Over the years, there have been many studies looking at the effects of caffeine and – more recently – L-theanine on human performance and mood.  However, I have noticed a growing body of research looking at the synergistic effect of both as found in tea.  Most recently, I read a study, sponsored by The Journal of Nutrition which looked at the effects of caffeine and L-theanine on cognitive performance.

I’m sure all readers are familiar with caffeine, either from personal experience or reading.  For those of you, however, who are not familiar with L-theanine, just a few bits of information.  L-theanine is found only in tea in any significant amount.  It is an amino acid that has a relaxing effect physiologically and subjectively.  This is further supported by research that shows distinct increases in the alpha brain-wave frequency.  Alpha, as many of you may know (especially if you were of college age in the 1960s), has been long associated with a relaxed, but alert state, of consciousness.

Without going into too much detail about how the study was set up, they looked at 44 young adults who consumed a RTD tea beverage, concocted for this study, that contained 40 mg of caffeine and 97 mg of L-theanine, along with sweeteners and lemon flavor, in a powder form combined with water.  The beverage used for the placebo group contained the same ingredients, except the caffeine and L-theanine.  The normal ratio of caffeine to L-theanine found in tea (35–61 mg of caffeine and 4.5–22.5 mg) was jacked up on the L-theanine side for this study because they were more interested in looking at what L-theanine adds to caffeine.  The subjects were given a variety of performance tasks related to attention and speed of processing and had their blood pressure and alertness/tiredness periodically monitored.

The results showed that the synergistic effect of caffeine and L-theanine specifically improved attentional functioning on challenging, complex tasks vs. previous findings on caffeine showing attentional improvement on more simple tasks.  In addition, as you might imagine, the combination also showed an increase in perceived alertness and reduction in fatigue as reported by a subjective measure completed by participants.  The final results also showed that, although there was a slight increase in systolic blood pressure, it was smaller than what is typically found in studies looking at the effects of caffeine alone on blood pressure.  The authors further pointed out that previous meta-analyses of the effects of tea on blood pressure suggest that long-term consumption appears not to increase blood pressure and, in fact, has shown to be protective of stroke incidents.

It is for the above reasons that tea has had such a propitious history in helping people improve performance (and health), whether for meditation or figuring out complex mathematical equations.  Drink your tea and live life to its fullest.


This post first published on the blog 25 November 2010.