Caffeine* is a bitter ingredient that you may have tried in a variety of drinks such a coffee and tea. It is also found in foods such as cacao beans, guarana berries and kola nuts (1, 2).

Discovered thousands of years ago, caffeine was first consumed in 2737 BC as a tea when a Chinese Emperor boiled drinking water and added leaves from a nearby bush (3, 4). Coffee consumption, on the other hand, started by eating whole beans (5). It lasted until 1000 AD before infusions with boiled water started to be consumed(5). On average, modern Europeans consume 37-319 mg of caffeine per day (6).

Caffeine is a nervous system stimulant; it prevents your nerve cells (e.g., in the brain) from feeling tired. That’s why caffeine can have such an impact on your body’s functioning. Discover the effects of caffeine and how it works on Sports Performance.

Research has shown that when more than 75 mg of caffeine is consumed, you feel more alert (7, 8). With several cognitive functions taking effect, it can increase reaction time, attention, vigilance and even mood (1, 9-14). Effects on “reaction time” and “attention” appeal to the imagination; a person is able to react quickly to a signal and is better able to turn his/her attention to task-relevant information and not get distracted. Vigilance is the ability to sustain performance on lengthy, tedious tasks.

Due to its effects, caffeine may increase perceived energy or “mental energy” and therefore is likely to change your mood too (1, 15, 16). Some studies even suggest that habitual consumption of caffeine may improve long-term memory (10). Levels as low as 21-35 mg (in a 70 kg person) can impact cognitive performance (1, 9-14). By comparison, a large cup (240 ml) of brewed coffee contains 102-200 mg caffeine and a large cup of tea contains 40-130 mg caffeine, depending on the type (4). So, caffeine may be helpful when you need to stay focused at work and perfect for when you need to be on your guard and react quick.

When consuming caffeine, stimulatory effects may start 15 to 30 minutes later and last for several hours (6). Not surprisingly, caffeine may affect the quality of your sleep, especially in older generation (17). Sensitivity to caffeine is genetically determined (17). So, if you’re looking to improve focus, or sharpen alertness, do so with ease. Enjoy a cup of coffee as part of a healthy, balanced lifestyle.

*Caffeine levels of up to 400 mg per day, can be consumed by without any safety concerns. Pregnant & breastfeeding women are recommended to consumed up to 200 mg/d (1).

References

1. McLellan TM, Caldwell JA, Lieberman HR. A review of caffeine’s effects on cognitive, physical and occupational performance. Neuroscience & Biobehavioral Reviews. 2016;71:294-312.
2. EFSA. Scientific Opinion on the safety of caffeine. EFSA Journal. 2015;13 (5): 4102.
3. Arab L, Blumberg JB. Introduction to the Proceedings of the Fourth International Scientific Symposium on Tea and Human Health. The Journal of Nutrition. 2008;138(8):1526S-8S.
4. Heckman MA, Weil J, De Mejia EG. Caffeine (1, 3, 7‐trimethylxanthine) in foods: a comprehensive review on consumption, functionality, safety, and regulatory matters. Journal of food science. 2010;75(3):R77-R87.
5. Fredholm BB. Methylxanthines: Springer Science & Business Media; 2010.
6. EFSA. EFSA explains risk assessment. Caffeine2015. Available from: https://www.efsa.europa.eu/sites/default/files/corporate_publications/files/efsaexplainscaffeine150527.pdf.
7. EFSA. Scientific Opinion on the substantiation of health claims related to caffeine and increased fat oxidation leading to a reduction in body fat mass (ID 735, 1484), increased energy expenditure leading to a reduction in body weight (ID 1487), increased alertness (ID 736, 1101, 1187, 1485, 1491, 2063, 2103) and increased attention (ID 736, 1485, 1491, 2375) pursuant to Article 13 (1) of Regulation (EC) No 1924/2006. EFSA Journal. 2011;9(4):2054.
8. Konishi Y, Hori H, Ide K, Katsuki A, Atake K, Igata R, et al. Effect of single caffeine intake on neuropsychological functions in healthy volunteers: A double-blind placebo-controlled study. PloS one. 2018;13(10):e0202247.
9. Christopher G, Sutherland D, Smith A. Effects of caffeine in non‐withdrawn volunteers. Human Psychopharmacology: Clinical and Experimental. 2005;20(1):47-53.
10. Hameleers PM, Van Boxtel MJ, Hogervorst E, Riedel W, Houx P, Buntinx F, et al. Habitual caffeine consumption and its relation to memory, attention, planning capacity and psychomotor performance across multiple age groups. Human Psychopharmacology: Clinical and Experimental. 2000;15(8):573-81.
11. Haskell CF, Kennedy DO, Wesnes KA, Scholey AB. Cognitive and mood improvements of caffeine in habitual consumers and habitual non-consumers of caffeine. Psychopharmacology. 2005;179(4):813-25.
12. Smith A, Sutherland D, Christopher G. Effects of repeated doses of caffeine on mood and performance of alert and fatigued volunteers. Journal of Psychopharmacology. 2005;19(6):620-6.
13. Smith A. Effects of caffeine in chewing gum on mood and attention. Human Psychopharmacology: Clinical and Experimental. 2009;24(3):239-47.
14. Einöther SJ, Giesbrecht T. Caffeine as an attention enhancer: reviewing existing assumptions. Psychopharmacology. 2013;225(2):251-74.
15. O’Connor PJ, Kennedy DO, Stahl S. Mental energy: plausible neurological mechanisms and emerging research on the effects of natural dietary compounds. Nutritional Neuroscience. 2019:1-15.
16. Lieberman HR. Cognitive methods for assessing mental energy. Nutritional Neuroscience. 2007;10(5-6):229-42.
17. Clark I, Landolt HP. Coffee, caffeine, and sleep: A systematic review of epidemiological studies and randomized controlled trials. Sleep Medicine Reviews. 2017;31:70-8.