L-Theanine Benefits, Dosage for Anxiety, Sleep Support & Food Sources

What is L-theanine, and what is it used for? L-theanine (also called theanine or sometimes r-glutamylethylamide) is an amino acid that impacts nerve impulses in the brain and the release of neurotransmitters, including GABA.

It is known as natural anxiolytic because it can have a calming, sedative effect on the body and mind without making you feel drowsy, which is why it’s often used to help reduce anxiety, hyperactivity and sleep-related problems.

Most people don’t acquire a lot of theanine from their diets since it’s not available in many commonly eaten foods. It’s a unique amino acid because it’s not used to form proteins, unlike many other amino acids (such as l-carnitine, leucine, lysine, methionine or tryptophan), and is not used to make enzymes.

The greatest sources of L-theanine in our diets are green, black and white teas, but because most people don’t drink very large quantities of tea on a daily basis, L-theanine supplements can be beneficial.

As we’ll cover more below, drinking tea and taking L-theanine supplements can help reduce the effects of stress, protect the brain, support the cardiovascular system and much more.

What is L-theanine?

L-theanine is a calming amino acid found mostly in green tea, black tea, white tea and matcha. The best-known L-theanine benefits include promoting relaxation without drowsiness, helping the body respond to stress, supporting sleep quality, improving attention when paired with caffeine and helping maintain healthy blood pressure during stressful situations.

A common L-theanine dose for anxiety or stress support is 100 to 200 milligrams per serving, often taken once or twice daily, although clinical studies have used a range of about 50 to 450 milligrams per day depending on the outcome being studied.

L-theanine is considered a nondietary, nonessential amino acid because even though it has certain benefits, we don’t require it from our diets.

What does L-theanine do for you? It is used to help prevent and treat conditions including:

• Anxiety, depression and other mood-related disorders
• Insomnia and trouble sleeping
• Cognitive loss, dementia and Alzheimer’s disease
• Stroke
• High blood pressure and other cardiovascular problems
• Post-traumatic stress disorder (PTSD)
• Schizophrenia
• Poor attention span
• Substance dependence
• It may help improve the effects of drugs used to treat cancer drugs

L-theanine and the amino acid glutamine are structurally similar but have different effects and benefits. Both can be supportive of overall mental health and energy levels, but theanine is more capable of acting as a natural stress reliever.

Glutamine is one of 20 naturally occurring amino acids in dietary protein and the most abundant amino acid in the bloodstream, making up 30 percent to 35 percent of the amino acid nitrogen in your blood.

Glutamine is needed to produce the neurotransmitter called glutamate. It is considered an excitatory neurotransmitter, but L-theanine binds to the same receptors in the brain as glutamate and therefore has opposite, inhibitory effects.

Is L-theanine the same as caffeine? No, the two are different, although they are both found in beverages, including green tea.

Because L-theanine tends to promote relaxation, while caffeine promotes alertness, the two have opposite but complementary effects. However, studies suggest that both L-theanine and caffeine can have beneficial effects on cognition and mood when used appropriately.

L-theanine was first identified in tea leaves by Japanese scientists in 1949. One of the reasons that scientists first started studying theanine was because it was believed to be a source of umami, which basically means a savory, brothy taste that is only found in certain foods, like meat, fish, mushrooms and some vegetables.

Researchers believe that umami flavor may actually affect the brain in a way that helps decrease the risk for obesity, stimulate the metabolism, alter taste perception of bitter foods, boost satiety and fullness, and hold off hunger and cravings between meals.

In Ayurvedic medicine, the best source of theanine, green tea, is considered valuable for its high antioxidant content, but the caffeine in green tea is not recommended for every body type. Because green tea contains low amounts of caffeine, it’s considered a better choice than coffee and other stimulants, especially for Vata and Pita types who may already deal with restlessness and anxiety.

Another reason that green tea is considered a healing beverage in Ayurveda is because it can help balance out the effects of stimulants and stress. This is beneficial for achieving doshic balance, especially when green tea is consumed with herbs and spices.

Because each type has unique properties, many tea varieties are included in the Ayurvedic diet, such as:

• Jasmine green tea, which can also have sedating effects on the nervous system.
• Moroccan mint green tea, which can help to soothe digestive issues and nausea.
• Bancha tea, an expensive tea that’s a good source of catechins.
• Ginger green tea, which supports the immune system and digestive system.
• Cinnamon green tea, which fights inflammation.
• Genmaicha tea, which is warming and energizing.
• Matcha tea, which contains concentrated levels of L-thianine.

Green tea has been consumed in China and other parts of Asia for thousands of years. According to Traditional Chinese Medicine (TCM), tea is the most beneficial of all herbs and has numerous benefits, including improving alertness, supporting immunity, balancing body fluid production, quenching thirst, clearing heat and phlegm, and promoting healthy digestion and urination.

In TCM, the amount of green tea that’s recommended depends on the condition being treated. An average of three cups of green tea (approximately 750 milliliters) per day is commonly recommended, but upwards of 10 cups (2,500 milliliters) may be beneficial for certain health conditions.

While green tea is most valuable in TCM, many other types of teas are also encouraged, including white, black and oolong teas.

Benefits

What are the benefits of L-theanine? Below are some ways it can benefit your sleep, mental health, cognition and more.

L-theanine benefits at a glance

The main L-theanine benefits are tied to its ability to support a calm-but-alert mental state. Unlike many sleep aids or anti-anxiety compounds, theanine is often described as relaxing without being strongly sedating.

L-theanine is not a replacement for medical treatment for anxiety, insomnia, depression, ADHD or high blood pressure, but it may be a helpful supplement for otherwise healthy adults who want support for stress, relaxation, focus or sleep quality.

A systematic review published in Nutritional Neuroscience found 13 eligible trials and reported that 200 to 450 milligrams per day appears safe and effective for supporting healthy sleep in adults, while a 2021 randomized, triple-blind, crossover study used 200 milligrams and found increased alpha brain-wave activity and lower salivary cortisol after an acute stress challenge.

1. May help with anxiety, stress and relaxation

One of the most well-researched L-theanine benefits is its ability to promote relaxation and fight stress. It is said to be “a relaxing agent without causing sedation,” meaning it can help improve your ability to deal with stress without making you feel lethargic or tired.

This is the reason many people search for L-theanine for anxiety: It appears to support relaxation without the heavy sedative effect associated with some sleep aids or anti-anxiety medications.

If you suffer from nervousness, anxiety, depression or other stress-related issues, you can likely benefit from L-theanine’s relaxing effects, although it likely won’t have a strong enough effect to reduce severe anxiety.

In one study, L-theanine was shown to reduce scores on a tension-anxiety test compared to placebo. Both L-theanine and caffeine’s effects on mental task performance and physiological activities were investigated.

Participants were placed under conditions of physical or psychological stress, examining the effects of L-theanine. Results after the mental tasks showed that L-theanine significantly inhibited the blood-pressure increase associated with stress, while caffeine tended to have a similar but smaller inhibition of blood pressure.

Theanine may also increase alpha brain waves, which are associated with a state of “wakeful relaxation,” selective attention mechanisms, arousal and mental alertness.

One study tested the effects of L-theanine on brain waves 45, 60, 75, 90 and 105 minutes after ingestion of 50 milligrams of L-theanine. The results showed that there was a greater increase in alpha activity across time in the L-theanine condition relative to placebo.

According to the authors of the study, “These data indicate that L-theanine, at realistic dietary levels, has a significant effect on the general state of mental alertness or arousal. Furthermore, alpha activity is known to play an important role in critical aspects of attention, and further research is therefore focussed on understanding the effect of L-theanine on attentional processes.”

2. May help improve sleep and fight insomnia

Why is L-theanine good for sleep? It helps reduce stress and anxiety, which can keep you up at night if you’re constantly worrying, tossing and turning.

The effects that theanine has on sleep are mild, so it won’t work for every person to improve sleep quality. While it can have positive effects on sleep quality, it probably won’t be enough to help someone with moderate or severe insomnia to get a good night’s sleep.

Certain studies have found that L-theanine can help improve sleep quality in people with conditions that cause hyperactivity, including ADHD.

Another positive attribute of L-theanine when it comes to sleep is that it can counter the effects of stimulants. This means that if you drink lots of coffee or use other stimulants for medical reasons, L-theanine’s calming effects may help reduce wakefulness, jitters, etc.

A newer systematic review of L-theanine and sleep found that trials using L-theanine reported benefits for sleep latency, sleep maintenance, sleep efficiency, sleep satisfaction and feeling refreshed after waking. The review identified 13 eligible trials and noted that 200 to 450 milligrams per day appears to be a safe and potentially effective range for supporting healthy sleep in adults.

Some people choose to take L-theanine and melatonin together to help with sleep. A common dosage is around three milligrams of melatonin before bed taken with 100 to 200 milligrams of L-theanine.

The two can act together to reduce stress and help with sleep quality, although L-theanine taken in high doses (above 600 milligrams) may have opposite effects … and so may melatonin.

3. May help improve attention

Some people choose to use L-theanine and caffeine together in order to improve alertness, cognition and attention. The two have a “synergistic” relationship and can lead to improved focus without feeling overly “wired” or jittery.

For this purpose, consuming about 200 milligrams each of L-theanine and caffeine tends to lead to the best results.

4. Can help protect memory and cognition

In one double-blind, placebo-controlled study, patients with mild cognitive impairment were given 360 milligrams of green tea extract along with 60 milligrams of theanine (a combination called LGNC-07) three times daily for 16 weeks. Researchers found that LGNC-07 helped improve recognition skills without having any negative effects on verbal and visuospatial memory.

According to the study’s researchers, “Brain theta waves, an indicator of cognitive alertness, were increased significantly in the temporal, frontal, parietal, and occipital areas after three hours in the eye-open and reading states. Therefore, this study suggests that LGNC-07 has potential as an intervention for cognitive improvement.”

One way in which L-theanine may help protect the brain is by preventing excessive glutamate stimulation of brain cells (excitotoxicity), which some believe is linked to neurodegenerative disorders, stroke and schizophrenia. By blocking some of glutamate’s effects, L-theanine may be able to offer neuroprotection for the aging brain.

5. May help support cardiovascular health

Green tea is the top source of L-theanine, and many studies have found evidence that green tea can help reduce inflammation and support heart health. Some experts believe that green tea is protective of cardiovascular health mostly because it provides theanine, rather than due to other active compounds like green tea catechins or theaflavins.

Theanine may help to prevent blood pressure spikes in response to stressful events and help regulate nitric oxide. Nitric oxide is a molecule that our bodies produce to help cells communicate, regulate blood pressure by dilating arteries, reduce inflammation, support the immune system, improve sleep quality and more.

The endothelium layer of our arteries produce nitric oxide, which helps relax narrowed blood vessels and increases oxygen and blood flow. Adequate production of nitric oxide can help protect against artery-blocking clots or obstructions, heart attacks, stroke, and other cardiovascular problems.

Further research has found that L-theanine may help support cardiovascular health by moderating the body’s blood pressure response to stress. In a randomized, placebo-controlled, crossover trial involving healthy adults, researchers observed that participants who consumed L-theanine experienced smaller increases in blood pressure during psychological stress tasks compared with placebo.

The authors concluded that L-theanine may help reduce stress-related cardiovascular strain, suggesting a potential role in supporting healthy blood pressure regulation and overall cardiovascular function.

6. Helps boost immune health

Research suggests that L-theanine may help support healthy immune function. Clinical studies have found that L-theanine, often combined with the amino acid cystine, may help reduce immune suppression associated with intense physical stress, support natural killer (NK) cell activity and enhance the body’s defense against common respiratory infections.

Some studies have also shown that L-theanine may help support the immune response to influenza vaccination in certain populations. Researchers believe these effects may be related to L-theanine’s ability to influence immune-cell signaling, glutathione production and inflammatory pathways.

7. May aid in cancer prevention and treatment

Preliminary research suggests that L-theanine may possess anti-cancer properties and could help support conventional cancer therapies. Laboratory and animal studies have found that L-theanine may help inhibit cancer cell growth, promote apoptosis (programmed cell death) and reduce tumor cell migration.

Additional research suggests it may enhance the effectiveness of certain chemotherapy drugs by helping increase drug accumulation within tumor cells while potentially reducing some treatment-related side effects.

For instance, theanine has shown potential to help with lung cancer, leukemia, melanoma and other types of cancer.

However, more high-quality human studies are needed before L-theanine can be recommended as a cancer treatment.

L-theanine vs. GABA

• L-theanine can help stimulate production of the inhibitory, relaxing neurotransmitter called GABA (gamma-aminobutyric acid).
• GABA, like serotonin and dopamine, is known as a neurotransmitter. It helps regulate emotions, moods, concentration, motivation and alertness. GABA can also affect sleep, appetite and sex drive.
• GABA is known to have calming, anti-anxiety effects, making it beneficial for lifting your mood and preventing nervousness or hyperactivity. By increasing GABA, this is one way that L-theanine has calming effects. By elevating GABA, L-theanine may help reduce symptoms of depression, such as fatigue, changes in appetite, insomnia and lack of motivation.
• Some anti-anxiety medications work by mimicking the effects of GABA, but these are commonly associated with drowsiness. What makes L-theanine so attractive as a calming agent is that it doesn’t impair motor skills or make you feel tired. In fact, it can increase alertness and promote relaxation at the same time.
• Injections of theanine have been found to increase cerebral concentrations of GABA most, sometimes by up to 20 percent when given in high doses. Taking moderate doses of theanine is likely to have a mild effect on GABA levels, although it can be enough to cause a noticeable difference in your mood.

Risks and side effects

Is L-theanine safe? Research suggests that it is safest when used in the short term, for about several weeks to four months.

It is typically taken by mouth one time per day for about three to 16 weeks. It’s not clear if it is always safe or effective if taken for longer periods.

How much L-theanine is safe to take? Most people can safely take up to 200 milligrams daily (usually split into two to three doses), although higher doses around 400 milligrams have also been used safely.

L-theanine can interact with certain medications, including those taken to control high blood pressure (called antihypertensive drugs) and stimulants. Theanine can decrease blood pressure, so don’t supplement with it before speaking with your doctor if you already take medications that lower your blood pressure.

Examples of medications that lower blood pressure include captopril (Capoten), enalapril (Vasotec), losartan (Cozaar), valsartan (Diovan) and diltiazem (Cardizem).

Theanine will also interfere with the effects of stimulants (including both foods/drinks and medications), since it can slow down activity of the nervous system. If you take any stimulant drug, including diethylpropion (Tenuate), epinephrine, phentermine (Ionamin) or pseudoephedrine (Sudafed), then don’t take L-theanine without consulting with your doctor.

Although this may be a good thing, L-theanine can also decrease the stimulating effects of caffeine and certain herbs, including coffee, tea, green tea extract, guarana, yerba mate, cola and other caffeinated sodas, and energy drinks.

Because there hasn’t been much research done focusing on safety of L-theanine supplementation during pregnancy, it’s best for pregnant women to avoid taking L-theanine (although drinking one to two cups of green tea during pregnancy is considered safe for most women).

Dosage and supplements

Because L-theanine is almost exclusively found in tea leaves, it can be hard to get enough from foods and drinks alone to notice its positive effects. This is why people turn L-theanine in supplement form.

Theanine supplements generally come in the form of L-theanine, which is the bioavailable supplement form of the amino acid theanine. Suntheanine is a theanine supplement made with a patented fermentation process.

While manufacturers of suntheanine may claim that it’s more potent, there doesn’t seem to be much difference between the quality of L-theanine and suntheanine when it comes to efficacy and tolerance.

L-theanine dose for anxiety

A common L-theanine dose for anxiety or everyday stress support is 100 to 200 milligrams per serving. Some people take it once daily, while others split it into two servings (for example, one in the morning and one later in the day).

For more noticeable anxiety or stress support, studies and clinical discussions often use about 200 to 400 milligrams per day. It is best to start with the lowest effective dose, especially if you are sensitive to supplements, caffeine, blood pressure changes or calming compounds.

For occasional stress, L-theanine is often taken 30 to 60 minutes before a stressful event. For sleep support, it is commonly taken 30 to 60 minutes before bed.

Where to find and how to use L-theanine:

Theanine supplements come in different forms, including capsules, pills and tablets.

To ensure you’re buying a quality product, always check the ingredients in the supplement formula. Purchase a supplement that is pure theanine/L-theanine and does not have fillers or other chemicals.

Keep in mind that some energizing theanine formulas may include caffeine, which would not be beneficial to reducing anxiety or helping with sleep.

• L-theanine is typically taken in dosage of 100 to 200 milligrams per day. It can be taken along with caffeine but doesn’t need to be.
• The calming effects of L-theanine usually kick in within about 30 to 60 minutes after taking it.
• To help treat insomnia, ADHD and hyperactivity, doses of 200 milligrams taken twice daily are usually most effective.
• Higher doses of L-theanine, around 400 milligrams, may be used to help manage symptoms of schizophrenia or severe anxiety disorders. This dose may be used for up to eight weeks.
• For help with reducing anxiety, a combination of L-theanine (400 mg per day) and the hormone pregnenolone (50 mg per day) is sometimes used.

Can you take L-theanine on an empty stomach? Yes, L-theanine can be taken either with meals or on an empty stomach.

If you haven’t recently eaten when taking L-theanine, you may feel the effects a bit more quickly and intensely (similar to drinking caffeine with a meal versus on its own/on an empty stomach). If you’re using L-theanine to help you sleep, try taking it about 30 to 60 minutes before bed.

Foods

Is L-theanine natural? Yes, it’s found in certain foods and beverages, including green tea (made from the leaves of the camellia sinensis plant).

Along with caffeine and catechins, L-theanine is one of the main active ingredients found in green tea. It’s believed that theanine actually gives green tea its slight umami flavor and helps counteract the bitter taste of green and black tea, along with other bitter-tasting foods, like cocoa.

How much L-theanine is in green tea? It comprises up to 50 percent of the total amino acids in tea.

About 0.9 percent to 3.1 percent of the dry weight of green tea leaves is theanine. This equates to about 25 to 60 milligrams of theanine per 200 milliliters of tea, or about 6.7 ounces. This amount of tea is typically made from about 2.5 grams of dried tea leaves.

Theanine content in green tea varies depending on the specific type of tea. Teas made from younger plants have higher theanine content than teas made from older plants. Theanine content is also reduced from fermentation (part of the process used to make tea leaves), but it becomes more concentrated when leaves are dried.

What other foods have L-theanine in them? L-theanine can also be found in leaves used to produce black and white teas, although most research has focused on theanine from green tea.

Other plants that provide L-theanine include:

• C. japonica and C. sasanqua. These are small shrubs that produce pink and red flowers. They are sometimes used to make tea, although not as commonly as camellia sinensis.
• The mushroom species called Xerocomus badius. Also called bay bolete, this is a brown, edible, pored mushroom found in Europe and North America.

Frequently asked questions

What is L-theanine?

L-theanine is a non-protein amino acid found mainly in tea leaves, including green tea, black tea, white tea and matcha. It is also available as a dietary supplement and is commonly used for relaxation, stress support, sleep quality and focus.

What are the main L-theanine benefits?

The main L-theanine benefits include supporting relaxation, reducing the effects of stress, promoting sleep quality, improving attention when combined with caffeine, supporting cognitive function and helping maintain healthy blood pressure during stressful situations.

What is the best L-theanine dose for anxiety?

A common L-theanine dose for anxiety or stress support is 100 to 200 milligrams per serving. Some studies and clinical uses involve 200 to 400 milligrams per day. People who are new to L-theanine should generally start with a lower dose and speak with a healthcare professional if they take medication or have a medical condition.

Does L-theanine make you sleepy?

L-theanine can promote relaxation, but it does not usually act like a strong sedative. Many people use it during the day because it may encourage a calm, focused state without causing drowsiness.

Can you take L-theanine every day?

Many studies have used L-theanine daily for several weeks, and it is generally well tolerated in healthy adults. However, long-term daily use should be discussed with a healthcare professional, especially for people who are pregnant, breastfeeding, taking blood pressure medication or using stimulant medications.

Is theanine the same as L-theanine?

Theanine is the general name, while L-theanine refers to the naturally occurring form most commonly found in tea and used in supplements.

Final thoughts

• L-theanine (or simply theanine) is a nondietary amino acid that is found in green, black and white teas, plus can be taken in supplement form.
• L-theanine has relaxing properties without making you feel drowsy. It can be used to make you feel calmer, improve attention span and focus, and support restful sleep.
• Not only is L-theanine calming and centering, but it can also help protect the heart and brain, plus help regulate blood pressure and reduce symptoms of schizophrenia.
• The best natural way to obtain L-theanine is to drink several cups of quality green tea and other teas every day.
• L-theanine is safe when taken in supplement form but will reduce effects of blood pressure medications and stimulants. The typical dosage is between 100 to 400 milligrams per day. Some people use low doses of L-theanine and caffeine together to improve focus without feeling jittery.