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High Strength L-Theanine Capsules - 400mg

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

98 reviews9410020
Only 16.6p per capsule
In stock
- Best Price
Only 15.0p per capsule
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Key features

  • Aids relaxation
  • May improve quality of sleep
  • Popular alongside 5HTP
  • Strongest & purest form available
High Strength L-Theanine 400mg capsule view
Capsule Size
23mm x 8mm Oblong capsule
  • Description
  • Product Information
  • Feefo Reviews Reviews

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
Ingredients containing allergens are highlighted in bold in the ingredients list. 
List of Ingredients
L-Theanine, Hydroxypropylmethyl Cellulose, Bulking Agent (Stoneground Rice Flour), Anti-caking Agent (Rice Hulls), Rice Extract (with Rice Hulls, Gum Arabic, Sunflower Oil)
Dosage / Suggested Intake
Swallow one to two capsules per day with food or as directed by your health professional
Legal Category
Food Supplement with L-Theanine


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 9.4 / 10 - 98 customers have independently reviewed and recommend High Strength L-Theanine from 98 reviews (showing latest 25 reviews)
Review Date
Review Details
great service
Good service
Service rating: Very prompt and efficient service
Product: Helps me to relax and get better sleep
Service rating: Ordered as previously happy with product and price. Now there is a much wider range available elsewhere with higher strength products available at lower cost.
Product: L theanine - taken for concentration and calm seems to have some benefits.
Service rating: They deliver things very quickly and in good packaging.
Product: These are good, they calm my moods right down. Strongly recommended for Fybro sufferers.
Fast efficient service as ever.
Service rating: As always super . From enquiry to delivery. Faultless.
Product: Smooth and calming product.
Service rating: Good products and great service.
Product: Find them very helpful and calming
Service rating: Fast delivery
Product: Amazed by their effectiveness. Very pleased, will buy again.
Service rating: Came very quickly
Product: Have been taking them for years
Service rating: Brilliant site
Product: Great for anxiety take before bed or in morning
Service rating: I think they are an honest firm with reasonable prices and I like the way they do not send their products in glass or plastic containers.
Product: It certainly seems to work for me.
Service rating: Fast delivery and high quality product. Loving how much it's enhanced my life already!
Product: I began taking L-Theanine after researching its positive effects on creativity and I can certainly say that this product does the job. Helps me stay focused, whilst calm at the same time.
Service rating: Speedy delivery ,good communication .
Product: It helps with my anxiety and my sleep
Service rating: Good customer service (originally was sent wrong item but they redelivered and sent A package to return the vitamins sent in error) however I’ve taken the same vitamins in pill form from 2 other brands and found them much more effective even though these are described as double the strength. Feel like these vitamins (l-theanine 400mg) just don’t really work.
Product: I have tried l-theanine from other brands taking pills half of the strength of these and they were far more effective. I didn’t feel like these worked at all unfortunately and would not purchase again.
Service rating: Prompt delivery, quality product, easy life
Product: Great product. This what I was looking for.
Service rating: Bought from them for quite a while, and will carry on doing.
Product: Tastes good. I use it with coffee mainly. It comes from green tea.
Service rating: Great choice of products, great quality, rapid service and always reliable.
Product: Great quality, the dosages is just right, quality is good and they are well sourced.
Great service
Brilliant product
The sale and delivery went through smoothly with no problems. I would use this company again.
Service rating: Excellent prompt service, love the pouch the tablets come in, keeps them fresh. Very happy with purchase.
Product: Im really impressed, will definitely be buying more. Overall benefits are very good.
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