As an amino acid, L-Theanine is regulated as a complementary medicine in Australia. Complementary medicines include a number of compounds, including amino acids, herbals, plant materials, plant extracts, and homeopathic products.
However, the regulatory status of L-theanine products in Australia is unclear. L-theanine supplements are not readily available in Australia and only one supplement containing Theanine is listed on the Australian Register of Therapeutic Goods (meaning it can be legally sold in Australia).
L-Theanine is a natural compound found in green tea extract (which is approved for dietary supplements in Australia). It is used as a supplement to improve mood, reduce feelings of stress and anxiety, promote cognitive function, and to support sleep.
While L-Theanine supplements are not widely sold in Australia, it is legal for Australian residents to purchase this product online and import it for personal use.



- Supports focus, attention & mood
- Helps to reduce stress & anxiety
- Neuroprotective & increases NGF
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In Australia, complementary medicines like the amino acid L-Theanine. are regulated under the Therapeutic Goods Act (1989). This is an act that regulates all manner of therapeutic goods ranging from complementary medicines to prescription medications.
All therapeutic goods must be included in the Australian Register of Therapeutic Goods to be legally sold in, or exported from, Australia.
The Act requires that complementary medicines be either listed or registered in the Australian Register of Therapeutic Goods. To be listed, a complementary medicine must contain only certain low-risk ingredients; products that contain high-risk ingredients must be registered with and reviewed by the Therapeutic Goods Administration.
Listed complementary medicines must be developed in accordance with good manufacturing practices, contain only low-risk ingredients, and only make truthful claims in relation to health maintenance.
The Therapeutic Goods Administration (TGA) does not regulate products sold on international websites. For this reason, consumers can buy L-theanine from international vendors and have it shipped to them in Australia.
The TGA recommends against buying therapeutic goods (including complementary medicines) over the Internet unless you are exactly aware of the composition of the product and of all the regulations applicable to its use in (and import to) Australia. [1]
L-Theanine Background and Uses
L-Theanine is an enantiomer of the non-essential amino acid Theanine. Molecules that have the same formula but a different structure are called isomers. Theanine has two isomers that are mirror images of one another, which is why they are called enantiomers.
Of the two forms of Theanine — L-Theanine and D-Theanine — L-Theanine is considered to be the most readily absorbed by the body.
L-Theanine is naturally found in green tea, which is produced from the dried leaves of Camellia sinensis.
Tea is one of the most consumed drinks in the world, second only to water. Drinking tea has long been associated with a sense of calm and relaxation and researchers have identified L-Theanine as one of the possible compounds responsible for this effect.
Population studies also indicate that green tea consumption, which is common amongst Asian populations, may be associated with lower cholesterol levels as well as instances of cardiovascular disease and cancer. [2]
L-Theanine supplements are now available and used for anxiety, Alzheimer’s disease, hypertension, and to increase the effect of chemotherapy drugs. [3]
L-Theanine Research
More research is needed before the efficacy and safety of L-Theanine can be established.
There is some indirect evidence to suggest L-Theanine may impact stress, anxiety, and concentration.
In laboratory studies, L-Theanine was observed to increase alpha band brainwave activity, which is an indirect measure of relaxation. [3]
The effect of Theanine on brainwave patterns has some researchers concluding that the amino acid has obvious psychoactive properties, [5] but more research is needed to understand the outcome of these effects.
Theanine supplementation has also been reported to reduce individuals’ self-diagnosed stress levels. In one study, volunteers who took L-Theanine self-reported lower anxiety levels. [3]
However, the ability of Theanine to impact the stress response may be limited. In one study that looked at the effects of L-Theanine on anticipatory anxiety in humans, participants who received a specific Theanine supplement (Suntheanine) reported reduced stress during baseline periods, but the supplement was not observed to lessen the effects of experimentally induced anxiety. [4]
In general, the evidence to suggest L-Theanine may affect a relaxation response mainly involves subjective reports and brainwave activity, which is only an indirect measure of relaxation. [4]
Mechanisms of Action
The mechanism underlying Theanine’s relaxing effects remains the subject of speculation. Researchers hypothesize Theanine may increase levels of the neurotransmitters Serotonin, Dopamine and Gamma-aminobutyric acid (GABA). [2] Additionally, it is believed that L-Theanine is a GABAergic compound, and may interact with GABA receptors similarly to endogenous GABA.
L-Theanine Consumer Reviews and Side Effects
Australia consumer reviews on Amazon.com.au give Theanine a high rating. Reports of reduced anxiety are prevalent throughout the hundreds of user comments.
There are few studies available that address the safety of theanine supplements. However, as a natural component of green tea, this amino acid has been widely consumed and is generally well tolerated.
The Natural Medicines Comprehensive database rates L-Theanine as “Possibly Safe” when taken orally for short periods (with 250 mg doses taken once a week for up to three weeks).
More research is needed to establish the safety of Theanine supplements. Consult with your doctor before taking Theanine to reduce the risk of side effects or drug interactions. Also, be sure to verify the regulatory status before important or using L-Theanine in Australia.
- An overview of the regulation of complementary medicine in Australia. Department of Health: Therapeutic Goods Administration. 2013 Mar 25. Accessed 20 Jan 2016.
- Theanine: Professional Monograph. Natural Medicines Therapeutic Research. Reviewed 2012 Dec 17, Updated 2015 Dec 30.
- Bryan J. Psychological effects of dietary components of tea: caffeine and L-theanine. Nutr Rev. 2008 Feb;66(2):82-90.
- Lu K, Gray MA, Oliver C, et al. The acute effects of L-theanine in comparison with alprazolam on anticipatory anxiety in humans. Hum Psychopharmacol. 2004 Oct;19(7):457-65.
- Gomez-Ramirez M, Higgins BA, Rycroft JA, et al. The deployment of intersensory selective attention: a high-density electrical mapping study of the effects of theanine. Clin Neuropharmacol. 2007 Jan-Feb;30(1):25-38.
- Shimbo M, Nakamura K, Jing Shi H, Kizuki M, Seino K, Inose T, Takano T. Green tea consumption in everyday life and mental health. Public Health Nutr. 2005 Dec;8(8):1300-6.
- Camfield DA1, 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 Aug;72(8):507-22. doi: 10.1111/nure.12120. Epub 2014 Jun 19.
Article last updated on: March 13th, 2018 by Nootriment