Although there have been several human studies looking at the bioavailability of EGCG when administered in varying doses, there have been no studies that have specifically investigated the cognitive effects of this catechin in humans. Therefore, the purpose of this study is to assess the cerebral blood flow (using Near Infrared Spectroscopy), cerebro-electrical activity (EEG) and behavioural effects of EGCG. A randomised, double-blind, placebo-controlled, balanced crossover study will assess the effects of 135 mg and 270 mg pure EGCG in 24 healthy, young adults (18-35). Prior to the first active study day participants will attend a screening/training visit where relevant exclusion criteria will be assessed including any food sensitivities. They will also complete a caffeine consumption questionnaire in order to control for potential caffeine withdrawal effects as a result of restrictions of the study.