L-theanine has recently gained popularity as an effective natural compound to promote relaxation and improve focus during times of stress. It is considered to be a nootropic or a compound that helps with mental function.
In this article, we discuss where L-theanine comes from, what benefits it may have for your brain, and the potential drawbacks of using L-theanine.
If you’re a tea drinker, then you probably already have experience with L-theanine.
L-theanine or theanine, scientifically known as N-ethyl-L-glutamine, is an amino acid that naturally occurs in just two species: the Camellia sinensis (tea plant) and Bay Bolete mushrooms (*).
It was first discovered in green tea leaves by Japanese scientists in the 1940s and was later found to occur naturally in all Camellia sinensis teas (white, green, oolong, and black teas) (*).
Scientists have been able to isolate L-theanine from tea and make this amino acid available as a stand-alone supplement.
L-theanine has four main effects on your brain that make it a powerful ally for your mental function and wellness.
L-theanine Increases GABA and Other Neurotransmitters in Your Brain
Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter that is responsible for keeping anxiety in check, decreasing inflammation, and enabling sleep.
L-theanine increases the production of GABA, as well as the neurotransmitters serotonin and dopamine. Together, these neurotransmitters are essential for the regulation of emotions, mood, and sleep (* , *).
Higher levels of these calming brain chemicals allow you to relax, sleep better, and deal with stress more easily.
L-theanine Lowers Excitatory Neurotransmitters
Glutamate, or glutamic acid, is considered the brain’s most important excitatory neurotransmitter. It is increased during stress and anxiety responses, and may even increase symptoms related to psychiatric illnesses (*).
L-theanine has a similar structure to glutamate and can block glutamate from binding to the glutamate receptors that would otherwise trigger stress and anxiety responses.
In addition to this, L-theanine is inhibitory — in other words, L-theanine can provide an opposite, calming effect that relieves anxiety (*).
Studies suggest that L-theanine has the potential to reduce excitatory brain chemicals and even protect brain cells against stress and age-related damage (*).
Increases Alpha Brain Waves
Brain waves are a measure of the electrical activity in your brain, measured in cycles per second or hertz (Hz). They typically range from about 1-100 Hz (*).
Alpha brain waves, between 7-13 Hz, indicate a state of awake relaxation, or “calm focus.” This is the mode in which ideas come readily and creativity skyrockets–think of this state as one similar to a meditative or flow state.
Several clinical trials performed on both high-anxiety and low-anxiety test participants concluded that L-theanine supplementation increased alpha brain waves within 30 minutes of administration, which helped foster a relaxed state in both groups (*).
Researchers also reported the intensity of alpha waves was dose-dependent. In other words, the more L-theanine that was administered, the more relaxed the test subjects began to feel (*).
Tea is already packed with flavonoids and catechin antioxidants like EGCG, but did you know L-theanine also acts as an antioxidant? (*)
Studies find that L-theanine can increase antioxidant activity in the brain and reduce damage caused by inflammatory compounds.
L-Theanine Fights Stress and Anxiety
L-theanine provides stress reduction and anxiety-reducing effects without excess drowsiness and impaired motor function.
Research shows that supplementing with L-theanine can help prevent the sudden rise in blood pressure and heart rate that people typically experience during times of stress (*).
A review of clinical trials found that L-theanine can also be effective in helping reduce stress levels during acutely stressful situations. It is still uncertain if taking L-theanine long-term provides lasting effects. People with high anxiety or a tendency to feel stressed may benefit the most from taking L-theanine (*).
L-Theanine Boosts Cognitive Function and Protects Brain Cells
There is a strong link between stress, anxiety, and cognition. Stress has a particularly negative effect on your ability to make decisions and it can also damage brain cells (*).
Recent studies find that L-theanine can support cognitive function and improve concentration thanks to its stress-relieving and neuroprotective effects (*).
L-theanine may directly improve cognitive performance by increasing measures of attention span and reducing reaction time in people who already experience anxiety (*).
When combined with caffeine, L-theanine can improve attention and alertness while keeping the brain relaxed (*).
One study found that combining 250 mg of L-theanine and 150 mg of caffeine, sped up reaction time, accelerated working memory reaction time, increased accuracy, boosted alertness, and decreased headaches and fatigue (*).
L-theanine even has potential as a therapeutic supplement in neurodegenerative diseases like Parkinson’s disease and Alzheimer’s disease. It protects the brain by acting as an antioxidant, is anti-inflammatory, improves dopamine availability, and decreases toxicity from glutamate (* , *).
L-Theanine May Reduce the Risk of Stroke
L-theanine has properties that may help prevent strokes and lessen the damage caused by strokes when they happen.
A stroke occurs when there is a blockage of blood to the brain, which results in the loss of brain cells. Strokes are either ischemic (due to lack of blood flow) or hemorrhagic (due to bleeding).
L-theanine has the ability to increase nitric oxide production in cells. Nitric oxide is essential for relaxing your arteries so blood can flow freely. It is also important for lowering blood pressure, which reduces the risk of stroke (* , *).
Animal trials have also demonstrated that L-theanine consumption twelve hours after a stroke may protect brain cells and decrease brain damage (*).
L-Theanine May Improve Immune Function
L-theanine may help improve the innate immune response by helping the body respond more quickly to previously encountered pathogens. In other words, if your immune response is faster, your body can be more effective at fighting off illnesses (*).
One cell study found that L-theanine might reduce inflammation and oxidative stress during an asthma response (*).
L-Theanine Increases Sleep Quality
Although L-theanine doesn’t have sedative properties, it can help you sleep better, especially if you have anxiety.
In one study, scientists discovered that people with anxiety got more restful sleep when they took high doses of L-theanine daily (*).
Other experiments show that L-theanine may boost sleep in seniors, young boys with attention deficit hyperactivity disorder (ADHD), and adults with major depressive disorder compared to placebo (* , *, *).
L-theanine is considered to be safe by the FDA with a maximum daily intake of up to 1,200 mg (*).
There are limited reports of side effects from taking L-theanine, but one study showed that L-theanine could increase headaches (*).
If you choose to get your L-theanine from drinking tea, there is the potential for side effects. The commonly reported side effects from drinking tea include GI discomfort, diarrhea, and indigestion (*).
People with low blood pressure may have to take caution with L-theanine given its blood pressure-lowering benefits.
That said, you should always talk to your doctor before starting a new supplement, especially if you’re pregnant, breastfeeding, taking medication, or have been diagnosed with a medical condition.
Though L-theanine is generally safe for use, it can still interact with certain drugs and medications.
The most well-known interaction of L-theanine is the combination of L-theanine with caffeine. It decreases the negative effects of caffeine such as jitters and anxiety from indulging in caffeinated beverages and dietary supplements like coffee, matcha, and guarana (*).
That could explain why some people combine L-theanine with caffeine to stay focused for long stretches of time, especially when working on cognitively demanding tasks (*).
The inhibitory effects of L-theanine may also apply to nicotine. An animal study found that supplementation with L-theanine decreased the “dopamine reward” associated with taking nicotine (*).
Not all of L-theanine’s interactions are inhibitory. L-theanine may increase the activity of chemotherapy medications including doxorubicin (DOX), adriamycin, and idarubicin (*).
People taking supplements or high blood pressure medications may want to take caution with L-theanine due to its lowering effect on blood pressure.
To be safe, check supplements for any possible interactions and speak with your healthcare provider before starting a new supplement.
Currently, there isn’t a set dose of how much L-theanine people should take in order to experience benefits.
As you may recall, tea is one of the only natural sources of L-theanine. High-quality tea has about 1-2% l-theanine by weight, so if you use a 3-gram heaping teaspoon of tea leaves to make a cup of tea, it should have approximately 30-60 milligrams of l-theanine per serving (* , *).
To meet the recommended dosage of L-theanine, you’d have to drink 3-6 cups of tea daily.
It is possible to drink 3-6 cups of tea daily to experience the full range of health benefits from L-theanine, but it may be easier to take it in supplement form.
Because there isn’t a standard dose for L-theanine, you may need to experiment with different dosages to discover what works best for you. Also, consult with a qualified healthcare provider.
The overwhelming amount of research demonstrating L-theanine’s effectiveness for achieving a state of “relaxed focus” has made it one of the most popular nootropics, and it’s certainly among the safest, too.
L-theanine’s ability to boost the neurotransmitter GABA, stimulate alpha brain waves, and lower excitatory brain chemicals makes it a noteworthy alternative to anti-anxiety medication, and it relaxes you without causing drowsiness.
Beyond relaxation and stress reduction, L-theanine can also protect your brain cells, improve your sleep quality, and ensure heart health.
To get the most brain benefits out of this helpful compound, find a high-quality supplement like our Keto Nootropic with MCTs and mix it with your morning coffee for ultimate focus.
Whether you are a biohacker or simply looking for a natural way to relax, L-theanine is certainly worth a try.
What is L-theanine best for?
L-theanine is best for helping you reduce stress and anxiety, improve sleep quality, and protect the brain against inflammation and damage.
Can I take L-theanine daily?
It is safe for most people to take L-theanine daily, as long as a daily amount of 1,200 mg is not exceeded from supplement and tea intake.
Is it safe to take L-theanine with other supplements?
L-theanine can be safe to take with other supplements, but it is important to check the function of these supplements. For example, it may decrease the stimulant activity of caffeine-containing supplements (while enhancing focus), but it increases the activity of supplements for blood pressure.
Lyon M et al. The effects of L-theanine (Suntheanine®) on objective sleep quality in boys with attention deficit hyperactivity disorder (ADHD): a randomized, double-blind, placebo-controlled clinical trial. 2011 December