Background: Prolonged periods of stress may lead to negative health consequences. AlphaWave® L-Theanine was safe and efficacious during an acute stress challenge. However, double-blind, placebo-controlled clinical trials investigating the longer term effects of L-theanine supplementation on stress are warranted.
Methods: Thirty healthy adults (18-65 years) with moderate stress were randomized to AlphaWave® L-Theanine (400 mg L-theanine/day) or placebo (n = 15/group) for 28 days. Stress was assessed by salivary cortisol, Perceived Stress Scale (PSS) and Depression, Anxiety and Stress Scale-21; sleep was assessed by the Healthy People Sleep Quality Index and actigraphy device; cognition was assessed by Computerized Mental Performance Assessment System; mood was assessed by Profile of Mood States. All outcomes were measured at baseline, Days 14 and 28. Safety included vital signs, clinical chemistry, haematology and adverse events (AEs).
Results: All AEs were resolved by the end of the study period or upon subsequent follow up, and out of range laboratory values and changes in vital signs were deemed not clinically relevant following AlphaWave® L-Theanine supplementation. Participants supplemented with AlphaWave® L-Theanine had decreases of 12.92% (p = 0.051) and 17.98% (p = 0.04) in PSS scores after 14 and 28 days, respectively, while those on placebo had respective decreases of 9.74% (p = 0.061) and 17.88% (p = 0.009). There were no significant differences between groups for change in salivary cortisol. The AlphaWave® L-Theanine group demonstrated decreased time asleep after 28 days and significantly reduced light sleep after 14 and 28 days compared to placebo (p ≤ 0.040). The AlphaWave® L-Theanine group significantly improved by 21.79% and 21.33% in Stroop test correct reaction time after 14 and 28 days, respectively, while those on placebo improved after 28 days only (p = 0.005).
Conclusions: AlphaWave® L-Theanine supplementation for 28 days was safe and significantly decreased perceived stress significantly decreased perceived stress and light sleep, improved sleep quality and enhanced cognitive attention in the studied population. Larger, randomized controlled trials with longer duration of AlphaWave® L-Theanine supplementation are warranted to reduce inter-individual variability and the potential placebo effect.
Trial registration: ClinicalTrials.gov identifier, NCT05808595.
Keywords: l-Theanine; Cognition; Mental health; Mood; Stress.
© 2024. The Author(s).