A prospective study of 40,530 Japanese adults found that those who consumed five or more cups of green tea per day had a 26 percent lower risk of cardiovascular mortality and a 16 percent lower all-cause mortality risk compared to those drinking fewer than one cup per day. The association was linear and dose-dependent. Multiple subsequent meta-analyses of Japanese and Chinese cohort studies have confirmed that regular green tea consumption is associated with significant reductions in cardiovascular disease, stroke, and type 2 diabetes.
EGCG and Its Mechanisms
Epigallocatechin gallate is the primary catechin in green tea and its most studied bioactive compound. EGCG inhibits the enzyme VEGF (vascular endothelial growth factor) receptor that drives tumour angiogenesis. It activates AMPK, a cellular energy sensor that improves metabolic function and insulin sensitivity. It crosses the blood-brain barrier and reduces the aggregation of amyloid-beta peptides associated with Alzheimer's disease. It modulates the gut microbiome toward higher Bifidobacterium and Akkermansia populations.
Practical Consumption
Most of the evidence uses three to five cups per day as the relevant dose. Green tea contains caffeine at roughly 30 to 50mg per cup, which is half that of coffee. It also contains L-theanine, an amino acid that promotes a focused but calm alertness by modulating alpha brain waves and reducing the anxiety-provoking effects of caffeine. For those sensitive to caffeine, matcha contains the same catechins and can be prepared as a latté with plant or dairy milk.