8 Best L-Theanine Supplements (2023) Reviewed and Compared

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Do you feel a rush of relaxation when sipping tea after a stressful day?

Sure, the warming sensation of tea can make you feel “Zen.” But these benefits may also be due to L-theanine, an amino acid associated with relaxation and focus.

What is L-Theanine?

L-theanine – also known as theanine – is an amino acid found most abundantly in green and black tea leaves. However, it differs from the amino acids you may know – like the ones in your post-workout drink.

Theanine is a non-proteinogenic amino acid. It’s not used in protein synthesis.

Instead, it interacts with your brain and nervous system. L-theanine supplements may even slow your brain waves down – something that happens during meditation and before you fall asleep. Talk about relaxation in a bottle!

Health Benefits of Supplementing with L-Theanine

L-theanine may be a natural solution to chronic stress and anxiety.

A 2020 systematic review found 200-400 mg of L-theanine daily improved acute stress and anxiety symptoms.

Its anti-stress properties may be due to the following mechanisms:

  1. L-theanine crosses the blood-brain barrier, where it inhibits excitatory brain activity.
  2. L-theanine stimulates an alpha brainwave state associated with calm, non-drowsy alertness. It’s the feeling of really being in the present moment. Research suggests this may occur just 40 minutes after taking 50–200 mg L-theanine.

If stress and anxiety control your life, theanine is worth a try. Plus, getting into a more relaxed state can have downstream effects on many areas of mental and physical health. I mean, I know I feel a lot better when I’m not stressed.

Supports Mental Focus

Research shows L-theanine improves concentration and reaction times in people with anxiety. It may also improve attention and executive functioning in older people.

However, you can supercharge these effects by combining L-theanine with caffeine. The two have a synergistic relationship. Theanine may even counteract the jittery downsides of caffeine.

This 2010 study found that 97 mg of L-theanine with 40 mg of caffeine reduced tiredness and improved focus and alertness during mentally demanding tasks. Another study found combining them supported alertness, attention span, reaction times, and working memory.

(Skip to the end for more on the health benefits of L-theanine).

8 Best L-Theanine Supplements

With that said, here’s our list of the 8 best L-theanine supplements on the market in 2022. They are all made according to Current Good Manufacturing Practices (cGMP) for quality and safety.

It was tricky organizing this list, simply because all the supplements are great. When you factor in quality, cost, and convenience, often the simple supplements win out. To get the benefits of l-theanine, we don’t need a supplement for 47 ingredients “proven” for their “nootropic” effects. So our advice is to keep it simple.

*Note: We have affiliate links throughout this article, which means we receive a commission if you purchase from any of our links. This supports our mission to bring complicated health and fitness info in an entertaining package. And it keeps us from putting up annoying things like banner ads. Those suck.

Every product on our list is third-party tested.

1) Double Wood Supplements L-Theanine Capsules

double wood supplements l-theanine

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Double Wood L-Theanine comes in convenient 200 mg capsules. Plus, it’s a steal at just $18.95 for 120 capsules. It’s not vegetarian-friendly, but there are other vegetarian options on this list.

Double Wood also goes the extra mile for quality. All of their products are proudly made in the USA, and share their lab results right on the website. Their l-theanine is gluten-free and non-GMO.

They also offer a 100% money-back guarantee. You have nothing to lose.

You can also get $15 off purchases of $100 or more at Double Wood with the code, HEALTH 15 and by using this link.

For the simplicity, quality, and great price, Double Wood L-Theanine is our top choice.

2) Micro Ingredients L-Theanine Powder

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Each serving of Micro Ingredients L-Theanine Powder provides 250 mg of pure, plant-based L-theanine sourced from tea leaves. It’s free from fillers and additives and easy on your stomach.

Their powder has a subtle, savory flavor and blends well with water, juice, smoothies, tea, and coffee. I love adding a small amount to my coffee to boost the cognitive benefits and minimize the caffeine “crash.” But you can also use it to make capsules if you’re squeamish about tasting your supplements.

A 100-gram bag contains 400 servings for just $17.94. It’ll last over a year if you take one serving per day.

Micro Ingredients has a wide range of simple, pure nutritional powders. They’re cGMP compliant, and all their products are third-party tested for quality.

3) Pure Bulk L-Theanine (Best Bulk Option)

Pure Bulk L-Theanine

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Pure Bulk L-Theanine is derived directly from tea plants. It’s free from additives and fillers and comes in both capsules and powder. The powder offers the best cost per gram.

Pure Bulk is a third-party trusted brand that provides Certificates of Analysis (COA) for all their products.

4) Life Extension Theanine XR™ Stress Relief

life extension theanine XR stress relief

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Life Extension Theanine XR tablets contain 400 mg of slow-release L-theanine from green tea. The extended-release technology helps to maintain a steady supply of theanine over six hours. You’ll stay calm and focused when you need it most.

Each GMP-certified tablet also provides 50 mg calcium and 40 mg phosphorus. They use vegetarian capsules, so it’s vegetarian, gluten-free, and non-GMO.

5) Sports Research L-Theanine + Caffeine 2-in-1

sports research l-theanine and caffeine

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If you’re looking for sustained focus Sports Research L-Theanine + Caffeine 2-in-1 formula is your go-to.

In green tea, l-theanine occurs naturally alongside caffeine. This “takes the edge” off the effects of caffeine, and can even reduce the jitters.

Each soft gel delivers 200 mg of Alpha Wave® L-theanine and 100 mg of organic PurCaf® caffeine in medium-chain triglyceride oil from coconut. It’s also certified keto-friendly, gluten-free, and non-GMO.

Alpha Wave is a purified form of L-theanine supported by clinical studies to reduce stress hormones and increase alpha brain wave activity.

6) Doctor’s Best L-Theanine with Suntheanine

Doctor's Best L-Theanine

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Doctor’s Best L-Theanine delivers 150 mg of Suntheanine® per capsule. Suntheanine may be the purest form of theanine on the market. It’s also vegan and free from GMOs, gluten, and soy.

You can grab it from the iHerb store — a marketplace for quality nutritional supplements at affordable prices.

7) Pure Bulk L-Theanine + Melatonin (Best Option for Sleep)

l theanine and melatonin

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Pure Bulk L-Theanine and Melatonin is a natural sleep aid. Each serving contains 200 mg of the same Pure Bulk L-theanine, paired with 100 mg of melatonin.

Melatonin is the “sleep hormone” secreted by your brain in response to darkness. Combining theanine and melatonin may counteract jet lag and other circadian rhythm disturbances.

For best results, take it an hour before bedtime. However, do NOT take this supplement daily. Taking too much exogenous melatonin can reduce your body’s natural production. 

8) NOW Foods Double Strength L-Theanine,q_auto:eco/images/now/now00148/w/10.jpg?ssl=1

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NOW Foods is a cGMP quality-assured brand. Their L-Theanine capsules deliver 200 mg of pure L-theanine plus 100 mg of inositol for extra nervous system support. They are non-GMO, vegan-friendly, and kosher. You can choose between 60 or 120 capsules.

How We Ranked

L-theanine is a simple, well-absorbed supplement. You don’t need to worry about bioavailability, but dose and form are important when buying the best L-theanine supplement for your needs.

Here’s what we took into consideration when ranking the products.

Strict Testing Standards

The FDA doesn’t regulate the supplement industry, and dodgy companies take advantage of this to make a quick buck.

We only choose reputable companies that subject their products to strict third-party testing. All the products are made according to Good Manufacturing Practice (GMP) regulations. You can rest assured each product here contains exactly what it says it does.


These products contain pure l-theanine, without additives, GMOs, and useless fillers.

We also included products containing other ingredients for added benefit. This was the case for Pure Bulk L-Theanine & Melatonin, Sports Research L-Theanine & Caffeine, and Life Extension Theanine XR.


We found theanine in tablet, capsule, and powder form. Capsules and tablets are the most convenient, but powders are cheaper and more versatile.


The products here offer between 100-500 mg of theanine per serving — enough to be therapeutic and safe.


Living a healthy lifestyle shouldn’t be financially stressful. We aim to list quality supplements that are also affordable.


Can L-Theanine Improve Sleep Quality?

The calming effects of L-theanine may encourage sleep quality for those experiencing stress-related sleep disturbances.

This study of people with anxiety found taking between 450–900 mg of L-theanine daily for two months improved sleep satisfaction.

It may also be helpful for children struggling with poor sleep because of ADHD.

What Should I Stack L-Theanine With for Sleep?

If you’re taking l-theanine to help you sleep, consider making yourself an evening supplement stack. Other effective, popular supplements include GABA and magnesium. On its own, l-theanine won’t promote drowsiness, so if sleep is your goal make it a part of your stack.

Double Wood Supplements sells all of these, and if you bundle them you can save. Use code HEALTH 15 to get $15 off your purchase of $100 or more.

While you could buy these together, it’s usually less expensive to grab the individual ingredients and create your own stack.

What Should I Stack L-Theanine With for Cognitive Function?

On the other hand, if you’re taking l-theanine to give a smooth focus for your productivity sessions, pair l-theanine with popular nootropic ingredients. This can include caffeine, l-tyrosine, alpha-GPC, and more. 

Does L-Theanine Lower Blood Pressure?

L-theanine may prevent blood pressure increases during mentally stressful tasks.

As for whether it can lower already high blood pressure, we don’t have data on this yet.

Can L-Theanine Improve Immunity?

This 2019 study found theanine may enhance immunity in athletes by reducing the immune suppressive effects of intense exercise. But we’re not sure if it improves immunity in other situations.

Can L-Theanine Improve Mood?

This study on people with major depressive disorder found that 250 mg of L-theanine per day – taken with their medication – reduced depression and anxiety.

While we’re not 100% sure of the mechanism, animal studies have shown L-theanine boosts “feel-good” neurotransmitters like serotonin and dopamine.

It’s obvious we need more clinical research, but the low-risk nature of L-theanine suggests it may be worth a try. That said, talk to your doctor to confirm if it’s safe for you.

What’s the Best L-Theanine Dose?

Human studies have used 50-900 mg of L-theanine, with no ill effects. However, doses around 200-400 mg may be most effective for anxiety, stress, mental focus, and sleep.

When taken with caffeine, the recommended ratio is 2:1 (for example, 200 mg of L-theanine to 100 mg of caffeine).

When is the Best Time to Take L-Theanine?

  • To boost cognition, take it first thing in the morning, and pair it with your morning coffee for added benefit.
  • Take it 30-60 minutes before bed to improve sleep quality.
  • Taking it in the morning and evening may be helpful for stress and anxiety. However, people with severe anxiety may need 3-4 200 mg doses taken throughout the day.

Does L-Theanine Have Side Effects?

Studies show L-theanine is generally safe for most people. However, it might not help people with already low blood pressure.

We encourage you to talk to your doctor before taking L-theanine, especially if you’re on blood pressure medication. We don’t want you fainting on us.

For another cognition-enhancing supplement, check out our guide on the best choline supplements, which includes info the super popular Alpha-GPC. 

Disclaimer: We are strangers on the internet. Talk to your healthcare provider before taking any dietary supplement, including l-theanine.

About the Author

Katherine is a South African-born nutritionist, freelance wellness writer, and rooibos tea enthusiast (iykyk). When she's not researching new "biohacking" trends and writing for her clients, you'll find Katherine swimming at a local Cape Town beach or practicing breathwork at any opportunity.

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