Best L-Theanine Supplements – Top 5 Brands of 2018

Green tea is no stranger to health enthusiasts.

It’s was reserved for Chinese emperors for its health promoting, and longevity-enhancing effects as early as 2800 BCE.

Modern scientific research has only bolstered these health claims, offering numerous mechanisms of action for the health-promoting effects of this modest herbal brew.

One of the main medicinal components researched in green tea is L-Theanine. It’s the compound responsible for green tea’s cognitive enhancement and relaxation benefits. It’s also the source of green teas umami flavor.

L-Theanine has since become a staple in the nootropic industry, with nearly every nootropic manufacturer offering their own version of L-Theanine products. It can be difficult to navigate through the maze of L-Theanine supplements available online and in-store.

Here is our list of the top 5 L-Theanine supplements on the market.

The Best L-Theanine Supplements

1. Suntheanine® L-Theanine 200mg

lta1Suntheanine is a patented version of pure L-Theanine.

It’s manufactured by the Japanese company, Taiyo Pharma. They’ve developed a way to produce pure L-Theanine by mimicking the fermentation process that occurs naturally in tea leaves.

In the tea plant, the leaves produce 2 enantiomers of the amino acid theanine, D-Theanine, and L-Theanine.

The vast majority of research on theanine has been done on L-Theanine, as this is the preferred isomer for effects on humans.

A recent study investigated the ratios of D-Theanine and L-Theanine in commercial products. Out of 6 popular commercial samples of L-Theanine, Suntheanine® was the only product to contain 100% pure L-Theanine. The other 5 products had significant amounts of the less effective D-Theanine. [6].

Interestingly, one study found that D-Theanine can reduce the overall benefits of the active L-Theanine enantiomer [7].

Most L-Theanine extracts have varying degrees of D-Theanine included in the dose. These companies almost never disclose the ratio of these two compounds).

Additionally, L-Theanine is considered a “fat-soluble” compound. This means that L-Theanine needs to follow fats and oils in the digestive tract in order to enter the bloodstream. If L-Theanine is eaten in the absence of fat, only a fraction will reach the bloodstream.

Suntheanine® has added fat directly to the capsule, ensuring optimal absorption of every molecule of L-Theanine you consume.

Overall Rating 5/5
Quality 5/5
Dose Per Capsule 200 mg Pure L-Theanine
Cost Per Capsule: $0.28
Quantity 60 Softgel Capsules


  • Contains pure L-Theanine (no D-Theanine)
  • Softgel capsules
  • Formulated with coconut oil to improve absorption
  • Comes with a money-back guarantee
  • Cost-effective


  • Extract not produced naturally in the tea plant

2. Superior Labs Pure L-Theanine

ltt2If you’re looking for the cleanest L-Theanine supplement you can find, you should pay attention to Superior Labs Pure L-Theanine.

This formula uses 100% pure theanine— NO ADDITIVES WHATSOEVER.

Each 250mg capsule contains, you guessed it,250mg of L-Theanine—no binding agents, fillers, absorptions enhancers, preservatives, flavoring agents, or added colors.

Superior Labs is based out of San Diego, California. They specialize in producing pure nutritional supplements without the use of added chemicals.

Many other supplement manufacturers add these agents to improve the appearance of the product with the use of coloring agents and fillers, or to make manufacturing easier with binding agents, and other additives to prevent their machinery from sticking. None of which has any impact on the efficacy profile of the supplement.

For the absolute cleanest, additive-free L-Theanine, Superior Labs is your best option.

Overall Rating 4/5
Quality 5/5
Dose Per Capsule 250mg
Cost Per Capsule: $0.24
Quantity 90 Capsules


  • Contains ZERO additives
  • Manufactured in third-party NSF certified labs
  • All products are screened for purity
  • Uses vegetarian capsules
  • 60-day money back guarantee


  • Contains both enantiomers of theanine (D- and L-theanine)

3. Nature’s Trove – L-Theanine 200mg

ltt3Supplements can get expensive, especially if you’re taking a variety of them. This is why it pays to know where to find budget options to add to your stack.

In the world of L-Theanine, nothing beats Nature’s Trove for low-budget options.

These capsules come in at an incredible 5 cents per capsule. This is nearly 80% cheaper than the average cost for L-Theanine supplements.

In many cases, cheaper supplements come with a catch. They may be diluted with fillers and additives, come from poor quality sources, or lack adequate quality control.

None of this is true for Nature’s Trove.

The sole reason this company is able to get the cost of their supplements so low is because they manufacture it themselves.

Most L-Theanine supplements on the market are manufactured in a separate lab, usually by a separate company. This means more people are involved in the process, which is more costly to the operation.

Nature’s Trove manufactures all of their supplements in New Jersey, USA, and sells them directly to the public.

Just like higher priced L-Theanine, Nature’s Trove conduct regular quality testing, are additive-free, and NSF certified.  Nature’s Trove produces the highest value of L-Theanine supplements on this list.

Overall Rating 4/5
Quality 3/5
Dose Per Capsule 200mg
Cost Per Capsule: $0.05
Quantity 365 Capsules


  • Great value
  • Low cost
  • Made in the USA
  • No additives or fillers
  • Vegetarian capsules


  • Some users have reported that the capsules clump together in the container
  • Contains unknown ratio of D-theanine to L-Theanine

4. Source Naturals L-Theanine Tablets

ltt4L-Theanine comes from the tea plant (Camellia sinensis). Many companies have focused solely on the L-Theanine and forgotten about the plant that produces it.

Source Naturals L-Theanine aims to maintain the most natural form L-Theanine can have by ensuring the L-Theanine they produce comes directly from the tea plant in its purest form.

Their company philosophy is “respect nature’s intelligence”.

For those looking for the most natural L-Theanine supplement, this is your best option.

Overall Rating 4/5
Quality 4/5
Dose Per Capsule 200mg
Cost Per Capsule: $0.31
Quantity 60


  • Made using less machine and chemical processing than other labs
  • Each batch is quality tested
  • Manufactured to maintain the form closest to that of natural tea leaves


  • Contains both L- and D-theanine
  • More expensive than other brands
  • Some users have reported drowsiness with this supplement

5. NOW L-Theanine 200 mg

ltt5One of the most common uses of L-Theanine is to reduce the effects of stress and anxiety.

NOW is one of the first supplement companies to combine L-Theanine, with another stress-reducing compound known as inositol.

Inositol has many similar effects to L-Theanine, offering support for stress and anxiety by promoting a feeling of calmness and clarity. It’s often categorized by some as a B vitamin, though this is up for debate in the scientific community.

Nevertheless, NOW discovered that if they added inositol to their L-Theanine, their customers were reporting stronger stress-reducing effects. It’s since become a standard addition to their L-Theanine supplements, and their customers are loving it.

This is a great L-Theanine supplement if your primary goal is to reduce stress and anxiety.


Overall Rating 4/5
Quality 4/5
Dose Per Capsule 200
Cost Per Capsule: $0.17
Quantity 120


  • Contains added inositol to boost antianxiety benefits
  • The company is a leader in sustainable business practices in the United States.
  • Lower than average cost per capsule
  • Vegetarian capsules


  • Inositol takes about a week to show benefits

Supplementing L-Theanine

Although green tea contains a number of useful molecules for treating cardiovascular, neurological, and gut conditions, many people are seeking L-Theanine for its cognitive enhancing abilities.

In order to obtain enough L-theanine to receive the nootropic benefits (500-750 mg/day), roughly 20,000 mL (20 liters) of green tea would need to be consumed each day.

This is impossible given that the maximum amount of water a person can safely consume is closer to about 6 liters per day.

So, how do we get enough L-Theanine to take advantage of the nootropic benefits? Supplementation.

The Benefits Of L-Theanine Supplementation:

L-Theanine supplements offer greater benefits to the brain than its form as raw tea leaves.

It shifts the balance of neurotransmitters in the human brain to support rest and relaxation. The most notable changes include the neurotransmitters dopamine [1], serotonin [1], glutamate [1], and melatonin [4].

Essentially, L-Theanine shifts the balance of neurochemicals towards a state of calmness and focus. This shift offers massive benefits to those experiencing stress, anxiety, hyperactivity, issues regarding sleep quality, and poor concentration.

The Effects Of L-Theanine:

L-Theanine Effects Reference
GABA Increases 5
Dopamine Increases 1
Serotonin Decreases 1
Glutamate Decreases 1


The Major Benefits of L-Theanine Includes:

  • Calms overactive thoughts
  • Shortens the time it takes to fall asleep
  • Improves the ability to stay asleep throughout the night
  • Reduces symptoms of anxiety
  • Lowers the sensation of stress
  • Promotes calm, clear focus
  • Improves memory
  • Protects the brain from oxidative damage

Who Needs L-Theanine?

Anybody experiencing heightened stress and anxiety can benefit from L-Theanine supplementation. Online herbal databases list L-Theanine for heart disease, cancer, insomnia, depression, anxiety, Alzheimer’s disease, and stomach ulcers.

Students often use it as a study-aid for its role in improving focus and concentration.

L-Theanine also has the benefit of reducing the side effects of caffeine use including jitteriness, anxiety, paranoia, heart palpitations, dizziness, and high blood pressure.

A better question is “who DOESN’T need some L-Theanine in their lives?”

Our Favourite L-Theanine

We take L-Theanine supplements regularly and have tried many different brands. Our favorite is Suntheanine®.

One of the biggest debates around this supplement is the different benefits of L-Theanine and D-Theanine. Recent evidence suggests that D-Theanine can interfere with the absorption of L-Theanine as well, making the supplement LESS effective overall.

In order to maximize the effectiveness of the L-Theanine, it can be helpful to eliminate as much D-Theanine as possible.

While other products don’t disclose the amount of D-Theanine in their formula, Suntheanine® guarantees 100% L-Theanine.

Users report immediate (within 15 minutes) effects, and long-lasting cognitive benefits after using this supplement.

This is why, in our opinion, Suntheanine® is the best L-Theanine supplement on the market.


  1. Yokogoshi, H., Mochizuki, M., & Saitoh, K. (1998). Theanine-induced reduction of brain serotonin concentration in rats. Bioscience, biotechnology, and biochemistry, 62(4), 816-817.
  2. Juneja, L. R., Chu, D. C., Okubo, T., Nagato, Y., & Yokogoshi, H. (1999). L-theanine—a unique amino acid of green tea and its relaxation effect in humans. Trends in Food Science & Technology, 10(6-7), 199-204.
  3. Goto, T., Yoshida, Y., Amano, I., & Horie, H. (1996). Chemical composition of commercially available Japanese green tea. Foods Food Ingredients J. Jpn, 170, 46-51.
  4. Nasiroleslami, M., & Mohitmafi, S. (2015). Effects of premedication with Melatonin and L-Theanine on Ketamine induced anesthesia in New Zealand White Rabbits. Journal of Paramedical Sciences, 6(1).
  5. Kimura, R., & Murata, T. (1971). Influence of alkylamides of glutamic acid and related compounds on the central nervous system. I. Central depressant effect of theanine. Chemical and Pharmaceutical Bulletin, 19(6), 1257-1261.
  6. Desai, M. J., & Armstrong, D. W. (2004). Analysis of derivatized and underivatized theanine enantiomers by high‐performance liquid chromatography/atmospheric pressure ionization‐mass spectrometry. Rapid communications in mass spectrometry, 18(3), 251-256.
  7. Desai, M. J., Gill, M. S., Hsu, W. H., & Armstrong, D. W. (2005). Pharmacokinetics of theanine enantiomers in rats. Chirality, 17(3), 154-162.
Kent Bennington

Kent Bennington

Kent is our in-house authority on nootropics and cognitive enhancement. He holds a Bachelor of Science in psychology and has a long-running interest in nootropics. Over the years he’s tried dozens of different nootropic stacks and has a strong understanding of what works, and what doesn’t. Kent spends most of his free time sharing his experiences with nootropics and writing an upcoming book on the subject of cognitive enhancement.

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