What is L-theanine and why is so good for your brain?

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L-theanine brings focus

Written by Jonas De Schaut, inspired by conversations with Dr. R. Demaerel

L-theanine is a component of...that's right, tea. Tea has been one of the most popular drinks in the world for centuries, and rightfully so. There are many variations but the most popular types of tea are black and green tea. For any type of tea, the leaves are always processed differently (drying, curling, fermenting, etc.). It is this very processing that gives all teas their unique flavor and that explains the differences in volumes of L-theanine. Matcha tea for example is a green tea that is shade-grown and ground to fine powder and has a relatively high amount of them.

Taylor Swift and L-Theanine?

Tea consists mainly of what we call flavonols. However, we can find many other bioactive components in tea. The best known are caffeine and catechin (an antioxidant).

Besides caffeine and antioxidants, we can find certain amino acids that would also have certain effects on our health and functioning.

One of these amino acids is L-theanine. The substance became known when Taylor Swift claimed to take it daily in 2019. This substance is said to have a calming effect at the same time and would also make you more alert. In addition, it is also attributed anti-viral properties. Recent scientific articles focus on the "stress-reducing effect". Of course, oftentimes these studies have to be taken with a pinch of salt. However, it is interesting to see what L-theanine actually does to your brain.

L-theanine is a bioactive substance. These are substances that we as humans take from our environment (plant or animal) and that we can then use to start/improve/accelerate working processes in our body. L-theanine is not essential - you won't die if you don't take it - but its intake could indeed make you more efficient and could thus explain the above described stress-reducing, soothing effects.

L-theanine is found in nature and more specifically in tea plants. It takes a while for the plant to produce it, but eventually it ends up in the leaves.

Relaxed state of alertness

How do we explain that this substance has a calming but non-sedating effect?
Our brains consist of millions of nerve cells that continuously communicate with each other via electrical pulses. These pulses, if you repeat an activity, can be more efficient and faster. It is a complex system that is in constant motion. (You can actually measure electrical waves activity with an EEG device) This is how we know that there are such things as alpha, beta, delta and gamma waves. The alpha waves predominate when you are in a relaxed state. Not coincidentally, it appears that after taking L-theanine, these alpha waves increase in certain cerebral cortex areas (occipital and parietal). These relaxing effects also have a lowering effect on blood pressure.

In addition to the calming effect, much attention is also paid to the effect of L-theanine on cognitive performance. L-theanine has the unique property of being able to cross the blood-brain barrier, something that most substances cannot do. The blood-brain barrier has to protect our brain from harmful external influences. In the brain it acts on certain receptors and/or functions as a signaling substance. For example, it is thought to have the same effect as glutamate, the substance that is very involved in memory and is typically reduced in the brains of patients with Alzheimer's dementia. In Alzheimer's patients, it has been found that L-theanine has a kind of "neuro-protective" effect that causes fewer cells to die from the toxic substances that cause the disease. In addition, it also affects dopamine and serotonin and in that way learning new things. Caffeine is also known to enhance cognition. It is interesting to see how L-theanine seems to work together with caffeine and thus increase its good properties.

L-Theanine in Matcha

Last but not least, L-theanine also provides the umami taste that most people love and is something typical that explains specific taste (and rising popularity) of matcha tea. One gram of Shēdo ceremonial matcha contains about 19.5 milligrams of L-theanine, so a typical serving (1.5 - 2 grammes) would come close to 40 milligrams. 

Not all matcha contains as much L-theanine though. L-theanine is mainly produced during the shade-growing process the tea plant undergoes. About 4 weeks before harvest, layers of shade are added over the tea farm fields, eventually blocking out about 90% of direct sunlight. The more rigorous this procedure has been followed, the greener your matcha will be and the more L-theanine it will contain.

For those of you who are looking for a truly umami matcha with high levels of L-Theanine, check out our Shēdo ceremonial matcha right here.