Theanine sleep supplement, stress, anxiety, and side effects, 100 mg per capsule, dosage and research studies
How well does it work for insomnia relief and treatment? Are there other natural and dietary supplements that are effective for sleep and as a treatment for anxiety?

March 1 2017

L Theanine is one of the major amino acid components in green tea and black tea. It is considered the main substance responsible for the taste of green tea. There’s been little research regarding supplementation in humans, therefore we don’t have a clear idea of benefits or side effects of this supplement, but it appears that it has a role to play in reducing stress and anxiety. l-Theanine blocks the binding of l-glutamic acid to glutamate receptors in the brain. Individuals who take a supplement are noted to have more alpha-brain wave activity in the brain which is sign of enhanced relaxation.
The L theanine content of commercial tea samples varies from 2 to 5 mg per gram of leaf.

How it may work
Orally administered l theanine is absorbed through the intestinal tract and hydrolyzed in the liver to glutamic acid and ethylamine.Ethylamine, a molecule that primes the response of an immune system element called the gamma-delta T cell, which may protect against infection.

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L-Theanine is an amino acid that helps promote a mild, restful, relaxed state with minimal daytime sedation. L-Theanine has much fewer side effects than other commonly used relaxing agents. For better sleep at night, consider Good Night Rx.

Supplement Facts: L Theanine – 200 mg

Exercise and immune function
Cystine and Theanine Supplementation Restores High-Intensity Resistance Exercise-Induced Attenuation of Natural Killer Cell Activity in Well-Trained Men.
J Strength Cond Res. 2010. Laboratory of Tissue Plasticity Science, Department of Life Sciences, The University of Tokyo, Tokyo, Japan; 2Future Institute of Sport Sciences, Waseda University, Saitama Prefecture, Japan, Graduate School of Frontier Sciences, The University of Tokyo, Chiba Prefecture, Japan.
We investigated the effects of supplementation with cystine, a dipeptide of cysteine, and theanine (CT), a precursor of glutamate, on immune variables during high-intensity resistance exercise. Cysteine and glutamate are involved in the formation of glutathione, which modulates the activity of natural killer (NK) cells. In this double-blinded clinical trial, 15 well-trained men were divided into 2 groups: placebo and CT). The placebo group was administered a powder containing cellulose (950 mg) and glutamate (30 mg), whereas the CT group was administered a powder containing cystine (700 mg) and theanine (280 mg), once daily for 2 weeks. The subjects trained according to their normal schedule (3 times per week) in the first week and trained at double the frequency (6 times per week) in the second week. Concentrations of immunoglobulin (Ig)M, interleukin (IL)-6, IL-8, and salivary IgA and the leukocyte count did not change significantly in either group. There was a significant decrease in the NK cell activity (NKCA) in the placebo group after the second week compared with that in the CT group. Phytohemagglutinin-induced lymphocyte blastoid transformation did not change significantly in either group. These results suggest that NKCA is not affected in a normal training schedule with or without CT supplementation. However, high-intensity and high-frequency resistance exercises cause attenuation of NKCA, which CT supplementation appears to restore. Therefore, in practical application, CT supplementation would be useful for athletes to restore the attenuation of NKCA during high-intensity and high-frequency training.

L Theanine and stress
l-Theanine reduces psychological and physiological stress responses.
Biol Psychol. 2006.
Because its characteristics suggest that it may influence psychological and physiological states under stress, the present study examined these possible effects in a laboratory setting using a mental arithmetic task as an acute stressor. Twelve participants underwent four separate trials: one in which they took l-Theanine at the start of an experimental procedure, one in which they took it midway, and two control trials in which they either took a placebo or nothing. The experimental sessions were performed by double-blind, and the order of them was counterbalanced. The results showed that l-Theanine intake resulted in a reduction in the heart rate (HR) and salivary immunoglobulin A (s-IgA) responses to an acute stress task relative to the placebo control condition. Moreover, analyses of heart rate variability indicated that the reductions in HR and s-IgA were likely attributable to an attenuation of sympathetic nervous activation. Thus, it was suggested that the oral intake of l-Theanine could cause anti-stress effects via the inhibition of cortical neuron excitation.

Research shows
L-Theanine is one of the predominant amino acids ordinarily found in green tea, and historically has been used as a relaxing agent.

May be useful for preventing ischemic neuronal damage.
Increases the idarubicin-induced antitumor activity and ameliorates its toxicities.

I was looking up some information about L-theanine dosage. Is it bad to take more then 300 mg?
Theanine supplements are generally safe, but we don’t have enough studies to know their long term benefits and risks. For occasional use we have not found 300 mg to cause any bad side effects but it is not possible to predict the response in any one individual.

L-Theanine summary and review
Human research with theanine is limited, and hence its clinical usefulness is not clear to me at this time. However, some users report that l-theanine helps them relax and helps with sleep.

L Theanine side effects, safety, danger
Not much research regarding the side effect profile of l theanine has been published. Dosages greater than 300 mg of l-theanine cause a side effect of transient lightheadedness. It is possible that adverse reactions regarding drowsiness could be elicited when combined with kava, 5-HTP, passion flower, valerian, or other herbs and nutrients that have a sedative effect. Rat studies have not found any l-theanine side effects of concern.

Theanine and blood pressure
Q. So I really want to start trying l-theanine for my life-long anxiety problems, as it is one of the only suppliments or drugs I have found that is touted for being helpful for anxiety, and yet not making the user feel dopey and tired. My concern is that I have low blood pressure (so much so that the nurses who check me always think they’ve done it wrong), and I have read that l-theanine lowers blood pressure. So my question is this: Does l-theanine lower blood pressure, or regulate it? Should a person with low blood pressure avoid this suppliment, or does it only lower blood pressure when it needs lowering? Is the lowering of blood pressure that comes along with this suppliment significant enough to worry about, even if it will take down the blood pressure of an already low person?
A. Not enough human studies have been done to determine the role of l-theanine in influencing blood pressure in those who have normal or low blood pressure. We could only find one human that showed theanine prevents the rise in blood pressure from caffeine intake. Very, very large theanine dosages given to rats lowers their blood pressure. Since the effects of herbs and amino acids are dose dependent, one option is to take half of a 100 mg capsule and monitor one’s blood pressure over the next few hours to see how it affects you and then base future dosages on the initial response. Have approval by your doctor.

L Theanine and caffeine
The combined effects of L-theanine and caffeine on cognitive performance and mood.
Nutr Neurosci. 2008. Unilever Research and Development, Colworth House, Sharnbrook, Bedford, UK.
The aim of this study was to compare 50 mg caffeine, with and without 100 mg theanine, on cognition and mood in healthy volunteers. The effects of these treatments on word recognition, rapid visual information processing, attention switching and mood were compared to placebo in 27 participants. Performance was measured at baseline and again 60 min and 90 min after each treatment. Caffeine improved subjective alertness at 60 min and accuracy on the attention-switching task at 90 min. The L-theanine and caffeine combination improved both speed and accuracy of performance of the attention-switching task at 60 min, and reduced susceptibility to distracting information in the memory task at both 60 min and 90 min. These results replicate previous evidence which suggests that L-theanine and caffeine in combination are beneficial for improving performance on cognitively demanding tasks.

Toxicity and Safety of L Theanine
A 13-week dietary toxicity and toxicokinetic study with l-theanine in rats.
Food Chem Toxicol. 2006. Borzelleca JF. Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA
This study was conducted to evaluate the safety of l-theanine Suntheanine when administered as a dietary admixture to male and female rats at concentrations providing doses of 0, 1500, 3000 or 4000 mg/kg body weight per day for 13 weeks. There were no consistent, statistically significant treatment-related adverse effects on behavior, morbidity, mortality, body weight, food consumption and efficiency, clinical chemistry, hematology, or urinalysis. There were no consistent treatment-related L theanine side effects in gross pathology, organ weights or ratios or histopathology. The increased incidence of renal tubular cell adenomas in high-dose females only were not consistent with the characteristics of a renal carcinogen (due to early onset and low number of animals affected) but were more consistent with a genetic predisposition than with direct organ toxicity. The no-observed-adverse-effect-level was 4000 mg/kg bw/day, the highest Suntheanine dose tested.

Theanine Research
Anti-obesity effects of three major components of green tea, catechins, caffeine and theanine, in mice.
In Vivo. 2004.
To elucidate the anti-obesity effects of three major components of green tea, catechins, caffeine and theanine, female mice were fed on diets containing 2% green tea powder and diets containing 0.3% catechins, 0.05% caffeine and 0.03% theanine for 16 weeks. Body weight and food intake were determined monthly during this period, kidneys, adrenals, liver, spleen, brain, pituitary and intraperitoneal adipose tissues (IPAT) were weighed and lipid levels in the serum and liver were measured at the end of this period. The body weight increase and weight of IPAT were significantly reduced by the diets containing green tea, caffeine, theanine, caffeine + catechins, caffeine + theanine and caffeine + catechins + theanine. Noticeably, the IPAT weight decreased by 76.8% in the caffeine + catechins compared to the control group. Serum concentrations of triglycerides and non-esterified fatty acids (NEFA) were decreased by green tea, catechins and theanine. Moreover, caffeine + catechins, caffeine + theanine and caffeine + catechins + theanine also decreased NEFA in the serum. The triglyceride level in the liver was significantly reduced by catechins and catechins + theanine in comparison with the control. These results indicated that at least caffeine and theanine were responsible for the suppressive effect of green tea powder on body weight increase and fat accumulation. Moreover, it was shown that catechins and caffeine were synergistic in anti-obesity activities.  I theanine side effects

Q. I’m using L-theaning and i think it just saved my life, it helped me with social anxiety, concentration, sleep or just feeling good. i had several panic attacks and now when i discovered this i just take it when i feel like it’s starting and it causing it to completely disappear. BUT, but question is, I know all the benzodiazepines (Valium, Xanax) are causing an increase in the GABA, but they are extramly addictive and dangerous. Is L-theanine addictive too? Sometime if i take like 300mg of L-theanine a day I start to feel depressed after like 6-8 hours, could it have something to do with it? I’ve been asking this a couple of psychiatrists and they just say they don’t know anything about alternative medicine and they don’t think any amino acids could cause any addiction
A. We don’t know enough about long term theanine use, hence it is difficult to say whether long term l theanine use causes low mood. However, as with most supplements, taking breaks is useful and other anti-anxiety agents can be substituted, such as 5-htp, kava, ashwagandha, passionflower, etc. I am not aware of any serious cases of addiction to amino acids. A lower dose of l-theanine, such as 200 mg, may not cause the low mood after several hours. Or, using l-theanine only in the evening could make a difference.

Q. I’ve been taking L-theanine for insomnia for about a month and it seems to really help. My question is this: If there are immune stimulating effects from L-theanine, could this amino acid possibly be bad for auto-immune diseases?
A. We have not seen any studies to indicate L theanine to have a major influence on the immune system. However, it often takes years of studies to determine the full impact of a supplement on the immune system, and thus far such studies regarding L theanine and the immune system have not been done.

Q. i just finished reading your page about yohimbe and there is one thing not mentioned there which i am concerned about. i am planning to take l-theanine or theanine for anxiety, maybe i will take 200mg or so in the morning, can i take yohimbe at noon time or in the afternoon? is it ok? Thanks and i would like like u to know that u have a wonderful website, sells good products, too
A. We have not seen any research with the combination of yohimbe and theanine, but if your doctor approves you can start with low dosages of each to see how your body reacts. Each person reacts differently to herbs and supplements, and to combinations of supplements.

Q. I have been taking L-theanine occasionally and I’ve noticed that the two times I’ve taken it fairly close to going to bed I’ve had insomnia! I’m taking it in an attempt to lower my creeping-up blood pressure with the hope that I’ll feel calmer and less stressed and that this will help my labile hypertension to stabalize. I would appreciate any information you might have about whether l theanine could be causing the insomnia and how it might be used for lowering blood pressure.
A. In some people l theanine may cause a slight alertness, and this may also depend if there are other supplements added to the l theanine product. See our page on hypertension for suggestions on blood pressure control.

Q. Absolutely love your site. I send it to everybody I know! What do you know about L-Theanine? A doctor recommends l theanine for anxiety. Just wondering what your thoughts were.
A. There are herbs and other nutrients more potent than l theanine for anxiety.

Q. Could you tell me please if taking L Theanine supplement, which is supposedly better absorbed than GABA, if L Theanine is more helpful for sleep than GABA.
A. In my opinion, L theanine is more potent than GABA. Good Night Rx is more potent than L theanine for sleep.

How nice to find a website that has solid information on more natural alternatives to pharmaceuticals! Hope you will be around a long time. I have been reading about L-Theanine and wondered if you have any information on whether it has been used to treat ADHD. My 7 year old son has been diagnosed with ADHD and we do not want to put him on stimulant medication.
I searched Medline for the keywords theanine ADHD and could not find any studies regarding the treatment of ADHD with a l theanine supplement. Sometimes the only way to tell if a supplement will work is by trial and error. Theanine appears to be a safe amino acid, at least in the short term. I am not aware of long term human studies using l theanine supplements.

I’ve been doing some research on natural sedatives and relaxants, as I have occasional trouble with anxiety and insomnia. I was once on Zanax, only for 2 weeks and was very sensitive to this, so much so, I developed a tolerance and bad rebound anxiety. So, I had to come off this very slowly. I’m afraid now even of natural herbs, etc. that may cause the same problems. Does L-Theanine work by occupying the same GABA receptors in the brain that prescribed benzodiazepines do?  Did try valerian for a while and did indeed have rebound anxiety taking this for 2 months.
It is uncommon to have a rebound effect from the use of herbs or amino acids. As with any type of natural or prescription sleep medication, it is a good idea to not take them every day. The exact way L theanine supplements work to help with sleep is still not fully clear to us. It’s also a good idea to change different herbs and supplements for sleep and anxiety rather than relying on just one or two.

Additional web pages
Tanacetum parthenium, also known as feverfew plant, grows widely across Europe and North America.
Terminalia arjuna has antioxidant properties and may be clinically helpful in cardiovascular health.

Sleep problems emails
Hi, I’m 35 years old, and have been a night owl for as long as I can remember. I always wake up foggy and never have much energy until late afternoon/evening. In addition, my sleep schedule has been severely disrupted over the past year due to a combination of grief over a loss, my night owl tendencies, and a sporadic caffeine habit. Recently, in an attempt to gain more energy in the mornings and daytime, I eliminated caffeine and began taking tyrosine (500-mg capsules) once or twice a day, never later than 3 pm. I’ve noticed a small increase in daytime energy, but a rather drastic side effect that I am wondering if you have seen before. My sleep schedule has been reset alright: I’m no longer even remotely a night owl, I’m dead tired about 12 to 13 hours after I wake up, and I’m sleeping well — but for 12 hours at a time. Even if I take only one tyrosine pill. I don’t sleep as long or as well but I’m still wiped out 12 hours after waking. And I don’t normally need 12 hours of sleep.

Suntheanine, a patented form of L Theanine, is a trademark of Taiyo International, Inc.
Promotes relaxation and stress reduction, it can be used during the day if someone is tense, or in the evening.