The Effects of Caffeine and L-theanine Both Alone and in Combination on Cerebral Blood Flow, Cognition and Mood

This study has been completed.
Sponsor:
Information provided by:
Northumbria University
ClinicalTrials.gov Identifier:
NCT00981955
First received: September 21, 2009
Last updated: July 22, 2010
Last verified: July 2010
  Purpose

Although the beneficial effects of caffeine on cognition and mood have been reported in a number of studies, relatively few studies have looked at the effects of caffeine in combination with other phytonutrients despite the fact that caffeine is seldom consumed in isolation. L-theanine is a naturally occurring amino-acid found in tea, and has been used historically as a relaxing agent (Haskell et al., 2008). Few have assessed the impact of l-theanine on cognition, but of those that have, the most interesting results were obtained when l-theanine was assessed in combination with caffeine (Haskell et al., 2008). It remains unclear what is underlying the reported effects.

Near Infrared Spectroscopy (NIRS) is an emerging neuroimaging technology that is capable of determining changes in cerebral blood flow (CBF) by measuring the optical properties of oxygenated and deoxygenated blood (Bunce et al., 2006). No study to date has used NIRS to assess cerebral blood flow following treatment with either caffeine, l-theanine or a combination of both. It is anticipated that the proposed study will provide some insight into the mechanism of the previously observed effects both alone and in combination.

A randomised, double-blind, placebo controlled, balanced crossover design study will assess the effects of 75mg caffeine, 50mg l-theanine and a 75mg caffeine/50mg l-theanine combination in 24 young healthy adults (18-35). Cognitive and mood assessments will take place at baseline and at 30 minutes following treatment whilst cerebral haemodynamics are measured via the technique of NIRS.


Condition Intervention Phase
Cognitive Function
Mood
Dietary Supplement: Caffeine and L-theanine
Phase 4

Study Type: Interventional
Study Design: Allocation: Randomized
Endpoint Classification: Efficacy Study
Intervention Model: Crossover Assignment
Masking: Double Blind (Subject, Investigator, Outcomes Assessor)
Primary Purpose: Basic Science
Official Title: A Randomised, Double Blind, Placebo-controlled Study to Evaluate the Effects of Caffeine and L-theanine Both Alone and in Combination on Cerebral Blood Flow, Cognition and Mood.

Resource links provided by NLM:


Further study details as provided by Northumbria University:

Primary Outcome Measures:
  • Cerebral blood flow [ Time Frame: 0-80 minutes post dose ] [ Designated as safety issue: No ]
  • Cognitive function [ Time Frame: 0-70 minutes post-dose ] [ Designated as safety issue: No ]
  • Mood [ Time Frame: 85 minutes post dose ] [ Designated as safety issue: No ]

Enrollment: 24
Study Start Date: August 2009
Study Completion Date: February 2010
Primary Completion Date: February 2010 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Active Comparator: 75mg caffeine Dietary Supplement: Caffeine and L-theanine
Acute oral administration of 75mg of caffeine, 50mg l-theanine, 75mg caffeine and 50mg l-theanine in combination or placebo. One dosage administered on each of four separate study days.
Other Name: Sun-theanine (l-theanine)
Active Comparator: 50mg l-theanine Dietary Supplement: Caffeine and L-theanine
Acute oral administration of 75mg of caffeine, 50mg l-theanine, 75mg caffeine and 50mg l-theanine in combination or placebo. One dosage administered on each of four separate study days.
Other Name: Sun-theanine (l-theanine)
Active Comparator: 75mg caffeine and 50mg l-theanine Dietary Supplement: Caffeine and L-theanine
Acute oral administration of 75mg of caffeine, 50mg l-theanine, 75mg caffeine and 50mg l-theanine in combination or placebo. One dosage administered on each of four separate study days.
Other Name: Sun-theanine (l-theanine)
Placebo Comparator: 0mg caffeine/l-theanine Dietary Supplement: Caffeine and L-theanine
Acute oral administration of 75mg of caffeine, 50mg l-theanine, 75mg caffeine and 50mg l-theanine in combination or placebo. One dosage administered on each of four separate study days.
Other Name: Sun-theanine (l-theanine)

  Eligibility

Ages Eligible for Study:   18 Years to 35 Years
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

  • Healthy
  • Aged 18-35
  • Either caffeine consumers (consume more than 150mg caffeine per day) or non-consumers (less than 44mg caffeine per day).

Exclusion Criteria:

  • Smoke or consume any tobacco products
  • Not proficient in English language
  • Pregnant (or seeking to become pregnant)
  • Taking recreational, over the counter/prescription medication (including the contraceptive pill), and/or dietary/herbal supplements
  • Have food allergies or sensitivities
  • Have history of/current head trauma, learning difficulties , ADHD, migraines or any gastric problems
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT00981955

Locations
United Kingdom
Northumbria University
Newcastle upon Tyne, Tyne & Wear, United Kingdom, Ne1 8ST
Sponsors and Collaborators
Northumbria University
Investigators
Principal Investigator: Crystal Haskell, PhD Northumbria University
  More Information

No publications provided

Responsible Party: Dr Crystal Haskell, Northumbria University
ClinicalTrials.gov Identifier: NCT00981955     History of Changes
Other Study ID Numbers: 25AA1
Study First Received: September 21, 2009
Last Updated: July 22, 2010
Health Authority: United Kingdom: Research Ethics Committee

Keywords provided by Northumbria University:
Caffeine
Ltheanine
Near Infrared Spectroscopy
Cerebral Blood Flow
Cognitive Function
Mood

Additional relevant MeSH terms:
Caffeine
Central Nervous System Stimulants
Physiological Effects of Drugs
Pharmacologic Actions
Central Nervous System Agents
Therapeutic Uses
Phosphodiesterase Inhibitors
Enzyme Inhibitors
Molecular Mechanisms of Pharmacological Action
Purinergic P1 Receptor Antagonists
Purinergic Antagonists
Purinergic Agents
Neurotransmitter Agents

ClinicalTrials.gov processed this record on July 26, 2014