Document Detail

Time for tea: mood, blood pressure and cognitive performance effects of caffeine and theanine administered alone and together.
MedLine Citation:
PMID:  17891480     Owner:  NLM     Status:  MEDLINE    
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.
Peter J Rogers; Jessica E Smith; Susan V Heatherley; C W Pleydell-Pearce
Publication Detail:
Type:  Comparative Study; Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't     Date:  2007-09-23
Journal Detail:
Title:  Psychopharmacology     Volume:  195     ISSN:  0033-3158     ISO Abbreviation:  Psychopharmacology (Berl.)     Publication Date:  2008 Jan 
Date Detail:
Created Date:  2007-11-21     Completed Date:  2008-03-31     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7608025     Medline TA:  Psychopharmacology (Berl)     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  569-77     Citation Subset:  IM    
Department of Experimental Psychology, University of Bristol, 12a Woodland Road, Bristol, BS8 1TU, UK.
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MeSH Terms
Affect / drug effects*
Arousal / drug effects
Attention / drug effects
Blood Pressure / drug effects*
Caffeine / antagonists & inhibitors,  pharmacology*
Cognition / drug effects*
Discrimination Learning / drug effects
Double-Blind Method
Facial Expression
Glutamates / pharmacology*
Heart Rate / drug effects
Pattern Recognition, Visual / drug effects
Reg. No./Substance:
0/Glutamates; 0/Tea; 3081-61-6/theanine; 58-08-2/Caffeine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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