L-Theanine: Tea's Amino Acid for Overall Wellness

Written by Jamie Witherby • December 7, 2018. Originally published by HVMN, modified for use here on Loreeebee.

In this article, we won’t just stick to why tea is so tasty. We’ll talk about the positive effects that L-theanine (L-thee-uh-neen) can have on your stress levels, cognitive performance, cardiovascular and immune health.

Discover the benefits of L-Theanine in tea. Photo by Pexels

Tea is coffee’s coy competitor in the cutthroat, yet throat-soothing, world of hot beverages. Both provide daily stimulant boosts, both are great to share with a loved one, and both are steeped in rich and complex histories. But popular teas (like green tea, black tea, and even tea extract and tea constituents) have something coffee doesn’t.

If you have a cup of green or black tea in front of you, take a sip. Savor those tocopherols and flavonoids lending the cup its signature color and flavor. The tea leaves’ distinct bitterness is supplied by natural antioxidants known as catechins.¹

There’s another flavor you should be experiencing, however. A pleasant, mouth-filling sensation that creates a rounded and savory taste, umami is often called the fifth taste after bitter, sour, sweet, and salty. Tea’s umami flavor is all thanks to the non-protein amino acid, L-theanine.¹

Brain Boost

A healthy body starts with a healthy brain. L-theanine has proven itself to be a powerful supplement for brain health by assisting with stress, sleep, attention, and memory.

Stress and Anxiety

If you’ve ever brewed a cup of tea to decompress from a stressful day or share with an anxious friend, congratulations—you have fabulous instincts.

Researchers have found L-theanine can reduce our physiological stress responses by altering the behavior of neurotransmitters in the brain.² This isn’t a slow, thirty-days-to-better-behavior modification process. L-theanine is tough, immediately jumping on defense to supply these benefits.

Taking L-theanine is like hiring a bodyguard for your brain.

Our brains balance activity through excitatory (upper) and inhibitory (downer) neurotransmitters. You’ve probably heard of some of the major excitatory neurotransmitters like dopamine and serotonin. The balance can shift, however, through an excess of these excitatory neurotransmitters. A shift can cause classic responses we’re familiar with like stress, anxiety, and the activation of the sympathetic nervous system (AKA the fight-or-flight response).

Taking L-theanine to mimic gamma-aminobutyric acid (a neurotransmitter that blocks impulses between nerve cells in the brain) can inhibit these excitatory responses and ease their physiological stress responses. This will allow you to enjoy a lower heart rate,² lower blood pressure,³ attenuation of the fight-or-flight response,² and reduced cortisol levels (major stress hormone).^2,3

If the classic calming effect isn’t revealing enough, let’s pull back the covers on how deeply relaxing L-theanine can be.

Sleep

To catch some Zs, first we have to catch some waves.

During sleep, it’s all about theta waves and delta waves. Theta waves occur in the first stages of sleep, generating two distinct rhythms of greater amplitude and lower frequency than the waking beta waves. Delta waves are the lowest frequency, highest amplitude waves generated during the deepest stages of sleep. Right before sleep, when you’re still in that daydream-like, relaxed state, it’s all about the alpha waves. The brain generates alpha waves during deeply relaxing activities such as meditation.^4,5

If you struggle to feel peaceful during meditation or get your mind to achieve that quiet calm right before bed, L-theanine can take you there. Studies have shown that L-theanine can generate alpha brain waves in the parietal and occipital regions of the brain, leading to a prolonged calming effect.^4,5 In a placebo-controlled study of young individuals with ADHD, L-theanine proved especially effective in helping them get to sleep and experience deep sleep.⁶

Sleep problems are often a concern for individuals with ADHD, and L-theanine proved to be a safe and effective therapy to improve sleep quality.

Focus and Attention

L-theanine has the power to both calm you down in the evenings and provide a boost in the morning. You know those days; lack of quality sleep the night before leaves you dull, each excruciating minute stretched out between sips of coffee. All that coffee can have a negative build-up, leading to a jittery, on edge feeling while desperately trying not to fidget during your conference room presentation.

The same amino acid that ushers you into dreamland can also deliver an attentive state of mind. Multiple human studies show that consuming L-theanine can increase focus, reaction times, and visual processing while reducing mental fatigue.⁷^,⁸ Essentially, subjects in these human studies performed attention tasks better after taking L-theanine. Their overall mental performance improved.

Even when the mind is in a relaxed state and creating those alpha waves, it’s focused. Consider meditation: its goal is mindfulness, focusing on an inner calm. Meditating is a form of dialed-in concentration that also happens to be calming.

Memory

Maybe you’re a master of mornings but you can’t remember the names of many of your closest coworkers. Enter L-theanine, which can assist with memory.⁹

To be clear: drinking a single cup of green tea will not suddenly remind you of where you left your keys. However, consuming L-theanine over time could help protect the neurons in your brain from injury or cognitive impairment and contribute to the development of the hippocampus. That’s the part of your brain responsible for storing memories⁹ not the future academic grounds of the large semi-aquatic African mammal.

Start young, and you could even stand a better chance against the oxidative damage and memory impairment of Alzheimer’s.¹ Oh, and remember how we talked about L-theanine reducing cortisol levels? Cortisol can negatively impact memory retrieval.¹¹ Reduce cortisol levels, and you may be able to retrieve those memories a little more easily.

We’ve touched upon what L-theanine can do for the brain, but let’s not forget about its benefits for the body. L-theanine couldn’t let your brain have all the fun. So freshen up your tea, and let’s talk about what your new amino acid can do for your body.

Immune System

Unfortunately, L-theanine is not the cure for the common cold. It has however been linked to increased protection against the flu and a boost in immune function when combined with another amino acid, L-cystine.¹² This combination improves the production of Immunoglobin G (IgG), an antibody with a vendetta against infection, and glutathione (GSH), an antioxidant.¹²

Antioxidants are valuable because they help our bodies remove free radicals. Free radicals are these unpaired, unstable, thieving little molecules that steal electrons from our lipid cell membranes (also called lipid peroxidation). The theft causes tissue and muscle damage and contributes to some of the big name diseases out there: diabetes, heart disease, and cancer. L-theanine has demonstrated powerful antioxidative properties.^13,14,15

Cardiovascular System

Because antioxidants help us remove the free radicals that lead to cardiovascular problems like heart disease, L-theanine can do some pretty amazing things for heart health.

Leaves from both green and black tea have been shown to improve cardiovascular health all on their own.^16,17 L-theanine sweetens the deal through its ability to mitigate blood pressure increases when the user undergoes acute stress. Translation? Less strain on the heart.¹⁸

Supplementing with L-theanine

Not a fan of green tea or black tea? Healthy adults can safely and easily supplement L-theanine at a dosage of 100-200 mg per day, a staggering five to ten times higher concentration than what you’ll find in a cup of green tea.¹ So even if you’re already pounding cup after cup of the umami taste bomb, you may not be enjoying all of its benefits…or at least not as efficiently. Consider supplementing with L-theanine to warm up for your day or to cool down at the end of it.

L-theanine hasn’t been linked to any adverse side effects or symptoms in the neuropharmacology sphere. Keep in mind though, that it should not be mixed with medications for high blood pressure because L-theanine reduces blood pressure. As with all new supplements and medications, consult with your healthcare provider before taking it.

Last Drops

Whether you’re a coffee connoisseur or a tenacious tea drinker, your mind and body will enjoy the benefits of adding L-theanine to the mix. To recap, those are: