Caffeine with L-Theanine: What Does the Science Say? Top 5 Studies

So, we now know the top 10 facts about caffeine, but what about combining caffeine with L-Theanine? One of the great things about L-Theanine is that it has a wonderful synergistic relationship with caffeine. However, you may not know exactly how this works or even if it works. In this article, we’ll look at the top 5 recent studies showing the beneficial effects of combining caffeine with L-Theanine. There have been a number of other studies with similar results published in the past. This is a great article for anybody looking for some substance behind the caffeine with L-Theanine claims.

1.    L-Theanine may be as effective as Caffeine in Improving Attention

One of the latest studies on the effects of caffeine with L-Theanine compared the effects of both substances individually and together, against placebo, for improving attention scores and physiological measures of attention (brain-scans). The researchers found that L-Theanine was as effective as caffeine at improving cognition and selective attention. These effects were seen in high doses of L-Theanine – around the same amount you’d get from eight cups of tea, or one L-Theanine capsule.[1]  

2.    L-Theanine helps reduce the side effects of Caffeine

In a recent study, scientists tried to see what the effects were when combining caffeine with L-Theanine. They found that L-Theanine eliminated the ‘vasoconstrictor’ effects of caffeine and improved behavioral scores.[2]   A ‘vasoconstrictor’ is a substance that makes your blood vessels smaller – temporarily increasing your blood pressure.[3] It seems that taking caffeine with L-Theanine helps to reduce these effects as well as improves your mood.  

3.    Taking Caffeine with L-Theanine helps to reduce Caffeine-related anxiety

[caption id=""attachment_1518"" align=""alignright"" width=""300""] Liftmode's Caffeine + L-Theanine, 99% purity[/caption] In our previous article on the top 10 facts about caffeine, we mentioned that caffeine can cause anxiety in some users. This anxiety and jitteriness is often dose-dependent – the larger the dose, the more anxiety. In a 2012 study, researchers found that taking caffeine with L-Theanine helps to reduce not only the vasoconstrictive effects of caffeine but also the anxiety. This is potentially great news for anybody who worries about their blood pressure of suffers from anxiety after using caffeine. Some people are a lot more sensitive to the effects of caffeine than others, and this could be great news if you’re one of them![4]  

4.    Using Caffeine with L-Theanine may boost the focusing effects of caffeine

We know that L-Theanine is effective at improving energy and focus as well as reducing some of the side effects of caffeine, but does it actually improve the effects of caffeine? A number of new studies have shown the synergistic relationship between caffeine and L-Theanine. Firstly, in a 2008 study, scientists discovered that using caffeine with L-Theanine significantly improved reaction times over using either supplement alone. They suggested that drinks and supplements containing caffeine with L-Theanine may have a different pharmacological profile to those containing caffeine or L-Theanine alone.[5] Secondly, in another 2008 study, researchers summarized all the studies to date on caffeine with L-Theanine. They found that L-Theanine might interact with caffeine to produce increased mental performance and cognition. They also suggested that more studies should be conducted in future.[6]  

5.    Caffeine with L-Theanine improves your Cognitive Performance

[caption id=""attachment_1532"" align=""alignright"" width=""300""] Caffeine with L-Theanine helps to improve your cognitive performance[/caption] In a 2010 study, scientists mentioned finding that caffeine with L-Theanine significantly improved subject’s cognitive performance. Task accuracy was improved, as were self-reported alertness and awareness ratings.[7] This study was conducted on 44 young adults and used fairly low doses of both caffeine and L-Theanine (97 mg L-Theanine and 40 mg caffeine). At higher doses, the effects may be even more noticeable.  


In conclusion, the latest science shows that there is a definite synergistic relationship when using caffeine with L-Theanine. L-Theanine may be as effective as caffeine at improving attention, especially when used in dosages of around 200 mg. Studies have shown that the combination of caffeine and L-Theanine helps to reduce some of the negative effects of caffeine – including reducing the increase in blood pressure and reducing caffeine-related anxiety. All in all, taking caffeine with L-Theanine is a great way to boost your cognition and focus, and may be beneficial in reducing some of the side effects of caffeine.


Medical Disclaimer

Not intended to treat, diagnose, or cure any disease or ailment. Please read and fully understand potential adverse effects before using this product. These statements have not been reviewed by the FDA and are not written by a medical professional. Please consult your doctor before using any supplements, especially if you have any medical conditions.


B.Sc. in Molecular Biology and Biochemistry Researched & written by Tristan and verified by the Research Team


[1] Acute effects of theanine, caffeine and theanine-caffeine combination on attention, CN Kahathuduwa et al., Nutr Neurosci. 2016 Feb 11. [Epub ahead of print] [2] A double-blind, placebo-controlled study evaluating the effects of caffeine and L-theanine both alone and in combination on cerebral blood flow, cognition and mood, FL Dodd et al., Psychopharmacology (Berl). 2015 Jul;232(14):2563-76. [3] The effect of daily caffeine use on cerebral blood flow: How much caffeine can we tolerate?, MA Addicott et al., Hum Brain Mapp. 2009 Oct;30(10):3102-14. [4] Effects of L-theanine or caffeine intake on changes in blood pressure under physical and psychological stresses, A Yoto et al., J Physiol Anthropol. 2012; 31(1): 28, Published online 2012 Oct 29 [5] The effects of L-theanine, caffeine and their combination on cognition and mood, CF Haskell et al., Biol Psychol. 2008 Feb;77(2):113-22. Epub 2007 Sep 26. [6] Psychological effects of dietary components of tea: caffeine and L-theanine, J Bryan, Nutr Rev. 2008 Feb;66(2):82-90. [7] The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness, T Giesbrecht et al., Nutr Neurosci. 2010 Dec;13(6):283-90

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