Green and Black Tea for the Primary Prevention of Cardiovascular Disease

Summary

A Cochrane review [Abstract] 1 included 11 studies with a total of 821 subjects. Seven studies examined a green tea intervention and 4 examined a black tea intervention. There were variations in the dosage and form (drink, tablets or capsules) of the black and green tea interventions, and the duration of the interventions ranged from 3 months to 6 months. No studies reported cardiovascular events.

Black tea was found to produce statistically significant reductions in LDL cholesterol (MD -0.43 mmol/L, 95% CI -0.56 to -0.31) and systolic blood pressure (SBP) (MD -1.85 mmHg, 95% CI -3.21 to -0.48. Diastolic blood pressure (DBP) did not decrease significantly (MD -1.27 mmHg, 95% CI -3.06 to 0.53) over 6 months. Green tea produced statistically significant reductions in total cholesterol (MD -0.62 mmol/L, 95% CI -0.77 to -0.46), LDL cholesterol (MD -0.64 mmol/L, 95% CI -0.77 to -0.52) and blood pressure (SBP: MD -3.18 mmHg, 95% CI -5.25 to -1.11; DBP: MD -3.42, 95% CI -4.54 to -2.30). When both tea types were analysed together they showed favourable effects on LDL cholesterol (MD -0.48 mmol/L, 95% CI -0.61 to -0.35) and blood pressure (SBP: MD -2.25 mmHg, 95% CI -3.39 to -1.11; DBP: MD -2.81 mmHg, 95% CI -3.77 to -1.86). Adverse events were measured in 5 studies and included a diagnosis of prostate cancer, hospitalisation for influenza, appendicitis and retinal detachment but these are unlikely to be directly attributable to the intervention.