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Want The Best L-Theanine Supplement? We Have 9 Recommendations.

Best L-Theanine Supplements At A Glance

Double Wood Supplements L-Theanine

Our Top Recommendation – Made In The USA

Double Wood Supplements L-Theanine

Double Wood Supplements are made in the USA, are 3rd-party lab-tested, and are manufactured in a GMP facility. We recommend their products whenever we have the opportunity.

Bulk Supplements L-Theanine Powder

Best Value L-Theanine Powder

Bulk Supplements L-Theanine Powder

No frills, no fillers. Get this if you want something to put in your smoothies.

Another Great Option

Thorne Research Theanine

Thorne Research uses Suntheanine, the proprietary l-theanine used in the majority of studies that show promising outcomes for theanine usage. Thorne enjoys a stellar reputation among health professionals and professional sports leagues such as the NFL, UFC, NBA, and MLB.

Promotes Focus And A Calm State

Nootropics Depot Caffeine + L-Theanine Capsules

Alertness and cognitive performance can improve when combining L-theanine with caffeine.

Best Tasting L-Theanine

KAL L-Theanine

KAL offers L-theanine in instant dissolving micro tablet form. Each tablet contains 25 mg of L-theanine and is pineapple flavored.

Great Value Suntheanine

Doctor’s Best L-Theanine

Best Suntheanine value

Doctor’s Best is another theanine supplement that gets you the additional assurance of Suntheanine, the proprietary L-theanine that’s used in the majority of studies that show the benefits of L-theanine.

Best Suntheanine L-theanine With Coconut Oil

Sports Research L-Theanine Suntheanine With Coconut Oil

This product contains virgin organic coconut oil and Suntheanine.

Best Low Dose L-Theanine

Life Extension L-Theanine

Looking for a lower dose, perhaps to deal with low-grade day-to-day stress? Each capsule provides 100 mg of L-theanine.

Best L-Theanine For Sleep

Physicians Choice Sleep Aid

While this one has only 50 mg of L-theanine, it has other ingredients that are said to help with sleep, including valerian root, melatonin, chamomile, and more. At $18.93 for 60 capsules, the value isn’t great L-theanine-wise—but if the other ingredients help you fall asleep, it may be worth it.

If stress has been getting you down lately, you’re not alone. Between worries about our health, jobs, and wondering if life will ever get back to “normal,” it feels like there’s a lot to worry about these days.

In addition to getting enough sleep, eating a healthy diet and engaging in regular exercise, many people are turning to supplements in an effort to feel more grounded and calm. L-theanine, which is known for its stress-busting, relaxing, sleep-inducing benefits is a big one. 

Suntheanine, which is produced in a way that mimics the natural process of green tea leaves, is the type of l-theanine found in many popular supplements. Here’s everything you need to know about Suntheanine, l-theanine, and the best supplements to try. 

What Is L-Theanine?

L-theanine, which is often just called “theanine,” is a water-soluble amino acid found in tea leaves, and sometimes mushrooms. When matcha first hit the mainstream market and made its way into coffee shops across the U.S., one of the benefits people talked about was that it contained L-theanine. L-theanine is a compound that gives you a feeling of “calm alertness,” and so it was considered a great alternative for anyone who gets the jitters from coffee. 

So while you can drink your L-theanine via matcha, when people are hoping to reap some serious benefits from it, they’ll usually take it in supplement form.

What Is Suntheanine?

When we hear about the benefits of L-theanine, we’re typically talking about Suntheanine. This is because, of the clinical studies used that talk about the benefits of L-theanine, Suntheanine (the name of both the company and the ingredient) is the type that’s used. It’s worth noting that Suntheanine has also funded many of these studies. 

Rather than actually extracting L-theanine from tea leaves, Suntheanine mimics this process, which the company claims results in “100% pure, L-isomer-theanine.” The clinical trials that have been conducted have shown that regular Suntheanine supplementation results in a state of relaxation without the drowsy factor, along with improved sleep, fewer PMS symptoms, and more. 

The main difference between L-theanine and Suntheanine is that L-theanine is naturally occurring (such as in a cup of tea), whereas Suntheanine mimics the process of green tea leaves through a patented process, leading to a more concentrated theanine than what you’d find in tea leaves. So if you’re thinking about Suntheanine vs L-theanine, the bottom line is that they are essentially the same, while Suntheanine provides the basis for many L-theanine supplements on the market.

L-Theanine Suntheanine Brand

Wondering which brands use Suntheanine? Here are our picks for the best L-theanine Suntheanine brands:

L-Theanine Suntheanine BrandDosage 
Thorne 200 mg/capsule
Doctor’s Best 150 mg/capsule
Sports Research 200 mg/capsule
Enzymatic Therapy 100 mg/capsule
Physician’s Choice 25 mg/capsule
You can read more about each of these products below in the section ‘What’s The Best L Theanine Brand? Here Are 9 Recommendations‘.

How Does L-Theanine Work?

L-theanine is an amino acid that the body does not naturally produce, and it’s not essential for human function. There may be some important reasons to ingest L-theanine, though: taking L-theanine could have a positive impact on the body and brain, particularly when it comes to lowering stress levels, getting enough sleep, and regulating emotions. 

There’s some evidence that L-theanine may elevate levels of GABA, dopamine, and serotonin — all “feel good” neurotransmitters in the brain. Typically, increasing levels of these chemicals in the brain can help regulate mood, helping people feel calmer and sleep better. 

It’s worth noting that while you can get L-theanine through tea, if you’re hoping to reap the benefits associated with L-theanine use, it’s probably best to do it via supplementation — the amount of L-theanine in tea is usually between 30 and 50 mg, as compared to the 50 to 200 mg found in supplements. It’s also worth noting that the theanine-to-caffeine ratio is about 1:3 in tea, vs 2:1 or more in supplements, so what L-theanine benefit you do get from tea may be ‘outweighed’ by the caffeine. 

Benefits Of L-theanine

A handful of studies have been conducted on L-theanine use. While they have some promising results that suggest L-theanine supplementation is a good idea if you’re looking to see a positive impact on your body and brain, it’s important to take these results with a grain of salt: they’re smaller studies, and many are funded by Suntheanine. When specific companies fund studies, it can result in a “funding bias,” or results that skew toward what the company was hoping the outcome would be.

There’s no evidence that this is the case with Suntheanine, but it’s worth thinking about. With that in mind, here are some potential benefits of L-theanine: 

  • It could lead to a more relaxed, yet alert, state of mind. When people talk about the feeling of “calm alertness” that comes with L-theanine — or a burst of energy without the jitters people often experience from coffee — they may be basing that off personal experience, but there’s also research to back it up: One study found that it increased the alpha brain waves associated with these feelings.
  • It could reduce anxiety. Another study found that when people drank water with dissolved Suntheanine in it, they reported less anxiety while completing a stressful task, and their heart rate was lower.  
  • It may help you sleep better. Struggling to get enough sleep? One study found that when people took L-theanine, it took them less time to fall asleep. But there’s evidence of the contrary, too: A small study conducted in Australia on people with Generalized Anxiety Disorder, which used a dosage several times higher than the first study, found that there was no difference in terms of anxiety, insomnia, and cognition between the people who took L-theanine and the people who didn’t.
  • It may have positive blood pressure benefits. One study found that when caffeine was paired with L-theanine, blood pressure didn’t increase as much compared to caffeine alone. The participants of this same study who took both caffeine and L-theanine did experience jitters, though — and it’s worth noting that the amount of caffeine consumed for this study was quite high, at 250 mg. 
  • It could have anti-cancer benefits. A study conducted on animals found that L-theanine use had anti-tumor properties, but a lot more research needs to be conducted before anyone can confidently say that the same holds true for humans. 

How To Get Started With L-Theanine

If you’re new to L-theanine and want to give it a try, here’s what you need to know about getting started.

Finding the right dosage for you

If you want to see real results with your L-theanine use, you’ll probably want to take 50 mg per day minimum, which is why getting a high dose of L-theanine by drinking tea can be tough. Whether or not you decide to increase that amount depends on the specific results you’re trying to achieve. 

For example, if you’re gearing up for something you know will be stressful — a big presentation at work, or a difficult conversation with a loved one — you may want to try 200 mg, which may lead to a lower resting heart rate and is used for anxiety relief. If you simply want to feel more relaxed, 50 mg is the amount that’s been shown to increase those alpha brain waves that are associated with a more relaxed state of mind. If you’re looking for the best L theanine for anxiety dosage, 200 mg twice a day is a safe bet. And if you want to sleep better, anywhere from 250 mg to 400 mg of L-theanine may help. 

When is the best time to take L theanine? 

When you take your L-theanine is up to you and depends on the main benefit you’re hoping to receive — if you’re looking to improve your sleep, for example, you may want to take it closer to bedtime — there’s some research that pairing it with your morning cup of coffee could help with blood pressure and improve cognitive function.

Side effects of L-theanine

While there are no known negative side effects of L-theanine supplementation, one thing worth noting is that green tea may make chemotherapy less effective. Because green tea contains L-theanine, if you’re currently undergoing chemotherapy, make sure to discuss this with your doctor. 

Additionally, if you’re pregnant or breastfeeding, make sure to consult your doctor before taking L-theanine.  

What to look for when buying L-theanine

The good news about buying L-theanine is that you don’t need to worry much about getting “fake” L-theanine—for the most part, L-theanine isn’t faked. If you are worried about this, however, simply check the bottle of the L-theanine supplement you’re considering to make sure it contains Suntheanine. 

Other than that, the main thing to consider is price. Unless you’re shopping for supplements that have other ingredients in them besides L-theanine, there’s no harm in choosing the least expensive option. Keep in mind that doses can vary widely, though, so pick a dose that caters to the specific problem you’re trying to solve — anxiety, mild stress, insomnia, etc — as you’re shopping. 


What’s The Best L-Theanine Brand? Here Are 9 Recommendations

Double Wood Supplements L-Theanine

Our Top Recommendation – Made In The USA

Double Wood Supplements L-Theanine

Products by Double Wood Supplements are made in the USA, 3rd-party lab tested, and are manufactured in a GMP facility. We recommend their products whenever we have the opportunity.

This product comes with 120 capsules, each containing 200 mg of L-theanine.

However, these capsules are made with gelatin, making them unfit for vegans or vegetarians.


Bulk Supplements L-Theanine Powder

Best value L-theanine powder

Bulk Supplements L-Theanine Powder

Want the most cost-effective way for taking L-theanine? Bulk Supplements offers this product in powder form, ranging in quantities from 50 g to 55 lbs (no joke!).

You can also choose to purchase them in the form of gelatin capsules as well, but the powder form is suitable for vegetarians and vegans as there are no other ingredients.


Thorne Research L-theanine

Runner-up for capsules

Thorne Research Theanine, 200 mg, 90 Capsules

Thorne Research Theanine uses Suntheanine, the proprietary l-theanine that’s used in the majority of studies that show promising outcomes for theanine usage. The Unwinder almost always recommends theanine products that use Suntheanine for this very reason.

Thorne Research enjoys a stellar reputation among health professionals and, interestingly, professional sports leagues such as the NFL, UFC, NBA, and MLB. They manufacture, process and test all the supplements they make in house; the facility is GMP compliant. Thorne is also recognized by one of the most scrupulous regulatory health bodies in the world, Australia’s Therapeutic Goods agency, as having an “A” rating.


Promotes focus and a calm state

Nootropics Depot Caffeine + L-Theanine Capsules

This product contains the perfect combination of L-theanine with caffeine. Each capsule contains 100 mg of caffeine along with 200 mg of L-theanine.


Great value Suntheanine

Doctor’s Best L-Theanine

Best Suntheanine value

Doctor’s Best is another theanine supplement that gets you the additional assurance of Suntheanine, the proprietary L-theanine that’s used in the majority of studies that show the benefits of L-theanine.

While still getting a great value, Doctor’s Best is a solid option.


Suntheanine L-theanine runner up

Sports Research L-Theanine Suntheanine With Coconut Oil

This isn’t the cheapest L-theanine supplement on the market, but it isn’t the most expensive either. Made with virgin organic coconut oil and Suntheanine, a 60-count bottle starts at $17.95.


Best low dose L-theanine

Life Extension L-Theanine

Looking for a lower dose, perhaps to deal with low-grad day-to-day stress? Life Extension, which contains sixty 100 mg pills ($.56 per 200 mg), could be a great bet. It is worth noting that Life Extension isn’t made with Suntheanine, though, so if you want the highest possible bioavailability you may want to skip it.


Best tasting L-theanine 

Kal L-Theanine

Want to get super-precise with your dosages? At just 25 mg per capsule, Kal 25 L-theanine will never leave you guessing. With 120 25 mg capsules, it works out to $.88 per 200 mg. The price value isn’t great here when compared with other brands, but if breaking your dosage down into 25 mg increments is important to you, Kal 25 is worth a try. These small doses can be helpful for kids who may need less L-theanine to see the effects, or if you want to maintain the benefits of L-theanine throughout the day.

Only 9 left in stock – order soon.


Best L-theanine for sleep

Physicians Choice Sleep Aid

While this one has only 50 mg of L-theanine, it has other ingredients that are said to help with sleep, including valerian root, melatonin, chamomile, and more. At $18.93 for 60 capsules, the value isn’t great L-theanine-wise—but if the other ingredients help you fall asleep, it may be worth it.


Where To Buy L-Theanine In Stores

Wondering which stores carry L-theanine supplements? You should be able to find some form of L-theanine at stores including Walgreens, CVS, Target, Walmart, Whole Foods, and most other major name pharmacies, supplement stores, and supermarkets.

However, not every location is guaranteed to carry Suntheanine products, so make sure to use caution when purchasing L-theanine in-person.


L-Theanine Anxiety Reviews

We found the following reviews left on Amazon from customers who reported experiencing major improvements in their anxiety after using L-theanine:


“I take a prescription anti-depressant and anti-anxiety medication, and lately with COVID stress, this is a safe addition for when I need it. It kicks in within about 30-45 minutes and it’s just enough for me to calm my mind and collect my thoughts in my room, away from all of my stressors. The only downside I would say, is that the calming I feel from it doesn’t last more than 2 hours.”

-AWyatt, purchased Theanine by Thorne


So first off I bought this product for several reasons I heard it helps with sleep, anxiety and increases HGH (Human Growth Hormone) so I bought it for the very first time recently and tried some on an empty stomach in the morning I noticed it worked like a nootropic I was thinking a lot clearer and sharper, fast forward to the end of the night and I took another one before bed it calmed me down, calmed my excessive thoughts and helped me fall asleep rather quickly I slept through out the night and didn’t wake up at all like I usually do in the middle of the night, I woke up feeling very refreshed and in a good mood. Fast forward to a couple days later I was having anxiety for some reason and I don’t usually get anxiety but I used to really bad so I know how it feels anyways I was having anxiety so I took an a capsule and within 30 minutes my anxiety calmed down almost completely and eventually did completely which was a blessing. I definitely recommend this product especially for the price I have tried many supplements and this is one you can feel working. I hope I helped :)”

– Jewlz Sanguine, purchased L-Theanine by Nutricost


Our daughter suffers with anxiety and anger outbursts. We have spent thousands of dollars on supplements. This is the only vitamin that we have purchased that has worked almost immediately. Our therapist recommended it. It has changed our lives and brought peace to our home. I just bought 5 bottles. Can’t thank this company enough. Signed happy mom and daughter.”

– Anna, purchased L-Theanine by Sports Research


Want to read more about L-theanine and its uses? Check out the following articles:


Editor’s note: we are regularly updating this review. If you see any problems, weird interpretations of the data, or just want to say hi, please reach out to hello@the-unwinder.com.

About the author

Leigh is a New York-based freelance journalist covering topics ranging from health and wellness to parenting and personal finance. Her work has been featured on Glamour, Well+Good, mindbodygreen, Parade NBC News, The Huffington Post, and more. When she’s not writing, you can probably find Leigh forward folding at Sky Ting Yoga, running along the Hudson, or coming up with a creative new take on avocado toast.

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