10 Best L-Theanine Supplements of 2025 [Registered Dietitian-Reviewed]
L-theanine is a natural amino acid that supports relaxation, focus, and stress relief by increasing GABA, serotonin, and dopamine levels. Often combined with caffeine for focus or magnesium for relaxation, it comes in capsules, chewable tablets, and softgels. Choosing a third-party tested supplement with the right dosage and quality ensures maximum health benefits while minimizing potential side effects like dizziness or drowsiness.
This buying guide, reviewed by registered dietitian Kathy Shattler, MS, RDN, ranks the best L-theanine supplements based on purity, absorption, and ingredient combinations. Whether for stress, sleep, or focus, we’ve considered key uses to help you find a high-quality option that fits your needs.
Quick List - Top L-Theanine Supplement
Vivaravida
L-Theanine, GABA, and Magnesium in Liposomal Softgels
A Registered Dietitian Nutritionist for over 25 years, Kathy has mastered numerous medical specialties and teaching methods: health promotion, counseling, academic teaching, endocrinology, psychiatry/mental health, supplements, diabetes, obesity, heart disease, aging, and alternative medicine. Experiences include: -Managing her own telehealth/nutrition consulting business -Directing a continuing education program for RDs and nurses -Consulting for long-term care regulatory affairs -Working with State and local health departments -Coordinating diabetes education programs Her experiences led her to reach people with life-changing information as a medical editor and writer. For over five years, Kathy has acquired increasingly complex roles. Passionate about the root causes of disease, she obtained her certification in Integrative Medicine and Functional Nutrition from the Academy of Nutrition and Dietetics three years ago. This series continues to influence her approach to writing.
David is a law graduate (LL. B) with a keen eye for the specifics and a commitment to helping people make smarter decisions. Since joining mybest in 2020, he’s been creating buying guides to make finding the best products, from everyday must-haves to niche finds, easy. Whether he’s teaming up with dietitians to find the best probiotic yogurts or sharing expert tips on the top supplements, his work makes it easier for US readers to navigate the clutter of online shopping. Beyond his work with mybest, David has written for Grotto Network, a digital platform by the University of Notre Dame, and has experience as a special educational needs assistant. These pursuits have sharpened his talent for reaching people and making explanations personal and practical. His love for nature and reflective moments keeps him grounded, adding a thoughtful touch to every piece he writes for mybest.
The expert oversees the Buying Guide only, and does not determine the products and services featured.
Table of Contents
- Why You Can Trust Us
- What Does Taking L-Theanine Do?
- L-Theanine’s Potential Mental Health Benefits and Side Effects
- How to Choose L-Theanine Supplements - Buying Guide
- Check the Dosage: 100-400 MG Is Common1
- Consider Suntheanine® for a Clinically Studied, High-Purity Form of L-Theanine2
- Choose L-Theanine With GABA, Caffeine, or Magnesium for Added Benefits3
- Pick Capsules or Softgels for Precise Dosages With Minimal Additives4
- Look for Brands That Undergo Third-Party Testing for Quality and Potency5
- Explore Our Guides to More Essential Supplements
Why You Can Trust Us
Every mybest article is crafted with hours of in-depth research and interviews with experts. Each month, we are continually expanding our database of products based on our research. By emphasizing user insight and reliable information, we deliver trustworthy content to readers.
What Does Taking L-Theanine Do?
L-theanine may promote relaxation without drowsiness, supporting sleep quality. It increases GABA, which enhances serotonin and dopamine levels linked to mood, motivation, and sleep regulation.
L-theanine is a natural amino acid in tea that helps promote calm focus without making you drowsy. It works by increasing alpha brain waves, which are linked to relaxation and mental clarity. It also boosts GABA, a neurotransmitter that reduces stress, while influencing serotonin and dopamine, which help regulate mood and focus. Many people pair L-theanine with caffeine to stay alert while avoiding jitters and distractions.
Taking 200 mg before bed may support better sleep by easing anxiety rather than acting as a sedative. This helps you relax so sleep comes naturally without grogginess. While research shows promise for anxiety and sleep, it’s not yet proven as a treatment for disorders. More studies are needed to confirm its full effects.
L-theanine has been found to improve working memory and executive functions in healthy populations. However, its effects on memory, mood, and sleep in chronically stressed individuals or those with medical conditions remain unclear.
L-Theanine’s Potential Mental Health Benefits and Side Effects
Kathy Shattler, MS, RDN, shared some potential mental health benefits and side effects of L-theanine supplementation.
Research from 2022 suggests that L-theanine may help alleviate depression symptoms by reducing hippocampal hyperexcitability, lowering monoamine oxidase levels, and supporting a healthy gut microbiome.
Preliminary studies indicate that Suntheanine® at 250 mg/day for eight weeks may improve sleep and behavior in individuals with schizophrenia. Similar positive effects have been found for obsessive-compulsive disorder, schizoaffective disorder, and Tourette’s syndrome.
While L-theanine is generally well tolerated, rare side effects such as dizziness, drowsiness, headaches, and shakiness may occur, likely due to individual sensitivity.
How to Choose L-Theanine Supplements - Buying Guide
Check the Dosage: 100-400 MG Is Common
L-theanine is typically taken in doses of 100–400 mg daily, with higher amounts like 450 mg/day used for sleep support.
Most clinical studies on L-theanine use doses between 100–400 mg per day, a range shown to enhance attention and focus. Research suggests that within this dosage, L-theanine helps reduce mind wandering and distractions, making it useful for cognitive performance. Many people take it in a single dose or split it throughout the day, depending on their needs.
While 100–400 mg is the most studied range, both lower and higher doses may have potential benefits. A study from 2018 saw some individuals with anxiety disorders who took 450-900 mg of L-theanine daily for 8 weeks reported better sleep. However, more studies are needed to fully understand how different dosages impact various individuals.
Consider Suntheanine® for a Clinically Studied, High-Purity Form of L-Theanine
Suntheanine® was found to improve some sleep disorder symptoms in male children with ADHD at 400 mg/day in a 2011 study. Another 12-week study showed 100 mg/day may support memory and attention in middle-aged adults.
Suntheanine® is a patented form of L-theanine made through a fermentation process that mimics how green tea naturally produces it. This high-purity version has been clinically studied for its relaxation, stress reduction, and cognitive benefits. Many people choose Suntheanine® for its consistent quality and well-documented effects compared to generic L-theanine supplements.
Research supports Suntheanine®'s effectiveness, including a 12-week study on middle-aged adults where 100 mg daily improved attention span. Suntheanine® may be a good option if you're looking for a clinically backed form of L-theanine with demonstrated benefits for focus and mental clarity.
Choose L-Theanine With GABA, Caffeine, or Magnesium for Added Benefits
L-theanine paired with GABA may boost sleep quality. With caffeine, it enhances attention and memory, while reducing jitters.
Pairing L-theanine with caffeine is a well-studied way to enhance focus and cognitive performance while reducing caffeine’s jittery side effects. A study found 50 mg caffeine + 100 mg L-theanine improved speed, mood and focus, while L-theanine prevented caffeine-induced blood pressure spikes. Other research shows that 250 mg of L-theanine with 150 mg of caffeine improves alertness, memory, and task performance better than either one alone.
For better sleep, L-theanine works well with GABA or magnesium. A GABA-L-theanine blend has been shown to improve sleep quality and duration more effectively than either alone. L-theanine and magnesium work together to promote deeper, more restorative sleep by enhancing brain activity and neurotransmitter balance.
Registered dietitian Kathy Shattler, MS, RDN, explains, “When combined with magnesium, L-theanine helps boost melatonin and key brain receptors linked to relaxation and sleep. This pairing supports healthy brain activity, improves neurotransmitter balance, and promotes a calm, restful state.”
Pick Capsules or Softgels for Precise Dosages With Minimal Additives
Capsules and softgels are the most common L-theanine supplements, providing precise dosages with minimal additives. They are easy to take and offer a straightforward, no-fuss option for daily supplementation. For those looking for a plant-based choice, vegetarian capsules are available, made without gelatin.
If swallowing pills is difficult, chewable L-theanine supplements can be a convenient alternative. These offer the same benefits in an easier-to-consume form, making them ideal for children or those who prefer not to take capsules.
Look for Brands That Undergo Third-Party Testing for Quality and Potency
Third-party testing ensures that an L-theanine supplement meets high standards for purity, potency, and safety. Independent laboratories verify that the product contains the advertised amount of L-theanine and is free from contaminants such as heavy metals, pesticides, and harmful additives. This process helps eliminate concerns about mislabeled ingredients or low-quality formulations, giving consumers confidence in the supplement’s effectiveness.
Brands that invest in third-party testing demonstrate transparency and commitment to quality. These products often display certification seals or provide lab results to confirm their compliance with strict testing protocols. Choosing a supplement that has undergone rigorous testing reduces the risk of consuming ineffective or impure formulations, ensuring a safe and reliable experience with L-theanine.
10 Best L-Theanine Supplements Ranking
Products | Image | Click to purchase | Key features | Details | |||||
|---|---|---|---|---|---|---|---|---|---|
Dosage | Suntheanine® | Additional Nutrients | Form | Third-Party Tested | |||||
1 | Amazon Elements L-Theanine | | Simple, Vegan L-Theanine with Kosher Certification | 200mg | Capsule | ||||
2 | Nature’s Trove L-Theanine | | Vegetarian L-Theanine in a Kosher-Certified Formula | 200mg | Capsule | ||||
3 | Pure Encapsulations L-Theanine Supplement | | Allergen-Free L-Theanine for a Minimalist Approach | 200mg | Capsules | ||||
4 | Vivaravida L-Theanine with GABA and Magnesium Glycinate | | L-Theanine, GABA, and Magnesium in Liposomal Softgels | 500mg | GABA, Magnesium Glycinate | Softgel | unknown | ||
5 | Sports Research L-Theanine | | Suntheanine L-Theanine with Organic Coconut Oil | 200mg | Softgel | ||||
6 | Doctor’s Best L-Theanine with Suntheanine | | Moderate-Dose Suntheanine L-Theanine | 150mg | Veg capsule | ||||
7 | Nature Made L-Theanine Chewable Tablets | | Tropical-Flavored Chewable L-Theanine | 200mg | Chewable | ||||
8 | SmarterVitamins Caffeine and L-Theanine Capsules | | Caffeine and L-Theanine in an Extended-Release Softgel | 100mg | Caffeine, MCT Oil | Softgel | unknown | ||
9 | Natural Factors Suntheanine L-Theanine Chewable | | Low-Dose Suntheanine in a Chewable Format | 200mg | Chewable | ||||
10 | Sports Research L-Theanine + Caffeine | | L-Theanine and Caffeine for Focused Energy | 200mg | MCT Oil, Caffeine | Softgel | |||
Simple, Vegan L-Theanine with Kosher Certification
Amazon Elements L-Theanine provides 200 mg of L-theanine per capsule, with 60 capsules in each bottle. The formula is vegan, gluten-free, and free from artificial colors, flavors, and preservatives. It is manufactured in a GMP-certified facility in the USA using both domestic and imported ingredients.
With a simple formulation containing only L-theanine and necessary capsule ingredients, this product is suited for those looking for a straightforward supplement. It carries Star K kosher certification, making it a potential option for individuals following kosher dietary guidelines.
| Suntheanine® | |
|---|---|
| Additional Nutrients | |
| Form | Capsule |
| Third-Party Tested |
Vegetarian L-Theanine in a Kosher-Certified Formula
Nature’s Trove L-Theanine provides 200 mg per capsule, with 120 vegetarian capsules per bottle. The product is manufactured in a GMP-certified facility in the USA and holds kosher certification. The label suggests it "may promote relaxation," though L-theanine’s effects can vary by individual.
The formula does not include additional active ingredients beyond L-theanine. As it comes in vegetarian capsules, it may be a suitable option for those avoiding gelatin-based supplements.
| Suntheanine® | |
|---|---|
| Additional Nutrients | |
| Form | Capsule |
| Third-Party Tested |
Allergen-Free L-Theanine for a Minimalist Approach
Pure Encapsulations L-Theanine delivers 60 capsules per bottle, each containing 200 mg of L-theanine. The company highlights its use of "pure ingredients" by formulating the product without common allergens or artificial additives.
Marketed as a supplement for relaxation and nervous system support, it includes no additional active compounds beyond L-theanine. The absence of common allergens may make it a suitable choice for individuals with dietary restrictions.
| Suntheanine® | |
|---|---|
| Additional Nutrients | |
| Form | Capsules |
| Third-Party Tested |
VivaravidaL-Theanine with GABA and Magnesium Glycinate
| Dosage | 500mg |
|---|
L-Theanine, GABA, and Magnesium in Liposomal Softgels
Vivaravida’s formula combines 800 mg of L-theanine with 200 mg of GABA and 100 mg of magnesium glycinate per serving. The softgel format uses liposomal delivery, a technology intended to improve absorption, though individual results may vary.
This product is designed for those looking to combine L-theanine with additional ingredients commonly associated with relaxation.
| Suntheanine® | |
|---|---|
| Additional Nutrients | GABA, Magnesium Glycinate |
| Form | Softgel |
| Third-Party Tested | unknown |
Suntheanine L-Theanine with Organic Coconut Oil
Sports Research L-Theanine contains 200 mg per softgel and features Suntheanine, a patented form of L-theanine. The product also includes organic coconut oil as a carrier and is made in a cGMP-compliant facility in the USA.
It is marketed as a non-caffeinated alternative to green tea and supports both relaxation and alertness. The use of Suntheanine may appeal to those looking for a branded ingredient with clinical research backing.
| Suntheanine® | |
|---|---|
| Additional Nutrients | |
| Form | Softgel |
| Third-Party Tested |
Doctor’s Best L-Theanine with Suntheanine
| Dosage | 150mg |
|---|
Moderate-Dose Suntheanine L-Theanine
Doctor’s Best L-Theanine contains 150 mg per capsule and uses Suntheanine, a patented L-theanine ingredient. The product is labeled as non-GMO, gluten-free, and vegan.
The lower dosage per capsule may appeal to those looking for a more moderate intake of L-theanine. The use of Suntheanine suggests a focus on a clinically studied ingredient.
| Suntheanine® | |
|---|---|
| Additional Nutrients | |
| Form | Veg capsule |
| Third-Party Tested |
Tropical-Flavored Chewable L-Theanine
Nature Made L-Theanine comes in chewable tablets, each providing 200 mg of L-theanine. The product is free from artificial colors and dairy and is marketed as a fast-acting supplement that works within 30 minutes.
The tropical fruit flavor may make it a more convenient option for individuals who prefer not to swallow capsules. However, the chewable format includes additional ingredients to enhance taste and texture, which may be a consideration for those avoiding sweeteners or additives.
| Suntheanine® | |
|---|---|
| Additional Nutrients | |
| Form | Chewable |
| Third-Party Tested |
SmarterVitaminsCaffeine and L-Theanine Capsules
| Dosage | 100mg |
|---|
Caffeine and L-Theanine in an Extended-Release Softgel
SmarterVitamins combine 200 mg of caffeine with 100 mg of L-theanine in liquid softgels. It also includes MCT oil sourced from coconuts. The caffeine-L-theanine combination is often used to support alertness without the jittery effects of caffeine alone.
The extended-release softgel format may result in a gradual release of caffeine, though individual tolerance varies. This product is designed for those looking for a nootropic stack rather than standalone L-theanine supplementation.
| Suntheanine® | |
|---|---|
| Additional Nutrients | Caffeine, MCT Oil |
| Form | Softgel |
| Third-Party Tested | unknown |
Low-Dose Suntheanine in a Chewable Format
Natural Factors offers a chewable L-theanine supplement containing 100 mg per tablet, using Suntheanine as its source. The product is non-GMO, soy-free, and gluten-free, with a tropical fruit flavor.
Designed for flexible dosing, it allows users to take up to three tablets daily. The lower dose per tablet may appeal to those preferring smaller amounts or multiple doses throughout the day.
| Suntheanine® | |
|---|---|
| Additional Nutrients | |
| Form | Chewable |
| Third-Party Tested |
L-Theanine and Caffeine for Focused Energy
This supplement combines 200 mg of L-theanine with 100 mg of organic caffeine sourced from green coffee beans. It also includes MCT oil and uses Alphawave, a branded form of L-theanine.
This nootropic supports mental focus and productivity, making it useful for studying or working out in the gym.
| Suntheanine® | |
|---|---|
| Additional Nutrients | MCT Oil, Caffeine |
| Form | Softgel |
| Third-Party Tested |
Top 5 L-Theanine Supplement
No. 1: Amazon Elements｜L-Theanine
No. 2: Nature’s Trove｜L-Theanine
No. 3: Pure Encapsulations｜L-Theanine Supplement
No. 4: Vivaravida｜L-Theanine with GABA and Magnesium Glycinate
No. 5: Sports Research｜L-Theanine
View Full RankingThe descriptions of each product are referenced from content available on manufacturer, brand, and e-commerce sites.
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