No Thanks

Your 10% Off Promo Code is on the Way! Thanks for signing up for emails.

You're now signed up to receive exclusive deals and savings opportunities!

Thanks again for connecting with us. Keep an eye on your inbox — your first coupon is on its way!

Thank You! This email address is already signed up

You are signed up for the following:

  • Offers
  • Recipes
  • E-Newsletter
  • Updates & Reminders

Thank you for your interest and be assured that you will continue to receive our emails at this address.

Look for your next communication from us within the next week.


We are having trouble processing your request.

Our apologies!

Please try again later.

Search Please enter an item number or keyword
Shop by
Do You
Need Help?

Swanson Ultra

Double Potency Suntheanine L-Theanine

Double Potency Suntheanine L-Theanine

Item:  SWU816

  • Double potency L-theanine supplement

  • Delivers 200 mg per capsule, an important amount supported by clinical research

  • Promotes calm, balanced mental health and emotional well-being*

200 mg 60 Veg Caps
Veg Caps Size: 1

MSRP $23.49
Yes! I want 10% off and free shipping over $50 on my next automatic shipment of this item.  days. Learn more
In Stock

Supplement Facts

Serving Size 1 Veggie Capsule

  Amount Per Serving % Daily Value
Suntheanine® L-Theanine 200 mg *

*Daily Value not established.

Other ingredients: Brown rice flour, hypromellose (vegetable capsule), may contain one or both of the following: magnesium stearate, silica.

Suggested Use: As a dietary supplement, take one veggie capsule per day with water before meals.

Suntheanine® is a registered trademark of Taiyo International, Inc.

Relative Size

Printable Size Guide

Shipping Weight

.10 lbs

  • Double potency L-theanine supplement

  • Delivers 200 mg per capsule, an important amount supported by clinical research

  • Promotes calm, balanced mental health and emotional well-being*

L-theanine is an amino acid found almost exclusively in tea plants and, in particular, green tea. The pioneers at Taiyo International discovered that the relaxing properties of green tea may be tied to this unique nutrient and developed Suntheanine through a patented process designed to amplify its calming potential.* Research indicates that Suntheanine stimulates alpha wave activity in the brain, which is associated with calm alertness.* Our new Double Potency Suntheanine L-Theanine delivers 200 mg per capsule, the upper limit shown to produce results in clinical research.

Swanson Ultra Double Potency Suntheanine L-Theanine Reviews

Summary of Customer Ratings & Reviews

Customer Ratings & Reviews

Double Potency Suntheanine L-Theanine is rated 4.6 out of 5 by 27.
Rated 5 out of 5 by from Reliable I have used this product for many years. It has a calming affect without interfering with cognitive function. And no side effects.
Date published: 2016-04-06
Rated 5 out of 5 by from Suntheanine For Sleep I am a working woman in my mid-50's and sometimes I will wake up at 2:00 in the morning and have trouble getting back to sleep. I read that Suntheanine is the relaxing component in tea. Not wanting to drink several cups of tea in the middle of the night, I decided to try these capsules and I have been pleasantly surprised by the results. Within 1/2 hour I am relaxed and sleepy enough to fall back asleep and I feel very refreshed when I wake up. I would recommend this product to anyone.
Date published: 2016-01-03
Rated 5 out of 5 by from love my l.theanine this supplement is a must for me to get through my day & i appreciate the douple potency ... highly recommend
Date published: 2015-03-05
Rated 5 out of 5 by from Must Have This helps me to relax into my sleep in combination with other things. It's a good value and consistent purity. I recommend Swansons to alll my friends.
Date published: 2015-02-17
Rated 5 out of 5 by from Should take correctlly Love this IF it's taken on an empty stomach, with caffeine (coffee, etc.). You will feel a mental boost and an improvement in mood taking it this way, otherwise not so much. Taken on a full stomach it's kind of a waste of money.
Date published: 2015-01-29
Rated 5 out of 5 by from Dosage I wanted the 200 mg dosage. This is still in the safe range.
Date published: 2015-01-28
Rated 5 out of 5 by from awesome This one works even better then the original! !!
Date published: 2014-12-30
Rated 5 out of 5 by from Great results I have been using this product for about a year and am completely satisfied with it. It has improved my ability to deal with stress and restlessness.
Date published: 2014-12-29
Rated 5 out of 5 by from Amazing Works very well, even better with a caffeinated beverage, If you are trying to stay awake and focus. Take it with out caffeine, to have a heavy nights sleep even with only 4 hours of rest. When I take it this way I feel like I have slept *!
Date published: 2014-10-30
Rated 4 out of 5 by from Calms you - esp with Stressful Job I find that taking one capsule in the morning and one in the afternoon helps me to stay relaxed during the day. It has a calming effect on the mind. Great for relaxing you and allowing you to remain calm in the face of a stressful day.
Date published: 2014-10-24
Rated 5 out of 5 by from Suntheanine L-Theniane I started using it just two weeks ago to help with my sleep and even though I still wake up during the night, it's less frequent and I sleep more deeply. Quite happy with the product.
Date published: 2014-04-02
Rated 5 out of 5 by from peace and calm This product works. I am left feeling calmer and more relaxed after using L-theanine.
Date published: 2014-02-04
Rated 5 out of 5 by from Comfort This really enables me to be relaxed and comfortable. It is important for my sense of well-being; better than deep breathing!
Date published: 2013-12-22
Rated 5 out of 5 by from Good theanine/good price Theanine is one of the few supplements I can take to relax, and even help my sleep. I like this dosage and the price, and it works well.
Date published: 2013-11-18
Rated 5 out of 5 by from Excellent value! I am amazed at the quality and efficiency of Swanson's L-Theanine! For a product of this high quality, I would be prepared to pay three times this amount, but Swanson's keeps so many of their products at such affordable prices! I have a very high-pressure lifestyle, and this supplement helps me deal with the intense pressures and I can leave those pressures behind at the end of the day. I find it much easier to relax and enjoy 'My Time'. Thank you Swanson's!
Date published: 2013-11-18
Rated 3 out of 5 by from Too strong! Had to stop taking these. 200 mg. too strong for me. 100 is better.
Date published: 2013-11-17
Rated 5 out of 5 by from The cheapest Having done the research intensively, I think this is the cheapest legit L-theanine in existence --- "Swanson Ultra Double Potency Suntheanine L-Theanine". If you already know L-theanine is what you need, this is the end of your search for a safe bargain!
Date published: 2013-10-26
Rated 5 out of 5 by from Easy to swallow I like the 200 mg dosage of the Suntheanine because I get the recommended amount in just one capsule instead of the usual two. I am also happy with the price. Suntheanine helps me breeze through stress. Thanks for a great product.
Date published: 2013-10-24
Rated 5 out of 5 by from Suntheanine L-Theanine I purchased this for my daughter after going through a divorce.She hasn't said anything about it, but to me she seems more calm.
Date published: 2013-10-20
Rated 5 out of 5 by from Double Potency Suntheanine L-Theanine I had been ordering L-Theanine from another site and came across it on Swanson's website. The price of it was 1/3 less than where I had been purchasing it. I take just one at night to help make it easier for me to sleep. I will continue to purchase this from Swanson.
Date published: 2013-09-07
Rated 4 out of 5 by from Good for lower-dose requirement This is a good-quality formulation of L-Theanine, just not the intensity that I needed. I recommend this to people who have the need for the basic properties of L-Theanine without extenuating circumstances.
Date published: 2013-09-03
Rated 2 out of 5 by from Sometimes you need a blend I tried taking this without feeling any results. It may work for someone who only needs this one missing supplement. I ended up going with something else sold on Swanson (Theanine Serene with Relora) which worked really well for me. If this doesn't work for you, maybe try this other one. It is pricey, but it works well.
Date published: 2013-08-28
Rated 5 out of 5 by from really helping me! A friend recommended I try this to treat my anger and irritability and general PMS moodiness. So I tried it, taking it 2-3 times daily. After several days, I started to feel like I was on an endorphine high, feeling really good! I feel happier, less frazzled and ready to snap. My anger is very cut down, and I can be a lot more patient and tolerate a lot more frustration. I've had a few relapses of anger, but I think overall it is really helping me, I'm glad I found it!
Date published: 2013-08-21
Rated 5 out of 5 by from It works I have struggled for years with not being able to focus during stressful times and sleeping at night. L-Theanine has done the trick. I like that I can take it only when I want or need it.
Date published: 2013-07-29
Rated 1 out of 5 by from Did not work for me. I have trouble sleeping and hoped that this product would help. Unfortunately, I saw absolutely no difference. I even tried taking triple the recommended dosage to no avail.
Date published: 2013-07-27
  • y_2018, m_2, d_16, h_21
  • bvseo_bulk, prod_bvrr, vn_bulk_2.0.7
  • cp_1, bvpage1
  • co_hasreviews, tv_1, tr_26
  • loc_en_US, sid_SWU816, prod, sort_[SortEntry(order=SUBMISSION_TIME, direction=DESCENDING), SortEntry(order=FEATURED, direction=DESCENDING), SortEntry(order=SUBMISSION_TIME, direction=DESCENDING)]
  • clientName_swansonhealth
Swanson Quality Assurance

Why Shop Swanson®?

We know how important your health is to you and your loved ones. That’s why we’re focused on delivering only high quality products you can trust at the best value.

Our lab evaluates every product to make sure it’s compliant with strict standards and government regulations, and we fully believe in and stand behind our products. If you’re dissatisfied for any reason, we’ll give you a full refund and pay return shipping.

Swanson's Standards

We are dedicated to offering the highest quality products at the best price. Find out more about how we ensure such a high standard in everything we do.

Learn More
Customer Service

Easy Refill

  • Get your favorite products delivered automatically
  • 10% off future orders of Swanson brand products in your subscription
  • FREE standard shipping on all future orders over $50
  • Control the frequency, delivery date, item quantity... or cancel at any time
  • Email reminders before each delivery
See all FAQs here