Plasma Caffeine Research Articles

Plasma, brain and spinal cord concentrations of caffeine are reduced in the SOD1G93A mouse model of amyotrophic lateral sclerosis following oral administration

Modifications to the small intestine and liver are known to occur during the symptomatic disease period of amyotrophic lateral sclerosis (ALS), a member of the motor neuron disease (MND) family of neurodegenerative disorders. How these modifications impact on oral absorption and pharmacokinetics of drugs remains unknown. In this study, model drugs representing different mechanisms of intestinal transport (caffeine for passive diffusion, digoxin for P-glycoprotein efflux, and sulfasalazine for breast cancer resistance protein efflux) were administered via oral gavage to postnatal day 114–120 male and female SOD1G93A mice (model of familial ALS) and wild-type (WT) littermates. Samples of blood, brain and spinal cord were taken at either 15, 30, 60 or 180 min after administration. In addition, the in vivo gastric emptying of 70 kDa fluorescein isothiocyanate-dextran (FITC-dextran) and the ex vivo intestinal permeability of caffeine were assessed. The area under the plasma concentration–time curves (AUCplasma) of digoxin and sulfasalazine were not significantly different between SOD1G93A and WT mice for both sexes. However, the AUCplasma of caffeine was significantly lower (female: 0.79-fold, male: 0.76-fold) in SOD1G93A compared to WT mice, which was associated with lower AUCbrain (female: 0.76-fold, male: 0.80-fold) and AUCspinal cord (female: 0.81-fold, male: 0.82-fold). The AUCstomach of caffeine was significantly higher (female: 1.5-fold, male: 1.9-fold) in SOD1G93A compared to WT mice, suggesting reduced gastric emptying in SOD1G93A mice. In addition, there was a significant reduction in gastric emptying of FITC-dextran (0.66-fold) and ex vivo intestinal permeability of caffeine (0.52-fold) in male SOD1G93A compared to WT mice. Reduced systemic and brain/spinal cord exposure of caffeine in SOD1G93A mice may therefore result from alterations to gastric emptying and small intestinal permeability. Specific dosing requirements may therefore be required for certain medicines in ALS to ensure that they remain in a safe and effective concentration range.

Comparison of caffeine consumption behavior with plasma caffeine levels as exposure measures in drug-target Mendelian randomization.

Mendelian randomization is an epidemiological technique that can explore the potential effect of perturbing a pharmacological target. Plasma caffeine levels can be used as a biomarker to measure the pharmacological effects of caffeine. Alternatively, this can be assessed using a behavioral proxy, such as average number of caffeinated drinks consumed per day. Either variable can be used as the exposure in a Mendelian randomization investigation, and to select which genetic variants to use as instrumental variables. Another possibility is to choose variants in gene regions with known biological relevance to caffeine level regulation. These choices affect the causal question that is being addressed by the analysis, and the validity of the analysis assumptions. Further, even when using the same genetic variants, the sign of Mendelian randomization estimates (positive or negative) can change depending on the choice of exposure. Some genetic variants that decrease caffeine metabolism associate with higher levels of plasma caffeine, but lower levels of caffeine consumption, as individuals with these variants require less caffeine consumption for the same physiological effect. We explore Mendelian randomization estimates for the effect of caffeine on body mass index, and discuss implications for variant and exposure choice in drug target Mendelian randomization investigations.

Association of Coffee Consumption and Prediagnostic Caffeine Metabolites With Incident Parkinson Disease in a Population-Based Cohort.

Inverse associations between caffeine intake and Parkinson disease (PD) have been frequently implicated in human studies. However, no studies have quantified biomarkers of caffeine intake years before PD onset and investigated whether and which caffeine metabolites are related to PD. Associations between self-reported total coffee consumption and future PD risk were examined in the EPIC4PD study, a prospective population-based cohort including 6 European countries. Cases with PD were identified through medical records and reviewed by expert neurologists. Hazard ratios (HRs) and 95% CIs for coffee consumption and PD incidence were estimated using Cox proportional hazards models. A case-control study nested within the EPIC4PD was conducted, recruiting cases with incident PD and matching each case with a control by age, sex, study center, and fasting status at blood collection. Caffeine metabolites were quantified by high-resolution mass spectrometry in baseline collected plasma samples. Using conditional logistic regression models, odds ratios (ORs) and 95% CIs were estimated for caffeine metabolites and PD risk. In the EPIC4PD cohort (comprising 184,024 individuals), the multivariable-adjusted HR comparing the highest coffee intake with nonconsumers was 0.63 (95% CI 0.46-0.88, p = 0.006). In the nested case-control study, which included 351 cases with incident PD and 351 matched controls, prediagnostic caffeine and its primary metabolites, paraxanthine and theophylline, were inversely associated with PD risk. The ORs were 0.80 (95% CI 0.67-0.95, p = 0.009), 0.82 (95% CI 0.69-0.96, p = 0.015), and 0.78 (95% CI 0.65-0.93, p = 0.005), respectively. Adjusting for smoking and alcohol consumption did not substantially change these results. This study demonstrates that the neuroprotection of coffee on PD is attributed to caffeine and its metabolites by detailed quantification of plasma caffeine and its metabolites years before diagnosis.

Caffeine pharmacokinetics following umbilical vein injection during delayed cord clamping in preterm lambs.

Spontaneous breathing during and after delayed cord clamping (DCC) stabilizes cardiopulmonary transition at birth. Caffeine stimulates breathing and decreases apnea in premature newborns. We evaluated the pharmacokinetics and physiological effects of early caffeine administration-direct injection into the umbilical vein (UV) during DCC or administered through a UV catheter (UVC) after delivery. Eighteen extremely premature lambs (125-127d, term gestation 145d) were exteriorized and instrumented. Lambs received caffeine-citrate at high (40 mg/kg) or standard-dose (20 mg/kg) via direct UV (DUV) injection during DCC, or via the UVC. Mean peak plasma caffeine concentrations were lower with high-dose DUV compared to UVC (18 ± 4.3 vs. 46 ± 12 mg/L, p < 0.05). With standard-dose caffeine, mean peak plasma levels were 7.48 ± 2.6 with DUV and 28.73 ± 9.4 mg/L with UVC. The volume of distribution was higher in the DUV group compared to UVC (2.5 ± 1.0 vs. 0.69 ± 0.15 L/kg) with an estimated 39 ± 18% entering the maternal circulation. Maternal peak concentrations were 0.79 ± 0.71 and 1.43 ± 0.74 mg/L with standard and high-dose DUV, respectively. Caffeine injected directly into the UV during DCC is feasible but achieves lower concentrations due to high volume of distribution including maternal circulation. Further trials evaluating DUV caffeine injection should use higher caffeine doses. Respiratory stimulation with early caffeine may reduce the need for intubation in preterm infants. In the preterm lambs, caffeine injection directly into the umbilical vein during delayed cord clamping is feasible. Plasma caffeine concentrations are less than half when administered directly into the umbilical vein during delayed cord clamping compared to administration via an umbilical venous catheter following birth likely attributed to a larger volume of distribution or injection site leak. There were no significant hemodynamic alterations following caffeine injection.

Effect of Coffee and Chocolate Ingestion on Clozapine Dose and on Plasma Clozapine and Norclozapine Concentrations in Clinical Practice.

Some reports point to dietary caffeine intake as a cause of increased plasma clozapine concentrations in certain patients. We compared clozapine dose and plasma clozapine and N-desmethylclozapine (norclozapine) concentrations in male and female smokers and nonsmokers in relation to reported (i) coffee (caffeine) and (ii) chocolate (caffeine and theobromine) intake in samples submitted for clozapine therapeutic drug monitoring, 1993-2017. There was information on coffee ingestion for 16,558 samples (8833 patients) from males and 5886 samples (3433 patients) from females and on chocolate ingestion for 12,616 samples (7568 patients) from males and 4677 samples (2939 patients) from females. When smoking was considered, there was no discernible effect of either coffee or chocolate ingestion either on the median dose of clozapine or on the median plasma clozapine and norclozapine concentrations in men and in women. However, cigarette smoking was associated with higher coffee and chocolate consumption. Although male nonsmokers who reported drinking 3 or more cups of coffee daily had significantly higher median plasma clozapine and norclozapine concentrations than those who drank less coffee, they were also prescribed a significantly higher clozapine dose. There was no clear effect of coffee ingestion on plasma clozapine and norclozapine in female nonsmokers. Inhibition of clozapine metabolism by caffeine at the doses of caffeine normally encountered in those treated with clozapine is unlikely even in male nonsmokers. Measurement of plasma caffeine in an appropriate sample should be considered in any future investigation into a presumed clozapine-caffeine interaction.

Genetic investigation into the broad health implications of caffeine: evidence from phenome-wide, proteome-wide and metabolome-wide Mendelian randomization

BackgroundCaffeine is one of the most utilized drugs in the world, yet its clinical effects are not fully understood. Circulating caffeine levels are influenced by the interplay between consumption behaviour and metabolism. This study aimed to investigate the effects of circulating caffeine levels by considering genetically predicted variation in caffeine metabolism.MethodsLeveraging genetic variants related to caffeine metabolism that affect its circulating levels, we investigated the clinical effects of plasma caffeine in a phenome-wide association study (PheWAS). We validated novel findings using a two-sample Mendelian randomization framework and explored the potential mechanisms underlying these effects in proteome-wide and metabolome-wide Mendelian randomization.ResultsHigher levels of genetically predicted circulating caffeine among caffeine consumers were associated with a lower risk of obesity (odds ratio (OR) per standard deviation increase in caffeine = 0.97, 95% confidence interval (CI) CI: 0.95—0.98, p = 2.47 × 10−4), osteoarthrosis (OR = 0.97, 95% CI: 0.96—0.98, P=1.10 × 10−8) and osteoarthritis (OR: 0.97, 95% CI: 0.96 to 0.98, P = 1.09 × 10−6). Approximately one third of the protective effect of plasma caffeine on osteoarthritis risk was estimated to be mediated through lower bodyweight. Proteomic and metabolomic perturbations indicated lower chronic inflammation, improved lipid profiles, and altered protein and glycogen metabolism as potential biological mechanisms underlying these effects.ConclusionsWe report novel evidence suggesting that long-term increases in circulating caffeine may reduce bodyweight and the risk of osteoarthrosis and osteoarthritis. We confirm prior genetic evidence of a protective effect of plasma caffeine on risk of overweight and obesity. Further clinical study is warranted to understand the translational relevance of these findings before clinical practice or lifestyle interventions related to caffeine consumption are introduced.

Origanum majorana L. polyphenols: in vivo antiepileptic effect, in silico evaluation of their bioavailability, and interaction with the NMDA receptor.

Introduction: Epilepsy is a chronic brain disease characterized by repeated seizures and caused by excessive glutamate receptor activation. Many plants are traditionally used in the treatment of this disease. This study aimed to evaluate the bioavailability of a polyphenolic extract obtained from Origanum majorana L. (OMP) leaves, as well as its antiepileptic activity and its potential mechanism of action. Methods: We have developed and validated a simple, rapid, and accurate stability-indicating reversed-phase liquid chromatographic method for the simultaneous determination of caffeine and quercetin in rat plasma. The OMP antiepileptic effect was evaluated with pilocarpine-induced seizures, and a docking method was used to determine the possible interaction between caffeic acid and quercetin with the N-methyl-D-aspartate (NMDA) receptor. Results and Discussion: Both compounds tested showed low bioavailability in unchanged form. However, the tested extract showed an anticonvulsant effect due to the considerably delayed onset of seizures in the pilocarpine model at a dose of 100mg/kg. The molecular docking proved a high-affinity interaction between the caffeic acid and quercetin with the NMDA receptor. Taken together, OLP polyphenols demonstrated good antiepileptic activity, probably due to the interaction of quercetin, caffeic acid, or their metabolites with the NMDA receptor.

Coffee Intake, Plasma Caffeine Levels, and Kidney Function: Two-Sample Mendelian Randomization Among East Asian and European Ancestries

IntroductionPrevious Mendelian randomization (MR) studies for the coffee-kidney association have reported inconsistent relationships in European populations and never examined mediators of this association. We aimed to evaluate this causal relationship using two-sample MR among both East Asian and European ancestries and to explore underlying mechanisms using plasma caffeine levels. MethodsAmong East Asians, the largest genome-wide association study (GWAS) results for coffee intake, plasma caffeine levels, and kidney outcomes were obtained from 152,634, 8,940, and 47,070 Japanese adults. Among Europeans, summary statistics were acquired from European GWAS with 428,860, 7,719, and 564,470 adults for each trait. We applied different MR methods (inverse-variance weighted with random effects, weighted median, weighted mode, and MR-Egger). ResultsAfter excluding possible pleiotropic variants, among East Asian ancestry, drinking an extra coffee intake per week showed a protective association on eGFRcre (β=0.077; 95% CI=0.003 to 0.150). Analysis in European ancestry also showed a causal relationship between drinking an extra coffee intake per day and eGFRcre (β=0.052; 95% CI=0.027 to 0.078). These results were consistent across different MR methods accounting for invalid instruments. Higher plasma caffeine levels were associated with lower eGFRcre among both East Asian (β=–0.071; 95% CI=–0.137 to –0.006) and European ancestries (β=–0.048; 95% CI=–0.057 to –0.040). ConclusionsOur cross-ancestry MR study found beneficial effects of coffee intake on eGFRcre. However, given the possible adverse effects of plasma caffeine levels on eGFRcre, results interpretation should be carefully considered and further investigations on non-caffeine and biological pathways are needed.

Concentration-effect relationships of plasma caffeine on EEG delta power and cardiac autonomic activity during human sleep.

Acute caffeine intake affects brain and cardiovascular physiology, yet the concentration-effect relationships on the electroencephalogram and cardiac autonomic activity during sleep are poorly understood. To tackle this question, we simultaneously quantified the plasma caffeine concentration with ultra-high-performance liquid chromatography, as well as the electroencephalogram, heart rate and high-frequency (0.15-0.4 Hz) spectral power in heart rate variability, representing parasympathetic activity, with standard polysomnography during undisturbed human sleep. Twenty-one healthy young men in randomized, double-blind, crossover fashion, ingested 160 mg caffeine or placebo in a delayed, pulsatile-release caffeine formula at their habitual bedtime, and initiated a 4-hr sleep opportunity 4.5 hr later. The mean caffeine levels during sleep exhibited high individual variability between 0.2 and 18.4 μmol L-1. Across the first two non-rapid-eye-movement (NREM)-rapid-eye-movement sleep cycles, electroencephalogram delta (0.75-2.5 Hz) activity and heart rate were reliably modulated by waking and sleep states. Caffeine dose-dependently reduced delta activity and heart rate, and increased high-frequency heart rate variability in NREM sleep when compared with placebo. The average reduction in heart rate equalled 3.24 ± 0.77 beats per minute. Non-linear statistical models suggest that caffeine levels above ~7.4 μmol L-1 decreased electroencephalogram delta activity, whereas concentrations above ~4.3 μmol L-1 and ~ 4.9 μmol L-1, respectively, reduced heart rate and increased high-frequency heart rate variability. These findings provide quantitative concentration-effect relationships of caffeine, electroencephalogram delta power and cardiac autonomic activity, and suggest increased parasympathetic activity during sleep after intake of caffeine.

Unraveling the link between plasma caffeine concentrations and inflammatory bowel disease risk through Mendelian randomization

BackgroundCaffeine is believed to possess anti-inflammatory properties, yet direct population-based evidence regarding its impact on inflammatory bowel disease (IBD) remains scarce. ObjectivesIn this study, we used 2-sample Mendelian randomization (MR) study to investigate the causal relationship between long-term plasma caffeine concentrations and IBD and its subtypes, ulcerative colitis (UC) and Crohn disease (CD). MethodsWe used single nucleotide polymorphisms (SNPs) associated with plasma caffeine concentrations at genome-wide significance within a ±100-kb range around the CYP1A2 or AHR genes as instrumental variables. Genome-wide association study (GWAS) data for IBD and its subtypes were obtained from FinnGen and International Inflammatory Bowel Disease Genetics Consortium. We conducted a meta-analysis of MR-related SNPs from both sources and used a multiplicative inverse variance–weighted random effects model to combine the effects of each SNP proxy on exposure to outcomes. ResultsIn our study, genetically predicted higher plasma caffeine concentrations were associated with a lower risk of IBD, with an odds ratio (OR) of 0.78 (95% confidence interval [CI]: 0.66, 0.91; PFDR = 0.004). This trend was also observed in UC and CD, with ORs of 0.79 (95% CI: 0.66, 0.94; PFDR = 0.014) and 0.78 (95% CI: 0.62, 0.98; PFDR = 0.032), respectively. ConclusionOur study indicates a potential causal link between genetically predicted higher plasma caffeine concentrations and a reduced risk of IBD, including its subtypes UC and CD.

Caffeine Intake, Plasma Caffeine Level, and Kidney Function: A Mendelian Randomization Study.

Caffeine is a psychoactive substance widely consumed worldwide, mainly via sources such as coffee and tea. The effects of caffeine on kidney function remain unclear. We leveraged the genetic variants in the CYP1A2 and AHR genes via the two-sample Mendelian randomization (MR) framework to estimate the association of genetically predicted plasma caffeine and caffeine intake on kidney traits. Genetic association summary statistics on plasma caffeine levels and caffeine intake were taken from genome-wide association study (GWAS) meta-analyses of 9876 and of >47,000 European ancestry individuals, respectively. Genetically predicted plasma caffeine levels were associated with a decrease in estimated glomerular filtration rate (eGFR) measured using either creatinine or cystatin C. In contrast, genetically predicted caffeine intake was associated with an increase in eGFR and a low risk of chronic kidney disease. The discrepancy is likely attributable to faster metabolizers of caffeine consuming more caffeine-containing beverages to achieve the same pharmacological effect. Further research is needed to distinguish whether the observed effects on kidney function are driven by the harmful effects of higher plasma caffeine levels or the protective effects of greater intake of caffeine-containing beverages, particularly given the widespread use of drinks containing caffeine and the increasing burden of kidney disease.

Determination of Caffeine in Human Plasma by Using Liquid Chromatography-Tandem Mass Spectrometry

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated to determine caffeine (CAF) in human plasma. The plasma samples were extracted by protein precipitation using CAF-D3 as an internal standard (IS). The chromatographic separation was performed on GL Sciences InertSustain C18 Column (4.6 x 50 mm, 5 µm) maintained at 40 °C with a mobile phase consisting of formic acid, water, and methanol at a 1 mL/min of flow rate using two separate lines. CAF was detected and identified by mass spectrometry with electrospray ionization (ESI) in positive ions and multiple-reaction monitoring (MRM) mode. The MRM transitions of m/z 195.10 &amp;gt; 138.00 for CAF and 198.10 &amp;gt; 141.10 for IS were used for quantification. The standard curve was linear in the range of 10 - 10000 ng/mL for CAF. The within-batch precision and accuracy were evaluated by analyzing QC samples at five different concentration levels with six replicates in a batch. The between-batch precision and accuracy were determined by analyzing three different batches. The within-batch accuracy and precision was -8.76% - 9.61% and 0.95% - 7.22%, respectively. The between-batch accuracy and precision was -7.47% -1.42% and 1.83% - 8.66%, respectively. The results of the intra- and inter-day precision and accuracy studies were within the limits. The validated method applied to a pharmacokinetic study and the test product containing 60 mg CAF administered to total of 12 subjects. The mean ± SD of maximum plasma concentration (Cmax) was found to be 147.94 ± 139.39 ng/mL and the mean ± SD of area under the plasma concentration-time curve from zero to last measurable concentration (AUC0-tlast) was found to be 1119.59 ± 1468.30 h.ng/mL for the fasting conditions. The median time to reach peak plasma concentration (Tmax) was found to be 12.00 (6.50 - 12.00). The developed and validated method can be used for bioavailability and bioequivalence studies in human plasma samples.

Lifestyle factors, serum parameters, metabolic comorbidities, and the risk of kidney stones: a Mendelian randomization study.

The early identification of modifiable risk factors is important for preventing kidney stones but determining causal associations can be difficult with epidemiological data. We aimed to genetically assess the causality between modifiable factors (lifestyle factors, serum parameters, and metabolic comorbidities) and the risk of kidney stones. Additionally, we aimed to explore the causal impact of education on kidney stones and its potential mediating pathways. We conducted a two-sample Mendelian randomization (MR) study to explore the causal association between 44 modifiable risk factors and kidney stones. The FinnGen dataset initially explored the causal relationship of risk factors with kidney stones and the UK Biobank dataset was used as the validation set. Then, a meta-analysis was conducted by combining discovery and validation datasets. We used two-step MR to assess potential mediators and their mediation proportions between education and kidney stones. The combined results indicated that previous exposures may increase the risk of kidney stones, including sedentary behavior, urinary sodium, the urinary sodium/potassium ratio, the urinary sodium/creatinine ratio, serum calcium, 25-hydroxyvitamin D (25OHD), the estimated creatinine-based glomerular filtration rate (eGFRcrea), GFR estimated by serum cystatin C (eGFRcys), body mass index (BMI), waist circumference, type 2 diabetes mellitus (T2DM), fasting insulin, glycated hemoglobin, and hypertension. Coffee intake, plasma caffeine levels, educational attainment, and the urinary potassium/creatinine ratio may decrease the risk of kidney stones. Ranked by mediation proportion, the effect of education on the risk of kidney stones was mediated by five modifiable risk factors, including sedentary behavior (mediation proportion, 25.7%), smoking initiation (10.2%), BMI (8.2%), T2DM (5.8%), and waist circumference (3.2%). This study provides MR evidence supporting causal associations of many modifiable risk factors with kidney stones. Sedentary lifestyles, obesity, smoking, and T2DM are mediating factors in the causal relationship between educational attainment and kidney stones. Our results suggest more attention should be paid to these modifiable factors to prevent kidney stones.

Genetic association between coffee/caffeine consumption and the risk of obstructive sleep apnea in the European population: a two-sample Mendelian randomization study.

The association between coffee/caffeine consumption and obstructive sleep apnea (OSA) risk remains unclear. To determine the relationship between coffee/caffeine consumption and the risk of OSA, using the Mendelian randomization (MR) method in the European population. Two sets of coffee consumption-associated genetic variants were, respectively, extracted from the recent genome-wide meta-analysis (GWMA) and genome-wide association study (GWAS) of coffee consumption. Taking other caffeine sources into account, genetic variants associated with caffeine consumption from tea and plasma caffeine (reflecting total caffeine intake) were also obtained. The inverse variance weighted (IVW) technique was utilized as the primary analysis, supplemented by the MR-Egger, weighted-median, and MR-Pleiotropy RESidual Sum and Outlier (PRESSO) techniques. Leave-one-out (LOO) analysis was performed to assess whether the overall casual estimates were driven by a single SNP. Additional sensitivity analyses were performed using similar methods, while the genetic variants associated with confounders, e.g., body mass index and hypertension, were excluded. The IVW method demonstrated that coffee consumption GWMA (OR: 1.065, 95% CI 0.927-1.224, p = 0.376), coffee consumption GWAS (OR: 1.665, 95% CI 0.932-2.977, p = 0.086), caffeine from tea (OR: 1.198, 95% CI 0.936-1.534, p = 0.151), and blood caffeine levels (OR: 1.054, 95% CI 0.902-1.231, p = 0.508) were unlikely to be associated with the risk of OSA. The other three methods presented similar results, where no significant associations were found. No single genetic variant was driving the overall estimates by the LOO analysis. These findings were also supported by the sensitivity analyses with no confounding genetic variants. Our study found no association between coffee/caffeine consumption and the risk of OSA.

Immediate effect of caffeine on sympathetic nerve activity: why coffee is safe? A single-centre crossover study

PurposesHabitual coffee drinking is ubiquitous and generally considered to be safe despite its transient hypertensive effect. Our purpose was to determine the role of the sympathetic nervous system in the hypertensive response.MethodsIn a single-centre crossover study, medical caregivers were studied after consumption of standard coffee (espresso), water and decaffeinated coffee (decaff) given in random order at least 1 month apart. Plasma caffeine levels, mean arterial pressure, heart rate, total peripheral resistance and muscle sympathetic activity were recorded. Baroreflex activity was assessed using burst incidence and RR interval changes to spontaneous blood pressure fluctuations.ResultsA total of 16 subjects (mean [± standard error] age 34.4 ± 2 years; 44% female) were recruited to the study. Three agents were studied in ten subjects, and two agents were studied in six subjects. Over a 120-min period following the consumption of standard coffee, mean (± SE) plasma caffeine levels increased from 2.4 ± 0.8 to 21.0 ± 4 µmol/L and arterial pressure increased to 103 ± 1 mmHg compared to water (101 ± 1 mmHg; p = 0.066) and decaff (100 ± 1 mmHg; p = 0.016). Peripheral resistance in the same period following coffee increased to 120 ± 4% of the baseline level compared to water (107 ± 4; p = 0.01) and decaff (109 ± 4; p = 0.02). Heart rate was lower after both coffee and decaff consumption: 62 ± 1 bpm compared to water (64 bpm; p = 0.01 and p = 0.02, respectively). Cardio-vagal baroreflex activity remained stable after coffee, but sympathetic activity decreased, with burst frequency of 96 ± 3% versus water (106 ± 3%; p = 0.04) and decaff (112 ± 3%; p = 0.001) despite a fall in baroreflex activity from – 2.2 ± 0.1 to – 1.8 ± 0.1 bursts/100 beats/mmHg, compared to water (p = 0.009) and decaff (p = 0.004).ConclusionThe hypertensive response to coffee is secondary to peripheral vasoconstriction but this is not mediated by increased sympathetic nerve activity. These results may explain why habitual coffee drinking is safe.

Appraising the causal relationship between plasma caffeine levels and neuropsychiatric disorders through Mendelian randomization

BackgroundCaffeine exposure modifies the turnover of monoamine neurotransmitters, which play a role in several neuropsychiatric disorders. We conducted a Mendelian randomization study to investigate whether higher plasma caffeine levels are causally associated with the risk of anorexia nervosa, bipolar disorder, major depressive disorder (MDD), and schizophrenia.MethodsSummary-level data on the neuropsychiatric disorders were obtained from large-scale genome-wide association studies (GWASs) of European ancestry participants (n = 72,517 to 807,553) and meta-analyzed with the corresponding data from the FinnGen study (n = 356,077). Summary-level data on plasma caffeine were extracted from a GWAS meta-analysis of 9876 European ancestry individuals. The Mendelian randomization analyses estimated the Wald ratio for each genetic variant and meta-analyzed the variant-specific estimates using multiplicative random effects meta-analysis.ResultsAfter correcting for multiple testing, genetically predicted higher plasma caffeine levels were associated with higher odds of anorexia nervosa (odds ratio [OR] = 1.124; 95% confidence interval [CI] = 1.024–1.238, pFDR = 0.039) and a lower odds of bipolar disorder (OR = 0.905, 95% CI = 0.827–0.929, pFDR = 0.041) and MDD (OR = 0.965, 95% CI = 0.937–0.995, pFDR = 0.039). Instrumented plasma caffeine levels were not associated with schizophrenia (OR = 0.986, 95% CI = 0.929–1.047, pFDR = 0.646).ConclusionsThese Mendelian randomization findings indicate that long-term higher plasma caffeine levels may lower the risk of bipolar disorder and MDD but increase the risk of anorexia nervosa. These results warrant further research to explore whether caffeine consumption, supplementation, or abstinence could render clinically relevant therapeutic or preventative psychiatric effects.

Pharmacokinetic parameters of caffeine in laboratory animals in the context of assessing the functional state of the liver.

To date, the assessment of the functional state of the hepatobiliary system by analyzing changes in the clearance of exogenous caffeine is one of the most promising hepatic stress tests. The purpose of the study was to establish the pharmacokinetic change in the levels of exogenous caffeine in the blood plasma of laboratory animals in order to further induce various liver pathologies and subsequently assess the change in its clearance. For the study, non-linear laboratory rats were used (18 males, 18 females, average live weight 180 g ± 4%, age 3 months), Of the experimental animals, 3 groups were formed (6 females and 6 males each), each of which was injected subcutaneously with a 20% solution of caffeine sodium benzoate (Mosagrogen LLC, Russia) in increments of 50 mg/kg (50, 100, 150) in terms of pure caffeine.When using dosages of 100 and 150 mg/ kg, we noted a non-linear biotransformation of the test substance, namely, peak concentrations 4 hours after administration, which is also a standard pharmacokinetic indicator for dosages passing along the upper limit of the therapeutic latitude of the drug and is due to the fact that that at such dosages, the cytochrome P-450 enzyme system does not differ in reactivity compared to the absorption time of the substance.As a result of the experiment, we established the initial and peak levels of caffeine for further study of its changes during the artificial induction of hepatopathy of various origins in a specific experimental group of laboratory animals. We also noted the absence of dependence on the sex of the listed levels, and such results are consistent with the data obtained by other researchers.

Appraisal of the causal effect of plasma caffeine on adiposity, type 2 diabetes, and cardiovascular disease: two sample mendelian randomisation study

ObjectiveTo investigate the potential causal effects of long term plasma caffeine concentrations on adiposity, type 2 diabetes, and major cardiovascular diseases.DesignTwo sample mendelian randomisation study.SettingGenome-wide association study summary data for...

Early-life fecal metabolomics of food allergy.

Intestinal microenvironmental perturbations may increase food allergy risk. We hypothesize that children with clinical food allergy, those with food sensitization, and healthy children can be differentiated by intestinal metabolites in the first years of life. In this ancillary analysis of the Vitamin D Antenatal Asthma Reduction Trial (VDAART), we performed untargeted metabolomic profiling in 824 stool samples collected at ages 3-6months, 1year and 3 years. Subjects included 23 with clinical food allergy at age 3 and/or 6 years, 151 with food sensitization but no clinical food allergy, and 220 controls. We identified modules of correlated, functionally related metabolites and sought associations of metabolite modules and individual metabolites with food allergy/sensitization using regression models. Several modules of functionally related intestinal metabolites were reduced among subjects with food allergy, including bile acids at ages 3-6months and 1year, amino acids at age 3-6months, steroid hormones at 1year, and sphingolipids at age 3 years. One module primarily containing diacylglycerols was increased in those with food allergy at age 3-6months. Fecal caffeine metabolites at age 3-6months, likely derived from breast milk, were increased in those with food allergy and/or sensitization (beta=5.9, 95% CI 1.0-10.8, p=.02) and were inversely correlated with fecal bile acids and bilirubin metabolites, though maternal plasma caffeine levels were not associated with food allergy and/or sensitization. Several classes of bioactive fecal metabolites are associated with food allergy and/or sensitization including bile acids, steroid hormones, sphingolipids, and caffeine metabolites.

Association of Maternal Caffeine Consumption During Pregnancy With Child Growth

Greater caffeine consumption in pregnancy is associated with reduced birth size, but potential associations with childhood growth are unclear. To evaluate the associations of pregnancy caffeine and paraxanthine measures with child growth in a contemporary cohort with low caffeine consumption and a historical cohort with high caffeine consumption. The Environmental Influences on Child Health Outcomes cohort of the National Institute of Child Health and Human Development Fetal Growth Studies (ECHO-FGS; 10 sites, 2009-2013) was a pregnancy cohort with 1 child measurement between ages 4 and 8 years (follow-up in 2017-2019). The Collaborative Perinatal Project (CPP) was a pregnancy cohort (12 sites, 1959-1965) with child follow-up through 8 years (1960-1974). The current secondary analysis was conducted in 2021 and 2022. Concentrations of caffeine and its primary metabolite, paraxanthine, were quantified from plasma (ECHO-FGS) and serum (CPP) collected in the first trimester. Cut points for analyses were defined by quartiles in ECHO-FGS and quintiles in CPP. Child z scores for body mass index, weight, and height were evaluated, as well as fat mass index and percentage and obesity risk measured at 1 time between age 4 and 8 years in ECHO-FGS. In a secondary analysis of the CPP cohort, child z scores and obesity risk longitudinally through age 8 years were evaluated. In ECHO-FGS (median caffeine intake <50 mg/d), 788 children (mean [SD] age, 6.8 [1.0] years; 411 boys [52.2%]) of women in the fourth vs first quartile of plasma caffeine concentrations had lower height z scores (β = -0.21; 95% CI, -0.41 to -0.02), but differences in weight z scores were only observed in the third quartile (β = -0.27; 95% CI, -0.47 to -0.07). In CPP, beginning at age 4 years, 1622 children (805 boys [49.7%]) of women in the highest caffeine quintile group had lower height z scores than their peers from the lowest group, with the gap widening with each successive year of age (β = -0.16 [95% CI, -0.31 to -0.01] at 4 years; β = -0.37 [95% CI, -0.57 to -0.16] at 8 years). There were slight reductions in weight at ages 5 to 8 years for children in the third vs first caffeine quintile (β = -0.16 to -0.22). Results were consistent for paraxanthine concentrations in both cohorts. Intrauterine exposure to increasing levels of caffeine and paraxanthine, even in low amounts, was associated with shorter stature in early childhood. The clinical implication of reductions in height and weight is unclear; however, the reductions were apparent even with levels of caffeine consumption below clinically recommended guidelines of less than 200 mg per day.