This Is Why We're Starting Our Day With Caffeine and Theanine

"Do you know the story about Kaldi the Ethiopian goatherd? Legend has it, over a thousand years ago, Kaldi, an observant Abyssinian goatherd, took note of the berries that his goats were eating with such enthusiasm. Being an adventurous young man, Kaldi decided to try the berries himself. To his delight, the berries made him feel elated and energized. He filled his pockets with them and took them to his tribe’s chief monk. He and the monk tried cooking the berries in a pot. But, the resulting drink was the most bitter brew they had ever tasted. Disgusted, the monk threw the berries into the fire – roasting the world’s first coffee beans! The two smelled the delicious aroma coming off the fire, and coffee was born.[1] Today, coffee is the second most consumed drink in the world (second only to tea), and the world’s most prevalent stimulant.[2] But, as we all know, it has its drawbacks. Aside from the mental focus, mood enhancement and energizing effects, coffee can make you jittery, give you sweaty palms, a racing heart, a headache, and – worst of all – it can make you feel anxious.[3]

Enter L-Theanine…


What’s so Great About L-Theanine?

Theanine is one of the main active ingredients found in green tea and also in several species of mushrooms. It helps to promote relaxation without causing drowsiness and is especially useful when taken alongside caffeine. It is best known for its ability to reduce mental fatigue and feelings of stress.[4] Theanine is also able to improve cognitive performance – perhaps not to the same extent as caffeine, but definitely, enough to be noticeable.[5] Researchers have found that Theanine can help to promote healthy sleep. It is not a sedative, though, so the sleep-promoting benefits are thought to be related to its stress-reducing effects.[6] One of the best things about Theanine is that it has almost zero toxicity levels – it is very safe and may even confer some health benefits. Researchers have shown that it helps with inflammation and may improve blood flow.[7] At small to medium servings, it is a mild cognitive enhancer and a mellower alternative to caffeine. At larger servings, it can be used to help promote healthy sleep. In your brain, Theanine helps to increase the production of GABA and dopamine and may help to reduce cortisol – also known as the ‘stress hormone’.[8] [9] [10] Theanine’s relaxing and stress-reducing properties help to reduce the common side effects felt from caffeine. How do we know this is true? Well, apart from all the research that’s been done on these two compounds, you can actually test this yourself without even using any supplements. Tea contains both Caffeine and Theanine. A typical cup of green tea contains around 35 mg of Caffeine and no more than 10 mg of Theanine.[11] [12] A better test would be to use black tea (which is made from the same plant as green tea, just processed differently). A cup of black tea usually contains around 20-30 mg caffeine and 20 – 25 mg Theanine. [12]  [13] Even if you drank 2-3 cups of tea in a row, it’s unlikely that you’d notice any of the side effects associated with coffee. That’s because the Theanine content is blocking those effects. The obvious problem with tea – which contains both caffeine and L-Theanine, is that the levels of these compounds are way too low. To get a similar kick to what you feel from a strong cup of coffee, you’d need to drink several cups of tea. You’d be using the bathroom far too regularly to be functional.  

Why combine Caffeine and Theanine?

The combination of Caffeine and Theanine is sometimes considered to be the ‘original nootropic’. Nootropics are substances that improve cognitive function, memory, creativity, or motivation. In 2017, researchers conducted a study on 20 healthy young individuals, who were given either placebo, caffeine, l-theanine, or a cup of black tea. The researchers measured a number of outcomes like cognitive reaction time and neurophysiological measures of attention. They found that caffeine and theanine both improved cognitive performance significantly more than placebo or black tea, BUT the combination of theanine and caffeine improved cognitive performance by a long shot! [14] This is why so many people are using Theanine combined with caffeine – either by taking Theanine capsules alongside a cup of coffee, or bypassing the coffee altogether and using Caffeine + Theanine capsules. This is sometimes called a ‘supplement stack’ – where you take two different supplements together for their synergistic relationship.  

Why take Caffeine + Theanine capsules?

L-Theanine capsules are formulated with 200 mg Theanine per capsule – which, when combined with a cup of coffee (around 50 – 100 mg), will produce noticeable benefits in terms of focus, alertness, and cognitive function. Caffeine + L-Theanine capsules are packed with 100 mg caffeine and 150 mg Theanine, for people who’d prefer to skip out on coffee. That’s the equivalent caffeine content of a strong, large cup of coffee, combined with the Theanine content of several strong cups of tea. If you compare capsules to powder supplements, they’re just much easier to take! No need for micro-scoops or measuring scales, simply pop the capsule in your mouth and swallow! In terms of monetary savings, let’s assume you’re drinking a large cup of strong coffee every morning – with a full 100 mg caffeine. The average large-sized coffee sets you back around $3. This is without any Theanine, mind you. Now, if you were to purchase a 300 count tub of caffeine + Theanine capsules, this is the equivalent of 300 cups of coffee WITH added L-Theanine! If you were buying a cup of coffee every morning, that’d cost you over $900. So you can imagine how much you’re saving by using these capsules. Even if you’re a coffee addict and you definitely won’t cut out the morning brew – well, the noticeable benefits that you feel from adding a Theanine capsule to your morning coffee, in terms of cognitive performance and mood: these benefits are well worth the price!  

How do you take Theanine and Caffeine capsules?

Caffeine and L-Theanine capsules contain 100 mg Caffeine and 150 mg L-Theanine. The synergistic relationship between the two is what’s important! For these capsules, the recommended serving size is 1-2 capsules, once or twice daily. In terms of Theanine, 200 mg is the ideal serving size for most people – and that’s how much is in a single capsule. To use Theanine as a mild cognitive enhancer, a lower serving size is recommended. For sleep, you’ll need a larger serving size of around 400 mg (or two capsules). The one thing to remember is that large servings of well over 400 mg may make you feel a bit drowsy. So you just need to watch for that. But, taking 1-2 capsules, once or twice daily definitely shouldn’t produce any negative effects, so it’s actually a great mellow alternative to caffeine.  

What are the Side Effects of Theanine and Caffeine?

As we mentioned before, Theanine is relatively free from side effects and may actually help to reduce some of the adverse effects that people feel from caffeine. At larger servings, it may cause slight drowsiness and headaches but these are not generally present at the recommended serving size. Unfortunately, caffeine isn’t as benign as Theanine and needs to be used responsibly. Even at small servings, caffeine can increase your blood pressure and your heart rate. It is a vasoconstrictor, which means that it causes the blood vessels to get smaller (although it is thought that Theanine may counter this effect to a certain level). There are several important points to remember about caffeine use:
  • It has a long half-life of over 6 hours, so don’t use it any time close to sleep!
  • It is possible to overdose on caffeine. Anything above 400 mg8 per day is said to be unhealthy, so it’s important to stick to the recommended serving size.
  • Caffeine is addictive and can cause withdrawal symptoms after prolonged use.
Please use these capsules responsibly- as with all supplements!   * Medical Disclaimer Not intended to treat, diagnose, or cure any disease or ailment. Use with CAUTION.


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] Nzegwu, N. (1996). The History of Coffee. [Online]. Available at: [2] Daly, J.W., Holmén, J., Fredholm, B.B. (1998). [Is caffeine addictive? The most widely used psychoactive substance in the world affects same parts of the brain as cocaine]. (Article in Swedish). Lakartidningen, 16;95(51-52):5878-83. [3] Spritzler, N. (2017). 9 Side Effects of Too Much Caffeine. [Online]. Available at: [4] Patel, K. (2018). Theanine. [Online]. Available at: [5] Dodd, F. L., Kennedy, D. O., Riby, L. M., Haskell-Ramsay, C. F. (2015). 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. Psychopharmacology, 232(14), 2563–2576. [6] Rao, T.P., Ozeki, M., Juneja, L.R. (2015). In Search of a Safe Natural Sleep Aid. J Am Coll Nutr, 34(5):436-47. [7] Hwang, Y.P., Jin, S.W., Choi, J.H., Choi, C.Y., Kim, H.G., Kim, S.J., Kim, Y., Lee, K.J., Chung, Y.C., Jeong, H.G. (2017). Inhibitory effects of l-theanine on airway inflammation in ovalbumin-induced allergic asthma. Food Chem Toxicol, 99:162-169. [8] Yokogoshi, H., Kobayashi, M., Mochizuki, M., Terashima, T. (1998). Effect of theanine, r-glutamylethylamide, on brain monoamines and striatal dopamine release in conscious rats. Neurochem Res, 23(5):667-73. [9] Nathan, P.J., Lu, K., Gray, M., Oliver, C. (2006). The neuropharmacology of L-theanine(N-ethyl-L-glutamine): a possible neuroprotective and cognitive enhancing agent. J Herb Pharmacother, 6(2):21-30. [10] White, D.J., de Klerk, S., Woods, W., Gondalia, S., Noonan, C., & Scholey, A. B. (2016). Anti-Stress, Behavioural and Magnetoencephalography Effects of an l-Theanine-Based Nutrient Drink: A Randomised, Double-Blind, Placebo-Controlled, Crossover Trial. Nutrients, 8(1), 53. [11] West, H. (2017). How much caffeine is in green tea? [online] Available at [12] Lee, J. (2013). L-Theanine for Anxiety – Self Medicating Anxiety with Tea? [online]. Available at: [13] Mayoclinic Staff. (2017). Caffeine content for coffee, tea, soda and more. [online]. Available at: [14] Kahathuduwa, C.N., Dassanayake, T.L., Amarakoon, A.M.T., Weerasinghe, V.S. (2017). Acute effects of theanine, caffeine and theanine-caffeine combination on attention. Nutr Neurosci. Jul;20(6):369-377."

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