Why You Need to Be Taking L-Theanine

l-theaninePeople often ask me why I use supplements. After all, our hunter-gatherer ancestors didn’t take them. Our ancient ancestors didn’t take them, nor did our medieval ones or our pre-industrial ones. In fact, nutritional supplementation is one of the most modern inputs you can imagine and, in a perfect world while eating a perfect diet, it should be unnecessary.

But the world is not perfect. We don’t have the same foods available to us that our ancestors ate during the formative years of our evolution, and even if we did, modern farming practices altered mineral levels in the soil. Supplementation can restore some semblance of a “natural” food environment.

Overcoming the stressors of modernity, however, is harder, because it’s not a matter of avoiding the wrong foods and eating the right ones then smoothing out the rough patches with smart supplements. Modern stressors are mostly unavoidable. You have to deal with them. Endure them. And that’s where supplements can really help. Like L-theanine.

What is L-Theanine?

One of my favorite anti-stress supplements is L-theanine. It’s an amino acid found in green and white tea that is structurally similar to glutamine, GABA, and glutamate. It crosses the blood-brain barrier after oral dosing, appearing in the hippocampus and increasing alpha-waves in the brain in less than an hour. It’s clearly “doing stuff” up there. But what are the benefits?

L-Theanine Benefits

The majority of L-theanine’s benefits revolve around our response to stress and anxiety. L-theanine takes the edge of things. More specifically and in addition, L-theanine:

  • Reduces stress
  • Lowers anxiety
  • Improves performance
  • Smoothes out the effect of caffeine
  • Improves sleep
  • Restores immune function
  • Protects against alcoholic liver damage

L-Theanine as a Stress Reducer

When you meditate, your brain is pumping alpha waves. When you’re having a restful morning with . not much to do but hang around and quietly enjoy your time, you’re alpha wave-dominant. When you’re sitting on the beach listening to the waves lap the shore, a brain scan would reveal a ton of alpha wave activity. And when you take 50 mg of L-theanine, your alpha brainwaves kick in after about an hour.1

L-Theanine as an Anxiety Buster

L-theanine isn’t a benzodiazepine. It won’t brute force your brain into an overwhelming state of supreme chill. For L-theanine to reduce your anxiety, you must actually be anxious. Now, much anxiety is hidden, even to ourselves. We may not know that we’re anxious about something. We may not recognize it. So theanine can really help, as long as there’s something for it to help against.

The downside is that it’s subtler than taking a pharmaceutical anti-anxiety med; you don’t “feel it” as much as taking something like xanax. The upside is that it doesn’t make you drowsy and it’s non-addictive. In fact, most people tolerate theanine so well that researchers have been unable to identify a toxic dose. I’m not suggesting you take an entire bottle, of course. There may be a toxic dose, somewhere, somehow. But subjects have taken 400 mg of L-theanine every day for 8 weeks straight without apparent ill effect.

L-Theanine as a Performance Enhancer

L-theanine is most effective at improving the cognitive performance of people undergoing stress. In studies, this takes the form of artificially stressful environments—loud noises, oppressive rules, that sort of thing. In real life, stress is more unpredictable, and I’d argue that most of us are in stressful environments, even if we’re not consciously aware of it. If you’re lucky enough to live a totally stress-free life, L-theanine may not help your performance.

Here’s what I mean: In subjects doing mental tasks in a stressful environment, taking theanine improved performance, reduced blood pressure, and lowered subjective stress-anxiety levels.2

L-Theanine and Caffeine

If you get the jitters or anxiety from caffeine, have 100-200 mg of L-theanine with it. The combination has been shown to smooth out the effects of caffeine and reduce anxiety while retaining performance. That’s why you feel awake and alert after a cup of tea, but without the jittery feeling that coffee gives you.

L-Theanine: Sleep Enhancer

Much like its relationship with mental performance, the ability of L-theanine to enhance sleep depends on the psychological status of the individual.

If you suffer from anxiety or stress, L-theanine has been shown to improve sleep quality and efficiency and reduce sleep latency and usage of sleeping meds.3

If you’re a kid with ADHD, 400 mg of L-theanine can help with sleep quality.4

If you’re being treated for clinical depression, 250 mg of theanine per day should help reduce sleep disturbances at night.5

If you’re being treated for schizophrenia, 250 mg of daily L-theanine should improve sleep quality.6

But if you have good sleep and good mental health, L-theanine won’t be a big boost to your sleep quality—unless you have significant stress in your life (which most do).

L-Theanine for Immune System Restoration

Back about 20 years ago, I developed an anti-stress supplement meant to combat the overreach and overtraining so many endurance athletes experience. Like me. See, I would get dozens of colds each year. Even though I looked healthy and fit, my immune system was constantly playing catch up. All my running and training didn’t leave any resources for the rest of my physiology. Everything was devoted to recovery.

That supplement, originally called Proloftin but now called Adaptogenic Calm, included L-theanine in addition to four other key anti-stress ingredients. I developed it to fix my own issues, and sure enough, it worked (and as it turned out, many others had the same problem).

As we can see from recent research, it wasn’t just placebo. In one study, endurance athletes supplemented with a cysteine and L-theanine product starting ten days prior to training. They ran immune tests before and after training, and the group who got the cysteine and L-theanine supplement had lower C-reactive protein, lower neutrophil count, and higher lymphocyte levels, indicatives of a lower inflammatory and immune load.7

L-Theanine and Liver Health

We don’t have direct evidence of isolated L-theanine improving a person’s liver’s resistance to things like alcohol, but we do have two other lines of evidence.

First, the animal studies that show supplemental L-theanine protects the liver against alcohol-induced injury and increases liver glutathione content (the antioxidant we use to detoxify ethanol).89

Second, the many observational studies linking green tea consumption to improved liver health and  robustness, like the one where green tea consumption seemed to protect against fatty liver.10

L-Theanine: Dosage You Should Take

Oral doses as low as 50 mg have been shown to induce alpha brain waves in healthy humans and doses up to 600 mg per day have been safely tested. Generally, people can tolerate an awful lot of L-theanine without any problems. In fact, you’d have to eat hundreds of grams of pure L-theanine powder to even approach the LD50.

How I Use L-Theanine

The most common way I take L-theanine is by popping a few caps of Adaptogenic Calm, the anti-stress supplement I’ve been making and using for over a decade. You don’t have to take Adaptogenic Calm to get L-theanine, but I’m pretty happy with the synergistic effects of the ingredients.

On the rare occasion I feel acutely stressed out, I’ll take some L-theanine powder under my tongue and let it sit there. L-theanine is water-soluble, so in theory it should absorb sublingually. It certainly feels like it does—I get an almost immediate effect. The taste is subtly sweet. Not something you seek out, not something you avoid either.

You can also get it from green tea, but it will be difficult to hit the 100/200 mg mark found to be most effective in clinical trials through tea alone. Average theanine doses in a cup of green tea range between 25-60 mg. It’s doable, especially if you luck out with a theanine-rich source of tea—you just have to drink a good amount.

That’s it for my take on L-theanine. All in all, it’s a great compound to keep on hand and, perhaps, take on a regular basis. Very little downside, almost all upside.

Have you ever tried L-theanine? Notice anything? How do you use it yourself?

Thanks for reading, everyone.

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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21 thoughts on “Why You Need to Be Taking L-Theanine”

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  1. I buy the bulk powder on Amazon. I have to take a lot more than the recommended dose and this way is much more cost effective.

  2. I’d heard the benefits for reducing stress and anxiety and bought a cheap bottle a while back. It worked, I quickly felt my whole body relax, but it made me so lightheaded I had to stop taking it. I have naturally low blood pressure and it seems to lower blood pressure, so that may be why. It also doesn’t take much for something to make me lightheaded. Caffeine does it, so does exercise and heat (less so if I abstain from caffeine), and I discovered black cohosh also makes me really lightheaded. I’d love to take l-theanine for the stress benefits, is there any way around the side effect I’ve experienced? I’ve tried upping my salt dramatically but it’s hard to keep up. Any advice is appreciated.

    1. I’d look for something else to relieve stress and anxiety if I were you. Not everything works for everybody. You might also want to check with an MD if you get lightheaded very often.

  3. If you get the jitters or anxiety from caffeine, have 100-200 mg of L-theanine with it.
    – maybe one should not consume caffeine then ?

  4. Are there any known interactions with either anti-coagulants or antiarrythmics?

  5. After reading about it on MDA and doing a bit of research, I bought a small bottle of L-theanine at the local Vitamin Cottage yesterday. Took one with dinner last night but didn’t notice much, although I did sleep pretty well. 100mg might not be strong enough. I’ll try taking two of them this a.m.
    I stick with a low-caffeine green tea and rarely drink coffee, so I don’t need anything to offset jitters. I do have a fairly stressful life. Hoping this stuff will help to keep me calm.

    1. Looking forward to hearing how this works for you Skeezix! I drink limited coffee and my life is not stressful and I have trouble getting to sleep at night! I’ll be watching here.

  6. When is the optimal time to take it for improving sleep? Just before bed?

    1. Stimulating effect? I don’t think that’s the goal with l-theanine …

      1. For some of us it is. One of my doctors recommended this to me since it can improve my mental clarity similar to caffeine without the additional side effects. I take 200 mg everyday and it has really helped me avoid taking caffeine even when my sleep wasn’t optimal the night before. It gives the same mental boost without the physical reaction.

  7. I buy bulk and fill my own capsules. My dose is about 500 mg/day. Sometimes I take up to 1000mg/day depending on circumstances. I have Generalized Anxiety Disorder and l-theanine keeps it under control.

  8. I am always interested in undoing the damage to my sleep pattern that 30 years of night shift work has left me with. I investigated your Adaptaogenic Calm product and, respectfully, was surprised to find it contains magnesium oxide and calcium carbonate. I avoid those low quality, so called “garbage ingredients”. In fact, wouldn’t be surprised if I learned about them from listening to you, Brad or Elle. This, sadly, opens up a bit of a trust issue with the quality of your products that I didn’t expect.

  9. I have an intensely stressful job, and under the best of circumstances, am not a good sleeper. Started taking this the day after reading this article. I feel so much calmer and have been sleeping well, waking up more rested. I’m able to navigate the stress with calmer nerves and even felt a little joy today! Forgot one day and was up in the middle of the night. This recommendation was a life saver – thank you!

  10. I use L-Theanine often and it is the best thing I have tried for stress. I recommend it to people as well.

  11. Is taking more l-theanine effective? I feel like 200mg is not enough, so I started trying out 400mg, but it still feels like it’s not really working.

  12. I have read that suntheanine is the better choice when buying an L-Theanine supplement. True?

  13. What is the best time to take L-Theanine for anxiety and sleep? Morning or before bed?

  14. What about taking ltheanine past 8 weeks? I’ve used probably 100 tablets which is like 15 weeks, wondering if I should stop?