L-Theanine Capsules

L-theanine is a non-dietary amino acid that promotes relaxation. ✝

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Sachet of 6 caps x 200mg Bottle of 120 caps x 200mg


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What is L-theanine?

L-theanine (γ-glutamylethylamide) is nonessential amino acid primarily found in the green tea plan (Camellia sinensis). In fact it is now believed that L-theanine gives tea its distinctive aroma and taste. There are a number of studies showing anxiolytic effects (i.e., anxiety reduction) of L-theanine.1, 4 Therefore, L-theanine can offer a lot of beneficial effects for those suffering from anxiety. This naturally occurring amino acid is best known for its relaxing properties without sedation. In other words, it helps people relax without making them sleepy.

In addition to its anxiolytic effects, L-theanine improves concentration and learning abilities. It is associated with the ability to remove external distractions and focus only on the tasks at hand (i.e., increased selective attention).5 Interestingly, a greater enhancement in cognitive function is demonstrated when L-theanine is taken with caffeine as these two substances appear to be synergistic. For example, a combination of L-theanine and caffeine has been demonstrated to have an additive effect on attention when taken in high doses.5

In terms of physiological signs under stress, a study by Kimura et al.1 demonstrated reduced heart rate and salivary immunoglobulin A (s-IgA) following an acute stress task. This suggests anti-stress effect on the sympathetic nervous system. Further evidence suggests that L-theanine may be effective at promoting weight loss, strengthening immune system and even preventing from certain cancers and cardiovascular diseases.6 L-theanine modulates the brain activity as demonstrated by the electroencephalograph (EEG) studies. These studies show that brain waves are smoothed out which causes a relaxed yet alert mental state.

L-theanine is a very effective substance that can cross the blood-brain barrier (BBB) and directly affect the central nervous system (CNS). After oral ingestion it is transported to the brain where it crosses the BBB within 30 minutes, with peak concentrations observed approximately 2 hours post-ingestion.4 In terms of its chemical structure (see below), L-theanine is very similar to glutamine (an essential amino acid), that is a precursor to GABA and glutamate neurotransmitters.

Key benefits:

  • Promotes relaxation without sedation
  • Improves mood
  • Reduces stress
  • Enhances cognition

Recommended dosage:

The recommended daily dosage of L-theanine is between 100–200 mg.

Mechanisms of action:

L-theanine is a precursor to serotonin and increases the levels of dopamine. Dopamine is a very important neurotransmitter that is linked with any rewarding activities. Serotonin is often called a “happy” neurotransmitter directly involved in mood regulation. Positive mood enhancement can stop negative and depressing thoughts. Therefore, adequate levels of serotonin are required for a stable and generally healthy mood. Additionally, L-theanine has been shown to block the binding of L-glutamic acid to glutamate receptors in the brain.1 A longer use of L-theanine has been shown to facilitate long-term potentiation and an increase in brain-derived neurotrophic factor (BDNF) expression.4

Chemical structure:

L-theanine chemical structure

Side effects:

L-theanine has been approved by the FDA, meaning that it is safe for human consumption. However, it is not recommended to use L-theanine whilst breast feeding. As far as side effects are concerned, there are not many negative effects reported following the use of recommended dosages of L-theanine. Higher dosages may lower the blood pressure though. This has implications for those people who take any type of high blood pressure (hypertension) medication as used in combination the blood pressure can drop to a dangerous level. Finally, there is no evidence to suggest that users of L-theanine develop chemical dependence.

Compound facts:

Serving size: 1 capsule

Servings per bottle: 120

Amount per serving: L-theanine 200mg

This product is free from: Artificial Flavours, Colours & Preservatives, Lactose, Yeast & Gluten

Suitable for: Vegetarians and Vegans


  • Dietary products should not be used as a substitute for a well-balanced and healthy diet.
  • Store in a cool dry place, out of reach of children.
  • Do not use if you are pregnant or breastfeeding.


✝ These statements have not been evaluated by the Food and Drug Administration (FDA) The above products are not intended to diagnose, treat, cure or prevent any disease. You should consult a physician before taking a new product or a nootropic. This product should not be taken by pregnant or nursing mothers, people suffering from cardiovascular disease or those under 18 years of age.

Any studies cited here are not conclusive and are limited to their closed environment nature; they might not determine ones experience with a nootropic, due to a large number of unaccounted variables falling outside the scope of such studies.

The reviews available here are the opinions of contributors who may or may have not used these products, and do not necessarily represent the views of ThoughtFoods. These reviews represent one’s opinion and should not be taken as fact or recommendation. ThoughtFoods makes no warranty to the accuracy of information provided by these reviews.

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1.   Kimura, K. et al. (2007). L-theanine reduces psychological and physiological stress responses, Biol Psychol. 74 (1), 39-45.

2.    Dodd, F.L. et al. (2015). A double-blind, placebo-controlled study evaluating the effects of caffeine and L-theanine both alone and in combination on cerebral blood flow, cognition and mood, Psychopharmacology. 232 (14), 2563-76.

3.    Mu, W. et al. (2015). An overview of biological production of L-theanine, Biotechnol Adv. 33, 335-42.

4.    White, D.J. et al. (2016). Anti-stress, behavioural and magnetoencephalography effects of an L-theanine-based nutrient drink: a randomised, double-blind, placebo-controlled, cross-over trial, Nutrients. 8 (1).

5.    Kahathuduwa, C.N et al. (2016). Acute effects of theanine, caffeine and theanine-caffeine combination on attention, Nutr Neurosci. [Epub ahead of print].

6.    Vuong, Q.V. et al. (2011). L-theanine: properties, synthesis and isolation from tea, J Sci Food Agric. 91 (11), 1931-9.

L-Theanine Capsules Reviews

ThoughtFoods L-Theanine Capsules

5(based on 1 reviews)

By Emma T. on11 May 2016
Reduces anxiety & stress
L-theanine calms my mind during and after a long day at work. I’m also able to focus better, especially when working under deadlines and pressure. If you find yourself feeling anxious and stressed, I do recommend L-theanine for its calming and anti-anxiety effects. It’s a second bottle I’ve bought here and both times delivery was really fast. As a part-time student, I also like how you provide references for more information 
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