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

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.

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

Our recommendation

Doctor’s Best L-Theanine

Best Suntheanine value

If you want the additional assurance of Suntheanine while still getting a great value, Doctor’s Best is a solid option. At $0.21 per 200 mg of L-theanine and ninety 150 mg capsules, this bottle will last you a while.


Best L theanine for energy

Nutriana L-Theanine With Caffeine

If you’re looking for your Ll-theanine with a side of caffeine for less jittery energy, Nutriana is a good deal. This supplement contains 200 mg of theanine and 100 mg of caffeine per pill. Although L-theanine mitigates the side effects of caffeine, this may still be a bit much if you’re highly sensitive to caffeine. It’s also worth noting that Nutriana does not contain Suntheanine. Overall it is a good value though: this supplement comes out to $.29 per 200 mg.


Best L theanine for anxiety

Genesis Today Mood Balance Supplement

If doing a number on your anxiety is your priority, you may want to try Genesis Today. In addition to 100 mg of L-theanine per capsule ($.66 per 200 mg) Genesis Today also includes anxiety-busting ingredients like 5-htp and rhodiola rosea. Just note that the recommended dose for anxiety is 200 mg per day twice a day, so you may need to load up on some extra supplements to reap the benefits. Because rhodiola rosea is mildly stimulating, this should not be taken later in the evening; the rhodiola rosea dosage is low enough to be used in the afternoon, however.


Best Value

Nutricost L-Theanine

At just $.09 per 200 mg of L-theanine and $10.99 for 120 capsules of 200 mg each, cost-wise it doesn’t get much better than this. One thing to note is that Nutricost doesn’t use Suntheanine, so if you’re concerned about quality, this may not be the supplement for you.


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 using Suntheanine

Enzymatic Therapy L-Theanine Suntheanine

Want a lower dose pill that does contain Suntheanine? Enzymatic Therapy contains one hundred eighty 100 mg capsules and breaks down to $0.40 / 200 mg. While non-Suntheanine supplements aren’t necessarily an indicator of poor quality, if going with a patented brand is important to you, this supplement is a good bet.  


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 for precise dosing 

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.


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.


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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