The effects of tea on psychophysiological stress responsivity and post-stress recovery: a randomised double-blind trial
- 1.7k Downloads
Tea has anecdotally been associated with stress relief, but this has seldom been tested scientifically.
To investigate the effects of 6 weeks of black tea consumption, compared with matched placebo, on subjective, cardiovascular, cortisol and platelet responses to acute stress, in a parallel group double-blind randomised design.
Materials and methods
Seventy-five healthy nonsmoking men were withdrawn from tea, coffee and caffeinated beverages for a 4-week wash-out phase during which they drank four cups per day of a caffeinated placebo. A pretreatment laboratory test session was carried out, followed by either placebo (n = 38) or active tea treatment (n = 37) for 6 weeks, then, a final test session. Cardiovascular measures were obtained before, during and after two challenging behavioural tasks, while cortisol, platelet and subjective measures were assessed before and after tasks.
The tasks induced substantial increases in blood pressure, heart rate and subjective stress ratings, but responses did not differ between tea and placebo treatments. Platelet activation (assessed using flow cytometry) was lower following tea than placebo treatment in both baseline and post-stress samples (P < 0.005). The active tea group also showed lower post-task cortisol levels compared with placebo (P = 0.032), and a relative increase in subjective relaxation during the post-task recovery period (P = 0.036).
Compared with placebo, 6 weeks of tea consumption leads to lower post-stress cortisol and greater subjective relaxation, together with reduced platelet activation. Black tea may have health benefits in part by aiding stress recovery.
KeywordsTea Stress Cortisol Heart rate Blood pressure Platelet activation Caffeine Mood
We are grateful to Peirluigi Giacobazzi and Kesson Magid for their assistance in data collection and biological assays. Leigh Gibson is now at Roehampton University, London, Raisa Vounonvirta at the Institute of Cancer Research, Sutton, UK, and Jorge Erusalimsky is at the University of Wales Institute, Cardiff.
- Hamer M, Williams ED, Vuononvirta R, Gibson EL, Steptoe A (2006b) The association between coffee consumption and markers of inflammation and cardiovascular function during mental stress. J Hypertens (in press)Google Scholar
- Haskell CF, Kennedy D, Milne AL, Wesnes KA, Scholey AB (2005) Cognitive and mood effects of caffeine and theanine alone and in combination. Behav Pharmacol 16(Suppl 1):S26Google Scholar
- Michelson AD, Barnard MR, Krueger LA, Valeri CR, Furman MI (2001) Circulating monocyte–platelet aggregates are a more sensitive marker of in vivo platelet activation than platelet surface P-selectin: studies in baboons, human coronary intervention, and human acute myocardial infarction. Circulation 104:1533–1537PubMedCrossRefGoogle Scholar
- Perez-Vizcaino F, Ibarra M, Cogolludo AL, Duarte J, Zaragoza-Arnaez F, Moreno L, Lopez-Lopez G, Tamargo J (2002) Endothelium-independent vasodilator effects of the flavonoid quercetin and its methylated metabolites in rat conductance and resistance arteries. J Pharmacol Exp Ther 302:66–72PubMedCrossRefGoogle Scholar
- Schneiderman N, McCabe PA (1989) Psychophysiologic strategies in laboratory research. In: Schneiderman N, Weiss SM, Kaufman PG (eds) Handbook of research methods in cardiovascular behavioral medicine. Plenum, New York, pp 349–364Google Scholar
- Steptoe A (1997) Behavior and blood pressure: implications for hypertension. In: Zanchetti A, Mancia G (eds) Handbook of hypertension—pathophysiology of hypertension. Elsevier Science, Amsterdam, pp 674–708Google Scholar
- Steptoe A, Gibson EL, Vuononvirta R, Hamer M, Wardle J, Rycroft JA, Martin JF, Erusalimsky J (2006) The effects of chronic tea intake on platelet activation and vascular biology: a double-blind placebo controlled trial. Atherosclerosis (in press)Google Scholar
- von Kanel R, Mills PJ, Fainman C, Dimsdale JE (2001) Effects of psychological stress and psychiatric disorders on blood coagulation and fibrinolysis: a biobehavioral pathway to coronary artery disease? Psychosom Med 63:531–544Google Scholar