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High Strength L-Theanine Capsules - 400mg

UK's strongest L-Theanine - Pure & potent double-strength capsules

(77 reviews)9610020
Buy High Strength L-Theanine Capsules - 400mg
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  • Aids relaxation
  • May improve quality of sleep
  • Popular alongside 5HTP
  • Strongest & purest form available
Supplement Description

Introducing our new double-strength L-Theanine capsules. L-Theanine supports a sense of calm, contentment and well-being. It crosses the blood brain barrier and has been shown to increase brain alpha waves in less than 40 minutes. Alpha brain waves are an indication of a state of relaxation and mental alertness similar to that achieved through meditation, this promotes a feeling of relaxation but with an alert state of mind. This is particularly useful to know as it can be taken during the day to support relaxation without a sedating effect.

Theanine is an amino acid found predominantly in tea.  When you have a stressful moment or a shock the immediate thought (well for us Brits anyway) is to have a 'cuppa'! A joke to some maybe, but is there a real reason as to why? Yes, it's L-Theanine, which is believed to be responsible for the calming and relaxing effect brought about by a good old cup of tea.

L-theanine facilitates the production of GABA (a neurotransmitter that has a calming effect on the brain), it has also been shown to support quality sleep and may have a positive effect on memory and learning. 

Purest form available, strong and high grade material

A single capsule provides 400mg of this high-grade amino acid in a vegetarian capsule - currently the strongest form available in the UK.

Nutritional Information
Each capsule typically provides:
L-Theanine 400mg
Allergen Advice
Any allergens are highlighted in bold in the ingredients list.
List of Ingredients

L-Theanine, Hydroxypropylmethyl Cellulose, Maltodextrin, Silicon Dioxide.

Suitable for vegetarian and vegan diets.

Dosage / Suggested Intake
Swallow one capsule per day with food, or as directed by your health professional.
Capsule Size
23mm x 8mm Oblong capsule
Legal Category
Food Supplement
Customer Reviews for High Strength L-Theanine 400mg

The views expressed below are the personal opinion of Just Vitamins customers. Just Vitamins does not endorse these views, nor should they be regarded as health claims or medical advice. All reviews are collected and verified as genuine by a 3rd party called Feefo.

Overall product rating 9.6 / 10 - 77 customers have independently reviewed and recommend High Strength L-Theanine from 77 reviews (showing latest 50 reviews)
Review Date
Review Details
Service rating: Very fast service and good prices of supplements! Would highly recommend!
Product: High potency and works very well to calm down and relax me.
Excellent service
Service rating: Just Vitamins is my go to vendor for majority of my supplement needs.
They have the best quality, constantly innovate on packaging and product constitution, and are extremely competitive on price.
I have been very satisfied with their L-Theanine as it provides the relaxation I sorely need in a high stress environment.
I do not hesitate in recommending Just Vitamins to anyone considering purchasing from them.
Product: This is a product I use regularly to destress and to help me sleep. The quality is good compared to rivals and the pricing is just right.
Service rating: Excellent and fast service
Product: I’m very pleased with the supplements which I bought , my health has improved significantly
Service rating: Excellent service, fast delivery. Very pleased.
Product: Definitely feel the positive effects of the supplement. This is a repeat order so that says it all.
Service rating: Item received very quick and kept informed of progress.
Product: Wanted to calm nerves as important speech and helped a lot.
Service rating: Ordering was simple and easy and they arrived earlier than expected and cost less than previous suppliers.
Product: Did what it said on the label and arrived in an easy to store resealable bag.
Service rating: Good selection. Decent choices of sizes and strengths. Price is a negative though.
Product: Works! Felt a big difference within a half hour and has continued working every day since!
Service rating: Fast, efficient, I can't fault them. Would highly recommend.
Product: they are cheap and reliable, if this is the supplement you need, these are fine.
Service rating: Arrived quickly and well packaged. Would definitely order from here again
Product: Definitely helps keep the jittery aspects of the caffeine buzz away. If you're caffeine sensitive like me, this helps keep you level and avoid the shakiness that can come with caffeine
Quick delivery and great product.
Service rating: First class service 9
Product: Good quality products at a good price
Service rating: Quick delivery and easy to use website. Product is good and I like their easy packaging so it fits in the letter box
Product: Seems to be working would buy again
The tablets came very quickly and the discount was very good.
Service rating: Fast delivery. Great quality of vitamins, will order again.
Product: Good quality product. Will order again.
Bra priser o snabb leverans
Service rating: Supurb! Just Vitamins do everything well. One of my favourite health supplement companies.
Product: One of the best relaxation products on the market.
Excellent. Would use again. .
Service rating: Prompt delivery. Great product. Competitive price.
Product: Helps me relax. Relives tension.
Service rating: Prompt delivery as always. I’m very pleased to see 400mg L Theanine back in stock. I had to buy from a different company last time as only 200mg were available. I don’t want to have to take two capsules when I can take one so it’s good to be back with Just Vitamins!
Product: Just Vitamins products always arrive quickly. Their use of sealed bags instead of plastic tubs means multiple orders can be delivered in an A4 padded envelope together. Also the packaging does not cantain plastic. Great service.
Service rating: Prompt delivery
Product: Not sure if it is helping yet as I haven’t taken it for long enough
Great as always
Quick delivery and quality products. Trusted them for years and never had a problem.
Service rating: Very prompt service, would definitely recommend
Product: Very effective, works quickly for me.
There was a glitch in my order and they fixed it, no quibbles.
shipped quickly without hassle the items i purchased.
Brilliant. Helped me sleep. Warm fuzzy feeling is both relaxing and enjoyable.

A must have !
Service rating: The site works as it should do with a dedicated page for re-ordering items you've bought before.
They could improve this re-order page by allowing you to delete items that you have had problems with and have no intention of buying again, especially when they have refunded the cost of the item(s) complained about.
Product: I find they have the calming effect claimed for this product.
Service rating: Quickly dispatched and delivered only negative is the tablets don’t work for me
Product: No side effects but no good effects either. I take these to help with anxiety induced tremors.
Feedback Response: Hi, sorry to hear that you did not find this supplement to be effective for you. Perhaps you might get better results with 5-HTP?
Let us know how you get on.
Ian - Just Vitamins Customer Team
Service rating: Fast delivery, great prices.
Product: L-theanine is subtle but very effective. I have found that it's great for a) a calm focus, b) reducing stress and c) helping you achieve a deep long sleep without any drowsiness in the morning.
Service rating: Quick delivery good website cheap prices.
Product: Why three stars because the vitamens placed in plastic bag instead of can or box so when i picked it from my mail box it was very warm.
Very quick service. Great vitamins
Service rating: Very fast delivery and good communication
Product: Good but not massive results.
Ordering has been a bit confusing but delivery has been good.
I hope that the quality is good , no way of knowing that.
Service rating: Very prompt service
Product: Helps reduce anxiety quickly
Service rating: The vitamins are reasonably priced, the service prompt and efficient. I love how the vitamins are packaged as they can be posted through my letterbox.
Product: They definitely help with my sleep and lessen my anxiety
Service rating: Easy to order, fair pricing and fast delivery.
Product: Calming effects - very good
Service rating: Great products, good price and fast delivery.
Product: Helps calm my mind, relax and focus.
Service rating: Because their vits are excellent quality and their service is very good too.
Product: high strength so I don't need to take twice daily so saving money
Service rating: Would recommend they do just what they say very good
Product: The service is very good as is the product
Service rating: Everything is high quality and well thought from product to delivery. I will use again. Thanks
Product: I cannot live without it now it makes a real difference.
Very good
Service rating: Just ordered one type of product, which was very good.Overall experience was pleasant and delivery was very fast.
Product: Did not try similliar products from competition but it does what it's supposed to with a very good price!
Service rating: Great Products, prompt delivery, thanks!
Product: Great Quality, affordable prices, nice packaging
Good service
Wish you had thenine in smaller portions
Service rating: Product has yet to arrive and its been 3 likes, will update review if it arrives.

Product arrived later than expected but due to a 3rd party postal service, so no complaints about Just Vitamins service.
Product: Cant review as not arrived
Feedback Response: Thank you for your feedback.We dispatch all orders (including yours) on the next working day of receipt, but unfortunately we are at the mercy of the local postal service once it leaves us.  Our customer services team will be contacting you.
Really fast delivery!! Good prices,what I wanted was cheaper with JustVits than anywhere else. Excellent product. Will definitely use again and would recommend!
Service rating: Order arrived very quickly and always does.
Product: I believe L-Theanine to be a derivative of green tea and so helps against depression.
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