What is L-theanine good for?
L-theanine is an amino acid that is found primarily in green, black and white tea, as well as in certain types of mushroom.
Theanine actually accounts for approximately 1% of the total dry weight of green, black and white teas, but it can be even higher for certain varieties of tea such as matcha and gyokuro green teas, due to the way in which the plants are intentionally shaded from direct sunlight during production.
Benefits for stress & anxiety
L-theanine is known for its relaxing properties, and it is part of the reason why drinking tea can have such a calming effect on the mind. Research has demonstrated that L-theanine is able to reduce symptoms of stress and anxiety in people that are undergoing stress, as well as improving symptoms in people that suffer from schizophrenia.
L-theanine is also thought to be beneficial for people who suffer from elevated blood pressure in stressful situations.
Benefits for sleep quality
L-theanine's ability to promote relaxation carries over into what many consider its most important benefit, and that is its sleep-promoting properties, resulting in improved sleep quality. Specifically, it is thought that L-theanine's ability to reduce the body's resting heart rate contributes to this.
Role in the immune system
In addition to its positive effects on the mind, L-theanine has also shown promising results for our physical health.
For example, research shows that L-theanine may improve the function of the immune system, potentially decreasing the risk of respiratory tract infections and reducing inflammation of the small intestine, which is the centerpiece of the immune system.
When should I take L-theanine?
L-theanine does not need to be taken with a meal for absorption, and in fact research suggests that taking it on an empty stomach could be the best way to maximize its bioavailability.
If you are interested in taking advantage of L-theanine for its sleep-promoting qualities, taking it just before going to bed, on an empty stomach, will be the best choice, ensuring restful sleep and reducing the chance of sleep disruption.
What does L-theanine combine well with?
L-theanine with L-tyrosine and caffeine, for athletic performance
Research shows that when L-theanine is combined with L-tyrosine and low-dose caffeine, this results in improved athletic performance during exhaustive exercise, so that is something to take into account if you are already taking L-tyrosine as part of your pre-workout routine.
L-theanine with green tea extract, for cognitive health
Also, some studies regarding L-theanine's effects on cognitive health also incorporated green tea extract, and it was found that this combination improved memory and attention span in people who suffer from mild cognitive impairment.
The caffeine found in green tea extract could also contribute towards improved cognitive function.
L-theanine with magnesium, for improved sleep quality
Interestingly, L-theanine's ability to reduce stress and anxiety seems to be amplified even further when paired with magnesium, including the promotion of high-quality sleep.
Animal studies have shown that a combination of L-theanine and magnesium not only reduced the amount of time it took for mice to get to sleep and increased sleep duration compared to taking L-theanine alone, but it also enhanced the level of melatonin, a key compound for a healthy sleep cycle.
L-theanine with caffeine, for improved focus
As mentioned above regarding green tea extract, despite L-theanine being known for inducing relaxation and promoting restful sleep, studies have found that combining L-theanine with caffeine results in increased focus and attention when performing cognitively demanding tasks.
What are natural sources of L-theanine?
If you are interested in achieving your daily L-theanine intake through your diet, rich sources of L-theanine include:
- Green tea
- Black tea
- White tea
L-Theanine data sources & further reading
- https://health.clevelandclinic.org/l-theanine
- https://www.sleepfoundation.org/sleep-aids/l-theanine-for-sleep
- https://www.health.com/l-theanine-benefits-7554183
- https://www.naturesrise.com/blogs/brainfood/when-to-take-l-theanine
- https://www.healthline.com/health/l-theanine
- https://www.webmd.com/vitamins/ai/ingredientmono-1053/theanine
- https://pubmed.ncbi.nlm.nih.gov/18681988/
- https://www.health.com/l-theanine-and-magnesium-8639718
- https://nutriscienceusa.com/insight/scientific-assessment-of-the-synergistic-effects-of-l-theanine-and-ashwagandha/
- https://www.naturesrise.com/blogs/brainfood/l-theanine-and-ashwagandha
- https://pubmed.ncbi.nlm.nih.gov/21303262/
Last updated by Asklepios on 30th January, 2025