L-theanine: The Unique Amino Acid That Helps With Relaxation, Focus & Sleep

L-theanine: The Unique Amino Acid That Helps With Relaxation, Focus & Sleep

Want to feel calm throughout the day? Then learn the best sources of L-theanine, an anomaly of a compound that has numerous health benefits.

You probably know that amino acids are the building blocks of protein. But there’s always an exception to the rule. In fact, there are hundreds of exceptions when it comes to amino acids. You see, in addition to the 20 common amino acids that are encoded in protein, there are over 900 non-protein amino acids. Researchers believe non-protein amino acids help protect plants against insects. They also play a key role in plant metabolism. 

What is L-Theanine?

L-theanine is a non-protein amino acid that may play a key role in your own metabolism, and help protect you, not against insects, but stress, brain fog and anxiety. 

Isolated in 1949 by Japanese scientists, L-theanine is abundant in tea leaves, especially in green tea. In recent years, the compound has gained notoriety for its ability to induce calmness. A 2019 research article in the journal Nutrients, says L-theanine “has the potential to become a nutraceutical ingredient that mitigates and prevents stress-related psychic confusion in modern society.”

The good news is taking L-theanine is as easy as popping a pill. Walk into any natural grocer with a supplement aisle and you’ll likely find L-theanine supplements. But you may also want to boost your intake of green tea and a select few other foods that are rich sources of this compound that can make you feel mellow. 

Benefits of L-Theanine

According to several studies, here are some of the research-backed benefits of L-theanine:

  • Neuroprotective
  • Cognitive-enhancing
  • Prevents monoamine loss, thereby supporting mood (more on this below) 
  • Anti-stress and anti-anxiety properties
  • Improves sleep quality
  • Increases attention span
  • May mitigate the effects of psychiatric disorders

How Does L-Theanine Work?

You have billions of neurotransmitters that are constantly hard at work regulating your brain function, your breathing pattern, and other vital functions. These chemical messengers that facilitate communication signaling between neurons and target cells throughout the body also determine your psychological state. 

Serotonin is a monoamine neurotransmitter that among other functions, controls your appetite and sleep quality, hormone secretion, attention span, memory, and mood regulation. 

One popular theory of depression is the Monoamine Hypothesis, which posits that depression is the result of underactivity of monoamines, especially the precursor to serotonin, 5-HT.

L-theanine works in part by preserving monoamine neurotransmitters. In addition, it also elevates levels of another non-protein amino acid, GABA. GABA is often regarded as the most important neurotransmitter for counteracting the effects of anxiety. But GABA is also a noteworthy non-protein amino acid that’s not only essential for optimal health, but also for many physiological and developmental processes in plants, says an article in Frontiers in Plant Science

And according to Michael Breus, PhD, writing in Psychology Today, L-theanine also reduces the levels of brain chemicals that can overstimulate the brain. If you’ve ever experienced severe allergy symptoms, you’ve had the unpleasant experience of having your body overwhelmed by the excitatory chemical, histamine. Epinephrine (adrenaline) and dopamine (the “reward” chemical) are a couple other excitatory neurotransmitters. GABA, mentioned above, counteracts these excitatory neurotransmitters. 

Another way in which L-theanine works is by boosting alpha brain waves, which is the heightened yet relaxed state of mind that takes place during meditation and REM sleep cycles. Alert yet calm … these are two attributes that many people strive for but seem very elusive.

But that’s not all. Another way that L-theanine can improve your life… Research shows that it acts in one way like an adaptogenic herb, in that it lowers levels of the stress hormone, cortisol.

Best Sources of L-Theanine

Green tea isn’t the only kind of tea rich in L-theanine. Black tea is also a good source. So, too, are some edible types of mushrooms. 

Unfortunately, that’s about the end of the list of naturally-occuring foods with lots of L-theanine. 

If you want to biohack your way to better sleep, more calmness and improved cognitive performance, you may want to take an L-theanine supplement. 

Keep in mind that in research studies that demonstrated positive effects when supplementing with L-theanine, it took about four weeks for the benefits to be really noticed. 

L-Theanine For Weight Loss? 

In a recent post on this blog, the best umami foods to control portion sizes were revealed. Considered the fifth taste of food, umami possesses a savory, fatty mouthfeel, which helps trigger satiety earlier than other tastes. L-theanine, says the aforementioned Dr. Breus is thought to be a food that triggers umami on the taste buds. 


If you need yet another reason to drink green tea, getting loads of L-theanine in your diet is another strong selling point. If you don’t like green tea, your best bet to get your daily dose of this non-protein, calm-inducing, mental-boosting compound is via a high-quality supplement. 

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