4 Best L-Theanine Supplements of 2025 [Full Comparison]

I’ve tried a handful of L-theanine supplements over the years, but Momentous is the one I keep coming back to—and that says a lot. Like many people, it’s easy to get stressed or feel overwhelmed during the day, especially when I’m juggling a lot of tasks at once.

What I’ve found with Momentous L-Theanine is that it helps smooth out that mental static without making me feel sluggish or sedated. In my experience, it delivers a sense of calm focus and alertness that’s perfect for daytime use—especially when paired with a morning coffee, since it seems to take the edge off the caffeine boost in a really balanced way.

It is perhaps at nighttime, however, when it really delivers. If you’re someone who struggles with sleep latency (the time it takes to fall asleep) then Momentous L-Theanine is really worth checking out. Combined with good sleep hygiene, I’ve found it helps me transition to sleep—and stay asleep—better than any other product I’ve tried (and I’ve tried a few!).

It’s also worth trying it in combination with Magnesium L-Threonate and Apigenin as part of Momentous Sleep, which is a synergistic combination first recommended by neuroscientist Dr. Andrew Huberman.

Of course, when it comes to supplements it’s difficult to know if what’s on the label is actually what’s in the jar. With Momentous L-Theanine, which holds the NSF Certified for Sport certification, you don’t need to worry about that as it is guaranteed to be pure, safe, and effective. It’s reassuring to know that what I’m putting in my body has been rigorously tested and is free from contaminants—a detail that matters a lot to me.

That said, Momentous might not be the best option for those on a tight budget. If you’re shopping solely on price, there are definitely more wallet-friendly options. But if you prioritize quality, purity, and peace of mind, I’d say the extra cost is worth it.

Momentous L-Theanine is a great fit for anyone who wants to enjoy better relaxation and sleep quality as well as stress relief and reduced anxiety. If that sounds like you, I highly recommend checking it out for yourself.

Key Things to Know About This Product

• Third-Party Tested: No, but produced in cGMP facilities

• Money-Back Guarantee: Yes

• Gluten Free: Yes

• GMO Free: Yes

Product Details:

• Price: $21.99

• Number of Servings: 90

• Amount of L-theanine per serving: 100 mg

• Serving Size: 1 capsule

• Subscription: No

• Free shipping: Yes, on orders $50+

Pros:

• Cost effective

• Uses decaffeinated green tea leaves

• Produced in cGMP facilities

Cons:

• Not third-party tested

• Lower dose (100 mg)

If you’re looking for an affordable way to try L-theanine, Now Foods L-Theanine is a solid, no-frills option. I gave it a try during a particularly hectic few weeks at work, and while the effects were more subtle than some of the higher-dose products I’ve used, I still noticed a gentle calming effect—especially when I took it mid-afternoon to help with that wired-but-tired feeling.

One of the things I appreciate is that it’s made with decaffeinated green tea leaves and produced in cGMP (certified Good Manufacturing Practices) facilities, which speaks to a decent level of manufacturing quality, even though it’s not third-party tested. For the price—$21.99 for 90 tablets—it’s hard to beat, especially if you’re someone who’s just starting to experiment with L-theanine or prefers to stick to lower doses.

At 100 mg per capsule, it’s on the milder side, so it might not be strong enough for people who need a more noticeable effect. But I found it easy to double the dose when needed without side effects.

Overall, Now Foods L-Theanine is a budget-friendly, reliable pick that works best for those looking for the health benefits of L-theanine without breaking the bank.

Key Things to Know About This Product

• Third-Party Tested: Certified Gluten Free

• Money-Back Guarantee: Yes

• Gluten Free: Yes

• GMO Free: Yes

Product Details:

• Price: $61

• Number of Servings: 60

• Amount of L-theanine per serving: 200 mg

• Serving Size: 1 capsule

• Subscription: Yes - save 10%

• Free shipping: Yes - free expedited shipping on all orders

Pros:

• Dosage

• Free from all allergens

• Free expedited shipping on all orders

Cons:

• Price

• Certified gluten free but no other third-party testing or certifications

Pure Encapsulations L-Theanine is a popular L-theanine supplement that is highly rated and reviewed by customers who say it delivers reliable, calming support without any unwanted extras.

Customers report using it during periods of high stress and/or when wanting to improve sleep and relaxation.

As with the Momentous product, it has a 200 mg dose of L-theanine per capsule, which customers say is just the right dosage, helping to reduce stress and anxiety without any side effects such as drowsiness.

Although this product lacks NSF certifications, it is certified gluten free and is completely free from common allergens, including soy, dairy, and artificial additives. That said, at $61 for 60 servings, it’s definitely on the pricier end. For this price tag, I’d really expect to see an NSF Certified for Sport certification, like the Momentous product has.

Still, if you’re someone who values hypoallergenic, quality supplements and fast, free shipping, this is a contender. 

Key Things to Know About This Product

• Third-Party Tested: Yes, OK Kosher

• Money-Back Guarantee: Yes

• Gluten Free: Yes

• GMO Free: Yes

Product Details:

• Price: $24.99

• Number of Servings: 60

• Amount of L-theanine per serving: 150 mg

• Serving Size: 1 capsule

• Subscription: Yes - save 20%

• Free shipping: No

Pros:

• Contains Suntheanine, a clinically proven and patented form of L-theanine

• Highly rated and reviewed by customers

• Price

Cons:

• Lower dose than others

• Strong subscription savings

• No NSF certifications

Tomorrow’s Nutrition Suntheanine offers a different form of L-theanine, using the patented and clinically proven Suntheanine formulation. Long-time L-theanine supplement users say they can feel a difference between this form and the standard form, with Suntheanine providing a smoother and more sustained feeling of relaxation. They also report it noticeably helps with improved focus and concentration without any side effects such as drowsiness, nausea, or dizziness.

When it comes to dose, the 150 mg of L-theanine is slightly lower than other options reviewed here, but this could work favorably for first-time users looking to get accustomed to it.

While this product is OK Kosher certified, it does not carry any other certifications, such as NSF Certified for Sport. That said, it is more cost effective than other options, equating to $0.41 per serving (compared to $0.66 for Momentous or $1.01 for Pure Encapsulations), which, for a product that’s clinically proven and patented is really reasonable.

If you’re looking for a higher dosage of L-theanine, and third-party testing and certifications are of paramount importance, then this might not be the best L-theanine option for you, but if you’re curious about the benefit of L-theanine and want to try a clinically backed form without spending a premium this could be worth a try.