What is L-Theanine?
L-Theanine is a common amino acid found in tea . The substance is also classed as a glutamic acid, which can be found in the species of basidiomycete mushroom known as Boletus badius as well . Discovered in 1949, theanine is an additive to many foods and beverages including chocolates, teas, and soft drinks. The FDA classifies theanine as a Generally Recognized As Safe (GRAS) ingredient .
Where Does it Come From?
Theanine is derived from the leaves of the camellia sinesis plant. Its leaves and leaf buds are used in combination with warm water to produce tea. Tea has been used for centuries as a natural remedy, especially in China, to help improve heart health [4, 5].
More recently, studies have shown that green tea specifically has a wide variety of health benefits, ranging from protecting cells from free radicals to increasing anti-bacterial proteins to boost the immune system [6, 7]. It is primarily used, however, for its anxiolytic properties and nootropic benefits when paired with caffeine [8, 9].
L-Theanine for Anxiety
Based on the benefits associated with tea, many people have started taking L-Theanine as a supplement for similar effects. Similarly to the benefits mentioned above, there is a wide variety of positive health effects associated with theanine. These can include the following:
- Improved concentration [10, 11]
- Improved mood 
- Enhanced mental performance in both cognitively impaired and otherwise healthy persons (particularly when combined with caffeine) [10, 13, 14]
- Lower blood pressure [15, 16]
- Reduced heart rate 
- Reduced mental and physical stress responses 
- Increased alpha wave production in the brain 
- Alleviation of both physical and mental symptoms of PMS (Premenstrual syndrome) 
What Else is Theanine Used For?
In addition to these benefits, studies have shown that the consumption of theanine either through drinking tea or taking supplements can have preventative effects on the growth of unhealthy cells [20, 21, 22].
L-Theanine is also said to have effects that are comparable to many sedatives, though it is not itself classed as a sedative. This makes theanine particularly useful for relaxation without drowsiness . An example of this use is a product called Theanine Serene with Relora.
L-Theanine has also been shown to have some neuroprotective effects, including preventing ischemic neuronal damage, according to one gerbil study . It can also help individuals that have suffered strokes, or those suffering from degenerative brain illnesses [25, 26]. The latter is a result of theanine’s interactions with glutamate receptors in the brain and its ability to curb glutamate toxicity, which plays an important role in the degeneration of brain functions associated with various neurological ailments .
Read more about L-theanine benefits in our post which reviews its combination with caffeine.
L-Theanine Side Effects
There have not been very many studies conducted into the negative side effects associated with taking L-Theanine, though results would seem to indicate that they are rare and quite mild [28, 29].
If your primary source of theanine is through drinking tea, potential side effects relate to the caffeine content and not theanine itself; many of these side effects only present with excessive caffeine consumption. These can include side effects such as:
- Frequent urination
- Gastroinstestinal problems, most notably diarrhoea 
Overall, theanine is largely quite safe. No empirical studies into theanine’s toxicity in humans have been conducted; however, animal studies have failed to produce toxic effects .
As is the case with any new supplement, anyone considering buying theanine should consult a medical professional before taking it to ensure that the supplement is suitable for them, and to make sure that they are aware of any potential adverse side effects that may arise.
L-Theanine Dosage for Anxiety
A safe a low key way to reap the health benefits associated with theanine is to drink a cup of tea a few times a day.
Some people, however, prefer to regulate their health more stringently, and as such opt for L-Theanine supplements.
L-Theanine as a supplement is generally sold in capsule or powdered form, but these capsules can vary in size. A typical size is about 100mg and it is recommended to take 2 or 3 of these capsules daily.
However, many individuals choose to buy theanine in bulk powder form and measure out their doses on a digital scale. This is usually more cost effective and allows for easier dosage alterations.
Some people also like to stack L-Theanine with other substances as part of their supplement routine. As started above, it is common to supplement L-Theanine with caffeine. Many recommend this as a stack for nootropic beginners due to the fact that its adverse side effects are very rare and mild. This stack is great for promoting a calm focus without caffeine jitters.
The appeal of this stack is that theanine is exceptionally adept at counteracting the negative side effects that are often associated with caffeine. The calming effects of theanine can allow users to experience all of the benefits of caffeine without the unpleasant side effects. It is also very mild, so there is little fear of negative side effects or overstimulation.
Where to Buy L-Theanine
- Lift Mode – 100g for $15.88
- Powder City – 100g for $9.53
- Bulk Supplements – 100g for $15.96
Theanine for Anxiety Reviewed
All in all, L-Theanine is a relatively safe, low impact supplement. Anyone looking to buy L-Theanine can expect to be pleased with its calming and relaxing effects, and may find that it helps them with concentration and focus.
These benefits, while not overly potent, are pleasant. This, coupled with the safe nature of the supplement and its lack of adverse side effects, make for a popular and useful supplement. Anyone wanting to get more use out of it can use it in conjunction with caffeine, as outlined above, to great effect.