In a study published in Science Direct, theanine consumption for stress and anxiety in human clinical trials was investigated.
Five randomised controlled trials with L-theanine (200-400 mg/day; up to eight weeks) in a total of 104 participants met the inclusion criteria.
Four studies included participants who had no pre-existing mental illnesses and one study used participants with existing mental conditions.
All studies were placebo-controlled but one study also compared L-theanine against a commonly used anti-anxiety pharmaceutical (alprazolam).
“The findings in four studies indicated significant improvements in reducing stress and anxiety,” noted the study.
It concluded: “L-theanine supplementation can assist in reducing acute stress and anxiety in people experiencing stressful situations.”