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Natural Support for Mood, Sleep and Mental Focus: L-Theanine

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Feeling stressed? Anxious? Irritable?

L-theanine may be just what you’re looking for.

Studies have shown that this powerful little amino acid promotes relaxation, which can help reduce feelings of stress, anxiety and irritability – all without making you drowsy.

Other research-backed potential benefits of L-theanine include:

• Improved sleep quality.
• Increased mental focus and concentration.
• Immune system support.
• Reduction of PMS symptoms.

The L-Theanine – Green Tea Connection

We’ve all heard about the numerous health benefits of green tea. What you may not know, though, is that one of the main components of green tea is the amino acid L-theanine.  (Actually, black and oolong teas also contain L-theanine, but most of the research thus far has focused on green tea.) The only other natural food known to contain L-theanine is the Bay Bolete (Boletus badius) mushroom.

How L-Theanine Works

L-theanine is one of the few supplements that readily crosses the blood-brain barrier. In doing so, it exerts subtle changes in the brain’s biochemistry. One of the changes researchers discovered is that L-theanine significantly increased dopamine concentrations in the brain.(1) Dopamine is a neurotransmitter said to affect human emotions.

Another way in which L-theanine works is by increasing alpha waves on the surface of the brain. Alpha wave generation in the brain is considered to be an index of relaxation.

In a 1998 study, 50 females between 18 and 22 years old were divided into high and low general anxiety groups. Each group was given water, 50 mg L-theanine solution, or 200 mg L-theanine solution once a week for two months.  Brain waves were measured for 60 minutes after each administration. Within 40 minutes, alpha wave generation was significantly increased on the brain surface of the L-theanine groups, signifying relaxation without drowsiness.(2)

The Relaxation Effect

The relaxation effect experienced when alpha waves are increased has been compared to getting a massage, taking a hot bath or meditating. This effect on the brain can actually be seen on an EEG.  Following the administration of L-theanine, brain waves are smoothed out, but not flattened.(3) The result is a relaxed body and a calm, but alert mind.

Research with human volunteers has demonstrated that L-theanine creates its relaxing effect approximately 30 to 40 minutes after ingestion.(4)

How L-Theanine Differs From Other Anti-Stress & Anti-Anxiety Herbs

The main difference between L-theanine and other anti-stress/anti-anxiety herbs – like valerian root, kava kava, skullcap, and passion flower to name a few – is that it does not cause drowsiness. You get all the benefits of relaxation without the accompanying sedation.

Balancing Your Wake/Sleep Cycle

L-theanine has been shown to improve sleep quality. You may be wondering how that is possible since it does not cause drowsiness but rather promotes mental alertness. The key is relaxation. Sleep therapists recommend doing something that relaxes you, like listening to music, before bedtime. If your body is relaxed and your mind is calm before you go to bed, you are more likely to fall asleep faster and get a better quality of sleep.

In 2004, Japanese researchers gave 32 men either 200 mg of L-theanine or a placebo one hour before bedtime for six days.  Participants were then crossed over to the other treatment group for another six days. Their sleep patterns were recorded on a wrist device.  Although the L-theanine didn’t cause the men to sleep longer, it did help them to sleep better.

Sleep quality, recovery from exhaustion, and refreshed feelings all improved when they were taking the L-theanine. Interestingly, when they were taking the L-theanine, subjects felt like they slept longer than they actually did.(5)

Additional L-Theanine Benefits

While L-theanine is best known for its relaxation benefits, research is revealing a number of other important benefits, including:

Increased mental focus and concentration – In a study done in 1999 at the University of Shizuoka in Japan, researchers found that in addition to facilitating relaxation, L-theanine may benefit learning performance, mental clarity, and concentration.(6) The results of a 2011 study demonstrated that highly anxious students who received 200 mg of L-theanine experienced a slowing of their heart rate, improved attention performance and better reaction times than their counterparts who received a placebo.(7)

Immune System Support – In vitro studies, a pilot study and a small clinical trial all suggest that L-theanine supports enhanced gamma-delta T lymphocyte function, which may play a role in the observed decrease in cold and influenza symptoms, as well as in cancer prevention.(8-10)

Reduction of PMS Symptoms – A 2008 study found L-theanine to be effective in helping reduce the symptoms of premenstrual syndrome.  It was most effective in reducing the symptoms of irritability, anger, mood swings and crying.(11)

L-Theanine Calm-Plex – What Makes It Different

L-Theanine Calm-Plex is a special formula developed by ProHealth that effectively combines L-theanine with two additional mood-enhancing ingredients – GABA and 5-HTP. These natural compounds work synergistically to help maintain balanced neurotransmitter levels in the brain. Together they support proper memory and nervous function, while promoting a strong sense of well being and relaxation.

L-theanine:  L-Theanine Calm-Plex contains the Suntheanine® brand of L-theanine – the purest form of L-theanine available. Many products marketed as L-theanine are actually a combination of D-theanine and L-theanine, which is not absorbed or utilized as effectively by the body.

GABA:  GABA primarily functions in the body as a powerful inhibitor of neurotransmitters and to help maintain relaxed levels of neuron activity. Over-stimulated or over-active neurons may lead to feelings of restlessness, irritability, and sleeplessness. GABA inhibits nerve cells from over-firing, to promote feelings of calmness, stability and well-being.

5-HTP:  5-HTP is manufactured in the body from the amino acid L-Tryptophan and is used to produce the neurotransmitter serotonin.  Research has shown that serotonin plays a key role in maintaining mood, cognitive function, and neuron communication.

Need-To-Know Information

Dosage  –  The majority of studies have found 200 mg to be an effective dose for most purposes. Unlike most other amino acids, L-theanine can be taken with or without food and at any time. The effects are usually evident within about 30 minutes and are measurable up to five hours after ingestion.

Contraindications  Consult your physician before taking L-theanine if you are taking prescription medications, particularly if you are taking antidepressants, stimulants or medications to lower blood pressure.  Do not administer L-theanine to infants.

Side Effects –  L-theanine has no currently known side effects. It has been granted GRAS (generally recognized as safe) status by the U.S. Food and Drug Administration (FDA).

In Summary

L-theanine promotes a sense of relaxation, calmness and well-being without making you drowsy. Additional benefits may include improved sleep, increased mental alertness and concentration, immune system support and a reduction in PMS symptoms.

* Supplement research writer Karen Lee Richards is the Lead Expert specializing in Fibromyalgia and ME/CFS, for HealthCentral’s ChronicPainConnection. Karen co-founded the National Fibromyalgia Association (NFA) and was Executive Editor of Fibromyalgia AWARE magazine for four years.


1.  Yokogoshi H, et al. Effect of theanine, r-glutamylethylamide, on brain monoamines and striatal dopamine release in conscious rats. Neurochem Res. 1998 May;23(5):667-73.

2.  Ito K, et al. Effects of L-theanine on the release of alpha brain waves in human volunteers. Nippon Nogeikagaku Kaishi 1998;72:153-7.  No abstract.

3.  Kakuda T, et al. Inhibiting effects of theanine on caffeine stimulation evaluated by EEG in the rat. Biosci Biotechnol Biochem. 2000 Feb;64(2):287-93. Full text can be downloaded:  http://www.jstage.jst.go.jp/article/bbb/64/2/287/_pdf.

4.  Juneja LR, et al. L-theanine a unique amino acid of green tea and its relaxation effect in humans. Trends Food Sci Tech 1999; 10:199-204.

5.  <a target=”_blank” href=”http://www.nutraingredients.com/Research/Green-tea-lulls-brain-into-quality-sleep

“>Green tea lulls brain into quality sleep. NutraIngredients.com. 17 March 2004.

6.  Terashima T. et al. Effect of Suntheanine Intake on Learning Ability. Fourth Shizuoka Forum on Health and Longevity. Nov 18, 1999 p.82-83. No abstract.

7.  Higashiyama A, et al. Effects of L-theanine on attention and reaction time response. Journal of Functional Foods. Volume 3, Issue 3, July 2011, Pages 171-178.

8.  Kamath AB, et al. Antigens in tea-beverage prime human Vgamma 2Vdelta 2 T cells in vitro and in vivo for memory and nonmemory antibacterial cytokine responses. Proc Natl Acad Sci U S A . 2003;100(10):6009-6014.
Full text:  www.ncbi.nlm.nih.gov/pmc/articles/PMC156317

9.  Bukowski JF, Percival SS. L-theanine intervention enhances human gammadeltaT lymphocyte function. Nutr Rev. 2008;66(2):96-102.

10.  Percival SS, et al. Bioactive food components that enhance gammadelta T cell function may play a role in cancer prevention. J Nutr. 2008;138(1):1-4.

11.  Timmcke, J, et al. <a href=”http://www.fasebj.org/cgi/content/meeting_abstract/22/2_MeetingAbstracts/760

” target=”_blank”>Efficacy and short term safety of L-theanine in a randomized, double-blind, parallel-group study in humans. The FASEB Journal. 2008; 22:lb760.

Note: This information has not been reviewed by the FDA. It is general information and is not meant to prevent, diagnose, treat or cure any illness, condition or disease. It is very important that you make no change in your healthcare plan or health support regimen without researching and discussing it in collaboration with your professional healthcare team.

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One thought on “Natural Support for Mood, Sleep and Mental Focus: L-Theanine”

  1. jenunsa says:

    I tried taking this Suntheanine a while back and it did nothing whatsoever for me. No effect at all.
    I tried varrying the dose and still nothing.

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