Green tea originates in the Yunnan region of southwest China, where legend attributes its discovery to the mythical emperor Shen Nong around 2737 BCE, when tea leaves reportedly blew into a pot of boiling water he was preparing. Whatever the precise historical accuracy of that legend, tea cultivation and ceremony became deeply embedded in Chinese culture for thousands of years before spreading to Japan, where it developed its own elaborate ceremonial tradition, and eventually worldwide.
Green tea is distinguished from black and oolong tea by minimal oxidation processing, which preserves higher levels of catechins — the antioxidant plant compounds now studied extensively for cardiovascular and metabolic effects, and the basis of green tea's substantial modern research profile.
Green tea catechins have a consistent, if modest, evidence base across multiple independent meta-analyses, primarily for weight and metabolic markers in people who are overweight or obese. An umbrella review found significant effects on weight and waist circumference. A separate meta-analysis of 11 randomized controlled trials (613 participants) found green tea catechin supplementation significantly reduced waist circumference and triglycerides, and increased HDL cholesterol, though found no significant effect on blood pressure. A meta-analysis specifically combining green tea with exercise training found a small but consistent additional weight-loss benefit compared to exercise alone.
Researchers across these reviews consistently describe the effects as "small" or "modest" rather than dramatic — this is not a remedy that produces major weight loss or cardiovascular transformation on its own, but a real, replicated, small effect layered onto broader lifestyle factors. The consistency of direction across several independently-conducted meta-analyses is what earns green tea a "Moderate" rating.
Leaves steamed or pan-fired shortly after picking (to halt oxidation), then dried; steeped in hot water as tea, or ground into powder (matcha) for a more concentrated preparation.