L-theanine: The Natural Anxiolytic

L-theanine is a recognized anxiolytic, known to alleviate anxiety and improve sleep quality¹. Research indicates that it mitigates mental and physical stress by decreasing heart rate and blood pressure, instilling a sense of tranquility².

Distinguishing it from other natural anxiolytics like valerian and hops, L-theanine doesn’t function by sedating or slowing central nervous system activity. Instead, it promotes tranquility by elevating levels of calming neurotransmitters in the brain³. L-theanine offers several potential benefits, including⁴⁵:

• Supporting relaxation for enhanced mental and physical health,
• Alleviating both physical and psychological stress,
• Promoting relaxation without inducing drowsiness,
• Boosting concentration levels,
• Enhancing attention and focus.

What Is L-Theanine?

L-theanine, also recognized as N-ethyl-L-glutamine, is a unique non-protein amino acid primarily found in tea leaves. Notably, it does not serve as a building block for enzymes. This amino acid possesses calming properties that soothe the mind without causing drowsiness³⁴⁵.

Research has indicated that L-theanine may have neuroprotective properties, shielding brain cells from oxidative stress⁶. Additionally, there are suggestions of its potential in mitigating cognitive decline associated with aging⁷. Among the various sources, green tea, a variant of Camellia sinensis, stands out due to its rich L-theanine content, which can make up approximately half of its total amino acids⁸.

Mechanism of Action

Being a water-soluble amino acid, L-theanine, when consumed, undergoes absorption in the intestinal tract. Subsequently, in the kidneys, it is hydrolyzed into components, namely glutamic acid and ethylamine. Crucially, L-theanine can traverse the blood-brain barrier rapidly, reaching peak concentrations within the brain in just under an hour post-consumption¹⁴.
Theanine’s molecular structure bears a resemblance to glutamate, a predominant excitatory neurotransmitter. This similarity enables it to bind to glutamate receptors, mitigating their activity.¹⁰ By doing so, Theanine effectively reduces excessive glutamate levels, curbing the overstimulation of these receptors typically caused by stress. This results in enhanced tranquility and relaxation.⁴⁹¹¹

This amino acid modulates various brain chemicals, amplifying levels of inhibitory neurotransmitters and concurrently suppressing excessive production of excitatory neurotransmitters.⁵⁹

Furthermore, L-theanine elevates the levels of neurotransmitters such as dopamine, serotonin, and GABA, which play crucial roles in mood regulation, alertness, sleep quality, and energy balance.¹³¹²
Theanine has dual benefits for stress management. It helps in reducing the production of cortisol, a hormone that can be detrimental when overly produced during stress, and it also promotes the generation of Alpha waves (α-waves). These α-waves are associated with a relaxed, yet alert state of mind⁵⁹¹³.

How Do L-Theanine Supplements Act in the Body?

When consumed, L-theanine can penetrate the brain barrier within about an hour. It displays a plasma half-life ranging between 54 to 78 minutes¹⁴. The levels of this amino acid in the brain wane over time, leading to a complete washout approximately 24 hours post-ingestion, given a dose of 4,000 mg/kg¹⁵.

Studies have reported that after oral intake, brain concentrations of L-theanine are approximately 2µM/g. Serum concentrations peak at a bit above 12.5µM/mL within the same hour. Moreover, 16 hours post-ingestion, these brain levels start to decline¹⁵. Notably, regions like the hippocampus have shown an elevation in theanine concentrations after its oral administration¹⁷.
Regular consumption of L-theanine, typically in doses between 50-250mg, has been shown to stimulate α-wave production in healthy individuals.⁵⁹ This effect appears to be especially prominent in individuals experiencing high levels of controlled anxiety, though findings from various studies have been mixed.¹⁹²⁰

The enhancement in α-wave production due to L-theanine is more noticeable during periods of closed-eye relaxation²¹, as well as during the performance of visuospatial tasks approximately 30-45 minutes post-consumption.⁹¹¹ Notably, L-theanine seems to impact only the α-1 wave (8-10Hz) and has no effect on the α-2 wave (11-13Hz).⁹

Elevated alpha wave levels, which can be facilitated by L-theanine, are associated with numerous cognitive benefits including improved working memory, problem-solving skills, and overall cognitive performance.²³²⁴²⁵

Alterations in brain wave activity have been proposed as the primary mechanism by which theanine promotes relaxation and enhances concentration.

Research has investigated the role of theta wave function in relation to theanine intake. In particular, one study had participants consume theanine (60 mg) combined with green tea extract (360 mg) three times daily for over 16 weeks²⁶.

Documented Advantages of L-Theanine Supplementation

L-theanine offers a range of health benefits, impacting both physical and psychological well-being.

Alleviates Anxiety and Stress

L-theanine’s capabilities in reducing anxiety, mitigating the physical manifestations of stress, and fostering a sense of calmness have been extensively reported^4591827.

L-theanine, a key compound found in tea, has demonstrated remarkable stress-reducing properties in several studies. It has been found to effectively reduce cortisol levels, commonly referred to as the “stress hormone.”⁵ Additionally, it can diminish both psychological and physiological stress responses⁴²¹. Moreover, its intake has been associated with enhanced states of alert relaxation⁵⁹¹⁷.

Improved Memory, Attention, and Mood

The calming effects of L-theanine extend beyond just stress reduction. It has been suggested to enhance attention, concentration, and learning capabilities. One mechanism through which L-theanine may act is by enhancing sensorimotor gating. This process filters unnecessary external stimuli, preventing the overload of irrelevant information in the brain’s higher cognitive areas²⁸²⁹. Such cognitive enhancements are just a glimpse into the myriad of benefits that L-theanine offers.

Numerous studies have underscored the “gating” effect of L-theanine in mitigating distractions and amplifying mental focus, leading to enhanced attention and cognitive performance²⁵²⁶. When synergized with caffeine, L-theanine acts as an efficacious nootropic, enhancing cognitive function³. This pairing neutralizes certain adverse effects of caffeine, such as vasoconstriction, thereby optimizing cerebral blood flow and uplifting mood and cognitive abilities²⁵³⁰.

Furthermore, the amalgamation of L-theanine and caffeine has demonstrated potential in augmenting memory, honing selective attention, and elevating the amplitude of brain theta waves, indicative of heightened cognitive alertness⁹¹³.

Enhances Sleep

Research has portrayed L-theanine as a natural, non-sedative sleep aid that induces relaxation predominantly by alleviating anxiety¹¹⁸.

L-theanine’s role in promoting sleep has been explored, revealing potential benefits for those struggling to find rest. Research indicates that L-theanine may not only facilitate the process of falling asleep but also aid in maintaining a deep and restful slumber³¹.

Reduced Blood Pressure

Emerging evidence suggests that oral intake of L-theanine can significantly lower both systolic and diastolic blood pressure. Notably, this effect is most pronounced among individuals characterized as “high responders,” who exhibit marked spikes in blood pressure due to psychological stressors².
While caffeine, on its own, has been linked to increased blood pressure in stressful contexts³², its combination with L-theanine appears to mitigate this effect². Such findings present L-theanine as a potential preventive measure against hypertension, especially for young individuals who show heightened blood pressure responses to psychological stress. Chronic episodes of transient stress-induced blood pressure elevations can, over time, lead to hypertension³³.

Recommended Dosage

Studies investigating the anxiolytic effects of L-theanine have typically employed single doses ranging from 200 to 250 mg⁵¹⁸.

Single-dose trials have administered up to 100 mg of L-theanine to evaluate its potential cognitive and alertness-enhancing benefits¹⁹¹¹²⁵.

For trials spanning 6 to 16 weeks, doses between 120 to 200 mg have been taken twice daily⁵. Currently, there isn’t a standardized L-theanine dose recommended specifically for enhancing immune system performance.

Once consumed, L-theanine traverses the blood-brain barrier. Its effects can be observed within 30 minutes post-administration and can be measured for up to 5 hours thereafter¹¹¹⁵. It is metabolized in the kidneys and subsequently converted into glutamic acid and ethylamine¹⁴.

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