ThereL-theanine, an amino acid, is a compound found in the leaves ofgreen tea, especially in Japanese tea. It is recognized for its beneficial effects on the central nervous system, improving 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 the clinical studies that support its use in promoting mental health.
The effects of L-theanine on cognition
L-theanine is an interesting compound to improve thecognition. 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 function in people with Alzheimer's disease. The results showed that l-theanine improved immediate verbal memory and visuospatial working memory in 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 ofstress and anxiety by acting on the nervous system. Studies have shown that l-theanine can reduce levels of cortisol, 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 looked at the effect of L-theanine on anxiety in people 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
L-theanine can also improve thesleep by increasing alpha waves in the brain, which are associated with relaxation and drowsiness. It can also reduce the length of time it takes to fall asleep and increase the quality of sleep.
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 periods of wakefulness.
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 reducing anxiety. It can also increase levels of dopamine and serotonin, two neurotransmitters involved in regulating mood and anxiety. Finally, it can also increase levels of acetylcholine, a neurotransmitter involved in cognition.
Sources of L-theanine
L-theanine is an amino acid found naturally in tea leaves, especially green tea 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 varying between 5 and 50 mg per cup.
- Black tea: Black tea also contains L-theanine, although levels are generally lower than in green tea.
- Mushrooms: Mushrooms, especially shiitake mushrooms, contain small amounts of L-theanine.
- Berries: Certain 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 capsule or tablet form, under the recommendation of a healthcare professional.
Side effects of L-theanine
L-theanine is generally considered safe and well tolerated, with little to no reported side effects. However, high doses can cause side 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 improve cognition, reduce stress and anxiety, improve sleep, and promote muscle relaxation. Its mechanisms of action are complex and not yet fully understood, but studies suggest that it can act on GABA receptors, increase dopamine and serotonin levels, and increase acetylcholine levels. L-theanine is found primarily in green tea and is generally considered safe and well tolerated, although high doses may cause adverse effects. In sum, L-theanine is a natural substance with promise for improving mental and physical health and deserves further attention in future research.
References:
- Kimura, Kenta et al. L-Theanine reduces psychological and physiological stress responses. Biological psychology vol. 74.1 (2007): 39-45. doi:10.1016/j.biopsycho.2006.06.00606
- Nobre, Anna C et al. L-theanine, a natural constituent in tea, and its effect on mental state. Asia Pacific journal of clinical nutrition vol. 17 Suppl 1 (2008): 167-8.8.
- Owen, Gail N et al. The combined effects of L-theanine and caffeine on cognitive performance and mood. Nutritional neuroscience vol. 11.4 (2008): 193-8. doi:10.1179/147683008X30151313
- 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:10.1186/1880-6805-31-2828
- Lu, Kai et al. The neuroprotective effect of L-theanine on NMDA-induced cytotoxicity in HT22 cells. Journal of environmental biology vol. 36.5 (2015): 1007-13.3.
- Nathan, Pradeep J et al. The Neuropharmacology of L-Theanine(N-Ethyl-L-Glutamine): A Possible Neuroprotective and Cognitive Enhancing Agent. Journal of herbal pharmacotherapy vol. 6.2 (2006): 21-30. doi:10.1080/J157v06n02_0202
- 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.2006.06.00606