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Best L-theanine

Which L-theanine is best?

If you are looking for a natural way to relieve stress and increase focus, consider an L-theanine supplement. According to PubMed, this amino acid is naturally found in tea leaves and certain types of mushrooms and is often taken to reduce the symptoms of anxiety and increase performance when paired with caffeine. 

L-theanine supplements can appear in pill, capsule and even gummy form. Now Foods Double Strength L-theanine Capsules are the top pick because they are vegan with a high dosage. 

What to know before you buy L-theanine

What is L-theanine?

If you have ever felt both relaxed and focused after drinking a cup of green tea, then you have probably experienced the benefits of L-theanine. While most prevalent in green tea leaves, this amino acid can also be found in black tea, white tea and certain species of mushroom. It is a nonessential amino acid, which means your body doesn’t require it to function. 

In its natural state, L-theanine has a distinct flavor and is thought to be responsible for the savory, umami taste found in certain varieties of green tea. There is also a closely-related amino acid named D-theanine that does not appear to have the same health benefits when ingested. 


Like other stress support supplements, L-theanine works best when combined with healthy lifestyle choices like regular exercise and avoiding alcohol and nicotine. When taken alone, studies have indicated that L-theanine supplements can be used to promote relaxation, relieve stress and might even treat sleep issues like insomnia. The amino acid can also improve focus and task switching abilities when combined with caffeine. 

Additionally, when ingested alongside the natural catechins found in green tea, L-theanine might also boost your immune system and fend off against common illnesses like the flu. The amino acid could help treat individuals who live with high blood pressure, and one study showed that L-theanine could be helpful for kids with attention deficit hyperactivity disorder.


L-theanine is generally considered safe for daily consumption, particularly in supplement form. That being said, there is little research on long-term usage, and individuals with low blood pressure should talk with their doctor before starting an L-theanine supplement regimen. If you choose to consume L-theanine through green tea, the caffeine found in that beverage could have its own side effects, including an upset stomach or nausea. 

What to look for in quality L-theanine


Like most supplements, L-theanine can appear in a wide variety of different forms, including capsules, pills and fruit-flavored gummies. This last form is particularly convenient for people who don’t like swallowing pills. 

Dietary restrictions and certifications

Individuals that follow a vegan or vegetarian lifestyle should look closely at the packaging to make sure that the supplement will work with their dietary restrictions. Avoid any L-theanine products that contain gelatin or magnesium stearate, as these are animal byproducts. You can also look for a supplement that has been certified by a third-party organization like Vegan Action or People for the Ethical Treatment of Animals. Similarly, you can look for an L-theanine supplement that has been certified organic and free of gluten and genetically modified organisms.


Most L-theanine supplements contain a dosage of 100-200 milligrams with suggestions to take the supplement once or twice a day. For reference, a single 8-ounce cup of green tea contains around 25 milligrams of the amino acid. 

How much you can expect to spend on L-theanine

The cost of L-theanine supplements can vary depending on the dosage and size of the container. Most people can expect to spend around $10-$25 for a bottle of 60-100 pills. 

L-theanine FAQ

Does L-theanine have a negative interaction with any other drugs? 

A. Because L-theanine lowers blood pressure, combining it with another medication that has the same effect could potentially make your blood pressure too low. If you take any prescription medications, talk with your doctor before taking L-theanine supplements. 

Can you take L-theanine every day? 

A. While L-theanine is generally considered safe to take every day, research has only been conducted for up to 8-week periods. This means that long-term safety is technically unknown beyond that length of time. 

What’s the best L-theanine to buy?

Top L-theanine

Now Foods Double Strength L-Theanine Capsules

What you need to know: These L-theanine capsules are vegan with a reasonable price tag and high dosage. 

What you’ll love: One of these vegan L-theanine capsules contains a considerably large dosage of 200 milligrams. In addition to being vegan and kosher, the supplement is free of GMOs and gluten. Users report that the calming effect occurs quickly. 

What you should consider: The double-strength capsules have the potential to make the user feel sleepy instead of relaxed. 

Where to buy: Sold by iHerb

Top L-theanine for the money

Lake Avenue Nutrition L-Theanine Capsules

What you need to know: If you are looking to try an L-theanine supplement without breaking the bank, these vegan capsules are a good deal. 

What you’ll love: Each L-theanine capsule contains a dose of 100 milligrams, making it a mild introductory supplement. One container contains 180 vegan capsules and the formula contains no soy, gluten or GMOs. 

What you should consider: Some users felt that these capsules were not strong enough. 

Where to buy: Sold by iHerb

L-theanine worth checking out

Sports Research L-Theanine with Caffeine Softgels

What you need to know: This supplement has a formula that contains generous doses of both L-theanine and caffeine. 

What you’ll love: One softgel pill contains 200 milligrams of L-theanine and 100 milligrams of caffeine, thereby giving the user both energy and calm focus. The supplements are also formulated with medium chain triglyceride oil derived from coconuts. MCT oil is purported to promote weight loss.

What you should consider: These softgels are more expensive than other supplements, and some users may experience negative side effects because of the caffeine content. 

Where to buy: Sold by iHerb

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Patrick Farmer writes for BestReviews. BestReviews has helped millions of consumers simplify their purchasing decisions, saving them time and money.

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