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Sarah Liao

What is L-Theanine?

Have you ever wondered why green tea soothes the soul but coffee always leads to the caffeine jitters?


These differences may be attributed to the amino acid, L-theanine, in green tea that is associated with many health benefits including improvements in cognition, mood, and reduction of stress and anxiety-like symptoms. L-theanine is touted in social media as a component that comes along with caffeination in tea without all the jittery symptoms. L-theanine has been studied in settings where it was part of a supplement as well as being a functional component of food/drink items. However, in settings with frequent green tea consumption (4-8 cups/day with 150-200 mg) rather than pure L-theanine, it is difficult to isolate the causative agent for any resulting outcomes as green tea also has many polyphenolic compounds (catchkins) that may interfere with the previously mentioned health outcomes. (1) This systematic review concludes that L-theanine taken during times of acute stress may provide beneficial properties through increased alpha wave production and decreased glutamate presence in the brain. There is still insufficient evidence to conclude that it can reduce stress, even in its purest form, in people with chronic conditions.


But L-theanine seems to show a greater impact in the resting state of healthy individuals as opposed to those with increased anxiety. (2) Caffeine combined with L-theanine seems to provide additive effects on cognition and attention. (2, 3) Nonetheless, overall, studies have found tea drinkers have lower levels of depressive symptoms but it is difficult to identify the specific potential anti-depressive agent considering other bioactive compounds in green tea. (4) At levels of 200-400 mg/day, L-theanine supplementation shows possible anti-stress and anxiety suppressive properties. (5)


L-theanine in tea could also possibly inhibit the caffeine-induced rise in blood pressure that comes with increased nervousness and is considered a somatic symptom of anxiety. This may be due to L-theanine reducing alertness/arousal and anxiety. Tea is perceived to be more relaxing compared to coffee, which may also reduce the caffeine-induced blood pressure increase. (6)


Summary of L-theanine’s Effect and Key Take Aways:

All in all, the science shows that tea may have a variety of benefits including providing additional focus when consuming caffeine but the extent to which L-theanine and caffeine impacts cognition, mood, and reduction of stress and anxiety-like symptoms is unclear. Supplementation levels of pure L-theanine with 200-400 mg/day may help with anxiety, stress, and focus, but for other benefits attributed to tea drinkers such as lower levels of depressive symptoms, you may consider also adding a cup of tea (or a few) into your life to collect all of the above! If you do decide to go the supplementation route, make sure there is “USP” on the label to ensure it is third-party tested meaning there are no further contaminants and the potency is as promised and check with your health care provider before trying any new supplements. But you may even consider replacing your afternoon cup of decaf or regular coffee with a cup of tea to allow for these possible benefits to seep into your life!


Just like coffee where there is dark/medium/light roast as well as varying specialty coffees, there is even more variety in tea. Teas also vary in their L-theanine content, shown in the below figure! (7)


To replicate the milky flavor similar to adding creamer to coffee, an alternative may be adding milk to the following forms of black tea - Earl Grey tea for the florally note, Assam black tea for the bold and malty flavors, Masala chai for an herb and spice filled alternative, and any Breakfast tea for a blend of many tea strains to provide a robust, clean finish. Whereas for those who are open to exploring different flavor profiles, one may consider incorporating green tea. Traditional green tea has a higher L-theanine content than black teas, which make it a great option. Matcha powder includes much more L-theanine when compared to typical green tea. (8) Matcha powder can be incorporated through matcha lattes, matcha seltzers, or even refreshing matcha lemonades.


Try some of these alternatives for your next mid-day boost and let us know how you feel on our Instagram at @Danajfnutrition!



References:

  1. Williams J, Sergi D, McKune AJ, Georgousopoulou EN, Mellor DD, Naumovski N. The beneficial health effects of green tea amino acid l-theanine in animal models: Promises and prospects for human trials. Phytother Res. 2019;33(3):571-583. doi:10.1002/ptr.6277

  2. Lu K, Gray MA, Oliver C, et al. The acute effects of L-theanine in comparison with alprazolam on anticipatory anxiety in humans. Hum Psychopharmacol. 2004;19(7):457-465. doi:10.1002/hup.611

  3. Dassanayake TL, Kahathuduwa CN, Weerasinghe VS. L-theanine improves neurophysiological measures of attention in a dose-dependent manner: a double-blind, placebo-controlled, crossover study. Nutr Neurosci. 2022;25(4):698-708. doi:10.1080/1028415X.2020.1804098

  4. Hintikka J, Tolmunen T, Honkalampi K, et al. Daily tea drinking is associated with a low level of depressive symptoms in the Finnish general population. Eur J Epidemiol. 2005;20(4):359-363. doi:10.1007/s10654-005-0148-2

  5. Williams JL, Everett JM, D'Cunha NM, et al. The Effects of Green Tea Amino Acid L-Theanine Consumption on the Ability to Manage Stress and Anxiety Levels: a Systematic Review. Plant Foods Hum Nutr. 2020;75(1):12-23. doi:10.1007/s11130-019-00771-5

  6. Rogers PJ, Smith JE, Heatherley SV, Pleydell-Pearce CW. Time for tea: mood, blood pressure and cognitive performance effects of caffeine and theanine administered alone and together. Psychopharmacology (Berl). 2008;195(4):569-577. doi:10.1007/s00213-007-0938-1

  7. Li MY, Liu HY, Wu DT, et al. L-Theanine: A Unique Functional Amino Acid in Tea (Camellia sinensis L.) With Multiple Health Benefits and Food Applications. Front Nutr. 2022;9:853846. Published 2022 Apr 4. doi:10.3389/fnut.2022.853846

  8. Unno K, Furushima D, Hamamoto S, et al. Stress-Reducing Function of Matcha Green Tea in Animal Experiments and Clinical Trials. Nutrients. 2018;10(10):1468. Published 2018 Oct 10. doi:10.3390/nu10101468


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