Key takeaways:
~ L-theanine is an amino acid found in tea and is also available as a supplement.
~ Studies on theanine point to positive benefits for anxiety and possible ADHD.
~ Theanine may also decrease inflammatory cytokine production.
~ Genetic interactions with l-theanine involve caffeine metabolism and TNF-alpha production.
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What is l-theanine?
L-theanine is an amino acid with a similar chemical structure to glutamate, which is a neurotransmitter. It is found in green tea and mushrooms, and l-theanine is readily available as a supplement.
People often take l-theanine supplements for anxiety, and studies do back up this claim somewhat. But l-theanine is more than just a ‘chill pill’, as you will see from the research on inflammation and brain health.
In tea, l-theanine makes up about 1 -2% of the dry weight of the leaves. This is true for both black and green teas, with different tea varieties containing different amounts.[ref]
On average, a cup of tea contains about 25mg of l-theanine. Interestingly, l-theanine takes away some of the bitter taste of caffeine by binding to the taste receptors for umami, a savory taste.[ref]
In the brain, l-theanine binds to glutamate receptors. But l-theanine doesn’t have as strong an affinity to the receptor as glutamate, so it doesn’t replace it entirely. Instead, it somewhat inhibits glutamate reuptake and increases brain levels of GABA.[ref] GABA acts as an inhibitory neurotransmitter, putting the brakes on brain excitement.
Recent research also shows that l-theanine binds to cannabinoid receptor 1 (CB1). This competitive binding then inhibits the CB1 receptor.[ref]
Studies on l-theanine for anxiety:
L-theanine has been tested in clinical trials for anxiety. Let’s take a look at some of the results:
A 2006 cross-over trial found that theanine reduced heart rate and stress response molecules in response to acute stress tasks. The heart rate variability results showed that the reduction in heart rate was “attributable to an attenuation of sympathetic nervous activation.”[ref]
A randomized, placebo-controlled, cross-over and double-blind trial looked at the effects of 200mg/d of l-theanine on adults with no mood issues. The results showed a decrease in depression and anxiety traits as well as better sleep. Cognitive function, executive function, and verbal fluency all improved.[ref]
On the other hand, an 8-week trial in people with Generalized Anxiety Disorder found that l-theanine did not reduce anxiety.[ref]
Researchers looked at different doses of l-theanine and measured the startle response. [ref] Doses of 200-400 mg did decrease the startle response, but at doses over 400 mg, there was no additional benefit.
Related article: Inflammation genes and anxiety
How does l-theanine stack up against benzos?
A clinical trial looked at the anxiety reduction from 200 mg of l-theanine vs. alprazolam (benzodiazepine) or a placebo. The study results showed that l-theanine helped with relaxation during non-stress conditions, but neither alprazolam nor l-theanine had acute anxiety-reducing effects during anticipatory anxiety.[ref] To me, the difference between anticipatory stress and a suddenly anxious situation is similar to dreading a final exam for a week vs. having a pop quiz.
Studies on l-theanine for depression:
Surprisingly, there isn’t a lot of published research on l-theanine for depression. Anxiety and depression often go hand-in-hand, so I expected to find more research on the combination.
A clinical trial using 250mg/day of l-theanine in adults with major depressive disorder showed that anxiety traits improved. Sleep disturbances were helped by the l-theanine also.[ref]
Studies on l-theanine for ADHD:
A clinical trial of 2.5 mg l-theanine and 2 mg/kg of caffeine showed positive results for adults with ADHD. The study found that the combination improved inhibitory cognition and inhibitory control.[ref]
Related article: ADHD genes
Sleep studies with l-theanine:
It would make sense that something that can decrease anxiety would help people who have sleep problems due to constantly worrying about things all night. Plus, supplement sellers of l-theanine often promote its use for sleep. But, to be honest, the research on the topic is slim.
- A randomized, double-blind, placebo-controlled trial using 100 mg of l-theanine 4x per day in boys with ADHD showed some improvements in sleep quality.[ref]
- Additionally, the clinical trial mentioned above for stress-related symptoms also noted improved sleep quality scores in participants taking l-theanine.[ref]
Will l-theanine give you nightmares?
An animal study showed that GABA plus l-theanine effectively decreased the time it took to fall asleep and the time spent sleeping. It also almost doubled the time spent in REM sleep.[ref] I mention this animal study because some people report that l-theanine causes vivid dreams, which may go along with changes in REM sleep.
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Conclusion:
Tea is one of the most popular beverages consumed worldwide, and l-theanine is a beneficial component.
Clinical trials on l-theanine show that there may be mild benefits for anxiety for some people.
More interesting, and also related to decreasing anxiety, are the benefits for reducing and modulating the immune response. Overall, theanine is generally regarded as safe and seems to have few safety concerns.
Related Articles and Genes:
GABA levels: Genetic variants that impact this inhibitory neurotransmitter
GABA (gamma-aminobuyteric acid) is a neurotransmitter that acts to block or inhibit a neuron from firing. It is an essential way that the brain regulates impulses, and low GABA levels are linked with several conditions including anxiety and PTSD.
Is Anxiety Genetic?
This article covers genetic variants related to anxiety disorders. Genetic variants combine with environmental factors (nutrition, sleep, relationships, etc) when it comes to anxiety. There is not a single “anxiety gene”. Instead, there are many genes that can be involved – and many genetic pathways to target for solutions.
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