The L-theanine, an amino acid, is a compound found in green tea leaves, particularly in Japanese tea. It is recognized for its beneficial effects on the central nervous system, enhancing cognition, reducing stress and anxiety, improving sleep, and promoting muscle relaxation. In this article, we will review the properties of L-theanine, its mechanisms of action, as well as clinical studies supporting its use in promoting mental health.
The effects of L-theanine on cognition
L-theanine is an interesting compound for improving the cognition. Studies have shown that it can improve attention, working memory, information processing speed, and mental flexibility. These effects are likely related to L-theanine's ability to increase the release of neurotransmitters, including dopamine and serotonin, which are involved in cognitive processes.
A study published in the journal Nutrients examined the effect of L-theanine on cognitive functions in people with Alzheimer's disease. The results showed that L-theanine improved immediate verbal memory and visuospatial working memory in the participants.
The effects of L-theanine on stress and anxiety
Stress and anxiety are common problems in modern society. Fortunately, L-theanine can help reduce levels of stress and anxiety by acting on the nervous system. Studies have shown that L-theanine can reduce cortisol levels, a stress hormone, as well as blood pressure levels. It can also improve mood and reduce the perception of mental fatigue.
A study published in the Journal of Clinical Psychiatry examined the effect of L-theanine on anxiety in individuals with generalized anxiety disorder. The results showed that L-theanine significantly reduced anxiety symptoms and improved sleep quality.
The effects of L-theanine on sleep
La L-theanine can also improve the sleep by increasing alpha waves in the brain, which are associated with relaxation and drowsiness. It can also reduce the time needed to fall asleep and improve sleep quality.
A study published in the journal Pharmacology Biochemistry and Behavior examined the effect of L-theanine on sleep in rats. The results showed that L-theanine improved sleep quality by increasing total REM sleep time and reducing wake periods.
The mechanisms of action of L-theanine
The mechanisms of action of L-theanine are not yet fully understood, but studies suggest that it may act in several ways to produce its beneficial effects. L-theanine may act on GABA receptors, which are involved in relaxation and anxiety reduction. It can also increase levels of dopamine and serotonin, two neurotransmitters involved in mood and anxiety regulation. Finally, it may also increase levels of acetylcholine, a neurotransmitter involved in cognition.
Sources of L-theanine
L-theanine is an amino acid naturally found in tea leaves, particularly in green and black tea leaves. It is also present in small amounts in some other plants, such as mushrooms and berries.
Here are some examples of foods that contain L-theanine:
- Green tea: green tea is the richest source of L-theanine, with levels ranging between 5 and 50 mg per cup.
- Black tea: Black tea also contains L-theanine, although the levels are generally lower than in green tea.
- Mushrooms: mushrooms, particularly shiitake mushrooms, contain small amounts of L-theanine.
- Berries: some berries, such as blackberries and raspberries, also contain small amounts of L-theanine.
It is important to note that L-theanine is also available as a dietary supplement, usually in the form of capsules or tablets, under the recommendations of a healthcare professional.
Side effects of L-theanine
La L-theanine is generally considered safe and well-tolerated, with few or no reported side effects. However, high doses may cause adverse effects such as headaches, nausea, vomiting, and abdominal pain.
Conclusion
L-theanine is an interesting compound for improving mental and physical health. Studies have shown that it can enhance cognition, reduce stress and anxiety, improve sleep, and promote muscle relaxation. Its mechanisms of action are complex and not yet fully understood, but research suggests it may act on GABA receptors, increase dopamine and serotonin levels, and raise acetylcholine levels. L-theanine is primarily found in green tea and is generally considered safe and well-tolerated, although high doses may cause adverse effects. In summary, L-theanine is a promising natural substance for enhancing mental and physical health and deserves further attention in future research.
References:
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- Yoto, Ai et al. “Effects of L-theanine or caffeine intake on changes in blood pressure under physical and psychological stresses.” Journal of physiological anthropology vol. 31,1 28. doi:10.1186/1880-6805-31-28
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- Kimura, Ryo et al. “L-Theanine reduces psychological and physiological stress responses to visual stimulation.” Biological psychology vol. 74,1 (2007): 39-45. doi:10.1016/j.biopsycho.2006.06.006