Caffeine is a compound that can be found in coffee, green tea, Guarana, cocoa, yerba mate, and other plants. Caffeine is typically produced for supplemental use by water extraction of green tea leaves and other sources. Caffeine is quickly absorbed by the stomach and small intestine, and then dispersed to different parts of the body, including the brain.1

Major Health Benefits

Caffeine is known to stimulate the central nervous system and boost energy metabolism.2 Low doses (e.g., several cups of coffee per day) of caffeine may increase attention, concentration and ability to perform cognitive tasks.2-4 Benefits of caffeine ingestion on physical performance in team sports, sprinting, or resistance training have been observed.5,6


Excessive consumption of caffeine may cause agitation, disorientation, anxiety, and sleep disturbances.3,7,8 Consumption of caffeine during pregnancy has been associated with a reduction in fetal growth.9



  1. Higdon, Jane. Oregon State University: Linus Pauling Institute. 2005 (Reviewed by Katan, MB in 2008). Accessed in July 2015.
  2. Nehlig A, Daval JL, Debry G. Caffeine and the central nervous system: mechanisms of action, biochemical, metabolic and psychostimulant effects. Brain Res Brain Res Rev. 1992 May-Aug;17(2):139-70. PMID: 1356551.
  3. Bolton S. Caffeine: Psychological Effects, Use and Abuse.  Orthomolecular Psychiatry1981;10 (3): 202–211. (PDF).
  4. Snel J, Lorist MM. Effects of caffeine on sleep and cognition. Prog Brain Res. 2011;190:105-17.PMID: 21531247.
  5. Astorino TA, Roberson DW. Efficacy of acute caffeine ingestion for short-term high-intensity exercise performance: a systematic J Strength Cond Res.2010 Jan;24(1):257-65.PMID:19924012.
  6. Davis JK, Green JM. Caffeine and anaerobic performance: ergogenic value and mechanisms of action. Sports Med. 2009;39(10):813-32. PMID: 19757860.
  7. Winston AP (2005). Neuropsychiatric effects of caffeine. Advances in Psychiatric Treatment2005; 11 (6): 432–439. (Journal Page)
  8. Hughes RN. Drugs Which Induce Anxiety: Caffeine. New Zealand Journal of Psychology1996; 25 (1): 36–42. (PDF).
  9. Brent RL, Christian MS, Diener RM. Evaluation of the reproductive and developmental risks of caffeine. Birth Defects Res B Dev Reprod Toxicol. 2011 Apr;92(2):152-87. doi: 10.1002/bdrb.20288. Epub 2011 Mar 2. Review. PubMed PMID: 21370398; PubMed Central PMCID: PMC3121964.