Psychopharmacology

, 195:569 | Cite as

Time for tea: mood, blood pressure and cognitive performance effects of caffeine and theanine administered alone and together

  • Peter J. Rogers
  • Jessica E. Smith
  • Susan V. Heatherley
  • C. W. Pleydell-Pearce
Original Investigation

Abstract

Rationale

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.

Objectives

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.

Results

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.

Conclusions

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.

Keywords

Caffeine Theanine Tea Coffee Blood pressure Mood Alertness Anxiety Cognition 

Notes

Acknowledgement

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Unilever plc for donation of the theanine-containing drinks used in this study and Mars UK for permission to cite the unpublished results on effects of theanine on blood pressure from a previous study. The unpublished research on perceived effects of coffee and tea (Bristol Dietary Caffeine and Health Study) was supported by BBSRC (grant BBS/B/01855).

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Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • Peter J. Rogers
    • 1
  • Jessica E. Smith
    • 1
  • Susan V. Heatherley
    • 1
  • C. W. Pleydell-Pearce
    • 1
  1. 1.Department of Experimental PsychologyUniversity of BristolBristolUK

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