Green Tea

Research summary

• Green tea's longevity evidence rests mainly on large Asian cohort studies, with several meta-analyses and one small negative trial adding important context.
• The Ohsaki Study, following 40,530 Japanese adults for up to 11 years, found women who drank 5 or more cups of green tea daily had 23% lower all-cause mortality and 31% lower cardiovascular mortality than those drinking less than one cup a day (dose-response trends significant at p<0.001 and p=0.004); the association was present but weaker in men.
• A meta-analysis of 18 prospective cohorts covering over 55,000 deaths found the highest green tea consumers had 20% lower all-cause mortality and 33% lower cardiovascular mortality than the lowest consumers, and a broader dose-response meta-analysis of tea consumption generally found each additional daily cup was associated with roughly 1.5-4% lower risk across all-cause mortality, cardiovascular mortality and stroke.
• A large Chinese meta-analysis of 21 studies and 1.3 million participants found green tea drinkers specifically had 15% lower cardiovascular mortality than non-drinkers.
• The evidence for cancer prevention is notably weaker: a 2020 Cochrane review covering more than 1.1 million participants found green tea associated with somewhat lower cancer incidence but no association at all with cancer-specific mortality, rating the certainty of that evidence as low.
• A small trial randomizing 51 healthy adults to high- or low-catechin green tea for 9 weeks found no significant difference in adiponectin levels or any measured cardiovascular risk factor between groups.
• Overall, the mortality signal is real and reasonably consistent, but it comes almost entirely from observational cohorts concentrated in Japan and China, where tea-drinking habits correlate closely with other unmeasured lifestyle factors, and the one controlled trial available did not confirm a mechanistic effect on cardiovascular risk markers over a short follow-up.