Caffeine

Last Updated: September 28 2022

Caffeine is a stimulatory anti-sleep compound extracted from coffee beans. Habitual caffeine use leads to tolerance, which dulls several of caffeine’s effects.

Caffeine is most often used for

Summary

What does caffeine do?

Caffeine comes from coffee beans, but it can also be synthesized in a laboratory. It has the same structure whether it’s in coffee, energy drinks, tea, or pills.

Caffeine is a powerful stimulant, and it can be used to improve physical strength and endurance. It is classified as a nootropic because it sensitizes neurons and provides mental stimulation.

Habitual caffeine use is also associated with a reduced risk of Alzheimer's disease, cirrhosis, and liver cancer.

Caffeine’s main mechanism concerns antagonizing adenosine receptors. Adenosine causes sedation and relaxation when it acts upon its receptors, located in the brain. Caffeine prevents this action and causes alertness and wakefulness. This inhibition of adenosine can influence the dopamine, serotonin, acetylcholine, and adrenaline systems.

For practical tips on the optimal use of caffeine, check out our Supplement Guides.

What else is Caffeine known as?
Note that Caffeine is also known as:
  • Coffee extract
  • Tea extract
  • 1 3 7-Trimethylxanthine
Caffeine should not be confused with:
  • Caffeic acid
Dosage information

Caffeine dosages should be tailored to individuals. If you are new to caffeine supplements, start with a 100mg dose. Typically, 200mg of caffeine is used for fat-burning supplementation, while higher doses of 3–6 mg/kg of body weight are typically used to increase strength.

Caffeine can be supplemented through popular beverages, like coffee, tea, and energy drinks, but it can also be taken in a pill form.

Many of caffeine’s effects, including fat burning, strength benefits, and euphoria, are subject to tolerance, and may not occur in people used to caffeine, no matter how large the dose is.

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      References
      2.^Vieira MA, Maraschin M, Pagliosa CM, Podestá R, de Simas KN, Rockenbach II, Amboni RD, Amante ERPhenolic acids and methylxanthines composition and antioxidant properties of mate (Ilex paraguariensis) residueJ Food Sci.(2010 Apr)
      3.^Burdock GA, Carabin IG, Crincoli CMSafety assessment of kola nut extract as a food ingredientFood Chem Toxicol.(2009 Aug)
      4.^Heishman SJ, Henningfield JEStimulus functions of caffeine in humans: relation to dependence potentialNeurosci Biobehav Rev.(1992 Fall)
      5.^Barone JJ, Roberts HRCaffeine consumptionFood Chem Toxicol.(1996 Jan)
      6.^Frary CD, Johnson RK, Wang MQFood sources and intakes of caffeine in the diets of persons in the United StatesJ Am Diet Assoc.(2005 Jan)
      7.^Knight CA, Knight I, Mitchell DCBeverage caffeine intakes in young children in Canada and the USCan J Diet Pract Res.(2006 Summer)
      11.^Gummadi SN, Bhavya B, Ashok NPhysiology, biochemistry and possible applications of microbial caffeine degradationAppl Microbiol Biotechnol.(2012 Jan)
      13.^Zhang L, Kujawinski DM, Federherr E, Schmidt TC, Jochmann MACaffeine in your drink: natural or syntheticAnal Chem.(2012 Mar 20)
      18.^Jeukendrup AE, Randell RFat burners: nutrition supplements that increase fat metabolismObes Rev.(2011 Oct)
      19.^Diepvens K, Westerterp KR, Westerterp-Plantenga MSObesity and thermogenesis related to the consumption of caffeine, ephedrine, capsaicin, and green teaAm J Physiol Regul Integr Comp Physiol.(2007 Jan)
      21.^Carrillo JA, Christensen M, Ramos SI, Alm C, Dahl ML, Benitez J, Bertilsson LEvaluation of caffeine as an in vivo probe for CYP1A2 using measurements in plasma, saliva, and urineTher Drug Monit.(2000 Aug)
      22.^Liguori A, Hughes JR, Grass JAAbsorption and subjective effects of caffeine from coffee, cola and capsulesPharmacol Biochem Behav.(1997 Nov)
      24.^Thakur RA, Michniak BB, Meidan VMTransdermal and buccal delivery of methylxanthines through human tissue in vitroDrug Dev Ind Pharm.(2007 May)
      25.^Kamimori GH, Karyekar CS, Otterstetter R, Cox DS, Balkin TJ, Belenky GL, Eddington NDThe rate of absorption and relative bioavailability of caffeine administered in chewing gum versus capsules to normal healthy volunteersInt J Pharm.(2002 Mar 2)
      29.^Blanchard J, Sawers SJComparative pharmacokinetics of caffeine in young and elderly menJ Pharmacokinet Biopharm.(1983 Apr)
      30.^Blanchard J, Sawers SJThe absolute bioavailability of caffeine in manEur J Clin Pharmacol.(1983)
      31.^Bonati M, Latini R, Galletti F, Young JF, Tognoni G, Garattini SCaffeine disposition after oral dosesClin Pharmacol Ther.(1982 Jul)
      34.^Cox GR, Desbrow B, Montgomery PG, Anderson ME, Bruce CR, Macrides TA, Martin DT, Moquin A, Roberts A, Hawley JA, Burke LMEffect of different protocols of caffeine intake on metabolism and endurance performanceJ Appl Physiol.(2002 Sep)
      35.^Marks V, Kelly JFAbsorption of caffeine from tea, coffee, and coca colaLancet.(1973 Apr 14)
      36.^Mumford GK, Benowitz NL, Evans SM, Kaminski BJ, Preston KL, Sannerud CA, Silverman K, Griffiths RRAbsorption rate of methylxanthines following capsules, cola and chocolateEur J Clin Pharmacol.(1996)
      37.^Fredholm BB, Bättig K, Holmén J, Nehlig A, Zvartau EEActions of caffeine in the brain with special reference to factors that contribute to its widespread usePharmacol Rev.(1999 Mar)
      38.^Eteng MU, Eyong EU, Akpanyung EO, Agiang MA, Aremu CYRecent advances in caffeine and theobromine toxicities: a reviewPlant Foods Hum Nutr.(1997)
      39.^Tansy MF, Kendall FMExperimental and clinical aspects of gastrocolic reflexesAm J Dig Dis.(1973 Jun)
      40.^Lohsiriwat S, Kongmuang P, Leelakusolvong SEffects of caffeine on anorectal manometric findingsDis Colon Rectum.(2008 Jun)
      41.^Stacewicz-Sapuntzakis M, Bowen PE, Hussain EA, Damayanti-Wood BI, Farnsworth NRChemical composition and potential health effects of prunes: a functional foodCrit Rev Food Sci Nutr.(2001 May)
      42.^Crozier TW, Stalmach A, Lean ME, Crozier AEspresso coffees, caffeine and chlorogenic acid intake: potential health implicationsFood Funct.(2012 Jan)
      47.^Chen Y, Xiao CQ, He YJ, Chen BL, Wang G, Zhou G, Zhang W, Tan ZR, Cao S, Wang LP, Zhou HHGenistein alters caffeine exposure in healthy female volunteersEur J Clin Pharmacol.(2011 Apr)
      51.^Kennedy JS, Leduc BW, Scavone JM, Harmatz JS, Shader RI, Greenblatt DJPharmacokinetics of intravenous caffeine: comparison of high-performance liquid chromatographic and gas chromatographic methodsJ Chromatogr.(1987 Nov 27)
      52.^Newton R, Broughton LJ, Lind MJ, Morrison PJ, Rogers HJ, Bradbrook IDPlasma and salivary pharmacokinetics of caffeine in manEur J Clin Pharmacol.(1981)
      53.^Collomp K, Anselme F, Audran M, Gay JP, Chanal JL, Prefaut CEffects of moderate exercise on the pharmacokinetics of caffeineEur J Clin Pharmacol.(1991)
      54.^Burg AW, Werner ETissue distribution of caffeine and its metabolites in the mouseBiochem Pharmacol.(1972 Apr 1)
      57.^Yang A, Palmer AA, de Wit HGenetics of caffeine consumption and responses to caffeinePsychopharmacology (Berl).(2010 Aug)
      62.^Womack CJ, Saunders MJ, Bechtel MK, Bolton DJ, Martin M, Luden ND, Dunham W, Hancock MThe influence of a CYP1A2 polymorphism on the ergogenic effects of caffeineJ Int Soc Sports Nutr.(2012 Mar 15)
      64.^Ghotbi R, Christensen M, Roh HK, Ingelman-Sundberg M, Aklillu E, Bertilsson LComparisons of CYP1A2 genetic polymorphisms, enzyme activity and the genotype-phenotype relationship in Swedes and KoreansEur J Clin Pharmacol.(2007 Jun)
      65.^Djordjevic N, Ghotbi R, Bertilsson L, Jankovic S, Aklillu EInduction of CYP1A2 by heavy coffee consumption in Serbs and SwedesEur J Clin Pharmacol.(2008 Apr)
      66.^Djordjevic N, Ghotbi R, Jankovic S, Aklillu EInduction of CYP1A2 by heavy coffee consumption is associated with the CYP1A2 -163C>A polymorphismEur J Clin Pharmacol.(2010 Jul)
      67.^Djordjevic N, Carrillo JA, Roh HK, Karlsson S, Ueda N, Bertilsson L, Aklillu EComparison of N-Acetyltransferase-2 Enzyme Genotype-Phenotype and Xanthine Oxidase Enzyme Activity Between Swedes and KoreansJ Clin Pharmacol.(2011 Nov 21)
      68.^Djordjevic N, Carrillo JA, Gervasini G, Jankovic S, Aklillu EIn vivo evaluation of CYP2A6 and xanthine oxidase enzyme activities in the Serbian populationEur J Clin Pharmacol.(2010 Jun)
      70.^Aklillu E, Carrillo JA, Makonnen E, Bertilsson L, Ingelman-Sundberg MXanthine oxidase activity is influenced by environmental factors in EthiopiansEur J Clin Pharmacol.(2003 Oct)
      71.^Saruwatari J, Nakagawa K, Shindo J, Tajiri T, Fujieda M, Yamazaki H, Kamataki T, Ishizaki TA population phenotyping study of three drug-metabolizing enzymes in Kyushu, Japan, with use of the caffeine testClin Pharmacol Ther.(2002 Aug)
      72.^Guerciolini R, Szumlanski C, Weinshilboum RMHuman liver xanthine oxidase: nature and extent of individual variationClin Pharmacol Ther.(1991 Dec)
      75.^Tantcheva-Poór I, Zaigler M, Rietbrock S, Fuhr UEstimation of cytochrome P-450 CYP1A2 activity in 863 healthy Caucasians using a saliva-based caffeine testPharmacogenetics.(1999 Apr)
      78.^Schrenk D, Brockmeier D, Mörike K, Bock KW, Eichelbaum MA distribution study of CYP1A2 phenotypes among smokers and non-smokers in a cohort of healthy Caucasian volunteersEur J Clin Pharmacol.(1998 Jan)
      79.^Butler MA, Lang NP, Young JF, Caporaso NE, Vineis P, Hayes RB, Teitel CH, Massengill JP, Lawsen MF, Kadlubar FFDetermination of CYP1A2 and NAT2 phenotypes in human populations by analysis of caffeine urinary metabolitesPharmacogenetics.(1992 Jun)
      80.^Parsons WD, Neims AHEffect of smoking on caffeine clearanceClin Pharmacol Ther.(1978 Jul)
      81.^Simon T, Becquemont L, Hamon B, Nouyrigat E, Chodjania Y, Poirier JM, Funck-Brentano C, Jaillon PVariability of cytochrome P450 1A2 activity over time in young and elderly healthy volunteersBr J Clin Pharmacol.(2001 Nov)
      85.^Arnaud MJThe pharmacology of caffeineProg Drug Res.(1987)
      87.^Zhang M, Poplawski M, Yen K, Cheng H, Bloss E, Zhu X, Patel H, Mobbs CVRole of CBP and SATB-1 in aging, dietary restriction, and insulin-like signalingPLoS Biol.(2009 Nov)
      88.^Lublin A, Isoda F, Patel H, Yen K, Nguyen L, Hajje D, Schwartz M, Mobbs CFDA-approved drugs that protect mammalian neurons from glucose toxicity slow aging dependent on cbp and protect against proteotoxicityPLoS One.(2011)
      89.^Wanke V, Cameroni E, Uotila A, Piccolis M, Urban J, Loewith R, De Virgilio CCaffeine extends yeast lifespan by targeting TORC1Mol Microbiol.(2008 Jul)
      90.^Powers RW 3rd, Kaeberlein M, Caldwell SD, Kennedy BK, Fields SExtension of chronological life span in yeast by decreased TOR pathway signalingGenes Dev.(2006 Jan 15)
      91.^Wanke V, Pedruzzi I, Cameroni E, Dubouloz F, De Virgilio CRegulation of G0 entry by the Pho80-Pho85 cyclin-CDK complexEMBO J.(2005 Dec 21)
      92.^Cameroni E, Hulo N, Roosen J, Winderickx J, De Virgilio CThe novel yeast PAS kinase Rim 15 orchestrates G0-associated antioxidant defense mechanismsCell Cycle.(2004 Apr)
      93.^Fabrizio P, Pozza F, Pletcher SD, Gendron CM, Longo VDRegulation of longevity and stress resistance by Sch9 in yeastScience.(2001 Apr 13)
      94.^Reinders A, Bürckert N, Boller T, Wiemken A, De Virgilio CSaccharomyces cerevisiae cAMP-dependent protein kinase controls entry into stationary phase through the Rim15p protein kinaseGenes Dev.(1998 Sep 15)
      95.^Liu Y, Burger SK, Ayers PW, Vöhringer-Martinez EComputational study of the binding modes of caffeine to the adenosine A2A receptorJ Phys Chem B.(2011 Dec 1)
      96.^Paluska SACaffeine and exerciseCurr Sports Med Rep.(2003 Aug)
      97.^Porkka-Heiskanen TMethylxanthines and sleepHandb Exp Pharmacol.(2011)
      98.^Huang ZL, Urade Y, Hayaishi OThe role of adenosine in the regulation of sleepCurr Top Med Chem.(2011)
      99.^Ferre S, Ciruela F, Borycz J, Solinas M, Quarta D, Antoniou K, Quiroz C, Justinova Z, Lluis C, Franco R, Goldberg SRAdenosine A1-A2A receptor heteromers: new targets for caffeine in the brainFront Biosci.(2008 Jan 1)
      100.^Elmenhorst D, Meyer PT, Matusch A, Winz OH, Bauer ACaffeine Occupancy of Human Cerebral A1 Adenosine Receptors: In Vivo Quantification with 18F-CPFPX and PETJ Nucl Med.(2012 Nov)
      103.^Fredholm BB, Abbracchio MP, Burnstock G, Daly JW, Harden TK, Jacobson KA, Leff P, Williams MNomenclature and classification of purinoceptorsPharmacol Rev.(1994 Jun)
      106.^Björklund O, Halldner-Henriksson L, Yang J, Eriksson TM, Jacobson MA, Daré E, Fredholm BBDecreased behavioral activation following caffeine, amphetamine and darkness in A3 adenosine receptor knock-out micePhysiol Behav.(2008 Dec 15)
      108.^Holtzman SG, Mante S, Minneman KPRole of adenosine receptors in caffeine toleranceJ Pharmacol Exp Ther.(1991 Jan)
      109.^Varani K, Portaluppi F, Merighi S, Ongini E, Belardinelli L, Borea PACaffeine alters A2A adenosine receptors and their function in human plateletsCirculation.(1999 May 18)
      110.^Conlay LA, Conant JA, deBros F, Wurtman RCaffeine alters plasma adenosine levelsNature.(1997 Sep 11)
      112.^Khaliq S, Haider S, Naqvi F, Perveen T, Saleem S, Haleem DJAltered brain serotonergic neurotransmission following caffeine withdrawal produces behavioral deficits in ratsPak J Pharm Sci.(2012 Jan)
      113.^Chen MD, Lin WH, Song YM, Lin PY, Ho LTEffect of caffeine on the levels of brain serotonin and catecholamine in the genetically obese miceZhonghua Yi Xue Za Zhi (Taipei).(1994 May)
      114.^Okada M, Kawata Y, Kiryu K, Mizuno K, Wada K, Tasaki H, Kaneko SEffects of adenosine receptor subtypes on hippocampal extracellular serotonin level and serotonin reuptake activityJ Neurochem.(1997 Dec)
      115.^Chin A, Svejda B, Gustafsson BI, Granlund AB, Sandvik AK, Timberlake A, Sumpio B, Pfragner R, Modlin IM, Kidd MThe role of mechanical forces and adenosine in the regulation of intestinal enterochromaffin cell serotonin secretionAm J Physiol Gastrointest Liver Physiol.(2012 Feb)
      119.^Shi D, Daly JWChronic effects of xanthines on levels of central receptors in miceCell Mol Neurobiol.(1999 Dec)
      120.^Conde SV, Nunes da Silva T, Gonzalez C, Mota Carmo M, Monteiro EC, Guarino MPChronic caffeine intake decreases circulating catecholamines and prevents diet-induced insulin resistance and hypertension in ratsBr J Nutr.(2012 Jan)
      121.^Bangsbo J, Jacobsen K, Nordberg N, Christensen NJ, Graham TAcute and habitual caffeine ingestion and metabolic responses to steady-state exerciseJ Appl Physiol.(1992 Apr)
      122.^Solinas M, Ferré S, You ZB, Karcz-Kubicha M, Popoli P, Goldberg SRCaffeine induces dopamine and glutamate release in the shell of the nucleus accumbensJ Neurosci.(2002 Aug 1)
      123.^Quarta D, Borycz J, Solinas M, Patkar K, Hockemeyer J, Ciruela F, Lluis C, Franco R, Woods AS, Goldberg SR, Ferré SAdenosine receptor-mediated modulation of dopamine release in the nucleus accumbens depends on glutamate neurotransmission and N-methyl-D-aspartate receptor stimulationJ Neurochem.(2004 Nov)
      126.^Carter AJ, O'Connor WT, Carter MJ, Ungerstedt UCaffeine enhances acetylcholine release in the hippocampus in vivo by a selective interaction with adenosine A1 receptorsJ Pharmacol Exp Ther.(1995 May)