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.

Visual paper-based sensor for the highly sensitive detection of caffeine in food and biological matrix based on CdTe-nano ZnTPyP combined with chemometrics

Caffeine naturally occurs in tea and cocoa, which is also used as an additive in beverages and has pharmacological effects such as refreshing, antidepressant, and digestion promotion, but excessive caffeine can cause harm to the human body. In this work, based on the specific response between nano zinc 5, 10, 15, 20-tetra(4-pyridyl)-21H-23H-porphine (nano ZnTPyP)-CdTe quantum dots (QDs) and caffeine, combined with chemometrics, a visual paper-based sensor was constructed for rapid and on-site detection of caffeine. The fluorescence of QDs can be quenched by nano ZnTPyP. When caffeine is added to the system, it can pull nano ZnTPyP off the surface of the QDs to achieve fluorescence recovery through electrostatic attraction and nitrogen/zinc coordination. The detection range is 5 × 10^-11~3 × 10^-9 mol L^-1, and the detection limit is 1.53 × 10^-11 mol L^-1 (R² = 0.9990) (S/N = 3). The paper-based sensor constructed exhibits good results in real samples, such as tea water, cell culture fluid, newborn bovine serum, and human plasma. Therefore, the sensor is expected to be applied to the rapid instrument-free detection of caffeine in food and biological samples.Graphical abstract.

Urinary glucose and ketone bodies as indicators of acute caffeine poisoning

AIM

In various countries, many fatal health problems have been reported due to high intake of caffeine-rich energy drinks, tablets, and powders. In patients with acute caffeine poisoning, determination of blood caffeine concentration is an important yet difficult task. We aimed to assess whether the presence of glucose and ketone bodies in urine reflected the blood caffeine concentration in patients with acute caffeine poisoning.

METHODS

From April 2010 to March 2018, 25 patients with an overdose of only caffeine-rich tablets were admitted to our hospital. Their clinical features were investigated. In addition, we investigated whether the glucose and ketone bodies in the urine reflected blood caffeine concentration in 23 patients who underwent the urine qualitative test at admission.

RESULTS

The majority of the patients were young healthy women, whose average caffeine ingestion was 15.6 ± 8.1 g. Initial urine examinations showed glucose in 60% (14/23) of patients and ketone bodies in 57% (13/23) of patients. Ketone bodies or glucose were found in 78% (18/23) of the patients. The correlation between blood caffeine concentration and urinary glucose was R = 0.625, blood caffeine concentration and ketone bodies was R = 0.596, and blood caffeine and both was R = 0.76.

CONCLUSION

Urine qualitative test is effective for differential diagnosis and severity assessment of acute caffeine poisoning in patients.

A Retrospective Study on the Epidemiological and Clinical Features of Emergency Patients with Large or Massive Consumption of Caffeinated Supplements or Energy Drinks in Japan

Objective We conducted a retrospective study on the epidemiological and clinical features of patients with acute caffeine poisoning in Japan. Methods Letters requesting participation were sent to 264 emergency departments of hospitals, and questionnaires were mailed to those that agreed to participate. Patients Participants were patients transported to emergency departments of hospitals between April 2011 and March 2016 after consuming large or massive amounts of caffeinated supplements and/or energy drinks (caffeine dose ≥1.0 g). Results We surveyed 101 patients from 38 emergency departments. Since April 2013, the number of patients has markedly increased. Of these young patients (median age, 25 years), 53 were men, and 97 had consumed caffeine in tablet form. Estimated caffeine doses (n=93) ranged from 1.2 to 82.6 g (median, 7.2 g). Serum caffeine levels on admission (n=17) ranged from 2.0 to 530.0 μg/mL (median level, 106.0 μg/mL). Common abnormal vital signs and laboratory data on admission included tachypnea, tachycardia, depressed consciousness, hypercreatinekinasemia, hyperglycemia, hypokalemia, hypophosphatemia, and hyperlactatemia. Common signs and symptoms in the clinical course included nausea, vomiting, excitement/agitation, and sinus tachycardia. Seven patients (6.9%) who had consumed ≥6.0 g of caffeine, or whose serum caffeine levels on admission were ≥200 μg/mL, developed cardiac arrest. Ninety-seven patients (96.0%) recovered completely, but 3 patients (3.0%) died. Conclusion The present analysis of data from more than 100 emergency patients revealed clinical features of moderate to fatal caffeine poisoning. We recommend highlighting the toxicity risks associated with ingesting highly caffeinated tablets.

Plasma lactate concentration as an indicator of plasma caffeine concentration in acute caffeine poisoning

Aim

Severe caffeine poisoning is rare, but is associated with high mortality. Plasma caffeine concentration is one of the indications of treatment of caffeine poisoning; however, it is not easily measured at most emergency departments. If the plasma lactate concentration and the plasma caffeine concentration were correlated, the plasma lactate concentration may be an indication of caffeine poisoning. In this study, we investigated the correlation between the plasma lactate concentration and the plasma caffeine concentration.

Methods

From April 2010 to March 2012, 18 patients with severe caffeine poisoning by overdose were admitted at our Emergency Center. The plasma lactate concentration and plasma caffeine concentration of 10 patients were determined at the same time at 12-24 h after admission. These findings were plotted and we analyzed the correlation and trends in these concentrations.

Results

There were strong correlations between the plasma lactate concentration and the plasma caffeine concentration at admission (n = 18) and at 12-24 h after admission (n = 10) (correlation coefficients, 0.95 and 0.91, respectively). There was a strong positive correlation between the trend of the plasma lactate concentration and the plasma caffeine concentration (n = 10). The correlation coefficient was 0.91.

Conclusion

These results are extremely beneficial for emergency department clinical physicians because such findings permit the determination of the severe caffeine poisoning patient. Additionally, the plasma lactate concentration might be one of the indicators of hospitalization and discharge.

Risk of caffeine toxicity associated with the use of 'legal highs' (novel psychoactive substances)

PURPOSE

Caffeine has desired stimulant effects similar to but weaker than both classical recreational drugs and novel psychoactive substances. This study was undertaken to determine the caffeine content of a sample of novel psychoactive substances, and we discuss the implications for the management of acute recreational drug toxicity.

METHODS

Six novel psychoactive products ('legal highs') that were not declared to contain caffeine were purchased from different Internet suppliers; one additional product was supplied by the UK police force. Analysis of these products was undertaken using infrared spectroscopy (IR), gas chromatography with mass spectrometry (GC-MS) and liquid chromatography with tandem mass spectrometry (LC-MS-MS) to identify the active ingredient(s) and measure the caffeine content of the product.

RESULTS

All seven products, which weighed approximately 1 g each, contained only caffeine as the active pharmacological compound. There was significant variation in the percentage caffeine content (<2 to 96%), with four powders containing very significant caffeine contents of 87-96%.

CONCLUSION

This study shows that individuals are at risk of significant caffeine toxicity related to the high caffeine content of some novel psychoactive substances. Clinicians, including clinical pharmacologists, need to be aware of this to ensure that the management of acute recreational drug toxicity is appropriate and that over-correction of any hypokalaemia does not occur.

Caffeine fatalities--do sales restrictions prevent intentional intoxications?

OBJECTIVE

Caffeine is widely available in beverages and in different over-the-counter products, including tablets containing 100 mg caffeine. Because intentional fatal intoxications with caffeine occur, the maximum quantity of caffeine tablets that can be bought over the counter in a single purchase was restricted from 250 to 30 in Sweden in the year 2004. The objective of this article was to study the effect of this decision on the number of fatal caffeine intoxications.

METHOD

In Sweden 95% of all cases undergoing forensic autopsy are screened for a number of drugs including caffeine. All cases during January 1993-September 2009 with a caffeine concentration above 80 microg/g blood were recorded.

RESULTS

During the study period toxicological investigations were performed in 83,580 forensic autopsies. Caffeine contributed to the fatal outcome in 20 cases (0.02%). Thirteen (65%) of these fatalities occurred before the introduction of the sales restriction. However, no fatal intoxications where caffeine contributed to the cause of death was recorded between May 2007 and September 2009.

CONCLUSION

Overdoses of tablets containing caffeine can be fatal, suicides as well as accidents occur. Restricting the maximum quantity of caffeine tablets available over the counter seemed to be effective in preventing suicides because of caffeine although some time elapsed until the effect was noted. Further monitoring is required to ensure that the observed lower caffeine mortality is a sustained effect.