Caffeine and Doping—What Have We Learned since 2004

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

included in the analysis. The authors detected a significant increase in the percentage of samples with detectable caffeine between 2004-2008 and 2015. Their investigations also reveal that there are significant differences between different sports disciplines in the consumption of caffeine. The highest urine caffeine concentrations were detected in disciplines having an aerobic-like nature, such as cycling, athletics and rowing. The highest increases between 2004-2008 and 2015 were detected in aquatics, but also disciplines relevant for public sports, such as football [13].
Reviewing these data, it is obvious that the removal of caffeine from the list of banned substances has not resulted is a strong increase in the consumption of caffeine, at least in the analyzed population of athletes and in Spain. However, the performance-enhancing effect of caffeine is believed to be dependent on a variety of factors, such as individual genetics [14,15], microbiome [16], nutrition [17], combination with other substances [12] and also the nature of performance [13]. Therefore, it is likely that the uptake of caffeine may not result in all athletes in an enhancement of performance, and this could explain the moderate increase in the total of all analyzed samples. Nevertheless, the data from Navaro et. all show a clear trend in an increased use of caffeine in athletes in the monitoring program. Taking in account that the use of caffeine in athletes that are not participating in the monitoring program and in public sports may also follow this trend, we have to conclude that a significant and increasing number of people worldwide consume caffeine with the aim to enhance performance. In these individuals, a high uptake of the substance meets high-intensity exercise. This is alarming in relation to the concerns about caffeine related to safety and possible adverse effects. The European food safety administration (EFSA) has published in 2015 a Scientific Opinion on the safety of caffeine [2]. EFSA has come to the conclusion that habitual caffeine consumption of up to 400 mg per day does not give rise to safety concerns for non-pregnant adults. Habitual caffeine consumption of up to 200 mg per day by pregnant women does not give rise to safety concerns for the fetus. Single doses of caffeine and habitual caffeine intakes of up to 200 mg consumed by lactating women do not give rise to safety concerns for breastfed infants. This seems to be good news; however, in relation to sports, it is of relevance that an increasing consumption of caffeine, especially in public sports, is via energy drinks. Energy drinks consumed for the uptake of caffeine are no sports drinks. They are hypertonic because they contain high concentrations of sugar [12], resulting in a slower uptake of water. Moreover, the high sugar concentrations may result in a higher thirstiness resolution in a higher consumption of such drinks and a least in a high uptake of caffeine [12]. There are no indications that an uptake of up to 200 mg also in combination with intensive physical performance does increase individual health risk (2). However, the risk of higher concentrations of caffeine in combination with physical activity is uncertain and there is a variety of safety concerns in relation to several physiological and pathologic scenarios [18]. Moreover, it is very likely that individuals consuming caffeine with the aim to enhance performance consume much higher amounts than 200 mg a day.
In conclusion, the data provided by Navarro et al., 2019, provide indications that the use of caffeine in elite sports has increased after its removal from the list of banned substances 2004. There is also increasing evidence that the ergogenic activity of caffeine and individual genetics, metabolics and variables determine these effects. Moreover, the safety of caffeine, at least at high doses and in combination with other substances, is still under debate. Therefore, further research is needed in this field. In the future, the monitoring of caffeine consumption in elite sports during doping control needs to be continued.
Funding: This research received no external funding.

Conflicts of Interest:
The author declares no conflict of interest.