Green Tea for Cognitive Function

Research suggests that green tea and its constituent compounds — particularly the catechin EGCG, L-theanine, and caffeine — may offer modest benefits for certain aspects of cognitive function, including attention, working memory, and emotional perception, based on a small number of randomized controlled trials and supporting review literature. Studies indicate that L-theanine alone appears to support attention and working memory in middle-aged and older adults, while matcha green tea as a whole food showed selective improvements in specific cognitive domains such as social acuity and, in one sex-stratified finding, overall cognitive scores in women, though primary outcome measures in these trials frequently did not reach statistical significance. Reviews of the broader polyphenol and plant-based diet literature position green tea among several foods associated with brain-protective effects, likely through antioxidant and anti-inflammatory mechanisms, and one review highlights the synergistic potential of caffeine and L-theanine together, though the evidence base for that combination remains mechanistically focused rather than clinically confirmed. Overall, the body of evidence is characterized by small sample sizes, inconsistent findings across outcomes and populations, and a reliance on short-duration trials, meaning that while the direction of the research is generally favorable, firm conclusions about green tea's role in supporting cognitive function cannot yet be drawn.