L-theanine Benefits for Brain Health

Nov 19, 2021 2:30:00 PM

Written By:
Dr. Ian Bier


People have been drinking tea for thousands of years, but only recently has science discovered the cognitive advantages of daily teatime.

Tea contains a compound called L-theanine that has the potential to support brain health and help manage stress. Occasional anxiousness can negatively impact brain function and cause difficulty with thinking, concentration, and memory.*

In addition, as people age, it is common to experience changes in memory and focus. If you are one of the many people who struggle with anxiousness, brain fog, or memory issues, you may benefit from L-theanine.*

What is L-theanine?

L-theanine is an amino acid naturally found in tea leaves, including green, black, and oolong varieties. It is believed to be a source of umami, the fifth taste, which is a deep, savory flavor. While tea is the most common source of L-theanine, some mushrooms also contain this amino acid.

Related content: Promoting Calm: How to support the increase of gaba

L-theanine is structurally similar to glutamate and GABA, two neurotransmitters vital to brain function. When ingested, L-theanine quickly crosses the blood-brain barrier and is able to positively influence brain activity.*

How Does L-theanine Work?

L-theanine carries out three primary actions in the brain:

Increases levels of calming brain chemicals*

L-theanine plays a role in the production and release of several neurotransmitters, including GABA, serotonin, and dopamine.1 These calming brain chemicals aid in regulating mood, promoting feelings of relaxation, and improving focus and memory.*Find out how L-theanine impacts brain health in our guide.

Suppresses the release of “excitatory” brain chemicals*

In addition to increasing calming neurotransmitters, L-theanine helps minimize the levels of brain chemicals linked with stress.2 *

By lowering these chemicals, L-theanine may help with the effects of stress on the brain and sharpens focus and attention.*

Stimulates alpha brain waves*

There are five types of brain waves, each indicating a level of brain activity. Alpha waves fall solidly in the middle of the spectrum and indicate a calm and relaxed state.

L-theanine’s ability to enhance alpha waves is linked to a decrease in anxiousness, especially for people who have feelings of worry.3* This suggests those who struggle the most with these concerns may have the most to gain from L-theanine.

L-theanine From Tea

Tea is the most common source of L-theanine. If you are interested in exploring its brain benefits, a soothing tea ritual is a good first step.* The concentration of L-theanine found in tea is lower than most supplements and is generally a safe way to test your response.

Not only does drinking tea provide a helpful dose of L-theanine, the ritual of enjoying a cup of tea can establish a calming daily routine that prepares you for relaxation and focus.* Cultivating a regular habit of drinking tea will give you the most benefit, as your brain will develop a soothing association between the ritual and the dose of L-theanine your brain receives.

When you drink tea, L-theanine is absorbed slowly in the digestive tract, allowing for a gradual supply of the amino acid to the brain. This may be ideal if you are seeking to soothe a baseline level of anxiousness that remains present in the background.

Different types of tea contain varying amounts of L-theanine, and the preparation method and processing of the tea leaves can influence L-theanine concentrations. Green tea, for example, contains the highest levels of L-theanine, followed by oolong tea, white tea, and then black tea. Additionally, it is believed that steeping finely ground tea in warm water for at least 30 minutes will extract the most L-theanine.

Though green and black teas also contain caffeine, the calming characteristics of L-theanine create a balancing effect instead of the caffeine jitters sometimes associated with coffee.

L-theanine From Supplements

If you are considering supplementing with L-theanine, it’s best to talk with your doctor to determine if it is right for you. The dose and delivery method can vary depending on the specific effect you hope to achieve. A healthcare practitioner can provide a personalized plan that will best meet your needs.

A liquid form of L-theanine may be recommended as a method to help combat stressful situations. For example, if you need to give a big presentation or plan to fly, you might use liquid L-theanine as a fast-acting calming agent.

To address baseline anxiousness, a tablet that absorbs slowly may be a better choice. There are also powdered forms of L-theanine that you can dissolve in a beverage and sip throughout the day to provide a steady dose.

Benefits of L-theanine

Improved sleep

The calming effect of L-theanine on the brain has the potential to improve your sleep.* When you feel less anxious and more relaxed, it may be easier to fall asleep at night and get the rest you need.

A recent study found that four weeks of taking 200mg of L-theanine resulted in falling asleep faster, fewer sleep disturbances, and less need for sleep aids.4*

Interestingly, another study looked at the impact of an L-theanine supplement on sleep patterns in boys with attention challenges. Findings showed those who took a daily 400mg dose slept better and had better quality sleep.5* This suggests a unique role for L-theanine in calming active minds and promoting the relaxation necessary for sleep.*


Reduced feelings of anxiousness

Mental health issues are endemic in our culture, with one in five adults experiencing anxiousness.

L-theanine is considered to be an anxiolytic, or a substance that may help with anxiousness.* What makes L-theanine unique is that, unlike some other anxiolytics, it is not a sedative. It provides a calming effect without causing sleepiness.* The result is a state of calm alertness that allows you to be peaceful and productive.*

In addition, L-theanine has positive effects on other mental and physical symptoms of stress.* One study demonstrated a normalized physiological reaction in subjects given L-theanine under stressful conditions.6* L-theanine may also help manage heart rate variability.*

Enhanced attention, focus, memory, and learning

When stressed, the body responds by releasing hormones such as cortisol and corticosterone. Exposure to these hormones can interfere with normal brain activity like focus and memory.

The ability of L-theanine to balance stress hormones gives it the potential to enhance cognitive function.* The results of one study—which examined four weeks of 200mg of daily L-theanine—demonstrated improvements in executive functioning skills such as working memory, attention, and focus.*

L-theanine also seems to have a greater attention-boosting effect when taken by people predisposed to high feelings of anxiousness.* This suggests that those with occasional exposure to stress hormones could especially benefit from L-theanine’s brain benefits.*

The combination of L-theanine and caffeine together, as found naturally in many teas, shows additional promise at boosting alertness and increasing the ability to switch effectively between tasks.7*

Final thoughts

If you think L-theanine might be right for you, talk to your doctor. L-theanine may interact with certain medications, including those for blood pressure, so always speak to your physician before supplementing. 

Children or women who are pregnant should also consult with their doctor before taking L-theanine. 

This incredible amino acid has the potential to boost brain health and cognitive function.* And because it is available in tea, drinking a few cups a day is an easy way to soothe the body and mind and help you focus, decrease stress, and get a good night’s sleep.*


L-theanine and Brain Health

[1] Nathan PJ, Lu K, Gray M, Oliver C. The neuropharmacology of L-theanine(N-ethyl-L-glutamine): a possible neuroprotective and cognitive enhancing agent. J Herb Pharmacother. 2006;6(2):21-30. PMID: 17182482.

[2] de Mejia EG, Ramirez-Mares MV, Puangpraphant S. Bioactive components of tea: cancer, inflammation and behavior. Brain Behav Immun. 2009 Aug;23(6):721-31. doi: 10.1016/j.bbi.2009.02.013.

[3] Akiko Higashiyama, Hla Hla Htay, Makoto Ozeki, Lekh R. Juneja, Mahendra P. Kapoor,
Effects of l-theanine on attention and reaction time response. Journal of Functional Foods. 2011;3(3):171-178. ISSN 1756-4646.

[4] Hidese S, Ogawa S, Ota M, et al. Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial. Nutrients. 2019;11(10):2362. Published 2019 Oct 3. doi:10.3390/nu11102362

[5] Lyon MR, Kapoor MP, Juneja LR. The effects of L-theanine (Suntheanine®) on objective sleep quality in boys...: a randomized, double-blind, placebo-controlled clinical trial. Altern Med Rev. 2011;16(4):348-354.

[6] Kimura K, Ozeki M, Juneja LR, Ohira H. L-Theanine reduces psychological and physiological stress responses. Biol Psychol. 2007;74(1):39-45. doi:10.1016/j.biopsycho.2006.06.006

[7] Camfield DA, Stough C, Farrimond J, Scholey AB. Acute effects of tea constituents L-theanine, caffeine, and epigallocatechin gallate on cognitive function and mood: a systematic review and meta-analysis. Nutr Rev. 2014;72(8):507-522. doi:10.1111/nure.12120

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.