Part of our Alpha GPC & NeuroMatcha guide library.
Short answer: L-theanine is an amino acid found in tea, and matcha is especially rich in it. In studies, L-theanine taken with caffeine modestly improved alertness and attention-switching accuracy in the first couple of hours, compared with a placebo. That is part of why tea is often described as feeling smoother than coffee. But the popular idea that L-theanine stops caffeine jitters is not well supported: in one trial it did not reduce jitteriness. And a cup of matcha usually contains less L-theanine than caffeine, much less than the amounts used in most studies.
"Calm energy" is how matcha is often sold, and L-theanine is usually given the credit. Here is what the research on L-theanine and caffeine actually shows, how much L-theanine a cup of matcha really contains, and what that means for how matcha feels compared with coffee.
What you'll learn
- What L-theanine is and why matcha has a lot of it
- What studies found when L-theanine and caffeine were taken together
- Whether L-theanine really prevents caffeine jitters
- How much L-theanine is in a cup of matcha, compared with the amounts studied
What is L-theanine?
L-theanine is an amino acid that occurs naturally in tea leaves. Tea plants grown for matcha are shaded before harvest, which helps the leaves keep more of it, and theanine is part of what gives matcha its savory, non-bitter taste (Kochman et al., 2020). Coffee does not contain L-theanine, which is one reason researchers have looked at it to explain why tea and coffee can feel different.
What happens when you combine L-theanine and caffeine?
Most studies give both as capsules or drinks in the lab, then test attention and mood over the next hour or two:
- A 2014 meta-analysis of 11 placebo-controlled studies found moderate effects in favor of caffeine plus L-theanine on alertness and attention-switching accuracy in the first 2 hours. The dose of caffeine appeared to matter more than the dose of L-theanine (Camfield et al., 2014).
- A 2025 meta-analysis of randomized trials found small-to-moderate benefits of L-theanine plus caffeine over placebo on reaction time, vigilance and attention switching, but noted that the confidence intervals often showed real uncertainty (Payne et al., 2025). Two of its five authors work for a tea company and a food company.
- In one study, 50 mg of caffeine with 100 mg of L-theanine improved both speed and accuracy on an attention-switching task and reduced distraction in a memory task, compared with placebo (Owen et al., 2008).
- In another, 40 mg of caffeine with 97 mg of L-theanine improved accuracy on a task-switching test and self-reported alertness (Giesbrecht et al., 2010).
Many of these studies were small and some were funded by tea or food companies, so the effects should be read as modest and short-term.
Does L-theanine stop caffeine jitters?
The evidence for this is weaker than marketing suggests. In a trial of 48 healthy adults given 250 mg of caffeine, 200 mg of L-theanine, both or neither, caffeine raised alertness, jitteriness and blood pressure. Adding L-theanine blunted the rise in blood pressure, but it did not significantly change jitteriness, alertness or other aspects of mood (Rogers et al., 2008). So if a strong coffee makes you jittery, adding L-theanine may not fix it; having less caffeine is the more reliable approach.
How much L-theanine is in matcha?
Less than you might think, relative to its caffeine. One analysis of a matcha powder found 9.85 mg of L-theanine and 16.1 mg of caffeine per gram (Koláčková et al., 2022). Products vary a lot: higher-theanine matcha has also been reported (Kochman et al., 2020). Here is how a typical drink compares with the amounts used in studies:
| L-theanine | Caffeine | |
|---|---|---|
| Matcha made with 2 g of powder (one analysis) | About 20 mg | About 32 mg |
| Owen et al., 2008 | 100 mg | 50 mg |
| Giesbrecht et al., 2010 | 97 mg | 40 mg |
| Rogers et al., 2008 | 200 mg | 250 mg |
The matcha figures are estimates from one lab analysis (Koláčková et al., 2022). In most studies, participants got about twice as much L-theanine as caffeine; a typical cup of matcha has the reverse.
The balance seems to matter. A Japanese research group found that matcha reduced stress in mice, and anxiety in a small human trial, only when the ratio of caffeine and EGCG (a tea catechin) to theanine and arginine was below 2 (Unno et al., 2018). Many matcha products do not meet that ratio, and labels rarely list L-theanine.
So why does matcha feel different from coffee?
- Less caffeine per cup. A matcha made with 1 to 2 grams of powder usually has less caffeine than a 12-ounce brewed coffee. See does matcha have caffeine?.
- Some L-theanine. It may make a modest difference to attention and alertness, as above, although the amount in one cup is small.
- How you drink it. A matcha latte sipped over breakfast is a different experience from a large coffee on an empty stomach.
None of this makes matcha caffeine-free. Caffeine peaks in your blood within about an hour and its effects can last 4 to 6 hours (MedlinePlus), and a 2023 meta-analysis suggests finishing a typical cup of coffee at least 8.8 hours before bed (Gardiner et al., 2023).
Should you add L-theanine to your coffee?
Some people take L-theanine supplements with coffee to recreate the tea effect. The studies above used about 97 to 250 mg of L-theanine with 40 to 250 mg of caffeine, and found modest, short-term effects on attention rather than a cure for jitters. If you want to try it, talk to your health care provider first, especially if you take medication. For how L-theanine compares with Alpha GPC, see Alpha GPC and L-theanine.
Common myths (quick reality check)
Myth: L-theanine cancels out caffeine. Reality: It does not remove caffeine or its effect on sleep. In one trial it did not reduce caffeine jitteriness, although it blunted the rise in blood pressure.
Myth: Matcha has more L-theanine than caffeine. Reality: In one lab analysis, matcha had about 10 mg of L-theanine and 16 mg of caffeine per gram. Studies usually used about twice as much L-theanine as caffeine.
Myth: The calm feeling from matcha is proven. Reality: Studies show modest, short-term effects on attention and alertness, mostly using capsules or lab drinks rather than matcha itself.
Frequently asked questions (FAQ)
What does L-theanine do with caffeine?
In studies, L-theanine taken with caffeine modestly improved alertness and attention-switching accuracy in the first 2 hours compared with a placebo. The caffeine dose appeared to matter more than the L-theanine dose.
Does L-theanine stop caffeine jitters?
The evidence is weak. In a trial of 48 adults, adding 200 mg of L-theanine to 250 mg of caffeine blunted the rise in blood pressure but did not significantly reduce jitteriness.
Does matcha have L-theanine?
Yes. Matcha is made from shade-grown tea leaves that keep more L-theanine, which contributes to its savory taste. The amount varies widely between products.
How much L-theanine is in a cup of matcha?
In one lab analysis, matcha had 9.85 mg of L-theanine and 16.1 mg of caffeine per gram, so a drink made with 2 grams would have about 20 mg of L-theanine and 32 mg of caffeine.
What ratio of L-theanine to caffeine is used in studies?
Many studies used about twice as much L-theanine as caffeine, for example 100 mg of L-theanine with 50 mg of caffeine.
Is matcha better than coffee for focus?
There is no direct evidence that matcha improves focus more than coffee. Matcha usually has less caffeine per cup and some L-theanine, which may make it feel gentler for some people.
Related guides
- Does matcha have caffeine?
- Alpha GPC and L-theanine
- Does Alpha GPC keep you awake?
- What does matcha taste like?
- Why caffeine crashes happen
Disclaimer and when to seek help
This article is for general education and is not medical advice. These statements have not been evaluated by the Food and Drug Administration. Our products are not intended to diagnose, treat, cure, or prevent any disease. Talk to your health care provider before taking L-theanine or caffeine supplements, especially if you are pregnant or breastfeeding, have a heart condition, anxiety or a sleep disorder, or take medication.
References
- Camfield DA, et al. "Acute effects of tea constituents L-theanine, caffeine, and epigallocatechin gallate on cognitive function and mood: a systematic review and meta-analysis." Nutrition Reviews, 2014;72(8):507-522. doi:10.1111/nure.12120
- Payne ER, et al. "Effects of tea (Camellia sinensis) or its bioactive compounds l-theanine or l-theanine plus caffeine on cognition, sleep, and mood in healthy participants: a systematic review and meta-analysis of randomized controlled trials." Nutrition Reviews, 2025;83(10):1873-1891. doi:10.1093/nutrit/nuaf054
- Owen GN, et al. "The combined effects of L-theanine and caffeine on cognitive performance and mood." Nutritional Neuroscience, 2008;11(4):193-198. doi:10.1179/147683008X301513
- Giesbrecht T, et al. "The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness." Nutritional Neuroscience, 2010;13(6):283-290. doi:10.1179/147683010X12611460764840
- Rogers PJ, et al. "Time for tea: mood, blood pressure and cognitive performance effects of caffeine and theanine administered alone and together." Psychopharmacology, 2008;195(4):569-577. doi:10.1007/s00213-007-0938-1
- Koláčková T, et al. "The effect of in vitro digestion on matcha tea (Camellia sinensis) active components and antioxidant activity." Antioxidants, 2022;11(5):889. doi:10.3390/antiox11050889
- Kochman J, et al. "Health benefits and chemical composition of matcha green tea: a review." Molecules, 2020;26(1):85. doi:10.3390/molecules26010085
- Unno K, et al. "Stress-reducing function of matcha green tea in animal experiments and clinical trials." Nutrients, 2018;10(10):1468. doi:10.3390/nu10101468
- MedlinePlus (U.S. National Library of Medicine). "Caffeine".
- Gardiner C, et al. "The effect of caffeine on subsequent sleep: A systematic review and meta-analysis." Sleep Medicine Reviews, 2023;69:101764. doi:10.1016/j.smrv.2023.101764
