Brain and Nervous System Support
Human studies have shown there is a significant increase in alpha brain waves within 40 minutes of ingesting L-theanine. Alpha brain waves are associated with a state of wakeful relaxation as well as focus and creativity. An eight-week, double-blind study found that 400 mg of L-theanine per day was safe and effective while also possessing neuroprotective, mood-enhancing and relaxation properties. Another double-blind study showed L-theanine lowered heart rate, improved salivary IgA levels and reduced sympathetic nervous system activation, demonstrating its ability to support a healthy stress response.
The stress-buffering mechanisms of L-theanine have been connected to its ability to increase serotonin and dopamine production in the brain. Research conducted on animal models suggests that L-theanine supports overall nervous system health and activity due to its positive effects on serotonin, dopamine and GABA levels as well as its modulation of excitatory and inhibitory neurotransmission. Studies have shown L-theanine crosses the blood-brain barrier intact and can continue to balance neurochemistry by blocking glutamate transport, reducing levels of extracellular glutamate and supporting the release of dopamine and glycine from neurons.
Liver Health, Detoxification, Antioxidant Status and Cardiovascular Support
Research designed to study ethanol metabolism and hepatic toxicity in animals suggests L-theanine increases specific liver enzyme activity that reduces blood ethanol concentration within one hour of ingestion compared to controls. It is also assumed L-theanine’s effect on cytochrome P450 2E1 activity, glutathione recycling and antioxidant mechanisms enhances detoxification and preserves healthy liver function. L-theanine has also been shown to significantly impede hydrogen peroxide-induced cell death and therefore may play an important role in supporting liver health. Further studies demonstrate L-theanine, along with green tea polyphenols, provides substantial antioxidant activity, which supports healthy LDL and oxidation levels and may subsequently benefit cardiovascular health. Animal and human research also suggests L-theanine supports healthy blood pressure already within the normal range due to its ability to diminish the negative side effects of caffeine.
