Caffeine Intake: Benefits, Myths, and Safety
Caffeine is a widely used stimulant that has been studied extensively and recommended for its ergogenic effects. The stimulant works by preventing adenosine to act upon its receptors in the brain which produces relaxation. Therefore, by ingesting caffeine, there is more alertness available. Some of the benefits include increased anaerobic running capacity (Graham-Paulson et al., 2016), an increase in power output in both trained and sedentary individuals (Grgic et al., 2018), and overall enhanced performance (Schneiker et al. 2006).
However, habitual caffeine intake can lead to a high tolerance meaning, the effects of caffeine are no longer felt by the individual. The best way to counteract these effects is to reduce caffeine intake or moderately drink it. Although habitual caffeine intake has been questioned regarding its effects on exercise performance, it is still unclear and mixed due to genetics, prior use, and lifestyle (Guest et al., 2021). Because of these factors, it is hard to come down to a conclusion about the effects of habitual caffeine intake.
Myths and Safety
Not only does it have ergogenic benefits but it has been studied repeatedly for its safety, therefore, it is safe to say that caffeine is a top ergogenic aid. However, even with the extensive research reporting the safety of ingesting caffeine, there still seems to be a bad rap around the ergogenic aid and some go as far as saying it can be carcinogenic. According to the American Cancer Society, the evidence supporting the association between coffee drinking and cancer is “unclear’ and instead, there are many health benefits from consuming coffee. Not only has drinking coffee been found to lower the risk of different types of cancer but also lower the risk of insulin resistance and type 2 diabetes which has been linked to breast, liver, and endometrial cancer incidence and/or mortality (The American Cancer Society, 2018).
As with most supplements, taking caffeine can lead to some side effects including anxiety, heart palpitations (Childs et al., 2008), headaches and sleep quality (Ramos-Campos et al., 2019). Childs et al. (2008) found that certain genotypes impact anxiety levels in subjects as opposed to just considering the dose. For example, the researchers looked at the associations between the anxiety-inducing effects of caffeine and the genotypes ADORA2A and DRD2 polymorphisms. They found a significant association between self-reported anxiety and ADORA2A after a moderate dose of caffeine. However, the subjects in this study were not caffeine users and so, might not be a good representation of the general public.
According to a systematic review, consumption of 400mg/caffeine in healthy adults was not associated with adverse cardiovascular or behavioral effects, and 300mg/caffeine in healthy, pregnant women was not associated with adverse reproductive and developmental effects (Wikoff et al., 2017). Nawrot et al. (2003) found no adverse effects after reviewing the potential adverse-effect areas such as acute toxicity, cardiovascular, bone and calcium, behavior and development, and reproductive toxicity and was later reviewed by Doepker et al. (2018) which confirmed the same results.
With the extensive research available on caffeine, not only athletes can benefit from the ergogenic aid and trust that it is safe to use but also the general population. As with mostly everything, it is the dose that makes the poison.
The co-hosts of Stronger by Science, Greg Nuckols and Eric Trexlor, discuss caffeine regarding heart health and the effects of habitual caffeine intake. They go over how there could be limitations to those studies showing a cardiovascular impact from drinking caffeine such as those who drink more coffee tend to smoke a lot, too. The co-hosts also go over the protective effects of drinking coffee.
References:
Childs, E., Hohoff, C., Deckert, J., Xu, K., Badner, J., & de Wit, H. (2008). Association between ADORA2A and DRD2 polymorphisms and caffeine-induced anxiety. Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology, 33(12), 2791–2800. https://doi.org/10.1038/npp.2008.17
Cornelis M. C. (2019). The Impact of Caffeine and Coffee on Human Health. Nutrients, 11(2), 416. https://doi.org/10.3390/nu11020416
Graham-Paulson, T., Perret, C., & Goosey-Tolfrey, V. (2016). Improvements in Cycling but Not Handcycling 10 km Time Trial Performance in Habitual Caffeine Users. Nutrients, 8(7), 393. https://doi.org/10.3390/nu8070393
Grgic, J., Trexler, E. T., Lazinica, B., & Pedisic, Z. (2018). Effects of caffeine intake on muscle strength and power: a systematic review and meta-analysis. Journal of the International Society of Sports Nutrition, 15, 11. https://doi.org/10.1186/s12970-018-0216-0
Guest, N. S., VanDusseldorp, T. A., Nelson, M. T., Grgic, J., Schoenfeld, B. J., Jenkins, N., Arent, S. M., Antonio, J., Stout, J. R., Trexler, E. T., Smith-Ryan, A. E., Goldstein, E. R., Kalman, D. S., & Campbell, B. I. (2021). International society of sports nutrition position stand: caffeine and exercise performance. Journal of the International Society of Sports Nutrition, 18(1), 1. https://doi.org/10.1186/s12970-020-00383-4
Nawrot, P., Jordan, S., Eastwood, J., Rotstein, J., Hugenholtz, A., & Feeley, M. (2003). Effects of caffeine on human health. Food additives and contaminants, 20(1), 1–30. https://doi.org/10.1080/0265203021000007840
Ramos-Campo, D. J., Pérez, A., Ávila-Gandía, V., Pérez-Piñero, S., & Rubio-Arias, J. Á. (2019). Impact of Caffeine Intake on 800-m Running Performance and Sleep Quality in Trained Runners. Nutrients, 11(9), 2040. https://doi.org/10.3390/nu11092040
Schneiker, K. T., Bishop, D., Dawson, B., & Hackett, L. P. (2006). Effects of caffeine on prolonged intermittent-sprint ability in team-sport athletes. Medicine and science in sports and exercise, 38(3), 578–585. https://doi.org/10.1249/01.mss.0000188449.18968.62
