaire. Our findings indicate the absence of an ergogenic effect on CMJ, MAT, and RSA performance in the evening after administering CAF (3 mg) or CAF (6 mg) compared to a placebo. Likewise, when CAF was ingested in the morning, there was an improvement in these performances with both CAF (3 mg) and CAF (6 mg), with greater improvement observed after CAF (6 mg). Additionally, neither the CAF dosage nor the TOD had a significant effect on the RPE. The occurrence of side effects increased significantly after the evening ingestion of CAF, particularly with a moderate dose of CAF (6 mg). Our findings indicate that the effectiveness of CAF depends on the TOD and CAF dosage. When ingested in the morning, a moderate dose of CAF (6 mg), rather than CAF (3 mg), is more effective in improving short-term physical performance without affecting CAF side effects in female athletes. Nevertheless, when ingested in the evening, neither dose was sufficient to enhance short-term physical performance, and both dosages increased the incidence of CAF side effects, particularly at a moderate dose.

Coffee and mental disorders: How caffeine affects anxiety and depression

Caffeine, the main psychoactive component in coffee, has garnered significant attention for its potential impact on the most prevalent mental health conditions like anxiety and depression. This chapter comprehensively examines the neurobiological effects of caffeine, its influence on anxiety and depression, and relevant clinical studies. Caffeine exerts its psychostimulant effects primarily through antagonizing adenosine receptors, modulating neurotransmitter systems, and influencing intracellular calcium signaling in the brain. Caffeine exhibits dose-dependent effects. While moderate caffeine consumption is safe in healthy adults and may offer benefits for mental health, excessive intake is linked to adverse effects on neurological and psychiatric health and can aggravate symptoms, highlighting the importance of adjusting consumption patterns. High caffeine intake correlates with elevated anxiety levels, especially in individuals predisposed to anxiety disorders. However, the relationship between caffeine consumption and the risk of depression is intricate, with some studies suggesting a potential protective effect of moderate intake, while others find no significant association. Individual variations in caffeine metabolism, sensitivity, and genetic factors considerably impact responses to caffeine. The chapter also explores the therapeutic potential of caffeine as an adjunct treatment and outlines challenges and future research directions in elucidating caffeine's multifaceted role in mental health.

Coffee and Alzheimer's disease

Coffee, a universally consumed beverage, is known to contain thousands of bioactive constituents that have garnered interest due to their potential neuroprotective effects against various neurodegenerative disorders, including Alzheimer's disease (AD). Extensive research has been conducted on coffee constituents such as Caffeine, Trigonelline, Chlorogenic acid, and Caffeic acid, focusing on their neuroprotective properties. These compounds have potential to impact key mechanisms in AD development, including amyloidopathy, tauopathy, and neuroinflammation. Furthermore, apart from its neuroprotective effects, coffee consumption has been associated with anticancerogenic and anti-inflammatory effects, thereby enhancing its therapeutic potential. Studies suggest that moderate coffee intake, typically around two to three cups daily, could potentially contribute to mitigating AD progression and lowering the risk of related neurological disorders. This literature underscores the potential neuroprotective properties of coffee compounds, which usually perform their neuronal protective effects via modulating nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), nuclear factor erythroid-derived 2-like 2 (Nrf2), interleukins, tumor necrosis factor-alpha (TNF-α), and many other molecules.

Caffeine and Purine Derivatives: A Comprehensive Review on the Chemistry, Biosynthetic Pathways, Synthesis-Related Reactions, Biomedical Prospectives and Clinical Applications

Caffeine and purine derivatives represent interesting chemical moieties, which show various biological activities. Caffeine is an alkaloid that belongs to the family of methylxanthine alkaloids and it is present in food, beverages, and drugs. Coffee, tea, and some other beverages are a major source of caffeine in the human diet. Caffeine can be extracted from tea or coffee using hot water with dichloromethane or chloroform and the leftover is known as decaffeinated coffee or tea. Caffeine and its derivatives were synthesized via different procedures on small and large scales. It competitively antagonizes the adenosine receptors (ARs), which are G protein-coupled receptors largely distributed in the human body, including the heart, vessels, brain, and kidneys. Recently, many reports showed the effect of caffeine derivatives in the treatment of many diseases such as Alzheimer's, asthma, parkinsonism, and cancer. Also, it is used as an antioxidant, anti-inflammatory, analgesic, and hypocholesterolemic agent. The present review article discusses the synthesis, reactivity, and biological and pharmacological properties of caffeine and its derivatives. The biosynthesis and biotransformation of caffeine in coffee and tea leaves and the human body were summarized in the review.

Impact of coffee and its bioactive compounds on the risks of type 2 diabetes and its complications: A comprehensive review

BACKGROUND

Coffee beans have a long history of use as traditional medicine by various indigenous people. Recent focus has been given to the health benefits of coffee beans and its bioactive compounds. Research on the bioactivities, applications, and effects of processing methods on coffee beans' phytochemical composition and activities has been conducted extensively. The current review attempts to provide an update on the biological effects of coffee on type 2 diabetes (T2D) and its comorbidities.

METHODS

Comprehensive literature search was carried out on peer-reviewed published data on biological activities of coffee on in vitro, in vivo and epidemiological research results published from January 2015 to December 2022, using online databases such as PubMed, Google Scholar and ScienceDirect for our searches.

RESULTS

The main findings were: firstly, coffee may contribute to the prevention of oxidative stress and T2D-related illnesses such as cardiovascular disease, retinopathy, obesity, and metabolic syndrome; secondly, consuming up to 400 mg/day (1-4 cups per day) of coffee is associated with lower risks of T2D; thirdly, caffeine consumed between 0.5 and 4 h before a meal may inhibit acute metabolic rate; and finally, both caffeinated and decaffeinated coffee are associated with reducing the risks of T2D.

CONCLUSION

Available evidence indicates that long-term consumption of coffee is associated with decreased risk of T2D and its complications as well as decreased body weight. This has been attributed to the consumption of coffee with the abundance of bioactive chemicals.

Design and Biocompatibility of Biodegradable Poly(octamethylene suberate) Nanoparticles to Treat Skin Diseases

Biodegradable aliphatic polyester formulations as carriers for topical drug delivery show the potential to encapsulate structurally different therapeutic compounds. Poly(octamethylene suberate) (POS) nanoparticles (POS-NPs) were used as a matrix to encapsulate four therapeutic molecules used to treat skin disorders: caffeine (CF), quercetin (QR), hydrocortisone (HC), and adapalene (AD). Hydrophobicity and chemical structure of bioactive compounds (BCs) influenced the physicochemical stability of drug-loaded nanoparticles. The particle size of drug-loaded nanoparticles was between 254.9 nm for the CF-POS-NP and 1291.3 for QR-POS-NP. Particles had a negative charge from -27.6 mV (QR) to -49.2 mV (HC). Drug loading content for all BC-POS-NPs varies between 36.11 ± 1.48% (CF-POS-NP) and 66.66 ± 4.87% (AD-POS-NP), and their entrapment efficiency is relatively high (28.30 ± 1.81% and 99.95 ± 0.04%, respectively). Calorimetric analysis showed the appearance of polymorphism for AD- and HC-loaded systems and the drug's complete solubilisation into all nanoparticle formulations. FTIR and NMR spectra showed apparent drug incorporation into the polymer matrix of NPs. The encapsulation of BCs enhanced the antioxidative effect. The prepared POS nanoparticles' cytotoxicity was studied using two dermal cell lines, keratinocyte (HaCaT) cells and fibroblasts (HDFn). The nanoparticle cytotoxic effect was more substantial on HaCaT cell lines. A reconstructed human epidermis (RHE) was successfully used to investigate the penetration of polymeric NPs. Based on permeation and histology studies, HC-POS-NPs and CF-POS-NPs were shown not to be suitable for dermal applications with the explored drug concentrations. AD presents a high permeation rate and no toxic impact on RHE.

Caffeine Concentrations in Human Milk Donated to a Human Milk Bank in Japan

BACKGROUND

Human milk banks have been established to provide human milk to preterm infants who are unable to obtain milk from their mothers. Donor screening methods vary, and prospective donors are commonly screened for drug and recreational substance use through behavioral screening. Although the risk of illegal drug consumption in Japan is extremely low, caffeine may be consumed unknowingly and can be found in human milk. To date, only a few reports have been conducted on the concentration of caffeine in donor milk.

RESEARCH AIM

This study aimed to examine the pre-pasteurization levels of caffeine in human milk donated to a milk bank in Japan.

METHODS

This was a cross-sectional, observational study of caffeine concentrations in human milk donated to a human milk bank in Japan. Caffeine concentration in the donor milk was measured using high-performance liquid chromatography.

RESULTS

Caffeine was detected in 70% of the donor milk samples (N = 350). The median (range) of caffeine concentration was 0.46 [< 0.10, 7.54] mg/L, and 64.0% of the samples had less than 1 mg/L of caffeine. The caffeine concentration varied widely among as well as within individuals.

CONCLUSION

The average caffeine concentration in Japanese donor milk samples was higher than that previously reported in samples from Spain, but the range was similar. Donors should be informed that caffeine intake should be within a moderate range, to further increase the safety of donor milk.

Clinical Evaluation of a Novel, Patented Green Coffee Bean Extract (GCB70®), Enriched in 70% Chlorogenic Acid, in Overweight Individuals

OBJECTIVE

Obesity and overweight are challenging health problems of the millennium that lead to diabetes, hypertension, dyslipidemia, nonalcoholic fatty liver disease (NAFLD), and atherosclerosis. Green coffee bean exhibited significant promise in healthy weight management, potentiating glucose-insulin sensitization and supporting liver health. The safety and efficacy of a novel, patented water-soluble green coffee bean extract (GCB70® enriched in 70% total chlorogenic acid and <1% caffeine) was investigated in 105 participants for 12 consecutive weeks. An institutional review board and Drugs Controller General (India) (DCGI) approvals were obtained, and the study was registered at ClinicalTrials.gov.

METHOD

Body weight, body mass index (BMI), waist circumference, lipid profile, plasma leptin, glycosylated hemoglobin (HbA1c), and total blood chemistry were assessed over a period of 12 weeks of treatment. Safety was affirmed.

RESULTS

GCB70 (500 mg BID) supplementation significantly reduced body weight (approximately 6%; p = 0.000**) in approximately 97% of the study population. About a 5.65% statistically significant reduction (p = 0.000**) in BMI was observed in 96% of the study volunteers. Waist circumference was significantly reduced by 6.77% and 6.62% in 98% of the male and female participants, respectively. Plasma leptin levels decreased by 13.6% in 99% of the study population as compared to the baseline value. Upon completion of 12 weeks' treatment, fasting glucose levels decreased by 13.05% (p = 0.000**) in 79% of the study population. There was a statistically significant decrease in HbA1c levels in both male and female participants (p = 0.000**), while 86.7% of the study participants showed a statistically significant decrease in thyroid-stimulating hormone (TSH) levels (p = 0.000**). The mean decrease in TSH levels on completion of the treatment was 14.07% in the study population as compared to baseline levels. Total blood chemistry analysis exhibited broad-spectrum safety.

CONCLUSIONS

This investigation demonstrated that GCB70 is safe and efficacious in healthy weight management.

Energy drinks in Tamale: Understanding youth perceptions, consumption patterns, and related factors

Energy drinks (EDs) have become a popular choice for young people seeking physical and cognitive boosts, with ingredients such as caffeine, taurine, and B vitamins aimed at improving academic, athletic, and alertness levels. However, the popularity of these drinks is also driven by low prices, taste, brand loyalty, and gendered marketing, with boys being more likely to consume them. Despite the supposed benefits, EDs have been associated with high-risk behaviours, deaths, and adverse health effects, especially those related to cardiovascular risk. Meanwhile, in Ghana, the use of EDs is on the rise. Hence, this study aimed to examine the prevalence and consumption patterns, perceptions, and factors associated with ED consumption among the youth of the Tamale Metropolis. The study was cross-sectional, consisting of 541 participants. The group consisted of 340 males and 201 females, between the ages of 15 and 45. A questionnaire was utilized to obtain data on the respondents' consumption patterns and perceptions of EDs, as well as their socio-demographic characteristics. The results of the study indicated that a large percentage of the respondents, 98.7%, had consumed EDs before, while 78.7% currently consume them. Respondents believed that EDs provided additional energy (81.00%) and reduced stress (62.30%). However, they also perceived side effects such as insomnia (60.60%) and restlessness (51.40%). Also, the highest proportion of respondents (83.4%) had poor knowledge of EDs. They were unaware of the classification of EDs and their ingredients, side effects, and benefits. Age, marital status, level of education, work intensity, EDs served at gatherings, and knowledge of EDs was significantly associated with ED consumption (p < .05). Consumption was higher among those aged 26 to 35 years, singles, individuals with no formal education, and those with high work intensity. The high consumption was also associated with low knowledge levels. It is recommended that public health and nutrition professionals engage in further advocacy efforts to improve the youth's knowledge and perception of EDs in a positive manner. In addition, lawmakers should use legislation to influence consumption rates and safeguard the health of consumers.

Caffeine intake in adults with cardiovascular diseases; A cross-sectional study

Background: Caffeine in the safe dose range has been associated with a reduction in the risk of chronic diseases. There is evidence that caffeine intake has both protective and negative effects on cardiovascular diseases. Aim: This study aimed to investigate caffeine intake in cardiovascular patients. Methods: The study sample was selected from individuals who applied to the Cardiology policlinic of Tekirdağ Namık Kemal University Hospital. A questionnaire was applied using face-to-face interview method to determine their demographic information, nutritional status and anthropometric measurements. Moreover, the nutritional status of the participants was determined by the Food Frequency Questionnaire and the type of cardiovascular disease was determined by a physician. The blood parameters of the sample for the last three months were questioned. The sample has been ninety people of whom fifty cardiovascular diseases (CVDs) were diagnosed and forty were non-diagnosed (ND). Results: The mean age of individuals (n = 90) was 43.2 ± 14.4. The BMI and waist circumference of the CVDs group were statistically significantly higher than the ND group (p < 0.001). While the total caffeine consumption of the ND group was 209.34 ± 143.85 mg/day, consumption of the CVDs group was 209.99 ± 196.76 mg/day. LDL cholesterol and total cholesterol did not show statistically significant difference between the two groups. However, HDL cholesterol was significantly higher in the ND group (p ≤ 0.001). Conclusion: Present results show that daily caffeine consumption may partially affect blood parameters associated with cardiovascular diseases, especially in the presence of coronary artery disease.

Optimizing Short-Term Maximal Exercise Performance: The Superior Efficacy of a 6 mg/kg Caffeine Dose over 3 or 9 mg/kg in Young Female Team-Sports Athletes

Caffeine (CAF) is among the most extensively researched dietary supplements worldwide. However, little is known about the relationship between dosage and performance enhancement, particularly in female athletes. This study aimed to explore the effects of three different CAF dosages (3 mg·kg-1, 6 mg·kg-1, and 9 mg·kg-1) on high-intensity exercise and the prevalence of undesirable side effects related to these doses among female team-sports athletes. All participants (n = 16; age: 16.9 ± 0.6 y; height: 1.64 ± 0.1 m; BMI: 21.6 ± 1.5 kg·m-2) were mild CAF consumers. This study had a randomized, crossover, double-blind design in which each athlete performed four experimental sessions after ingesting either a placebo (PLAC), 3 mg·kg-1 CAF (CAF-3), 6 mg·kg-1 CAF (CAF-6), or 9 mg·kg-1 of CAF (CAF-9), with an in-between washout period of at least 72 h. In each experimental session, 60 min after ingesting the capsules, participants underwent a countermovement jumps test (CMJ), modified agility t-test (MATT), repeated sprint ability (RSA) test, and a rating of perceived exertion (RPE) and completed the CAF side effects questionnaire. Our findings revealed that in comparison to the PLAC condition, the MATT, RSAmean, and RSAbest performances were significantly greater only under the CAF-6 and CAF-9 conditions. Although the RPE scores remained unchanged, CMJ performance improved under all CAF conditions. All the performance outcomes were better for the CAF-6 and CAF-9 conditions than for the CAF-3 condition. Notably, no significant difference between the CAF-6 and CAF-9 conditions was observed for any of these parameters despite the highest incidence of side effects being noted for the CAF-9 condition. In summary, our findings highlight the recommendation for a moderate CAF dosage of 6 mg·kg-1 rather than 3 or 9 mg·kg-1 to enhance various aspects of short-term maximal performance in mild-CAF-consumer female team-sports athletes while mitigating the occurrence of adverse CAF side effects.

Caffeine supplementation improves the cognitive abilities and shooting performance of elite e-sports players: a crossover trial

We explored the effect of 3 mg/kg of caffeine supplementation on the cognitive ability and shooting performance of elite e-sports players. Nine e-sports players who had received professional training in e-sports and had won at least eighth place in national-level e-sports shooting competitions. After performing three to five familiarization tests, we employed a single blind, randomized crossover design to divide participants into caffeine trial (CAF) and placebo trial (PL). The CAF trial took capsules with 3 mg/kg of caffeine, whereas the PL trial took a placebo capsule. After a one-hour rest, the Stroop task, the visual search ability test, and the shooting ability test were conducted. The CAF trial's performance in the Stroop task in terms of congruent condition (P = 0.023) and visual search reaction time with 20 items (P = 0.004) was significantly superior to those of the PL trial. In the shooting test, the CAF trial's kill ratio (P = 0.020) and hit accuracy (P = 0.008) were significantly higher, and the average time to target (P = 0.001) was significantly shorter than those of the PL trial. Caffeine supplementation significantly improves e-sports players' reaction times and shooting performance.

Targeting Alzheimer's Disease: Evaluating the Efficacy of C-1 Functionalized N-Aryl-Tetrahydroisoquinolines as Cholinergic Enzyme Inhibitors and Promising Therapeutic Candidates

We have synthesized 22 C-1 functionalized-N-aryl-1,2,3,4-tetrahydroisoquinoline derivatives showing biological activities towards cholinergic enzymes. Synthesis was performed using visible-light-promoted photo-redox chemistry, starting from a common intermediate, and the application of this synthetic methodology drastically simplified synthetic routes and purification of desired compounds. All synthesized derivates were divided into four groups based on the substituents in the C-1 position, and their inhibition potencies towards two cholinergic enzymes, acetyl- and butyrylcholinesterase were evaluated. Most potent derivatives were selected, and kinetic analysis was further carried out to obtain insights into the mechanisms of inhibition of these two enzymes. Further validation of the mode of inhibition of cholinergic enzymes by the two most potent THIQ compounds, 3c and 3i, was performed using fluorescence-quenching titration studies. Molecular docking studies further confirmed the proposed mechanism of enzymes' inhibition. In silico predictions of physicochemical properties, pharmacokinetics, drug-likeness, and medicinal chemistry friendliness of the selected most potent derivatives were performed using Swiss ADME tool. This was followed by UPLC-assisted log P determination and in vitro BBB permeability studies performed in order to assess the potential of the synthesized compounds to pass the BBB.

Naringin corrects renal failure related to Lesch-Nyhan disease in a rat model via NOS-cAMP-PKA and BDNF/TrkB pathways

This study explored the effect of naringin (NAR) on HGPRT1 deficiency and hyperuricemia through NOS-cAMP-PKA and BDNF/TrkB signaling pathways induced by caffeine (CAF) and KBrO3 in a rat model. Sixty-three adult male albino rats were randomly assigned into nine (n = 7) groups. Group I: control animals, Group II was treated with 100 mg/kg KBrO3 , Group III was treated with 250 mg/kg CAF, Group IV was treated with 100 mg/kg KBrO3  + 250 mg/kg CAF, Group V was administered with 100 mg/kg KBrO3  + 100 mg/kg haloperidol, Group VI was administered with 100 mg/kg KBrO3  + 50 mg/kg NAR, Group VII was administered with 500 mg/kg CAF + 50 mg/kg NAR, and Group VIII was administered with 100 mg/kg KBrO3  + 250 mg/kg CAF + 50 mg/kg NAR. Finally, group IX was treated with 50 mg/kg NAR. The exposure of rats to KBrO3 and CAF for 21 days induced renal dysfunction linked with Lesch-Nyhan disease. NAR obliterated renal dysfunction linked with Lesch-Nyhan disease by decreasing uric acid, renal malondialdehyde level, inhibiting the activities of arginase, and phosphodiesterase-51 (PDE-51) with corresponding upregulation of brain derived-neurotrophic factor and its receptor (BDNF-TrkB), Bcl11b, HGPRT1, and DARPP-32. Additionally, renal failure related to Lesch-Nyhan disease was remarkably corrected by NAR as shown by the reduced activities of AChE and enzymes of ATP hydrolysis (ATPase, AMPase, and ADA) with affiliated increase in the NO level. This study therefore validates NAR as nontoxic and effective chemotherapy against kidney-related Lesch-Nyhan disease by mitigating effects of toxic food additives and enzymes of ATP-hydrolysis via NOS-cAMP-PKA and BDNF/TrkB signaling pathways.

Current therapeutic targets and multifaceted physiological impacts of caffeine

Caffeine, which shares consubstantial structural similarity with purine adenosine, has been demonstrated as a nonselective adenosine receptor antagonist for eliciting most of the biological functions at physiologically relevant dosages. Accumulating evidence supports caffeine's beneficial effects against different disorders, such as total cardiovascular diseases and type 2 diabetes. Conversely, paradoxical effects are also linked to caffeine ingestion in humans including hypertension-hypotension and tachycardia-bradycardia. These observations suggest the association of caffeine action with its ingested concentration and/or concurrent interaction with preferential molecular targets to direct explicit events in the human body. Thus, a coherent analysis of the functional targets of caffeine, relevant to normal physiology, and disease pathophysiology, is required to understand the pharmacology of caffeine. This review provides a broad overview of the experimentally validated targets of caffeine, particularly those of therapeutic interest, and the impacts of caffeine on organ-specific physiology and pathophysiology. Overall, the available empirical and epidemiological evidence supports the dose-dependent functional activities of caffeine and advocates for further studies to get insights into the caffeine-induced changes under specific conditions, such as asthma, DNA repair, and cancer, in view of its therapeutic applications.

Legal Performance-enhancing Drugs Alter Course and Treatment of Rhabdomyolysis-induced Acute Kidney Injury

INTRODUCTION

Rhabdomyolysis-induced acute kidney injury (RIAKI) can interrupt physical training and increase mortality in injured warfighters. The legal performance-enhancing drugs caffeine and ibuprofen, which can cause renal injury, are widely used by service members. Whether caffeine or ibuprofen affects RIAKI is unknown. Cilastatin treatment was recently identified as an experimental treatment to prevent RIAKI at injury. To determine potential interacting factors in RIAKI treatment, we test the hypothesis that caffeine and ibuprofen worsen RIAKI and interfere with treatment.

MATERIALS AND METHODS

In mice, RIAKI was induced by glycerol intramuscular injection. Simultaneously, mice received caffeine (3 mg/kg), ibuprofen (10 mg/kg), or vehicle. A second cohort received volume resuscitation (PlasmaLyte, 20 mL/kg) in addition to caffeine or ibuprofen. In a third cohort, cilastatin (200 mg/kg) was administered concurrently with drug and glycerol administration. Glomerular filtration rate (GFR), blood urea nitrogen (BUN), urine output (UOP), renal pathology, and renal immunofluorescence for kidney injury molecule 1 were quantified after 24 hours.

RESULTS

Caffeine did not worsen RIAKI; although BUN was modestly increased by caffeine administration, 24-hour GFR, UOP, and renal histopathology were similar between vehicle-treated, caffeine-treated, and caffeine + PlasmaLyte-treated mice. Ibuprofen administration greatly worsened RIAKI (GFR 14.3 ± 19.5 vs. 577.4 ± 454.6 µL/min/100 g in control, UOP 0.5 ± 0.4 in ibuprofen-treated mice vs. 2.7 ± 1.7 mL/24 h in control, and BUN 264 ± 201 in ibuprofen-treated mice vs. 66 ± 21 mg/dL in control, P < .05 for all); PlasmaLyte treatment did not reverse this effect. Cilastatin with or without PlasmaLyte did not reverse the deleterious effect of ibuprofen in RIAKI.

CONCLUSIONS

Caffeine does not worsen RIAKI. The widely used performance-enhancing drug ibuprofen greatly worsens RIAKI in mice. Standard or experimental treatment of RIAKI including the addition of cilastatin to standard resuscitation is ineffective in mice with RIAKI exacerbated by ibuprofen. These findings may have clinical implications for the current therapy of RIAKI and for translational studies of novel treatment.

Evaluation of subchronic toxicity of the compound of diphenhydramine hydrochloride and caffeine after 28 days of repeated oral administration in Sprague-Dawley rats and beagle dogs

This study was designed to evaluate the subchronic toxicity of the compound of diphenhydramine hydrochloride (DH) and caffeine in Sprague-Dawley (SD) rats and beagle dogs. A total of 180 SD rats (15/sex/group) were randomly divided into the compound low-, medium- and high-dose groups (51, 102, 204 mg/kg), DH group (60 mg/kg), caffeine group (144 mg/kg) and the vehicle control group. Sixty beagle dogs (5/sex/group) were randomly divided into the compound low-, medium- and high-dose groups (male: 14.20, 28.30, 56.60 mg/kg, female: 5.66, 14.20, 28.30 mg/kg), DH group (male: 16.60 mg/kg, female: 8.30 mg/kg), caffeine group (male: 40.00 mg/kg, female: 20.00 mg/kg) and the vehicle control group. Rats and dogs were given continuous oral administration for 28 days following a 28-day recovery period. The adverse effects of the compound on rats and beagle dogs mainly included anorexia and liver function impairment. Most adverse effects induced by administration were reversible. Under the experimental conditions, the no-observed-adverse-effect level (NOAEL) of the compound of DH and caffeine was 51 mg/kg/day for SD rats and 28.30 mg/kg/day (male) and 5.66 mg/kg/day (female) for beagle dogs.

Serum Caffeine Concentration at the Time of Traumatic Brain Injury and Its Long-Term Clinical Outcomes

Caffeine is one of the most widely consumed psychoactive drugs in the general population. It has a neuroprotective effect in degenerative neurological disorders; however, the association between caffeine and traumatic brain injury (TBI) outcomes is contradictory. The objective of this study was to evaluate the association between serum caffeine concentration at the time of injury and long-term functional outcomes of patients with TBI visiting the emergency department (ED). This was a prospective multi-center cohort study including adult patients with intracranial injury confirmed by radiological examination, who visited five participating EDs within 72 h after TBI. The main exposure was the serum caffeine level within 4 h after injury, and the study outcome was a favorable functional recovery at 6 months after injury. Multi-variable logistic regression analysis adjusted for potential confounders was performed to calculate adjusted odds ratios (AORs) with 95% confidence intervals (CIs). Among the 334 study participants, caffeine was not detected in 102 patients (30.5 %). In patients with identifiable caffeine level, serum caffeine level was categorized into tercile groups; low (0.01-0.58 μg/mL), intermediate (0.59-1.66 μg/mL), and high (1.67-10.00 μg/mL). The proportions of patients with a 6-month favorable functional recovery were 56.9% in the no-caffeine group, 79.2% in the low-caffeine group, 75.3% in the intermediate-caffeine group, and 66.7% in the high-caffeine group (p = 0.006). In multi-variable logistic regression analysis, the low- and intermediate-caffeine groups were significantly associated with a higher probability of 6-month favorable functional recovery compared with the no-caffeine group [AORs (95% CI): 2.82 (1.32-6.02) and 2.18 (1.06-4.47], respectively. This study showed a significant association between a serum caffeine concentration of 0.01 to 1.66 μg/mL and good functional recovery at 6 months after injury compared with the no-caffeine group of patients with TBI with intracranial injury. These results suggest the possibility of using serum caffeine level as a potential biomarker for TBI outcome prediction and of using caffeine as a therapeutic agent in the clinical care of patients with TBI.

Coffee Consumption Behavior in Young Adults: Exploring Motivations, Frequencies, and Reporting Adverse Effects and Withdrawal Symptoms

Background

Coffee consumption by young people has increased dramatically over the last decades as there are substantial evidence of the physiological, cognitive, and emotional effects of coffee consumption. To reduce the risk of consuming related harm, it is necessary to understand the consumer's motivation for its use.

Objective

This study aimed to investigate coffee consumption behavior in young adults, assess the type of coffee consumption, explore motivation, document adverse effects and withdrawal symptoms of coffee intake.

Methods

A sample of 923 young adults were recruited voluntarily to complete a set of measures examining motivations, adverse effects, and withdrawal symptoms of coffee intake. Logistic regression analysis was performed to determine the association between coffee consumption and all independent variables. A p-value of 0.005 was considered as statistically significant.

Results

The results indicate that more than half of the participants consumed coffee. Coffee consumers were more like to be male, young adults, unmarried, poor sleep pattern (3-5 hours), and smokers. Main motivations of coffee intake were those related to reinforcing effects. The prevalence of dripper coffee consumption (85.59%) was observed to be highest with 20.1% participants consuming coffee in 2-3 times per day. Participants experienced restlessness, shaky, excited, difficulty in falling sleep, and fast heart beat as adverse effects of coffee consumption. Withdrawal symptoms such as headache, mood change, and tiredness were also noticed after consuming a high amount of coffee. Gender (p < 0.005), age (p < 0.003), family income (p < 0.004), BMI (p < 0.002) and sleeping pattern (p < 0.005) were found important variables associated with coffee intake.

Conclusion

The association reported in this study may allow for the implementation of appropriate strategies to address behaviors towards excessive coffee consumption and its link to an increased risk of poor health.

Intake of caffeine containing sugar diet remodels gut microbiota and perturbs Drosophila melanogaster immunity and lifespan

The diet-microbiome-immunity axis is one among the many arms that draw up the "we are what we intake" proclamation. As such, studies on the effect of food and beverage intake on the gut environment and microbiome and on modulating immunological responses and the host's susceptibility to pathogens are on the rise. A typical accompaniment in different sustenance we consume on daily basis is the trimethylxanthine alkaloid caffeine. Being a chief component in our regular aliment, a better understanding of the effect of caffeine containing food and beverages on our gut-microbiome-immunity axis and henceforth on our health is much needed. In this study, we shed more light on the effect of oral consumption of caffeine supplemented sugar diet on the gut environment, specifically on the gut microbiota, innate immunity and host susceptibility to pathogens using the Drosophila melanogaster model organism. Our findings reveal that the oral intake of a dose-specific caffeine containing sucrose/agarose sugar diet causes a significant alteration within the fly gut milieu demarcated by microbial dysbiosis and an elevation in the production of reactive oxygen species and expression of immune-deficiency (Imd) pathway-dependent antimicrobial peptide genes. The oral intake of caffeine containing sucrose/agarose sugar diet also renders the flies more susceptible to bacterial infection and shortens their lifespan in both infection and non-infection settings. Our findings set forth additional insight into the potentiality of diet to alter the gut milieu and highlight the importance of dietary control on health.

Over the Counter Supplements for Memory: A Review of Available Evidence

In 2021, the Global Brain Health Supplement Industry Market size was valued at US$7.6 billion. It is predicted to increase to US$15.59 billion by 2030. Memory and its enhancement are a segment of the market that comprised the highest global revenue share in 2021. In the USA alone, dietary supplement sales reached US$18 billion in 2018. The US Food and Drug Administration (FDA) does not have the authority to approve dietary supplements' safety, effectiveness, or labeling before products go on the market. The FDA often does not even review supplements before they go to market. Supplement manufacturers are thus responsible for ensuring their products are safe and that their claims are truthful. An extensive review of current supplements on the market was performed by surveying memory products for sale at local and national pharmacies and grocery stores. A list of 103 supplements was compiled and the ingredients in these memory supplements were reviewed. The 18 most common ingredients in these supplements were identified. Each of the supplements included at least one of the 18 most common ingredients. Scientific data relative to these ingredients and their effect on memory was searched using PubMed and Cochrane library databases. Currently, there is no compelling evidence for use of apoaequorin, coenzyme Q10, coffee extracts, L-theanine, omega-3 fatty acids, vitamin B6, vitamin B9, or vitamin B12 supplementation for memory. On the other hand, there is some current evidence for memory benefit from supplementation with ashwagandha, choline, curcumin, ginger, Lion's Mane, polyphenols, phosphatidylserine, and turmeric. There are current studies with mixed results regarding the benefit of carnitine, gingko biloba, Huperzine A, vitamin D, and vitamin E supplementation for memory. Dietary supplements geared toward improving cognition are a billion-dollar industry that continues to grow despite lacking a solid scientific foundation for their marketing claims. More rigorous studies are needed relative to the long-term use of these supplements in homogenous populations with standardized measurements of cognition. Health care providers need to be aware of any and all supplements their older adult patients may be consuming and be educated about their side effects and interactions with prescription medications. Lastly, the FDA needs to take an active position relative to monitoring marketed supplements regarding safety, purity and claims of efficacy.

Clinical Neurobiology of Sleep and Wakefulness

OBJECTIVE

This article focuses on novel neuronal mechanisms of sleep and wakefulness and relates basic science developments with potential translational implications in circadian neurobiology, pharmacology, behavioral factors, and the recently integrated potential pathways of sleep-related motor inhibition.

LATEST DEVELOPMENTS

During the past decade, remarkable advances in the molecular biology of sleep and wakefulness have taken place, opening a promising path for the understanding of clinical sleep disorders. Newly gained insights include the role of astrocytes in sleep brain homeostasis through the glymphatic system, the promotion of memory consolidation during states of reduced cholinergic activity during slow wave sleep, and the differential functions of melatonin receptors involving regulation of both circadian rhythm and sleep initiation. Ongoing investigations exploring sleep and circadian rhythm disruptions are beginning to unlock pathophysiologic aspects of neurologic, psychiatric, and medical disorders.

ESSENTIAL POINTS

An understanding of sleep and circadian neurobiology provides coherent and biologically credible approaches to treatments, including the identification of potential targets for neuromodulation.

Caffeine Consumption and Its Potential Health Effects on Saudi Adolescents in Jazan

Background Caffeine is the most popular product consumed globally in different types and amounts by various age groups. This study aimed to identify caffeine consumption patterns among adolescents in Jazan and explore related health effects. Methodology A cross-sectional study was conducted in Jazan on adolescents between 12 and 18 years of age. The consumption of coffee and caffeinated products and their potential health effects were evaluated using a self-reported online questionnaire. The data were analyzed using software for descriptive and inferential statistics. Results A total of 718 participants were enrolled in this study, with the age group of 16-18 years constituting the highest percentage (48.9%). Nearly 94% of the participants consumed coffee or caffeinated products, with 57% consuming the products infrequently. About 6.6% consumed coffee or caffeinated products more than three times daily, and about half of the participants used medium-sized cups. The most consumed type of caffeinated beverage was Arabic coffee, followed by tea, soft drinks, and Nescafe. Education level and age group showed a significant correlation with consumption patterns. The most common health effects of caffeine consumption were headaches, irregular sleep, and nausea, which were statistically related to age group, gender, and comorbid conditions. Conclusions Consumption of coffee and caffeinated beverages was relatively high among adolescents in this study. Further research on the habits of Saudi adolescent consumers, particularly across different areas of the country, is required.

Caffeine intoxication as a result of excessive consumption of bottled coffee products: a case report

Objectives: Most cases of caffeine intoxication result from the excessive intake of over-the-counter drugs and energy drinks. However, few cases of caffeine intoxication due to the excessive consumption of bottled coffee products have been reported. Herein, we present a case report of caffeine intoxication. Patient: A 39-year-old man experienced numbness and weakness in the extremities for three nights over five days. Results: Blood tests revealed hypophosphatemia and low 25-OH vitamin D concentration. The symptoms disappeared the next day without any additional treatment. A lifestyle interview revealed that he regularly consumed bottled coffee like it was water and had approximately 1 L of it from evening to night. He was diagnosed with weakness in the extremities due to hypophosphatemia caused by caffeine intoxication. Upon investigating some bottled coffee products, we found that only a few of them had labels disclosing caffeine content and warnings of the risks of excessive caffeine intake. Conclusion: We encountered a case of caffeine intoxication via coffee. Although rare in the past, caffeine intoxication might increase owing to the widespread use of bottled coffee products. The caffeine content of coffee products should be indicated on labels to warn consumers.

Toxicology of pharmaceutical and nutritional longevity compounds

Aging is the most prominent risk factor for many diseases, which is considered to be a complicated biological process. The rate of aging depends on the effectiveness of important mechanisms such as the protection of DNA from free radicals, which protects the structural and functional integrity of cells and tissues. In any organism, not all organs may age at the same rate. Slowing down primary aging and reaching maximum lifespan is the most basic necessity. In this process, it may be possible to slow down or stabilise some diseases by using the compounds for both dietary and pharmacological purposes. Natural compounds with antioxidant and anti-inflammatory effects, mostly plant-based nutraceuticals, are preferred in the treatment of age-related chronic diseases and can also be used for other diseases. An increasing number of long-term studies on synthetic and natural compounds aim to elucidate preclinically and clinically the mechanisms underlying being healthy and prolongation of life. To delay age-related diseases and prolong the lifespan, it is necessary to take these compounds with diet or pharmaceuticals, along with detailed toxicological results. In this review, the most promising and utilised compounds will be highlighted and it will be discussed whether they have toxic effects in short/long-term use, although they are thought to be used safely.

Experimental arena size alters larval zebrafish photolocomotor behaviors and influences bioactivity responses to a model neurostimulant

Zebrafish behavior is increasingly common in biomedical and environmental studies of chemical bioactivity. Multiple experimental arena sizes have been used to measure photolocomotion in zebrafish depending on age, endpoints observed, and instrumentation, among other factors. However, the extent to which methodological parameters may influence naïve behavioral performance and detection of behavioral changes is poorly understood. Here we measured photolocomotion and behavioral profiles of naïve larval zebrafish across arena sizes. We then performed concentration response studies with the model neurostimulant caffeine, again across various arena dimensions. We found total swimming distance of unexposed fish to increase logarithmically with arena size, which as related to circumference, area, and volume. Photomotor response during light/dark transitions also increased with arena size. Following caffeine exposure, total distance travelled was significantly (p < 0.001) affected by well size, caffeine treatment (p < 0.001), and the interaction of these two experimental factors (p < 0.001). In addition, behavioral response profiles showed differences between 96 well plates and larger well sizes. Biphasic response, with stimulation at lower concentrations and refraction at the highest concentration, was observed in dark conditions for the 96 well size only, though almost no effects were identified in the light. However, swimming behavior was significantly (p < 0.1) altered in the highest studied caffeine treatment level in larger well sizes during both light and dark periods. Our results indicate zebrafish swim more in larger arenas and arena size influences behavioral response profiles to caffeine, though differences were mostly observed between very small and large arenas. Further, careful consideration should be given when choosing arena size, because small wells may lead to restriction, while larger wells may differentially reflect biologically relevant effects. These findings can improve comparability among experimental designs and demonstrates the importance of understanding confounding methodological variables.

Effects of dietary irritants on intestinal homeostasis and the intervention strategies

Abundant diet components are unexplored as vital factors in intestinal homeostasis. Dietary irritants stimulate the nervous system and provoke somatosensory responses, further inducing diarrhea, gut microbiota disorder, intestinal barrier damage or even severe gastrointestinal disease. We depicted the effects of food with piquancy, high fat, low pH, high-refined carbohydrates, and indigestible texture. The mechanism of dietary irritants on intestinal homeostasis were comprehensively summarized. Somatosensory responses to dietary irritants are palpable and have specific chemical and neural mechanisms. In contrast, even low-dose exposure to dietary irritants can involve multiple intestinal barriers. Their mechanisms in intestinal homeostasis are often overlapping and dose-dependent. Therefore, treating symptoms caused by dietary irritants requires personalized nutritional advice. The reprocessing of stimulant foods, additional supplementation with probiotics or prebiotics, and enhancement of the intestinal barrier are effective intervention strategies. This review provides promising preliminary guidelines for the treatment of symptoms and gastrointestinal injury caused by dietary irritants.

Preparation and Evaluation of Caffeine Orodispersible Films: The Influence of Hydrotropic Substances and Film-Forming Agent Concentration on Film Properties

This study aimed to develop caffeine (CAF) orodispersible films (ODFs) and verify the effects of different percentages of film-forming agent and hydrotropic substances (citric acid-CA or sodium benzoate-SB) on various film properties. Hydroxypropyl methylcellulose E 5 (HPMC E 5) orodispersible films were prepared using the solvent casting method. Four CAF-ODF formulations were prepared and coded as CAF1 (8% HPMC E 5, CAF), CAF2 (8% HPMC E 5 and CAF:CA-1:1), CAF3 (9% HPMC E 5 and CAF:CA-1:1), and CAF4 (9% HPMC E 5 and CAF:SB-1:1). The CAF-ODFs were evaluated in terms of disintegration time, folding endurance, thickness, uniformity of mass, CAF content, thickness-normalized tensile strength, adhesiveness, dissolution, and pH. Thin, opaque, and slightly white CAF-ODFs were obtained. All the formulations developed exhibited disintegration times less than 3 min. The dissolution test revealed that CAF1, CAF2, and CAF3 exhibited concentrations of active pharmaceutical ingredients (APIs) released at 30 min that were close to 100%, whilst CAF4 showed a faster dissolution behaviour (100% of the CAF was released at 5 min). Thin polymeric films containing 10 mg of CAF/surface area (3.14 cm²) were prepared.

Association of Caffeine Consumption and Brain Amyloid Positivity in Cognitively Normal Older Adults

BACKGROUND

Several epidemiological studies have reported the protective role of caffeine on health outcomes; however, it remained debatable on caffeine consumption and brain amyloid positivity.

OBJECTIVE

We aimed to determine the relationship between caffeine consumption and brain amyloid pathology in cognitively normal older adults.

METHODS

The dataset used for analysis in this cross-sectional study was selected from the Anti-Amyloid Treatment in Asymptomatic Alzheimer's (A4) Study. Multivariable logistic regression analyses were performed to explore the association between caffeine consumption and amyloid positivity using odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

In total, 4,394 participants were included in the final analysis. No significant association between caffeine consumption and amyloid positivity was observed in the whole participants (OR, 0.95; 95% CI, 0.78-1.14; p = 0.558). Subgroup analysis showed that caffeine intake was significantly associated with decreased amyloid positivity in males (OR, 0.72; 95% CI, 0.54-0.97; p = 0.032) but not in females (OR, 1.14; 95% CI, 0.90-1.46; p = 0.280), and the association between caffeine and amyloid positivity was not affected by age or APOE genotypes. In addition, different levels of caffeine were not associated with amyloid positivity.

CONCLUSION

The findings suggest that caffeine consumption was not significantly associated with amyloid positivity in the whole sample. However, caffeine consumption may be inversely associated with amyloid positivity among males but not females. More studies are needed to explore the mechanisms underlying caffeine consumption and brain amyloid positivity.

Effect of Caffeine Consumption on Cardiovascular Disease: An Updated Review

The incidence of cardiovascular diseases has significantly increased with the expansion of the industrialization of societies, which is notably linked to lifestyle changes and an unhealthy diet. Hence, determining the healthiest diet habits and supplements seems to be an appropriate way to decrease the global burden of cardiovascular diseases. Currently, caffeine, one of the most widely consumed compounds in the world, has emerged with some promising results in the treatment of numerous pathophysiological conditions of cardiovascular diseases. A literature search was conducted in PubMed, Scopus, Science Direct, Google Scholar, and Web of Science databases for the relevant articles regarding the pharmacology, preclinical, and clinical studies on the potential effects of caffeine on cardiovascular diseases. While caffeine could improve cardiovascular outcomes through several mechanisms of action, the literature review revealed controversial clinical effects of caffeine on blood pressure, cardiac arrhythmias, acute coronary syndrome, stable angina, and heart failure. In the case of dyslipidemia, coffee consumption increased total cholesterol, triglyceride, and low-density lipoprotein. Taken together, the existence of multiple confounding factors in the caffeine studies has resulted in inconclusive data interpretation. Further well-designed studies with adequate control of the confounding factors are warranted to draw a clear conclusion on the cardiovascular efficacy and safety of caffeine.

Successful Use of Continuous Veno-Venous Haemodialysis in a Case of Potential Lethal Caffeine Intoxication

Here we describe the case of a potentially lethal caffeine intoxication after the reported ingestion of 10 g of caffeine. Due to hemodynamic instability with tachycardia and hypertension with an insufficient effect of continuous labetalol infusion, the patient was started on continuous veno-venous haemodialysis (CVVHD). After successful treatment for 15 h, CVVHD could be discontinued, and the patient was discharged home the next day. This case report is the first to report the use of CVVHD as a haemodialysis modality in the case of caffeine intoxication and illustrate the effect on caffeine clearance. We stress the importance of an early recognition of caffeine intoxication, so that haemodialysis can be considered in the case of a potentially lethal intoxication.

Antifibrotic Effects of Caffeine, Curcumin and Pirfenidone in Primary Human Keratocytes

We evaluated the small molecules (AFM) caffeine, curcumin and pirfenidone to find non-toxic concentrations reducing the transformation of activated human corneal stromal keratocytes (aCSK) to scar-inducing myofibroblasts (MYO-SF). CSK were isolated from 16 human corneas unsuitable for transplantation and expanded for three passages in control medium (0.5% FBS). Then, aCSK were exposed to concentrations of caffeine of 0−500 μM, curcumin of 0−200 μM, pirfenidone of 0−2.2 nM and the profibrotic cytokine TGF-β1 (10 ng/mL) for 48 h. Alterations in viability and gene expression were evaluated by cell viability staining (FDA/PI), real-time polymerase chain reaction (RT-PCR) and immunocytochemistry. We found that all AFMs reduced cell counts at high concentrations. The highest concentrations with no toxic effect were 100 µM of caffeine, 20 µM of curcumin and 1.1 nM of pirfenidone. The addition of TGF-β1 to the control medium effectively transformed aCSK into myofibroblasts (MYO-SF), indicated by a 10-fold increase in α-smooth muscle actin (SMA) expression, a 39% decrease in lumican (LUM) expression and a 98% decrease in ALDH3A1 expression (p < 0.001). The concentrations of 100 µM of caffeine, 20/50 µM of curcumin and 1.1 nM of pirfenidone each significantly reduced SMA expression under TGF-β1 stimulation (p ≤ 0.024). LUM and ALDH3A1 expression remained low under TGF-β1 stimulation, independently of AFM supplementation. Immunocytochemistry showed that 100 µM of caffeine, 20 µM of curcumin and 1.1 nM of pirfenidone reduce the conversion rate of aCSK to SMA+ MYO-SF. In conclusion, in aCSK, 100 µM of caffeine, 20 µM of curcumin and 1.1 nM of pirfenidone significantly reduced SMA expression and MYO-SF conversion under TGF-β1 stimulation, with no influence on cell counts. However, the AFMs were unable to protect aCSK from characteristic marker loss.

Coffee consumption, health benefits and side effects: a narrative review and update for dietitians and nutritionists

Coffee is one of the most popular beverages worldwide; however, its impact on health outcomes and adverse effects is not fully understood. The current review aims to establish an update about the benefits of coffee consumption on health outcomes highlighting its side effects, and finally coming up with an attempt to provide some recommendations on its doses. A literature review using the PubMed/Medline database was carried out and the data were summarized by applying a narrative approach using the available evidence based on the literature. The main findings were the following: first, coffee may contribute to the prevention of inflammatory and oxidative stress-related diseases, such as obesity, metabolic syndrome and type 2 diabetes; second, coffee consumption seems to be associated with a lower incidence of several types of cancer and with a reduction in the risk of all-cause mortality; finally, the consumption of up to 400 mg/day (1-4 cups per day) of caffeine is safe. However, the time gap between coffee consumption and some drugs should be taken into account in order to avoid interaction. However, most of the data were based on cross-sectional or/and observational studies highlighting an association of coffee intake and health outcomes; thus, randomized controlled studies are needed in order to identify a causality link.

Variability of caffeine content in green and roasted Coffea arabica regarding the origin, post-harvest processing, and altitude, and overview of recommended daily allowance

Caffeine content is a crucial attribute of coffee. Its concentration and thus maximum cups of Coffea arabica from Africa, Asia, Central America, and South America from different altitudes of growing areas, altitude, and process using different post-harvest processing (dry, wet, and pulped natural). Our results suggest that geographical origin might affect the alkaloid concentration in C. arabica. The caffeine concentration pattern in green samples was as follows: Central America > South America > Asia > Africa. Altitude affected the concentrations, lowlands > midlands > highlands, however, not significantly. Given caffeine is thermostable, the medium roasting process did not affect the concentration of caffeine directly, but a small increase was observed. Scientific opinion on the safety of habitual caffeine consumption of up to 400 mg per day does not raise safety concerns for non-pregnant adults. A cup (7 g coffee in 120 mL of water) was used for recalculation. Results suggest that mostly highlands and midlands coffee from Africa reached levels of caffeine that might be consumed in more than 5.5 cups a day.

The impact of coffee subtypes on incident cardiovascular disease, arrhythmias, and mortality: long-term outcomes from the UK Biobank

AIMS

Epidemiological studies report the beneficial effects of habitual coffee consumption on incident arrhythmia, cardiovascular disease (CVD), and mortality. However, the impact of different coffee preparations on cardiovascular outcomes and survival is largely unknown. The aim of this study was to evaluate associations between coffee subtypes on incident outcomes, utilizing the UK Biobank.

METHODS AND RESULTS

Coffee subtypes were defined as decaffeinated, ground, and instant, then divided into 0, <1, 1, 2-3, 4-5, and >5 cups/day, and compared with non-drinkers. Cardiovascular disease included coronary heart disease, cardiac failure, and ischaemic stroke. Cox regression modelling with hazard ratios (HRs) assessed associations with incident arrhythmia, CVD, and mortality. Outcomes were determined through ICD codes and death records. A total of 449 563 participants (median 58 years, 55.3% females) were followed over 12.5 ± 0.7 years. Ground and instant coffee consumption was associated with a significant reduction in arrhythmia at 1-5 cups/day but not for decaffeinated coffee. The lowest risk was 4-5 cups/day for ground coffee [HR 0.83, confidence interval (CI) 0.76-0.91, P < 0.0001] and 2-3 cups/day for instant coffee (HR 0.88, CI 0.85-0.92, P < 0.0001). All coffee subtypes were associated with a reduction in incident CVD (the lowest risk was 2-3 cups/day for decaffeinated, P = 0.0093; ground, P < 0.0001; and instant coffee, P < 0.0001) vs. non-drinkers. All-cause mortality was significantly reduced for all coffee subtypes, with the greatest risk reduction seen with 2-3 cups/day for decaffeinated (HR 0.86, CI 0.81-0.91, P < 0.0001); ground (HR 0.73, CI 0.69-0.78, P < 0.0001); and instant coffee (HR 0.89, CI 0.86-0.93, P < 0.0001).

CONCLUSION

Decaffeinated, ground, and instant coffee, particularly at 2-3 cups/day, were associated with significant reductions in incident CVD and mortality. Ground and instant but not decaffeinated coffee was associated with reduced arrhythmia.

Fluted pumpkin seeds protect the spermatogenesis score index and testicular histology of caffeine treated rats

The present study was designed to evaluate the protective effect of fluted pumpkin seeds (FPS) against caffeine (CAFF) induced testicular toxicity in rats. Thirty young healthy male Wistar rats (196 ± 12 g) were randomly organized into five sets of six animals per each group: control, caffeine (CAFF; 50 mg kg-1 bw) and FPS co-treatment groups (CAFF + 50 mg FPS, CAFF + 100 mg FPS and CAFF + 200 mg FPS kg-1  bw). CAFF and FPS were administered daily and twice per week respectively by oral gavage for 40 days. CAFF treatment decreased testicular lactate dehydrogenase enzyme activity level, which was attenuated on co-administration with FPS at 50 and 100 mg kg-1  bw. Furthermore, CAFF decreased seminiferous epithelia thickness and spermatogenesis score index and increased the number of tubules with abnormal histological features, which were attenuated on co-administration with FPS at 50 mg kg-1  bw much more than at the higher doses (p < 0.05). CAFF did not affect malondialdehyde and glutathione concentrations and glutathione peroxidase (GSH-Px) activity in the testes whereas FPS co-treatment at the higher doses elevated glutathione level and GSH-Px activity and did not affect spermatogenesis score index at the highest dose (200 mg kg-1  bw). Testicular malondialdehyde concentrations remained unaffected in all FPS co-treatment groups. Overall, FPS is able to minimize the CAFF-induced testicular injury at lower than at the higher tested doses.

Caffeine, D-glucuronolactone and Taurine Content in Energy Drinks: Exposure and Risk Assessment

The consumption of energy drinks (EDs) is increasing globally while the evidence and concern about the potential health risks are also growing. Caffeine (generally 32 mg/100 mL) together with a wide variety of other active components such as taurine (usually 4000 mg/L) and D-glucuronolactone (generally 2400 mg/L) are the main ingredients of EDs. This study aims to assess the exposures to caffeine, taurine and D-glucuronolactone from EDs in various consumption scenarios and consumer profiles and to characterize the risks by evaluating caffeine and taurine intakes with their reference values and by calculating the margin of safety (MOS) for D-glucuronolactone. While the exposure assessment results showed that caffeine intakes from EDs ranged from 80 to 160 mg (1.14-4 mg/kg b.w.) for the considered scenarios, the risk characterization estimated some risks that could be managed with consumption recommendations such as limiting EDs in 40, 60 and 80 kg b.w. consumers to 175, 262.5 and 350 mL, respectively, to prevent sleep disturbances and to 375, 562.5 and 750 mL to prevent general caffeine adverse health risks, respectively. Dietary exposure to D-glucuronolactone from EDs ranged from 600 to 1200 mg (7.5-30 mg/kg b.w.). As D-glucuronolactone MOS ≥ 100 is only observed when EDs consumption is limited to 250 mL, for individuals weighing above 60 kg, some risks were observed in some of the studied scenarios. A taurine exposure from EDs varied from 1000 to 2000 mg (12.5-50 mg/kg b.w.) and consumptions over 500 mL were estimated to generate intakes above the reference value. In conclusion, the management of these risks requires a European legal framework for EDs with maximum limits for the active components, volume size limitations and labeling improvements along with the development of education and awareness programs and risk communication actions in collaboration with the industry and society.

Disorders of Hippocampus Facilitated by Hypertension in Purine Metabolism Deficiency is Repressed by Naringin, a Bi-flavonoid in a Rat Model via NOS/cAMP/PKA and DARPP-32, BDNF/TrkB Pathways

Individuals who are hypertensive have a higher tendency of predisposition to other genetic diseases including purine metabolism deficiency. Therefore, the search for nontoxic and effective chemo protective agents to abrogate hypertension-mediated genetic disease is vital. This study therefore investigated the repressive effect of naringin (NAR) against disorder of hippocampus facilitated by hypertension in purine metabolism deficiency. Male albino rats randomly assigned into nine groups (n = 7) were treated for 35 days. Group I: control animals, Group II was treated with 100 mg/kg KBrO₃, Group III was treated with 250 mg/kg caffeine, and Group IV was treated with 100 mg/kg KBrO₃ + 250 mg/kg caffeine. Group V was administered with 100 mg/kg KBrO₃ + 100 mg/kg haloperidol. Group VI was administered with 100 mg/kg KBrO₃ + 50 mg/kg NAR. Group VII was administered with 250 mg/kg caffeine + 50 mg/kg NAR, and Group VIII was administered with 100 mg/kg KBrO₃ + 250 mg/kg caffeine + 50 mg/kg NAR. Finally, group IX was treated with 50 mg/kg NAR. The sub-acute exposure to KBrO₃ and CAF induced hypertension and mediated impairment in the hippocampus cells. This was apparent by the increase in PDE-5¹, arginase, and enzymes of ATP hydrolysis (ATPase and AMPase) with a simultaneous increase in cholinergic (AChE and BuChE) and adenosinergic (ADA) enzymes. The hypertensive-mediated hippocampal impairment was associated to alteration of NO and AC signaling coupled with lower expression of brain-derived neurotrophic factor and its receptor (BDNF-TrkB), down regulation of Bcl11b and DARPP-32 which are neurodevelopmental proteins, and hypoxanthine accumulation. However, these features of CAF-mediated hippocampal damage in KBrO₃-induced hypertensive rats were repressed by post-treatment with NAR via production of neuro-inflammatory mediators, attenuation of biochemical alterations, stabilizing neurotransmitter enzymes, regulating NOS/cAMP/PKA and DARPP-32, BDNF/TrkB signaling, and restoring hippocampal tissues.