L-Theanine and GABA are both compounds associated with reduced stress and increased relaxation. Due to these effects, they are sometimes used as supplements for those who want to manage anxiety and stress.
L-Theanine is an amino acid that is found in green tea. This amino acid has structural properties that are similar to Glutamate, an amino acid found in the body that is the precursor to GABA.
L-Theanine has effects on cognition and helps modulate brain waves. It may work by increasing GABA activity in the brain. It can be acquired by drinking green tea or by taking it as a supplement.
GABA, also known as gamma-aminobutyric acid, is a neurotransmitter made by the brain. It helps produce a calming effect on the central nervous system, according to the University of Michigan Health System. [1]
GABA is not found in fresh foods, but it can be acquired by eating yogurt, sauerkraut and other fermented foods. It is also available as a supplement.



- Supports focus, attention & mood
- Helps to reduce stress & anxiety
- Neuroprotective & increases NGF
Benefits of L-Theanine Supplements
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L-Theanine helps produce feelings of relaxation and calm by modulating alpha brain waves, according to a 2008 study published in the Asia Pacific Journal of Clinical Nutrition. [2]
It also affects GABA receptors in the brain. The effects of L-Theanine on GABA include upregulation, which means that this amino acid helps increase activity at GABA receptors.
GABA activity in the brain leads to reduced anxiety and increased relaxation by blocking signals in the central nervous system.
Using L-Theanine for anxiety might be effective, although more research is needed, and L-Theanine has not been approved by the FDA as a drug to prevent or treat any conditions. These supplements have shown some effectiveness when used by people who have lower levels of stress rather than those who struggle with a diagnosed anxiety disorder.
L-theanine supplements are also used for managing high blood pressure or lowering the risk of dementia. Their effectiveness for these uses requires more research.
Benefits of GABA Supplements
GABA supplements are commonly used for anxiety, tension, stress, elevating mood, and managing blood pressure.
These supplements have also been used for attention deficit-hyperactive disorder (ADHD), pain relief, and to promote fat burning for weight loss.
GABA supplements might be ineffective at reducing anxious thoughts and stress levels. The GABA in supplements enters the blood, but it usually cannot enter the brain. This makes GABA supplements an unreliable form of anxiety reduction, since they have difficulty crossing the blood-brain barrier.
In fact, the main difference between L-Theanine and GABA supplements is that Theanine has the ability to cross the blood-brain barrier, while GABA from supplements typically does not.
However, there are many people who say GABA supplements do work for them, and while it may be due to placebo effect, there are also alternative theories on why supplemental GABA may work for some people.
Some people may have personal differences in blood-brain barrier permeability which allows GABA into their brains. Alternatively, some research suggests that GABA receptors located in the gut may play a role in mood regulation. Both of these theories could reconcile the current scientific understanding of GABA and the many positive reviews. These would both be good areas for future studies.
The debate about mental effects aside, the Natural Medicines database has rated GABA supplements as Possibly Effective for lowering high blood pressure and decreasing motion sickness, although more research is still needed to fully understand these effects.
GABA is available as a dietary supplement only, and the FDA has not approved GABA as a drug to prevent or treat any conditions.
How to Take L-Theanine
L-Theanine is available in supplement form by itself or combined with GABA and other compounds that promote calmness and reduce stress.
For example, GABA L-Theanine Stress B lozenges are available online and at health and wellness stores. A large number of consumers who have used them report that they are effective at reducing stress and increasing calmness.
Dosages for L-Theanine supplements can vary from person to person depending on age, medical conditions and other factors. In general, dosages of 200 mg are considered safe for most people to take, according to the University of California, Santa Cruz. [3]
It is always recommended that you speak with your doctor before beginning any new supplements.
How to Take GABA
GABA supplements are available in tablet form, capsule form and other forms for oral use. The dosages for these products can vary widely based on age, health, and several other factors.
It is important to see a doctor before taking these supplements in order to determine a safe dosage.
GABA can usually be taken in amounts of 250 to 500 mg. Doses that are more than 750 mg are considered unsafe, since these higher amounts of GABA may lead to more anxiety or cause insomnia.
In general, doctors typically recommend 200 mg of GABA per day in four divided doses, according to the University of Michigan Health System. [4]
Side Effects of L-Theanine and GABA
In some individuals, L-Theanine supplements might have a negative effect on mental status or lead to lower blood pressure, although these effects are rare. Otherwise, these supplements are considered safe to use for a short period of time.
Those who take drugs for blood pressure should consult their doctor before using L-Theanine supplements. These supplements can interact with blood pressure medications. L-Theanine supplements can also interfere with the effects of caffeine and other stimulants.
GABA supplements are generally safe to take in smaller amounts and for a short period of time. Using these supplements for an extended period of time, such as 12 weeks or more, is not recommended due to the lack of research on long-term effects.
GABA supplements can cause tingling when taken in smaller doses. Doses of 10 grams or higher can cause more serious side effects, such as wheezing or a rapid heart rate. Large amounts of GABA taken at a time can also cause anxiety to increase.
Those who take medications for blood pressure should see their doctor before using GABA supplements. These supplements can have interactions with blood pressure medications.
L-Theanine and GABA supplements can be used together safely by most individuals. It is important to remember that GABA should only be used for a period of up to 12 weeks and L-Theanine should also be used for a short period of time.
- University of Michigan Health System. Gamma-Amino Butyric Acid: Uses. 2015.
- Nobre, A.C., Rao, A., Owen, G.N. L-theanine, a natural constituent in tea, and its effect on mental state. Asia Pacific Journal of Clinical Nutrition. 2008; 17 Suppl 1:167-8.
- University of Michigan Health System. Taurine: Uses. 2015.
- University of Michigan Health System. Gamma-Amino Butyric Acid: How It Works. 2015.
Article last updated on: June 28th, 2018 by Nootriment