The 5 Best L-Theanine Supplements of 2024, According to Experts
iStock
The products featured in this article have been independently reviewed. When you buy something through the retail links on this page, we may earn commission at no cost to you, the reader. Sports Illustrated editorial staff are not involved in the creation of this content. Learn more here.
If you’re looking for a way to be more focused and relaxed, and less anxious and fatigued throughout the day, it may be worth your while to add l-theanine to your daily supplement regimen.
“L-theanine has been shown to improve sleep quality not by being a sedative, but by reducing anxiety (i.e. by a calming, non-drowsy effect), which in turn promotes better sleep,” explains Alex Dimitriu, MD, a double board-certified physician in Psychiatry and Sleep Medicine and the founder of Menlo Park Psychiatry & Sleep Medicine. “It has been shown to increase the activity of alpha brain waves, which are associated with feelings of calm, creativity and improved focus. L-theanine is believed to work by calming the excitatory neurotransmitter, glutamate, while enhancing the activity of GABA—the major inhibitory neurotransmitter in the brain.”
This article introduces some of the best l-theanine supplements on the market in 2024 and lays out the potential health benefits of l-theanine supplementation according to sleep and anxiety experts.
This content is meant to be informative, but should not be taken as medical advice. It is not intended for use as diagnosis, prevention or treatment of health problems. Always speak with your healthcare provider before starting any new supplement or exercise regimen.
Our Picks for the Best L-Theanine Supplements in 2024:
- Best L-Theanine Supplement For Sleep: Utzy Naturals Stay Asleep
- Best L-Theanine Supplement For Anxiety: Life Extension L-Theanine
- Best GABA L-Theanine Supplement: Kal Gaba L-Theanine Stress B
- Best L-Theanine Supplement For Focus: Sports Research L-Theanine + Caffeine
- Best Caffeine L-Theanine Supplement: Proper Wild
Best L-Theanine Supplement For Sleep: Utzy Naturals Stay Asleep
Utzy Naturals
Key features & specs:
- L-Theanine per serving: 100 milligrams
- Certifications: N/A
- Subscription: Your choice of a 30-, 45- or 60-day shipping frequency, 15% savings
- Key ingredients: 5-HTP, gamma aminobutyric acid (GABA), hops strobile extract, l-theanine
- Price per serving: $1.04
Stay Asleep by Utzy Naturals is a high quality sleep supplement that contains ingredients such as 5-HTP, gamma aminobutyric acid, hops strobile extract and l-theanine to help your brain and body relax and stay asleep through the night. It incorporates 300 milligrams of 5-HTP, an amino acid studies have found bolsters serotonin levels in the brain when administered within the 200 to 400 milligram range, ultimately resulting in improved sleep onset and deeper, more rejuvenating rest for research participants.
Gamma aminobutyric acid, known as GABA, is thought to reduce stress, relieve anxiety and improve sleep. A peer-reviewed 2020 study published in Sleep Medicine linked participants with lower GABA levels to shorter sleep duration and worse working memory function. L-theanine has been shown to produce relaxing effects and may work with GABA to stimulate receptors, opposing caffeine stimulation. There are also 100 milligrams of hops strobile extract, a natural ingredient derived from hops that may reduce nocturnal activity to help you avoid waking up in the middle of the night.
The brand recommends taking one capsule an hour before your desired bedtime and notes you can take up to two if needed. Stay Asleep has a user rating of 4.4/5 on the Utzy Naturals website and has 28 reviews. Many positive reviews mention a restful night and that they didn’t experience grogginess in the morning. However, some reviews mention waking up in the middle of the night. If you do not see the desired improvement in your sleep, Utzy Naturals offers a 90-day money-back guarantee.
What we like:
- One capsule is an easy, manageable dose
- Contains research-backed ingredients
- Sleep aid option that does not include melatonin
What we don’t like:
- Expensive
Best L-Theanine Supplement For Anxiety: Life Extension L-Theanine
Life Extension
Key features & specs:
- L-Theanine per serving: 100 milligrams
- Certifications: Non-GMO LE Certified, gluten-free
- Subscription: Your choice of a one-, two-, three-, four-, five- or six-month shipping frequency, 5% savings
- Key ingredients: L-Theanine
- Price per serving: $0.30
Life Extension is a vitamin and supplement company with more than 40 years of experience creating products rooted in nutritional science. This Life Extension L-Theanine supplement contains 100 milligrams of pure l-theanine, as confirmed by the company’s laboratory analysis.
We rank it as the best l-theanine supplement for anxiety because it’s formulated to promote relaxation and support a healthy stress response. According to the brand, it provides a calming and mood enhancing effect for its users by encouraging brainwave patterns similar to those associated with meditation and massage.
It has a 4.5/5-star rating on Amazon from 456 customer reviewers at the time of writing. The overwhelmingly positive customer testimonials suggest that it works well to reduce anxiety, eliminate nervousness and provide a sense of calm.
What we like:
- Budget-friendly
- Certified non-GMO
- Excellent customer ratings
What to consider:
- Doesn’t contain any additional nutrients
Best GABA L-Theanine Supplement: Kal GABA L-Theanine Stress B
Kal
Key features & specs:
- L-Theanine per serving: 50 milligrams
- Certifications: Vegan
- Subscription: Your choice of a one-, two-, three-, four-, five- or six-month shipping frequency, 5% savings
- Key ingredients: L-Theanine, GABA, choline, inositol, vitamin C, thiamine (vitamin B1), niacin (vitamin B3), vitamin B6, folate (vitamin B9), vitamin B12, pantothenic acid (vitamin B5)
- Price per serving: $0.26
Kal is a vitamin brand that has been making trusted, quality products since 1932. The company’s GABA L-Theanine Stress B supplement is a dissolvable lozenge designed to provide relaxation support.
In addition to 50 milligrams of l-theanine, this product contains 50 milligrams of GABA, which according to some studies, works well in conjunction with l-theanine to provide a positive synergistic effect on sleep quality and duration as compared to the GABA or l-theanine alone. Additionally, this supplement provides a healthy dose of B vitamins, plus choline and inositol to support brain health, mood and metabolism. For best results, the brand recommends dissolving two lozenges in your mouth daily.
At the time of writing, Kal GABA L-Theanine Stress B has a 4.3/5-star rating on Amazon from 474 reviews. The taste of this supplement seems to be hit or miss with reviewers, but consumers typically praise its effectiveness, with some calling it an “anti-stress miracle.”
What we like:
- Budget-friendly
- Vegan-friendly
- Contains B vitamins, choline and inositol
What to consider:
- Relatively low dose of l-theanine per serving
- Contains xylitol, which isn’t safe for dogs
- Provides over 41,000 percent of the daily value (DV) for vitamin B12
Best L-Theanine Supplement For Focus: Sports Research L-Theanine + Caffeine
Sports Research
Key features & specs
- L-Theanine per serving: 200 milligrams
- Certifications: Keto Certified, Certified Gluten-Free, non-GMO, cGMP compliant, third-party quality tested
- Subscription: Your choice of a one-, two-, three-, four-, five- or six-month shipping frequency, 5-20% savings
- Key ingredients: AlphaWave® L-theanine, medium chain triglycerides (MCTs), PurCaf® organic caffeine (green coffee bean extract)
- Price per serving: $0.38
Created with athletes and active gym-goers in mind, Sports Research uses 40 years of innovation in sports nutrition to develop high-quality, science-backed supplements and performance essentials. Sports Research L-Theanine + Caffeine is made with MCT oil sourced from coconuts. It’s formulated to support energy levels, focus and alertness without causing the jitters like the typical energy drink might. The company recommends taking one softgel daily with food, and warns users not to exceed two softgels per day.
This l-theanine supplement stands out from other products on the market because it uses a registered l-theanine product called AlphaWave®—a highly purified and standardized form of l-theanine. Marketed as a nootropic, this supplement appears to be helpful for a variety of uses that require focused energy. Some reviewers say it helped them study better for their exams, while others praise it as a solid pre-workout supplement to improve performance in the gym.
What we like:
- Third-party tested
- Budget-friendly
- Designed to provide jitter-free energy and focus
What to consider:
- Contains MCTs, which can cause digestive discomfort in some
Best Caffeine L-Theanine Supplement: Proper Wild
Proper Wild
Key features & specs
- L-Theanine per serving: 120 milligrams
- Certifications: Vegan, gluten-free, non-GMO, soy-free, dairy-free
- Subscription: Not available
- Key ingredients: L-theanine, organic caffeine, juice concentrate, pink himalayan sea salt
- Price per serving: $3.99
Proper Wild is a plant-based energy shot brand and product created as an alternative to coffee and non-vegan energy drinks. It uses clean, simple ingredients to provide jitter-free, long-lasting energy without the crash. According to the brand, this vegan energy shot boosts your focus and productivity and helps consumers stay relaxed for hours. The product is sold as a variety six-pack containing different flavors, including Apple, Strawberry Kiwi and Lemon Lime.
As an energy shot, this l-theanine supplement is a nice alternative for people who don’t like swallowing pills and capsules. However, its current rating on Amazon suggests that it isn’t the best option for everyone. It has a 3.4/5-star rating from 466 reviews at the time of writing, with multiple reviewers reporting that they really disliked the taste. However, keep in mind that this product is intended to be taken (or thrown back) like a shot, not necessarily consumed (and enjoyed) like a smoothie. Still, for people with sensitive palates, we recommend one of the other supplements on our list.
Taste aside, this is one of our best l-theanine supplements because the positive customer reviews indicate that it works as intended to provide long-lasting, jitter-free energy and focus. For example, one Amazon review reads, “As a long time user and fan of energy drinks like 5 Hour Energy and Monsters, it was a pleasant surprise to discover Proper Wild energy shots. Unlike the others I mentioned, these actually seem to last throughout the day, not just for short intense bursts that leave me crashing like most energy drinks do. The smooth, clean stimulation and focus that Proper Wild provides is perfect, in that it's actually long lasting and doesn't give me any of the occasional side effects that I'd get from other energy supplements (like shakiness or nervousness).”
What we like:
- Vegan-friendly
- A non-pill alternative to l-theanine capsules
- Uses clean, simple ingredients
What to consider:
- Multiple reviewers reported disliking the taste of this supplement
- Pricey
What Is L-Theanine?
“L-theanine is a non-proteinogenic (not used in the biosynthesis of proteins) amino acid derived primarily from the tea plant, Camellia sinensis, as well as certain types of fungi," explains Dr. Sunjya Schweig, MD, an Integrative and Functional Medicine physician and Founder of the California Center for Functional Medicine (CCFM). "It was discovered in 1949 as a component of green tea and is actually part of what gives green tea its characteristic taste. It’s one of the reasons why drinking green tea can have a calming, yet stimulating effect.”
While l-theanine is best known for being a component of green tea leaves, it can also be found in black tea and some mushrooms.
Although l-theanine is not produced by the human body, it is not one of the nine essential amino acids because it isn’t essential to human health. Nonetheless, findings from animal and clinical studies indicate that l-theanine can provide a range of health benefits related to cognition, sleep and performance.
How Does L-Theanine Work?
“L-theanine influences the brain’s neurotransmitter system. Its structure is similar to glutamate, a naturally occurring amino acid that helps transmit nerve impulses in the brain," Schweig says.
"L-theanine can cross the blood-brain barrier and affect the brain directly. It helps increase levels of GABA, dopamine and serotonin, which are all neurotransmitters that play key roles in mood, sleep, cognition, reward and regulation of various other physiological processes. L-theanine can also reduce levels of chemicals in the brain that are linked to stress and anxiety. It increases the generation of alpha brain waves, associated with a state of relaxed, creative and effortless alertness.”
Benefits of L-Theanine
According to Dr. Schweig, there are several potential benefits to l-theanine supplementation, including:
- Improved mental focus and cognitive performance: Some research suggests that l-theanine, particularly in combination with caffeine, can improve focus, attention and cognitive performance.
- Enhanced sleep quality: It does this not by sedating but by reducing anxiety and promoting relaxation.
- Reduced stress and anxiety: L-theanine can increase the production of GABA, serotonin and dopamine, all of which have a calming effect on the mind, reduce feelings of stress and anxiety and help with sleep. Additionally, L-theanine’s ability to increase dopamine and serotonin in the nerve cells aid in relaxation, preventing anxiety and decreasing cortisol levels.
- Immune system support: Some studies suggest that l-theanine could enhance the function of the body's immune system. This is likely secondary to helping regulate cortisol levels.
- Neuroprotection: Preliminary evidence suggests that l-theanine could have neuroprotective effects, possibly helping to protect against neurological diseases like Alzheimer's and Parkinson's.
- Lipid-lowering properties: L-theanine has properties that reduce lipid levels by addressing hepatic-tumor-induced hyperlipidemia and inhibiting Low-Density Lipoprotein (LDL) activity, which is associated with the development of atherosclerosis. (This study was conducted on rats, and more human studies are needed.)
In regards to sleep, some consumers prefer l-theanine over other natural sleep aids like melatonin and magnesium because it can promote a relaxed state without causing drowsiness.
Side Effects of L-Theanine
“Side effects from l-theanine are rare and not severe,” Schweig says. “They might include headaches, dizziness and gastrointestinal symptoms, such as nausea or diarrhea. The risk of experiencing these side effects may increase with higher doses. It's recommended that individuals start with a lower dose and monitor their body's response before increasing the dosage."
Schweig notes that higher doses on a daily basis may lead to:
- Reduction in blood pressure (which could be advantageous for certain individuals)
- Decreased appetite
- Diarrhea
- Impaired concentration
- Headaches
- Nausea
How to Choose the Best L-Theanine for You
You’ll find that l-theanine product formulations vary widely from brand to brand. Some products contain only l-theanine, while others include natural herbs, caffeine, vitamins and/or other nutrients, like choline. As a result, consumers can target their supplement selection based on the specific effect they desire. This article aims to make this process a little easier for our readers by categorizing our favorite l-theanine supplements as best for either focus, sleep, gym performance, stress reduction or energy.
Our Methodology: How We Chose the Best L-Theanine Products
Our picks for the best l-theanine products were based on criteria like affordability, third party certification status, reputation of the manufacturer and consumer reviews. We looked for products that actually worked, according to customer testimonials, as well as products that provided additional nutrients (e.g. B vitamins) to support overall health. Additionally, we generally excluded products that contain ingredients with no nutritional value, like fillers, added sugars and preservatives.
L-Theanine FAQs
Is l-theanine safe?
“L-theanine is generally considered safe for most people when taken in moderate amounts, and no serious side effects or toxic reactions have been reported,” says Schweig. “However, it can interact with certain medications and substances, and its safety has not been thoroughly studied in pregnant or breastfeeding women or people with severe liver or kidney disease.”
Can I take l-theanine and GABA together?
“Both l-theanine and GABA are involved in the regulation of mood and mental state, and taking them together can potentially have a synergistic effect. Many supplements that help to regulate cortisol levels or aid with sleep contain both of them together, often along with other ingredients. However, everyone's biochemistry is unique, and combining these substances could have different effects in different individuals, so sometimes it is best to experiment initially with each ingredient alone,” Schweig advises.
Do doctors recommend l-Theanine?
“Yes, some doctors may recommend l-theanine supplementation for their patients. It has been shown to be helpful for reducing stress levels and improving mental focus and other cognitive functions. Additionally, its antioxidant properties may help protect against damage caused by free radicals in the body,” says Dr. Harold Hong, MD, a board-certified Psychiatrist at New Waters Recovery, located in North Carolina.
Can I take l-theanine with pre-workout?
“Yes, l-theanine can be taken with a pre-workout powder. It has been shown to reduce stress levels and improve focus, which may help increase performance during physical activity," Hong says. "However, it's best to discuss this combination with a healthcare professional before starting any new dietary supplement regimen."
Is l-theanine or ashwagandha better?
“There is a good amount of research supporting both of these supplements for stress, relaxation, neurogenesis and sleep," Dimitriu says. "Ashwagandha may confer additional benefits related to muscle growth."
Takeaway: Is L-Theanine Worth It?
Physicians and health experts support the use of l-theanine to reduce stress and anxiety, enhance focus and improve sleep quality. Additionally, research suggests that l-theanine supplementation may confer other benefits related to nervous system health, immunity and cardiovascular function. As with most dietary supplements, l-theanine products can cause mild side effects and potentially interact with prescription medicines. Talk to your doctor before supplementing with l-theanine to determine if it’s an appropriate supplement for your health and wellness goals.
Prices are accurate and items in stock as of publish time.
