Know Your Nutrients: L-theanine

This next post in the series which explores key nutrients that are required by our bodies to support our optimal health and wellbeing. Each nutrient will be described in terms of its role, highlighting various key benefits, including our potential for deficiency, dietary sources, and potential benefits for supplementation.

 L-theanine is an amino acid uniquely found in tea. It accounts for more than 50% of total amino acids in tea. L-theanine is water-soluble and considered as an important contributor to the distinctive aroma and taste of tea infusion. Evidence reveals that L-theanine administration is strongly related to various benefits including improvements in mood, cognition and a reduction of stress and anxiety-like symptoms.1

What is L-theanine?

Alongside caffeine and green tea catechins (group of flavonoids naturally in the fresh leaves of the tea plant), L-theanine is one of the main components. Aside from tea, L-theanine is not common in any of the foods that make up our diet. It is not one of the common nonessential amino acids either.

What are the health benefits of L-theanine?

There are many reported health benefits of tea consumption and it is widely acknowledged the benefits relate to anti-aging, anti-diabetic, pro-metabolic, immune boosting, and anti-depression effects.2 In an article in Nature titled “Drink tea and be merry”, Natasha Gilbert summaries the potential benefits of L-theanine on our brain health.3

Why is L-theanine potentially an important nutrient that we should be taking? Stress and anxiety have a substantial impact on us, our communities and wider society. The reported prevalence of these two conditions was estimated at 264 million people living with anxiety disorders (data for 2015).4 More recently, the prevalence of depression, anxiety, and post-traumatic stress disorder in health care workers during the COVID-19 pandemic has been reported to around 1 in 5 workers (~22%).5

Improvements in sleep quality, reduction in hypertension, cognition and mood improvements and positive emotional status have all been associated with the consumption of L-theanine.6 When consumed with caffeine, cognitive impairment is reduced, with beneficial antioxidant and anti-inflammatory activity in the brain.7

In a recent 2020 systematic review by Williams and colleagues, the researchers indicated that L-theanine has a potential anti-stress effect and anxiety suppressive properties at levels between 200-400 mg/day.  Furthermore, all included studies demonstrated some strengths and indicators of quality, for instance, eight of the nine studies were designed as randomised, double-blind, placebo-controlled trials (gold standard trial design) while one study used a randomised, single-blind, placebo-controlled design (excellent design).8


What should I know when taking theanine?

L-theanine is routinely taken to promote calmness and reduce anxiety. Furthermore, it is often taken with many stimulants (especially caffeine, usually 200 mg of each) as it has a stated lack of sedation (a state of calm), decreasing the edge of many stimulants. Whilst promoting cognition and attention.9

Theanine products

Bigvits are delighted to be able to offer a range of products containing L-Theanine. These include multi nutrient products aimed promoting calmness and mood stability with other key nutrients including Magnesium, GABA, Taurine, and Holy Basil Leaf (Biovea Theanine Complex), gummies designed for children to promote calmness (Jarrow Formulas), and standalone theanine products ranging is doses from 100 to 250 mg. As usual, all Bigvits products have been sourced from premium manufacturers, ensuring we are offering our customers optimal choices and aligned to forms used within research.

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L-Theanine is an amino acid food predominately in tea. It is routinely taken (100 to 250 mg) either on its own to promote calmness, anxiety and/or induce sleep, or with caffeine to enhance our cognitive performance, and sharpen our focus.


If you have a specific interest or would like to see a particular product or nutrient reviewed, please email your request to Educating our customers in respect to the importance of nutrients and the idiosyncrasies between formulas and products is at the heart of what we want to achieve.

This post is meant for educational purposes only and does not constitute medical or nutritional advice or act as a substitute for seeking such advice from a qualified health professional. In order to make the blog series easier to read, I have used a conversational tone in many places with personal pronouns, such as “I” and “you.” This is meant only to make it more pleasant to read,and is not meant to imply that the information constitutes any form of advice, whether personal or general.