L-theanine (γ-glutamylethylamide) is an amino acid found mainly in the green tea plant. This study examined the effects of an L-theanine-based nutritional drink on mood responses to a cognitive stressor. Additional measurements included an assessment of resting-state cognitive performance and alpha oscillatory activity using magnetoencephalography (MEG). Thirty-four healthy adults aged 18-40 years participated in this double-blind, placebo-controlled, balanced crossover study.
The primary outcome measure, subjective stress response to a multitasking cognitive stressor, was significantly reduced one hour after administration of the L-theanine beverage compared with placebo. Salivary cortisol response to the stressor was reduced three hours after administration of the active treatment. No treatment-related changes in cognitive performance were observed. Resting-state alpha oscillatory activity was significantly higher in posterior MEG sensors after active treatment compared with placebo at two hours after administration; however, this effect was seen only in those subjects who suffered more severely from anxiety.
This change in resting-state alpha oscillatory activity was not correlated with the change in subjective stress response or cortisol response, suggesting that further research is needed to assess the functional relevance of these treatment-induced changes in resting-state alpha activity.
These results support the anti-stress effects of l-theanine.
Found at Alkohol adé (german)
