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What is L-Theanine and its benefits

June 16, 2022 4 min read

What is L-Theanine and its benefits

L-theanine is one of the 3 key ingredients in our Brainfood products. It is an amino acid found in the leaves of Camellias Sinensis — the scientific name for the common green tea plant. It’s responsible for some of the savoury notes in green tea and is becoming a highly popular natural and safe calming agent.

Consumed to reduce feelings such as anxiety, L-theanine shares properties with gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter that functions in opposition to excitatory transmitters. The inhibitory nature of L-theanine allows it to decrease blood pressure and heart rate, and reduce stress hormone levels in the body.

Also known as a Nootropic — a cognitive enhancer — L-theanine can help improve cognitive function. Research continues to elucidate and document the mechanisms through which L-theanine confers its beneficial effects. Efficacious and found to be one of the safest nootropics, even more so than the caffeine from your coffee! 

Our Brainfood products include 200mg of pure L-Theanine in every serving - the equivalent to 25 cups of green tea!

Here are some of the many benefits of L-Theanine:


Caffeine included in our daily coffee or energy drinks can cause stress, anxiety, restlessness, and even increases blood pressure. L-theanine balances out these negative effects, ensuring our caffeine intake experience is more positive and pleasant. [1]

Because caffeine competes with adenosine, it has a stimulatory effect in the brain. However, overstimulation is a risk and can lead to the opposite of the desired effects sought from caffeine. This is where the inhibitory nature of L-theanine can prove useful, quickly mitigating the negative symptoms of overconsumption of caffeine. 

Many of caffeine’s negative properties stem from the fact that it’s a vasoconstrictor. This means that drinking a cup of coffee or energy drink will temporarily make your blood vessels smaller. Less room for blood flow forces the heart to work harder, meaning an increase in heart rate and blood pressure. For many people, their body interprets these symptoms as those of stress or anxiety and reacts accordingly.

L-theanine not only promotes relaxation, helping to reduce stress, but also combats the stress-inducing properties of caffeine [2]. It encourages healthy blood flow, preventing a physiologically taxing nervous system response. Beneficially, this attenuates the adverse health effects of elevated blood pressure, such as damaged arteries, heart disease, and the associated risk of stroke. [3]



Most side effects of relaxants are that they also induce drowsiness - L-Theanine by nature is fortunately non-drowsy [4]. After crossing the blood-brain barrier, L-Theanine inhibits the activity of glutamate receptors and causes anti-stress effects by reducing cortical neuron excitation. [5] 

As discussed, studies in healthy adults show that orally administered L-Theanine reduces anxiety and attenuates blood pressure increases, particularly under conditions of physical or psychological stress [6]. In a study looking at the effects of L-Theanine on the stress response (using a mental arithmetic task as an acute stressor), compared to placebo, L-Theanine reduced heart rate and salivary immunoglobulin A responses (S-IgA) in the subjects [7]. Researchers attributed these effects to an attenuation of sympathetic nervous activation. Animal studies suggest that L-Theanine increases brain levels of various neurotransmitters and that it has affinity for AMPA and kainate receptors (as an antagonist) and NMDA receptors (as an agonist) [8].

L-Theanine has also been shown to boost levels of GABA, as well as other hormones and compounds that promote calm, focus, regulated mood, and more. [9]



In a study on anxious university students subject to stressful cognitive testing, the students supplementing L-Theanine had significantly increased activity in the alpha band of brain waves, reducing heart rate, elevating visual attentional performance, and improving reaction time response among highly anxiety-prone subjects compared to a placebo. [10]


Alpha brain waves are associated with wakeful relaxation, often referred to by psychologists as 'flow state'. That’s the state of mind you experience when meditating, being creative, or participating in any activity that is completely immersive and engaging. L-theanine triggers alpha-wave activity [11], which enhances relaxation, focus, and creativity. One of the appealing aspects of L-theanine is that it works to relax without sedating. That can make L-theanine a good choice for people who are looking to enhance their “wakeful relaxation,” without worrying about becoming sleepy and fatigued during the day.

Fun fact - Ārepa is Te reo Māori transliteration for alpha - learn more about why we chose this name here.  



Antidepressants are now among the most widely prescribed medications worldwide, and data suggests that the use of these drugs is increasing. The problem is that for a substantial proportion of patients antidepressants are ineffective and the side effects can be intolerable. 

An exciting new study from Japanese researchers has found that L-theanine significantly reduced symptoms of depression, and improved cognitive functioning in people with depression. In this study, 20 people with major depressive disorder were given 250 mg L-theanine per day for 8 weeks and assessed for cognitive functioning, sleep, and depression. The authors of this study concluded that L-theanine was safe (no adverse side effects observed) and had multiple benefits on depressive symptoms including reductions in anxiety and cognitive impairments, and improved sleep. [12]



Sleep deprivation is associated with an elevated risk of various diseases and leads to poor quality of life and negative socioeconomic consequences. Sleep inducers such as drugs and herbal medicines may lead to dependence, have other side effects, or lack efficacy. L-Theanine has effects associated with conventional sleep inducers without any known side-effects. A study found 200mg improved participants quality of sleep but not the duration suggesting it was through its ability to reduce stress and induce a calming state allowing the brain to fall asleep naturally, rather than through sedation which often causes increased sleep duration. [13]



The ability of L-theanine to modulate neurotransmitter levels, as well as its antioxidant and anti-inflammatory properties means that chronic consumption can support long-term cognitive health - keeping your brain happy and healthy!

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