Tea Research Update - Cognition and Mood

One step closer to understanding tea's positive effect on cognition and mood
A combination of caffeine and L-theanine, naturally present in tea, has positive effects on cognition and mood in young adults according to researchers from Northumbria University.
Studies that have considered effects of tea on cognition and mood have found that, although the majority of effects can be explained by caffeine, some differences exist between tea and coffee, even when the caffeine level is matched. The current researchers are proposing L-theanine may hold the key to teas enhanced effects.

The current randomised, placebo controlled, double-blind, balanced crossover study investigated the cognitive and mood effects of the two compounds both alone [L-theanine (250 mg), caffeine (150 mg)] and in combination (250 mg/150 mg). The tasks selected to measure mood and cognition included attention tasks as well as specific memory and reasoning tasks, which are known to be sensitive to caffeine. Mood ratings were also assessed.

Twenty four undergraduate students (mean age 21.3 years) took part in the study and were asked to abstain from caffeine and alcohol 12 hours prior to the study. Participants were randomised to a treatment group and received 4 different beverages (250ml drinks as previously described) plus a placebo on separate occasions 7 days apart. On each occasion the tests were carried out before taking the drink, 30 minutes after the drink and 90 minutes post-drink. Each testing session lasted approximately 30 minutes.

Compared to the isolated effects of caffeine and L-theanine, the combined action resulted in improvements in visual tasks and 'mental fatigue' ratings. In addition the combination of caffeine and L-theanine also speeded up the completion of a number of cognitive tasks. Participants also reported fewer headache symptoms and felt more alert.

As the levels of L-theanine and caffeine used in this study are higher than those found in tea beverages, which are typically in the region of 40 mg caffeine and 20 mg L-theanine, the researchers suggest that further studies should be conducted looking at different doses of L-theanine, as well as researching L-theanine-caffeine combinations that examines the effects of everyday doses both in isolation and in combination at levels and ratios found in real tea beverages.

In the mean time, the results from this initial study suggest that beverages, like tea, containing L-theanine and caffeine may have a positive effect on cognition and mood.
Crystal F. Haskell, David O. Kennedy, Anthea L. Milne, Keith A. Wesnes and Andrew B. Scholey (2008) The effects of L-theanine, caffeine and their combination on cognition and mood. Biological Psychology 77: 113-122