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If you’ve ever enjoyed a soothing cup of caffeinated green tea and felt a wave of relaxation wash over you, you’ve already tasted the calming advantages of L-theanine. The ideal L-theanine supplement can extend beyond relaxation to enhance focus, improve sleep, and boost productivity as well. As per registered dietitian Sarah Koszyk, MA, RDN, NBC-HWC, L-theanine, prominently found in green tea, is an ingredient that’s both well-understood and still under exploration.
“Though it is amino acid in structure, unlike others, it does not become part of proteins,” Koszyk notes. Instead, L-theanine has a direct effect on the brain. “It mitigates excitatory signals while enhancing calming neurotransmitters like GABA,” says Taylor Fazio, a New York-based registered dietitian and wellness expert for The Lanby. “The outcome is a distinctive feeling that many describe as ‘relaxed alertness’—an experience of calm, focused clarity that promotes cognitive function without causing sedation or overstimulation.” In contrast to coffee, which might deliver a sudden jolt that can leave you feeling anxious or jittery, L-theanine provides a more serene energy enhancement that keeps focus smooth and stable.
Vogue’s Top Picks for L-Theanine Supplements
What’s even more promising is emerging research suggesting that L-theanine may also possess antioxidant qualities. “It might act as a gentle adaptogen, enhancing the body’s overall stress response,” says Koszyk. “This dual role as both a neuroactive compound and a phytonutrient with antioxidant potential makes L-theanine particularly intriguing.”
Given its myriad advantages, it’s only natural to want to weave this plant-derived ingredient into your daily routine. Up next, we consulted leading dietitians to help answer every question you have regarding L-theanine, including tips to select the finest supplements for your specific needs.
In This Story
- What is L-theanine?
- What are the benefits of L-theanine?
- What is the most effective form of L-theanine?
- Meet the Experts
Best Overall: Thorne Theanine
- Why We Recommend It: Both Koszyk and Fazio endorse Thorne’s Theanine capsules, highlighting their meticulous testing standards and commitment to safety, efficacy, and consistency. “It’s essential to select brands that utilize third-party testing for quality assurance, and Thorne embodies this principle,” explains Fazio. Koszyk concurs, adding that this capsule is excellent for anyone seeking a “trustworthy, clinical dose in capsule form.” To start, Koszyk suggests trying 200 milligrams in the morning and another 200 milligrams in the evening to gauge how your body reacts. “If you consume coffee or tea, consider pairing it with your caffeine intake as it can smooth out the energy spikes and calm jittery sensations,” she further advises. “Also, note timing: during the day, it can support focus and productivity, while in the evening, it aids in easing the transition to restful sleep without creating grogginess.”
- Key Ingredients: L-theanine
- Form: Capsule
- Serving Size: 1 capsule up to 3 times daily
- Certifications: NSF-certified, third-party evaluated
Best for Beginners: Golde Pure Matcha
- Why We Recommend It: Matcha has gained recognition as the “clean caffeine” substitute to coffee, as it’s a finely ground green tea boasting rich L-theanine content. “Matcha provides a concentrated and enjoyable way to introduce L-theanine into your body,” notes Koszyk. “Additionally, deriving L-theanine from tea or matcha also means you gain an array of antioxidants, polyphenols, catechins, flavonoids, and other phytonutrients that work synergistically, unlike a single-isolate supplement.” Koszyk advocates for choosing organic, ceremonial-grade options like this one, sourced from Uji, Japan. It’s also vegan, cultivated organically, cold-processed to maximize antioxidant benefits, and has a delightful flavor profile with hints of white chocolate and sweet cream. To craft a smooth and luxurious matcha beverage, whisk 1 teaspoon of matcha with warm water and your preferred sweetener until smooth, then pour over 8 ounces of your favorite milk for a refreshing pick-me-up at any time.
- Key Ingredients: Matcha green tea powder
- Form: Powder
- Serving Size: 1 tsp
- Certifications: Certified radiation-free, heavy metal-free, and organic
Best for Focus and Productivity: Moon Juice Neuro Magnesi-Om
Moon Juice
Neuro Magnesi-om
- Why We Recommend It: If enhancing focus and productivity is your aim, Fazio suggests taking L-theanine in the morning alongside caffeine. Research indicates that when used together, caffeine and L-theanine can uplift attention, accuracy, and alertness more effectively than either component alone. “Together, L-theanine moderates the stimulating effects of caffeine, minimizing jitteriness and energy crashes while promoting more sustained alertness,” Koszyk adds. “In a culture like ours, where caffeine use is prevalent, this effective combination is one of the primary reasons for L-theanine’s rising popularity.” Whereas Moon Juice’s standard Magnesi-Om works wonderfully right before sleep, this new version leverages organic mushrooms, ceremonial-grade matcha, magnesium L-threonate, plus both L-theanine and caffeine to deliver a robust morning boost (avoid taking it close to bedtime, as it could interfere with sleep).
- Key Ingredients: L-theanine, magtein magnesium L-threonate, lion’s mane, ceremonial-grade organic matcha
- Form: Powder
- Serving Size: 1 tsp
- Certifications: GMP-certified
Best for Stress Support: Pure Encapsulations L-Theanine
Pure Encapsulations
L-Theanine
- Why We Recommend It: Another preferred choice from Fazio, Pure Encapsulations L-theanine is straightforward and effective. “It’s hypoallergenic, rigorously tested, and suitable for individuals sensitive to supplements,” notes Fazio. “Moreover, it’s simply a 200 milligram capsule, making dosing very manageable.” While some substances energize or calm, l-theanine can help achieve a balanced mental state. “Research shows it boosts alpha brain waves, linked to creativity, clarity, and a calm yet alert state,” Fazio adds. “This makes it easier to stay focused during a busy workday or wind down in the evening.”
- Key Ingredients: L-theanine
- Form: Capsule
- Serving Size: 2 capsules
- Certifications: NSF-certified, GMP-certified, third-party tested
Best for Sleep and Relaxation: Mary Ruth’s Organics L-Theanine Liquid Drops
MaryRuth Organics
L-Theanine
- Why We Recommend It: The advantage of this liquid version of L-theanine is how effortlessly it can integrate into any routine—simply take the drops directly or mix them into a glass of water for an instant boost. “L-theanine supplements serve well for those who may not drink tea or seek a consistent, measurable dose for defined purposes like stress relief or improving sleep,” remarks Koszyk. For relaxation or sleep enhancement, Fazio suggests taking L-theanine in isolation during the evening. “The soothing effects generally manifest within an hour, allowing you to fine-tune timing,” she explains. “If you experience any mild effects like digestive discomfort or overly vivid dreams, adjusting the dose or changing your timing can often address these issues.”
- Key Ingredients: L-theanine, citric acid
- Form: Liquid
- Serving Size: 2 mL
- Certifications: USDA organic, Non-GMO Project verified, B Corp certified, Clean Label Project certified
All You Need to Know
L-theanine is a unique amino acid found primarily in tea leaves, predominantly in green tea. “Unlike the majority of amino acids, it isn’t a building block for proteins; instead, it directly impacts brain chemistry,” says Koszyk. “Studies demonstrate it increases alpha brain wave activity, leading to a meditative, focused state that can lessen stress, anxiety, sharpen concentration, and improve sleep quality for some.”
What are the benefits of L-theanine?
L-theanine offers numerous benefits, some still coming to light through research. “The most recognized benefit of L-theanine involves enhancing attention when combined with caffeine,” shares Fazio. “Studies reveal that this combination improves attention spans, reaction times, and working memory, while reducing the jitteriness caffeine often brings.” When taken alone, L-theanine exhibits additional benefits. “L-theanine is a gentle stress reliever that helps alleviate mental tension without inducing drowsiness, making it a suitable option for those wanting to remain calm during the day,” adds Fazio. “In the evening, it’s effective for easing into sleep, improving sleep quality, and minimizing night wakings.”
What is the most effective form of L-theanine?
When selecting a supplement, prioritize products with isolated L-theanine, not blends. “Blends can contain extra ingredients that may not meet your goals and might even trigger unintended effects, such as adding stimulants to a product meant for relaxation,” advises Fazio. “Ensure the label specifies L-theanine, as D-theanine is less effective.” Furthermore, all L-theanine shares the same molecular structure, be it from tea or supplements. “Matcha, being finely ground whole tea leaves, provides one of the highest natural concentrations,” notes Koszyk. “For many, regular consumption of green tea or matcha is an exceptionally effective way to access its soothing and focusing effects.”
- Sarah Koszyk, MA, RDN, NBC-HWC, is a registered dietitian operating in Silicon Valley and co-founder of MIJA, a health and wellness brand offering both oral and topical products.
- Taylor Fazio is a registered dietitian practicing in New York and advises for The Lanby.
