Evidence supporting the use of: L-theanine
For the health condition: Fear (excessive)

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Synopsis

Source of validity: Scientific
Rating (out of 5): 2

L-theanine is an amino acid found primarily in green tea (Camellia sinensis) and is often used as a supplement to promote relaxation and reduce stress. Its use to support or treat excessive fear—often conceptualized as anxiety or acute stress—has some basis in scientific research, although the evidence is not robust. Several small-scale human clinical trials and animal studies have examined the effects of L-theanine on anxiety and stress-related behaviors. These studies suggest that L-theanine may increase levels of neurotransmitters such as GABA, serotonin, and dopamine, which help regulate mood and emotional responses. In humans, L-theanine (usually in doses of 200–400 mg) has been shown to reduce subjective feelings of stress and anxiety, as well as physiological markers like heart rate and cortisol, particularly in stressful situations. However, most studies address general anxiety or stress rather than “fear” specifically, and research is often limited by small sample sizes and varying methodologies.

There is some evidence from neuroimaging studies that L-theanine modulates brain activity in areas involved in emotional processing. However, no major clinical guidelines endorse L-theanine for pathological fear or anxiety disorders, and more rigorous research is needed to determine its efficacy. In summary, while there is some preliminary scientific support for L-theanine’s calming effects, the evidence is modest (rated 2/5), and its role in treating excessive fear specifically remains to be fully validated.

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