Evidence supporting the use of: L-theanine
For the health condition: Worry

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Synopsis

Source of validity: Scientific
Rating (out of 5): 3

L-theanine is an amino acid naturally found in tea leaves, especially green tea (Camellia sinensis). Its use for supporting or treating worry—commonly referred to as anxiety—has a growing body of scientific evidence, with several clinical trials and systematic reviews conducted in recent years. L-theanine is believed to promote relaxation without sedation, primarily by influencing neurotransmitter levels in the brain, such as GABA, serotonin, and dopamine. Studies have shown that L-theanine supplementation (typically 200-400 mg) can help reduce subjective stress and anxiety in both healthy individuals and those experiencing heightened worry. For example, randomized controlled trials have demonstrated reductions in self-reported anxiety and improvements in some cognitive functions under stress after L-theanine administration.

Additionally, EEG studies indicate that L-theanine increases alpha brain wave activity, which is associated with a relaxed yet alert mental state. However, while the evidence is promising, it is not yet robust or widespread; many studies have small sample sizes, short durations, or are limited to acute rather than chronic worry. Most research supports its role as an adjunctive or supportive agent rather than a standalone treatment for clinical anxiety disorders. Overall, L-theanine is considered safe with minimal side effects, making it a popular option for those seeking non-pharmacological approaches to manage mild to moderate worry or situational anxiety.

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