Green tea extract may lower blood pressure

Daily supplements of extracts from green tea (Camellia sinensis) may reduce blood pressure, cholesterol and markers of oxidative stress, and all within three weeks, says a new study.

Reductions of systolic and diastolic blood pressures of 5 and 4 mmHg, respectively, were observed following daily supplements of green tea extracts, while total cholesterol levels were reduced by 10 mg/dL, according to findings of a randomised, double-blind, placebo-controlled, parallel study.

The study adds to an ever-growing body of science reporting the potential health benefits of green tea and its extracts, which already range from reduced risks of cardiovascular disease, Alzheimer’s, and certain cancers.

Researchers from the University of Florida, Brigham and Women’s Hospital and Harvard Medical School, and the Nutritional Science Research Institute, Boston, report their findings in Nutrition.

Green tea contains between 30 and 40 per cent of water-extractable polyphenols, while black tea (green tea that has been oxidized by fermentation) contains between 3 and 10 per cent. Oolong tea is semi-fermented tea and is somewhere between green and black tea.

The four primary polyphenols found in fresh tealeaves are epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG), and epicatechin (EC).

High blood pressure (hypertension), defined as having a systolic and diastolic blood pressure (BP) greater than 140 and 90 mmHg, is a major risk factor for cardiovascular disease (CVD) – a disease that causes almost 50 per cent of deaths in Europe.