Caffeine and L-Theanine

L-Theanine and Caffeine: The Best Pair for Energy

Many of us reach straight for the kettle in the morning. Whether you’re on team tea or coffee, starting the day without a brew may be almost unthinkable. Both tea and coffee contain caffeine, but there’s a difference in the way each makes you feel that comes down to more than that. Not only does tea contain caffeine, it also contains a molecule that coffee doesn’t. It’s called L-theanine, and the powerful pairing of L-theanine and caffeine has far more potential than you might think [1]. We’re going to tell you all about it, but be warned: reading on will inspire you to try it for yourself! 



Caffeine (the one you know)  

two cups of coffee

We’ve all heard about caffeine. It’s a molecule naturally found in tea and coffee, and also now found in manufactured items, such as sodas. It’s technically a drug. Caffeine acts by stimulating your central nervous system (that’s your brain) making you feel more alert and awake [2]. If you’re a coffee or tea drinker, you’ll know that buzz you get afterwards—that's from the caffeine. 



L-theanine (the one you don’t know)

cup of tea with L-Theanine

L-theanine is an amino acid (a specific type of biological molecule) that is found in tea. You may also have seen it in tablet form on drugstore shelves. Over the last 10 to 20 years, scientists have become more and more aware of the effects of L-theanine in the body, and it turns out that some of them are really useful. These effects include better sleep, better immune function, increased focus, and decreased stress [3]. If you’ve ever tried meditating (and been marginally successful), you’ll know it’s associated with a deep sense of relaxation but also high mental alertness. This is very similar to the effect produced by L-theanine in the body [4]. Sounds good to us! 



Tea(m)-work makes the dream work 

What’s most interesting about these two molecules is the effect they have together. A cup of tea is great—the soothing warmth helps us unwind while the kick of caffeine keeps us alert. However, research shows there’s more going on. The caffeine and L-theanine in tea are acting on your body as a team (who knew?). As always, we’re here to unpack the research and see what this dynamic duo could be doing for you. 

Alertness and Cognitive Performance 

A 2013 study that compared participants given L-theanine and caffeine compared to those given a placebo (a fake version of the drug) showed increase accuracy in some mental tasks [5]. A 2008 study showed that some aspects of memory and attention are improved more in participants who took caffeine and L-theanine than who just had caffeine [6]. Further investigations have shown increased reaction time and word recall time, and revealed that L-theanine alone does not produce these beneficial effects; it must be combined with caffeine [1]. What does that mean for you? Well, all these effects in your brain mean you can be more alert and better at ignoring distractions. So you can get more work done, be more focused and be your best self while you are distraction- and fatigue-free. 

And if that wasn’t enough, it seems L-theanine works by calming down some of the activity in your brain, which is almost the opposite of what caffeine does. Scientists have noticed this leads to a reduction in stress and anxiety. Win, win. With busy lives and stressful jobs, the need to chill is familiar to many of us. Caffeine and L-theanine might be just what you need [7]. There’s still a lot more research to do in this area, but it’s exciting stuff. It might explain why so many of us feel the need to reach for a cup of tea when we’re feeling stressed! 

Immune System 

Your immune system fights illness and disease. One of its main roles is protecting you from infectious diseases, such as colds and flu. These pesky bugs can completely throw you off your game (as you’ll remember if you got the flu this year). Every little thing you can do to keep your immune system strong is a defense against infection, and a great way to make sure you are your best self every day. 

One of the key components of your immune system is white blood cells. L-theanine enhances the action of certain types of white blood cells, specifically γδ (gamma delta) T lymphocytes. These cells are involved in the defense against tumors and infections. It is believed that L-theanine primes the cells so they are more ready to respond when the body is under threat. This leads to a stronger, faster response, and an associated decrease in symptoms [8]. A study of 200 healthcare workers found that those who took L-theanine were less likely to get the flu than those who did not [9].

Sleep Quality

 We all know that caffeine can keep us awake, and many of us use it if we’re feeling a little drowsy. In contrast, one of the fantastic things about L-theanine is that it has a relaxing effect. Researchers in the UK found that tea-drinkers had less disrupted sleep than coffee drinkers [10]. This research, and other work like it, has led to further investigations into why tea and coffee have different impacts on sleep. It’s looking more and more like the answer is—you guessed it—L-theanine.  

sleeping quality

Although in-depth research hasn’t yet been done, we can use other research to start to understand L-theanine and sleep. For example, stress and anxiety are known to decrease sleep quality; because L-theanine decreases stress and anxiety, we can predict that it likely increases sleep quality and/or quantity [11].



And there you have it...

...the effects of caffeine and L-theanine in combo might be just what you need to keep going through the day. Being less anxious, more alert, less distractible, and less vulnerable to coughs and colds is going to help you be your best self, get more out of every day and live your best life. The list of possible positive effects is even longer than we’ve mentioned here. For example, research suggests L-theanine may have a protective effect in our brains, reducing injury from events such as strokes [7]. It may be helpful in lowering blood pressure, which is great because caffeine raises blood pressure [12]! The data just keeps coming, and we hope you’re now as excited as we are about this dynamic duo. 

We’ve been working on the perfect product to deliver the powerful pair to you in a simple sachet. 

Writer: Ailsa McKinlay



[1] Haskell, C.F, et al. (2008) The effects of l-theanine, caffeine and their combination on cognition and mood, Biological Psychology, Volume 77, Issue 2, 2008, Pages 113-122, ISSN 0301-0511 - This 2008 article contains the write-up of experiments showing the combination of caffeine and L-theanine has a different effect on the body than caffeine alone, with specific focus on the brain. 
[2] Caffeine - Accessed 18/09/19 - A basic introduction to caffeine. This source has heaps of information and is a great place to go if you want to know more. 
[3] What You Should Know About L-Theanine - Healthline - Here’s a basic rundown of L-theanine. Easy to understand, covers lots of areas, but it’s very in-depth. 
[4] Mason, R. (2001).  200 mg of Zen. L-Theanine Boosts Alpha Waves, Promotes Alert Relaxation. Alternative and Complementary Therapies April 2001. - This is quite an unusual scientific article, but provides some helpful information nonetheless! It is particularly focused on brain activity. 
[5]  Giesbrecht, T. et al (2010) The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness, Nutritional Neuroscience, 13:6, 283-290, DOI: 10.1179/147683010X12611460764840 - More great primary research on the effects of L-theanine in the brain. This newer research builds on older research, helping us get a clearer picture of what’s happening in the body. 
[6] Owen, G. (2008) The combined effects of L-theanine and caffeine on cognitive performance and mood, Nutritional Neuroscience, 11:4, 193-198, DOI: 10.1179/147683008X301513 - This research compared the effects of caffeine alone to caffeine with L-theanine in healthy volunteers. It agrees with previously found data showing that L-theanine and caffeine can be used to improve performance in some cognitive tasks. 
[7] Bryan, J. (2008)  Psychological effects of dietary components of tea: caffeine and L-theanine, Nutrition Reviews, Volume 66, Issue 2, 1 February 2008, Pages 82–90 - This article is a review, meaning it amalgamates other research. If you’re up for an in-depth read about L-theanine, caffeine and psychology, this is a great place to go. 
[8] Jack F Bukowski, Susan S Percival, L-theanine intervention enhances human γδ T lymphocyte function, Nutrition Reviews, Volume 66, Issue 2, 1 February 2008, Pages 96–102 - This is a very technical study, looking into the exact way L-theanine works on cells. Most relevant for our purposes is the apparently improved immune response. 
[9] Matsumoto, Keiji et al. “Effects of green tea catechins and theanine on preventing influenza infection among healthcare workers: a randomized controlled trial.” BMC complementary and alternative medicine vol. 11 15. 21 Feb. 2011, doi:10.1186/1472-6882-11-15 - This write-up for a super-interesting study looking at flu in healthcare workers consuming L-theanine makes a good read if you’re new to scientific papers. 
[10] Hindmarch, I., Rigney, U., Stanley, N. et al. (2000) A naturalistic investigation of the effects of day-long consumption of tea, coffee and water on alertness, sleep onset and sleep quality. Psychopharmacology; 149: 203. - A look at tea and coffee drinking habits and their effect on sleep. They found a difference between tea and coffee drinkers, and it is this sort of work that has lead to further investigation into why there is a difference. 
[11] Saeed, M. Green tea (Camellia sinensis) and l-theanine: Medicinal values and beneficial applications in humans—A comprehensive review, Biomedicine & Pharmacotherapy, Volume 95, 2017, Pages 1260-1275, ISSN 0753-3322 - Although this article is focused on green tea, L-theanine is found in other teas and the principles of the findings are likely to still apply. 
[12] Rogers, P.J., Smith, J.E., Heatherley, S.V. et al. (2007) Time for tea: mood, blood pressure and cognitive performance effects of caffeine and theanine administered alone and together Psychopharmacology 195: 569. - This research also measures blood pressure when giving participants caffeine and L-theanine.  

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