L-Theanine, a naturally occurring amino acid, has a rich history of human consumption spanning over 5000 years, owing to its remarkable medicinal and brain-enhancing properties. Although it was officially discovered by Japanese scientists in 1949 and subsequently extracted in 1950, the benefits of L-theanine were acknowledged by individuals long before the compound was identified.
What is L-Theanine?
L-Theanine occurs naturally in tea (camelia sinensis), and it can also be found in certain fungal species like mushrooms. It is abundantly present only in various green tea varieties, such as Japanese Matcha, Gyokuro and high-grade Sencha. It plays a significant role in providing green tea with its distinct umami taste and contributes to the delightful, savoury, and brothy characteristics of the beverage. In contemporary times, L-theanine is readily available as a powdered extract and is commonly taken to promote a calm and relaxed state of mind, while also enhancing attention, focus, and cognitive function. Interestingly, unbeknownst to them, even before the compound was identified, Zen Buddhist monks intuitively derived the benefits of L-theanine through their consumption of green tea, which aided their ability to maintain heightened attention and focus during prolonged meditative sessions.
L-Theanine, Meditation, and Buddhism Tea Culture
Shennong, a legendary Chinese herbalist and emperor, is widely believed to be one of the earliest individuals to have consumed tea. According to the legend, while Shennong and his army were resting on a hillside feeling thirsty, his servant began boiling water. Serendipitously, a leaf carried by the wind found its way into Shennong's cup. Intrigued by the leaf's distinct colour and flavour, Shennong shared his discovery with others, starting a journey that would transform tea into a popular beverage.
Although tea drinking became more integrated into Chinese Buddhist culture during the Han Dynasty (206 BCE-220 CE), Buddhism itself differs from most religions as it does not venerate a deity or origin story. Instead, Buddhism emphasizes awareness and paying attention to one's personal journey in life, striving for enlightenment. As knowledge spread to neighbouring countries like Japan, Buddhism took on different sects over the years.
In Japan, dissatisfaction with the state of Buddhism led a monk named Eisai to travel to China to study its origins. After his second trip in 1191, Eisai returned to Japan as a master, bringing back Zen scriptures and tea seeds. Eisai is credited with introducing Zen Buddhism and tea culture to Japan, promoting the consumption of green tea as a tool to aid in meditation.
Tea, traditionally valued for its medicinal properties, gained prominence within Zen Buddhism as a means to cultivate the mind and body. Zen Buddhism aims to discipline the mind to allow the energy of the unconscious to manifest in the conscious realm and attain enlightenment. For Zen Buddhist monks, both the preparation and consumption of tea became a meditative practice in itself.
Tea was typically consumed throughout the day, assisting monks in remaining alert during long periods of meditation. In addition to the caffeine it contains, it can be inferred that l-theanine, an amino acid found in tea, played a significant role in enhancing their ability to maintain attention and focus as they sought to transcend consciousness and thoughts for extended periods.
How Does L-Theanine Work?
Once ingested, L-theanine is absorbed by the small intestine and crosses the blood-brain barrier, unlocking and exerting various pharmacological effects. In the brain, L-theanine increases the production of alpha waves, which are associated with states of meditation, creativity, and REM sleep. This leads to a relaxed yet wakeful state. L-theanine also enhances the levels of neurotransmitters such as GABA, serotonin, and dopamine. These neurotransmitters promote and allow us to enter a state of relaxation without causing sedation and play crucial roles in regulating mood, emotion, attention, concentration, and other cognitive processes. L-theanine also regulates stress and anxiety, safeguarding the brain against age-related cognitive decline. Additionally, L-theanine increases the expression of BDNF, a protein responsible for the health, repair, and generation of neurons in the hippocampus.
Health Benefits of L-Theanine
- Reducing stress and inducing a calming effect
- Enhancing cognitive performance, attention, and focus
- Protecting the aging brain from cognitive decline
- Preventing stroke and cardiovascular disease
- Improving sleep quality and duration
Reduction of stress and inducing a calming effect
Stress is a natural response mechanism of the body to any physical or mental demand. While some stress is healthy, chronic stress can lead to serious health consequences such as diabetes, ulcers, cardiovascular disease, and cancer. L-theanine helps reduce stress by blocking glutamate, an excitatory neurotransmitter in the brain. By binding to glutamate receptors, L-theanine inhibits its production, resulting in a calming and anti-anxiety effect. In a study involving university students with varying degrees of anxiety, L-Theanine significantly increased alpha brain waves in participants with high anxiety, suggesting a more pronounced effect when needed the most. L-Theanine also elevates GABA levels, another inhibitory neurotransmitter that produces a calming effect without drowsiness or affecting motor behaviour.
Enhancement of cognitive performance, attention, and focus
Research indicates a relationship between stress, anxiety, and cognitive performance, suggesting that chronic stress can negatively impact cognitive function and accelerate cognitive decline. Acting as an inhibitory neurotransmitter, L-theanine improves cognitive performance by blocking glutamate and increasing GABA levels in the brain. In a study, participants were given a low dose of L-theanine equivalent to 2.5 cups of black tea. Results showed that even at realistic dietary levels, L-theanine significantly improved mental alertness and arousal, as measured by electroencephalograph (EEG), indicating its positive effect on attention and keeping the mind calm through alpha-wave activity.
Protection of the aging brain and slowing cognitive decline
Glutamate is an important neurotransmitter involved in learning, memory, and motor function. However, excessive activation of glutamate receptors can lead to excitotoxicity, causing toxic neuronal death and contributing to neurological disorders such as stroke, Parkinson's disease, and Alzheimer's disease. By inhibiting neuronal excitation, oral intake of L-theanine has shown anti-stress effects that could help prevent excitotoxicity-induced cognitive decline. While more human studies are needed, animal research suggests that L-theanine can have a significant protective effect on cognition. For example, in one study, L-theanine administration reversed cognitive impairments and oxidative damage caused by chronic stress, potentially protecting against stress-induced neurological disorders.
Prevention of stroke and cardiovascular disease
Stroke, a type of cardiovascular disorder, is the second leading cause of death worldwide. It occurs when blood vessels are constricted or blocked, preventing oxygen and nutrients from reaching the brain. Stroke is also a major cause of neurological disorders such as depression and dementia. Studies have shown that L-theanine helps regulate nitric oxide production, a signalling molecule responsible for vasodilation. By promoting vascular health, L-theanine may reduce the risk of stroke and cardiovascular disease. Another study found that L-theanine could potentially prevent artery blockages and reduce the likelihood of a stroke by blocking molecules that adhere to the cellular walls of blood vessels. Additionally, L-theanine may aid in stroke recovery by protecting brain cells and limiting the affected area when administered immediately after a stroke.
Improvement of sleep quality and duration
L-theanine promotes relaxation by lowering heart rate, blocking excitatory neurotransmitters, and elevating alpha waves in the brain. These effects suggest that L-theanine supplementation could improve overall sleep quality and reduce the time it takes to fall asleep. In a study involving boys with ADHD, L-theanine significantly improved sleep percentages and sleep efficiency scores compared to a placebo group. Additionally, L-theanine partially counteracted sleep disturbances induced by caffeine in animal studies, demonstrating its potential to mitigate the negative effects of caffeine on sleep. Although more research is needed, the therapeutic benefits of L-theanine on sleep quality and duration are promising.
L-Theanine and Caffeine:
The combination of L-theanine and caffeine deserves special mention. Caffeine, a widely consumed stimulant, blocks adenosine receptors in the central nervous system, preventing drowsiness. While low-to-moderate amounts of caffeine are generally safe, high doses can lead to side effects such as anxiety, nervousness, high blood pressure, and insomnia. Studies suggest that L-theanine has a synergistic effect when combined with caffeine. In a double-blind, placebo-controlled study, the combination of L-theanine and caffeine improved attention tasks and overall mood ratings, while mitigating the negative vasoconstrictive and behavioural effects of caffeine.
In summary, L-theanine is a naturally occurring amino acid found in green tea and certain fungal species. It has been consumed for centuries and has played a significant role in tea culture, particularly in Zen Buddhism, where it aided in maintaining attention and focus during long meditation sessions. Modern research has revealed the scientific basis behind its benefits. L-theanine promotes a relaxed yet wakeful state by triggering alpha brain waves, regulates neurotransmitters related to mood and cognitive function, protects the brain from age-related decline, potentially prevents stroke and cardiovascular disease, and improves sleep quality. Furthermore, the combination of L-theanine and caffeine has shown positive effects on attention, mood, and mitigating caffeine's negative effects. Overall, L-theanine offers a range of health benefits and has the potential to enhance overall well-being.