Green tea has long been revered for its refreshing taste and numerous health benefits. One of the key components that contribute to both its unique flavour and its remarkable therapeutic properties is L-theanine. L-theanine, often known simply as theanine, is an amino acid that contributes to green tea's distinct umami flavour and aroma while also counterbalancing the bitterness of caffeine. Moreover, theanine has demonstrated various health benefits, such as promoting healthy stress responses, sleep, and cognitive function due to its calming properties.

The Effect of L-theanine on the Stress Response

Theanine's unique structure, resembling that of L-glutamic acid, enables it to interact with a variety of receptors in the central nervous system and offers calming properties that have caught the attention of researchers and health enthusiasts alike.

Studies in rodent models have revealed that theanine plays a pivotal role in modulating the metabolism of monoamines in the central nervous system. This impacts the levels of neurotransmitters like serotonin, dopamine, and norepinephrine, all of which play a crucial role in mood regulation.

Furthermore, theanine can influence the neurotransmission of glutamic acid and glycine, two amino acids with essential functions in the nervous system. It also acts as a partial co-agonist on the N-methyl-D-aspartate (NMDA) receptor, a receptor deeply involved in cognitive function, learning, and memory.

What's even more intriguing is how quickly theanine is absorbed by the body, including the brain. In less than 30 minutes from consumption, theanine reaches various tissues throughout the body, including the brain. Studies involving humans have unveiled theanine's capacity to increase alpha-wave activity in the brain, which is linked to a state of relaxation and tranquillity. This is one of the reasons theanine is celebrated for its calming effects.

Research suggests that theanine can promote relaxation and alleviate symptoms of stress without causing sedation. The calming properties of theanine are thought to be related to its ability to modulate neurotransmitters like serotonin, dopamine, and norepinephrine, which play critical roles in mood regulation.

Healthy Stress Responses

In our modern, fast-paced world, stress is an omnipresent challenge that affects our overall well-being. Theanine emerges as a natural ally in the battle against stress. A systematic review of nine randomised, placebo-controlled clinical trials, involving a total of 270 participants, suggested that theanine can play a pivotal role in promoting healthy stress responses, especially in situations of acute stress. This encompasses a range of physical and mental tasks, and the results are consistent with findings from earlier human and animal studies.

Moreover, theanine's potential in promoting healthy stress responses extends to cognitive function. Adults consuming theanine have reported improved focus, attention, and reduced mind wandering. In a study involving 69 adults aged 50 to 69, theanine administration resulted in enhanced attention, working memory, and executive function. These findings highlight the broad spectrum of benefits that theanine offers in supporting overall mental well-being.

Theanine has been investigated for its potential to enhance cognitive function. Studies have shown that it may improve attention, focus, and working memory. The combination of theanine with caffeine has been of particular interest, as it appears to promote cognitive performance while reducing the potential negative effects of caffeine, such as jitteriness and anxiety.

Theanine and Sleep Patterns

A good night's sleep is essential for physical and mental health. Theanine has been shown to be an effective aid in promoting healthy sleep without the dreaded side effect of daytime drowsiness.

A study involving 22 subjects demonstrated that theanine could enhance sleep quality and dream quality by reducing dream recall and nightmares. Those who received theanine reported feeling significantly more refreshed and less exhausted upon awakening compared to the placebo group. It's important to note, though, that theanine did not impact sleep duration.

In another study, involving 27 healthy daytime workers, theanine was administered in the morning, and the results were nothing short of astonishing. Not only did it not induce daytime drowsiness, but it also led to improved alertness, particularly for those who had a habit of going to bed after midnight. This suggests that theanine might be a fantastic solution for shift workers and those struggling with sleep-related issues.

Theanine's influence on sleep quality is another aspect worth exploring further. Its ability to enhance the quality of sleep without causing daytime drowsiness makes it a valuable tool for those seeking better rest. Theanine helps individuals fall asleep faster and experience more restorative sleep by reducing dream recall and nightmares. It can be particularly beneficial for individuals who struggle with sleep disorders or disturbances.

L-theanine and Mental Health

Research on L-Theanine and mental health has demonstrated several intriguing connections and potential benefits. While theanine is not a standalone treatment for mental health conditions, it shows promise as a complementary approach to improving mental well-being. Here are some key findings and insights:

1. Stress and Anxiety Reduction: Theanine is often studied for its ability to reduce stress and anxiety. Research suggests that it can promote relaxation and alleviate symptoms of stress without causing sedation. The calming properties of theanine are thought to be related to its ability to modulate neurotransmitters like serotonin, dopamine, and norepinephrine, which play critical roles in mood regulation.

2. Improved Cognitive Function: Theanine has been investigated for its potential to enhance cognitive function. Studies have shown it may improve attention, focus, and working memory. The combination of theanine with caffeine has been of particular interest, as it appears to promote cognitive performance while reducing the potential negative effects of caffeine, such as jitteriness and anxiety.

3. Sleep Quality: Research has indicated that theanine may help improve the quality of sleep. While it does not necessarily affect sleep duration, it can enhance the restorative aspects of sleep by reducing dream recall and nightmares. This could be beneficial for individuals with sleep disturbances or disorders.

4. Neuroprotective Properties: Some studies have explored theanine's potential neuroprotective properties. It may help protect brain cells from damage and oxidative stress, which could have implications for conditions associated with neurodegeneration and cognitive decline.

5. Attention-Deficit/Hyperactivity Disorder (ADHD): Preliminary research has suggested that theanine might have a role in managing symptoms of ADHD. While more comprehensive studies are needed, the calming effects of theanine could potentially benefit individuals with ADHD.

6. ADHD and Children: Research on the use of theanine in children with ADHD has gained attention. Some studies have suggested that it may be a safe and effective adjunct to conventional ADHD treatments, potentially reducing symptoms and improving attention and behaviour.

7. Schizophrenia: There is limited research on the potential use of theanine in individuals with schizophrenia. Some studies have indicated that theanine may have antipsychotic properties, but further investigation is required to establish its efficacy and safety for this population.

8. Depression: While theanine's potential role in managing symptoms of depression is not as well-established, its mood-regulating effects may have relevance in this context. Research in this area is still in its early stages, and more studies are needed to draw conclusive findings.

9. Anxiety Disorders: Studies have explored the potential of theanine in managing various anxiety disorders, including generalized anxiety disorder (GAD) and social anxiety disorder. Some research suggests that theanine may help reduce anxiety symptoms and improve overall well-being.

10. Post-Traumatic Stress Disorder (PTSD): Theanine's calming properties have also led to investigations into its potential for individuals with PTSD. While research is limited, some findings indicate that it may assist in reducing hyperarousal and promoting a sense of calm.

11. Combination Therapies: Theanine is often studied in combination with other supplements, medications, or therapies. For instance, it has been examined alongside antidepressants to assess its role in enhancing the effects of these medications. This approach reflects the interest in complementary therapies to address mental health conditions more comprehensively.

It's important to note that while theanine shows promise, it is not a replacement for conventional mental health treatments. Individuals experiencing mental health issues should consult with healthcare professionals for comprehensive assessment and guidance on appropriate interventions. Additionally, theanine is available as a dietary supplement and can be incorporated into a wellness regimen under the supervision of a healthcare provider.

Take Home

As the world continues to unlock the many secrets of green tea's health benefits, theanine emerges as a potent ingredient with great therapeutic use. Whether consumed alone or within a delightful cup of green tea, theanine possesses calming properties with significant clinical relevance for the general population. It has the potential to promote healthy stress responses, improve sleep quality, and enhance cognitive function. So, next time you enjoy a soothing cup of green tea, savour the calming drink that is L-Theanine and appreciate the wonderful gift of nature's tranquillity in every sip.

References

Williams, JL. et al. (2020). The effects of green tea amino acid L-theanine consumption on the ability to manage stress and anxiety levels: A systematic review. Plant Foods for Human Nutrition. 75(1), pp. 12-23. doi:10.1007/s11130-019-00771-5

Hidese, S. et al. (2019). Effects of L-theanine administration on stress-related symptoms and cognitive functions in healthy adults: A randomized controlled trial. Nutrients. 11(10), 2362. doi:10.3390/nu11102362

Baba, Y. (2021). Effects of L-theanine on cognitive function in middle-aged and older subjects: A randomized placebo-controlled study. Journal of Medicinal Food. 24(4), pp. 333-341. doi: 10.1089/jmf.2020.4803

Li, MY. et al. (2022). L-theanine: A unique functional amino acid in tea (Camellia sinensis L.) with multiple health benefits and food applications. Frontiers in Nutrition. 9:853846. doi:10.3389/fnut.2022.853846

Rao, TP. Ozeki, M. Juneja, LR. (2015). In search of a safe natural sleep aid. Journal of the American College of Nutrition. 34(5), pp. 436-447. doi:10.1080/07315724.2014.926153