As part of our Biohacking Masterclass Series, we will explore a number of different techniques and practices to improve your daily performance. This series will range from obvious subjects like exercise and nutrition to fringe subjects like breathing techniques and sleep hygiene. Consult your physician before implementing any of these topics. We are not your physician. Note: This post may contain affiliate links to the products we use.
While knocking back a cup or two of coffee has its perks, coffee-drinkers often experience an increase in stress-like physiological symptoms (i.e. increased cortisol). Is it possible to get the performance benefit of a hit of caffeine while mitigating the chemically-induced heart palpitations or “fight or flight” response?
As it turns out, the “secret” optimal combination of ingredients might be found in one of the most consumed beverages in the world.
If you’ve ever had a cup of tea and felt a unique combination of alertness and relaxation, you’ve likely felt the effects of a powerful little molecule called theanine.
Theanine is an amino acid found most commonly in tea plants (and in small amounts in certain mushrooms). When you drink tea and taste ‘umami’ (savory), you are likely tasting theanine. On its own, theanine is backed by some evidence of improved mental performance and calmness. For example, theanine consumption generates alpha brain waves. These brain waves are generally associated with increased alertness accompanied by increased relaxation. In other words, alpha waves are considered ‘flow state’ brain waves. 
When combined with caffeine, like you’d find in many tea varieties, theanine enhances cognitive function even further and across a far greater number of performance measures. [2-5]
What kind of performance-boost does the theanine/caffeine combination enable?
In lab settings, combining theanine with caffeine led to significantly increased attention and accuracy on cognitive performance tasks. Further, the increase in attention was not limited to one sense but spanned across visual (sight) and auditory (hearing) modalities. 
In other studies, theanine/caffeine combinations improved reaction time, accuracy of rapid visual information processing, numeric working memory speed, accuracy of sentence verification, and feelings of alertness while decreasing fatigue and headaches. 
In the most impactful studies, theanine/caffeine dosages ranged from approximately 100mg theanine and 40 mg caffeine all the way to 250mg theanine and 150 mg caffeine. The latter case would likely require exogenous supplementation of theanine, as there are approximately 7 mg of theanine per gram of green tea. In a cup of green tea, that will fall somewhere around 25 mg of theanine. [2-5]
What are some of the best tea sources of theanine?
As we have discussed, theanine is most concentrated in tea plants. Theanine is not limited to green, black, or other varieties, though the general consensus is that green teas have the most available theanine. Furthermore, shade grown green tea varieties are believed to have higher concentrations of theanine. An example of a shade grown tea variety is Gyokuro. When you consume Matcha, you are drinking the entire leaf of what could become a Gyokuro tea. In doing so, you are consuming higher amounts of not only theanine but other polyphenols as well.
- Nobre et al. L-theanine, a natural constituent in tea, and its effect on mental state. Asia Pac J Clin Nutr. 2008; 17(S1: 167-168.
- Higashiyama et al. Effects of L-theanine on attention and reaction time response. Journal of Functional Foods 3 (2011) 171-178.
- Giesbrecht et al. The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness. Nutritional Neuroscience. 2010, Vol 13.
- Einother et al. L-Theanine and caffeine improves task switching but not intersensory attention or subjective alertness. Appetite. 2009.
- Haskell et al. The effects of L-theanine, caffeine and their combination on cognition and mood. Biological Psychology 77 (2008) 113-122.