Assessment of anti-stress, behavioural, and neurophysiological effects of L-theanine: A randomised, double-blind, placebo-controlled, crossover trial

The present study will test the anti-stress, cognitive, and neurophysiological effects of acute L-theanine, Chamomile, Alpha GPC and phospholipid administration when compared to a placebo (vehicle control), using a randomised, controlled, double-blind, crossover design. Participants will be required to attend three sessions. The first visit is a screening and practice session, assessing eligibility and familiarising participants with cognitive tasks. Finally, structural brain information will be obtained during an MRI scan. Subsequently, two testing days will be conducted a minimum of 48 hours apart. Participants will be assigned to a treatment sequence, such that one of each treatment is received across the two testing days. At testing days participants will receive a standardised lunch upon arrival, followed by a 30-minute break, then undergo baseline assessment of stress, mood, and cognitive function. After baseline assessment, treatment will be administered. 30-minutes after administration of treatment, participants will once again undergo assessment of stress, mood, and cognitive function, followed by recording of brain activity during rest and an attention task using magnetoencephalography (MEG). After this, the assessment of stress, mood, and cognitive function will be conducted a third time. Participants will consume all interventions orally as a drink of approximately 430 ml (14.5 fl oz). Both active and vehicle control treatments contain identical ingredients of sweeteners (crystalline fructose and sucralose) and preservatives (sodium benzoate, potassium sorbate) , gum acacia and malic acid. In addition, the active treatment contains L-Theanine (200 mg, L-Tea-Active), L-Alpha Glycerylphosphorylcholine (Alpha GPC; 25 mg)), phosphatidylserine (1mg) and chamomile (10 mg).