Although both contain behaviourally significant concentrations of caffeine, tea is commonly perceived to be a less stimulating drink than coffee. At least part of the explanation for this may be that theanine, which is present in tea but not coffee, has relaxing effects. There is also some evidence that theanine affects cognitive performance, and it has been found to reduce blood pressure in hypertensive rats.
To study the subjective, behavioural and blood pressure effects of theanine and caffeine administered alone and together, in doses relevant to the daily tea consumption of regular tea drinkers.
Materials and methods
In a randomised, double-blind, placebo-controlled study, healthy adult participants (n = 48) received either 250-mg caffeine, 200-mg theanine, both or neither of these. They completed ratings of mood, including anxiety, and alertness, and had their blood pressure measured before and starting 40 min after drug administration. Anxiety was also assessed using a visual probe task.
Caffeine increased self-rated alertness and jitteriness and blood pressure. Theanine antagonised the effect of caffeine on blood pressure but did not significantly affect jitteriness, alertness or other aspects of mood. Theanine also slowed overall reaction time on the visual probe task.
Theanine is a physiologically and behaviourally active compound and, while it is unclear how its effects might explain perceived differences between tea and coffee, evidence suggests that it may be useful for reducing raised blood pressure.
This is a preview of subscription content, log in to check access.
Buy single article
Instant access to the full article PDF.
Price includes VAT for USA
Subscribe to journal
Immediate online access to all issues from 2019. Subscription will auto renew annually.
This is the net price. Taxes to be calculated in checkout.
Alsene K, Deckert J, Sand P, de Wit H et al (2003) Association between A2a receptor gene polymorphisms and caffeine-induced anxiety. Neuropsychopharmacol 28:1694–1702
Arts ICW, Hollman PCH (2005) Polyphenols and disease risk in epidemiologic studies. Am J Clin Nutr 81(suppl):317S–325S
Arts ICW, Hollman PCH, Feskens EJM, de Mesquita HBB, Kromhout D (2001) Catechin intake might explain the inverse relation between tea consumption and ischaemic heart disease: the Zutphen Elderly Study. Am J Clin Nutr 74:227–232
Balentine DA, Wiseman SA, Bouwens LCM (1997) The chemistry of tea flavonoids. Crit Rev Food Sci Nutr 37:693–704
Botella P, Parra A (2003) Coffee increases state anxiety in males but not in females. Hum Psychopharmacol 18:141–143
Cornelis MC, El-Sohemy A (2005) Coffee, caffeine, and coronary heart disease. Curr Opin Lipidology 18:13–19
Dubick MA, Omaye ST (2006) Grape wine and tea polyphenols in the modulation of atherosclerosis and heart disease. In: Wildman REC (ed) Handbook of nutraceuticals and functional foods, second edition. Taylor and Francis, London, pp 101–130
Dunwiddie TV, Masino SA (2001) The role and regulation of adenosine in the central nervous system. Annu Rev Neurosci 24:31–55
Ekborg-Ott KH, Taylor A, Armstrong DW (1997) Varietal differences in the total and enantiomeric composition of theanine in tea. J Agric Food Chem 45:353–363
Food Standards Agency (2004) Survey of caffeine levels in hot beverages. Food Survey Information Sheet 53/04. http://www.food.gov.uk/multimedia/pdfs/fsis5304.pdf
Goldstein A, Kaizer S, Whitby O (1969) Psychotropic effects of caffeine in man. IV. Quantitative and qualitative differences associated with habituation to coffee. Clin Pharmacol Ther 10:489–497
Gomez-Ramirez M, Higgins BA, Rycroft JA, Owen GN, Mahoney J, Shpaner M, Foxe JJ (2007) The deployment of intersensory selective attention: a high-density electrical mapping study of the effects of theanine. Clin Neuropharmacol 30:25–38
Hamer M (2006) Coffee and health: explaining conflicting results in hypertension. J Hum Hyptertens 20:909–912
Haskell CF, Kenedy DO, Milne AL, Wesnes KA, Scholey AB (2005) Behavioural effects of caffeine and theanine alone and in combination. J Psychophamacol 19(suppl):A45
Heatherley SV, Hayward RC, Seers HE, Rogers PJ (2005) Cognitive and psychomotor performance, mood, and pressor effects of caffeine after 4, 6 and 8 h caffeine abstinence. Psychopharmacology 178:461–470
Heatherley SV, Mullings EL, Tidbury MA, Rogers PJ (2006a) Caffeine consumption among a sample of UK adults. Appetite 47:266
Heatherley SV, Mullings EL, Tidbury MA, Rogers PJ (2006b) The Dietary Caffeine and Health Study: administration of a large postal survey in Bristol. Appetite 47:266
Hodgson JM (2006) Effects of tea and tea flavonoids on endothelial function and blood pressure: a brief review. Clin Exp Pharmacol Physiol 33:838–841
Howell DC (1997) Statistical methods for psychology. Duxbury Press, Belmont, CA
Hughes RN (1996) Drugs which induce anxiety: caffeine. New Zeal J Psychol 25:36–42
James JE (2004) Critical review of dietary caffeine and blood pressure: a relationship that should be taken more seriously. Psychosom Med 66:63–71
James JE, Rogers PJ (2005) Effects of caffeine on performance and mood: withdrawal reversal is the most plausible explanation. Psychopharmacology 182:1–8
James JE, Gregg ME (2004) Hemodynamic effects of dietary caffeine, sleep restriction, and laboratory stress. Psychophysiol 41:914–923
Jarvis MJ (1993) Does caffeine enhance intake above absolute levels of cognitive performance. Psychopharmacology 110:45–52
Juneja LR, Chu D-C, Okubo T, Nagato Y, Yokogoshi H (1999a) Corrigendum to “l-theanine—a unique amino acid of green tea and its relaxation effect in humans” [Trends in Food Science and Technology 10 (6–7) (1999) 199–204]. Trends Food Sci Technol 10:425
Juneja LR, Chu D-C, Okubo T, Nagato Y, Yokogoshi H (1999b) l-theanine—a unique amino acid of green tea and its relaxation effect in humans. Trends Food Sci Technol 10:199–204
Kakuda T, Nozawa A, Unno T, Okamura N, Okai O (2000a) Inhibiting effects of theanine on caffeine stimulation evaluated by EEG in the rat. Biosci Biotechnol Biochem 64:287–293
Kakuda T, Yanase H, Utsunomiya K, Nozawa A, Unno T, Kataoka K (2000b) Protective effect of γ-glutamylethylamide (theanine) on ischemic delayed neuronal death in gerbils. Neuroscience Letters 289:189–192
Kimura R, Murata T (1986) Effects of theanine on norepinephrine and serotonin levels in the rat brain. Chem Pharm Bull 34:3053–3057
Kimura K, Ozeki M, Juneja LR, Ohira H (2006) l-theanine reduces psychological and physiological stress responses. Biol Psychol 74:39–45
Lieberman HR, Wurtman HJ, Emde GG, Roberts C, Coviella ILG (1987) The effects of low doses of caffeine on human performance and mood. Psychopharmacology 92:308–312
Lovibond SH, Lovibond PF (1995) Manual for the Depression Anxiety and Stress Scales. Psychology Foundation of Australia Inc., Sydney, Australia
Lu K, Gray MA, Oliver C, Liley DT, Harrison BJ, Bartholomeusz CF, Phan KL, Nathan PJ (2004) The acute effects of l-theanine in comparison with alprazolam on anticipatory anxiety in humans. Hum Psychopharmacol Clin Exp 19:457–465
MacLeod C, Mathews A (1988) Anxiety and the allocation of attention to threat. Q J Exp Psychol 40:653–670
Mogg K, Bradley BP (2005) Attentional bias in generalized anxiety disorder versus depressive disorder. Cognitve Ther Res 29:29–45
Mogg K, Bradley BP, Williams R (1995) Attentional bias in anxiety and depression: the role of awareness. Br J Clin Psychol 34:17–36
Nantz MP, Rowe CA, Azeredo A, Marano LE, Bukowski JF, Percival SS (2007) A standardized green tea formula lowers serum amyloid alpha and blood pressure. FASEB J 21:225.3
Noordzij M, Uiterwaal CSPM, Arends LR, Kok FJ, Grobbee DE, Geleijnse JM (2005) Blood pressure response to intake of coffee and caffeine: a meta-analysis of randomised controlled trials. J Hypertens 23:921–928
Parnell H, Owen GN, Rycroft LA (2006) Combined effects of l-theanine and caffeine on cognition and mood. Appetite 47:273
Paterniti S, Alpérovitch A, Ducimetèire P, Dealberto M, Lépine J, Bisserb J (1999) Anxiety but not depression is associated with elevated blood pressure in a community of French elderly. Psychosom Med 61:77–83
Peters U, Poole C, Arab L (2001) Does tea affect cardiovascular disease? A meta-analysis. Am J Epidemiol 154:495–503
Rogers PJ (2001) A healthy body, a healthy mind: long term impact of diet on cognitive function and mood. Proc Nutr Soc 60:135–143
Rogers PJ (2007) Caffeine, mood and mental performance in everyday life. Nutr Bull 32(suppl 1):84–89
Rogers PJ, Dernoncourt C (1998) Regular caffeine consumption: a balance of adverse and beneficial effects for mood and psychomotor performance. Pharmacol Biochem Behav 59:1039–1045
Rogers PJ, Heatherley SV, Hayward SC, Seers HE, Hill J, Kane M (2005) Effects of caffeine and caffeine withdrawal on mood and cognitive function degraded by sleep restriction. Psychopharmacology 179:742–752
Rogers PJ, Heatherley SV, Mullings EL, Nutt DJ (2006a) Licit drug use and depression, anxiety and stress. J Psychopharmacol 20(suppl):A27
Rogers PJ, Heatherley SV, Mullings EL, Wu Y, Leonards U (2006b) Caffeine and anxiety. Appetite 47:274
Shimbo M, Nakamura K, Shi HJ, Kizuki M, Seino K, Inose T, Takano T (2005) Green tea consumption in everyday life and mental health. Public Health Nutr 8:1300–1306
Smit HJ, Rogers PJ (2000) Effects of caffeine on cognitive performance, mood and thirst in lower and higher caffeine consumers. Psychopharmacology 152:167–173
Southard DR, Coates TJ, Kolodner K, Parker FC, Padgett NE, Kennedy HL (1986) Relationship between mood and blood pressure in the natural environment: an adult population. Health Psychol 5:469–480
Spielberger CD (1991) State-Trait Anger Expression Inventory: professional manual. Psychological Assessment Resources Inc., Odessa, FL
Steptoe A, Gibson EL, Vounonvirta R, Williams ED, Hamer M, Rycroft JA, Erusalimsky JD, Wardle J (2007) The effects of tea on psychophysiological stress responsivity and post-stress recovery: a randomised double-blind trial. Psychopharmacology 190:81–89
Taubert D, Berkels R, Rossen R, Klaus W (2003) Chocolate and blood pressure in elderly individuals with isolated systolic hypertension. JAMA 290:1029–1030
Umezara K, Kobayashi K, Muramoto K, Kawahara M, Mitzutani A, Kakuda T, Kuroda Y (1995) Theanine, a glutamate analog, stimulates NMDA-receptors but suppresses excitatory effect of caffeine on cortical neurons. Society for Neuroscience 21:835(abstract)
van Dam RM, Hu FB (2005) Coffee consumption and risk of type 2 diabetes: a systematic review. JAMA 294:97–104
Vinson JA (2006) Caffeine and incident hypertension in women. JAMA 295:2135
Winklemayer WC, Stampfer MJ, Willett WC, Curhan GC (2005) Habitual caffeine intake and the risk of hypertension in women. JAMA 1294:2330–2335
Yamada T, Terashima T, Okubo T, Juneja LR, Yokogoshi H (2005) Effects of theanine, r-glutamylethylamide, on neurotransmitter release and its relationship with glutamic acid neurotransmission. Nutr Neurosci 8:219–226
Yamagishi S, Nakamura K, Matsui T, Takenaka K, Jinnouchi Y, Imaizumi T (2006) Cardiovascular disease in diabetes. Mini Reviews in Medicinal Chemistry 6:313–318
Yang YC, Lu FH, Wu JS, Wu CH, Chang CJ (2004) The protective effect of habitual tea consumption on hypertension. Arch Intern Med 164:1534–1540
Yao L, Lui X, Jiang Y, Caffin N, D’Arcy B, Singanusong R, Datta N, Xu Y (2006) Compositional analysis of teas drom Australian supermarkets. Food Chem 94:115–122
Yokogoshi H, Kobayashi M (1998) Hypotensive effect of γ-glutamylmethylamide in spontaneously hypertensive rats. Life Sci 62:1065–1068
Yokogoshi H, Kato Y, Sagesaka Y, Matsuura T, Kakuda T, Takeuchi N (1995) Reduction effect of theanine on blood pressure and brain 5-hydroxyindoles in spontaneously hypertensive rats. Biosci Biotech Bioch 59:615–618
Yokogoshi H, Kobayashi M, Mochizuki M, Terashima T (1998a) Effect of theanine, γ-glutamylethylamide, on brain monoamines and striatal dopamine release in conscious rats. Neorochem Res 23:667–673
The authors thank Unilever plc for donation of the theanine-containing drinks used in this study and Mars UK for permission to cite the unpublished results on effects of theanine on blood pressure from a previous study. The unpublished research on perceived effects of coffee and tea (Bristol Dietary Caffeine and Health Study) was supported by BBSRC (grant BBS/B/01855).
About this article
Cite this article
Rogers, P.J., Smith, J.E., Heatherley, S.V. et al. Time for tea: mood, blood pressure and cognitive performance effects of caffeine and theanine administered alone and together. Psychopharmacology 195, 569 (2008). https://doi.org/10.1007/s00213-007-0938-1
- Blood pressure