For this study, researchers randomly selected 56 obese adults with high blood pressure to receive a green tea extract capsule or a placebo (no green tea), daily for three months. It was a double blind study, so neither researchers nor participants knew who received the green tea extract and who received the placebo. The green tea capsule contained 379 mg of green tea extract, which provided 208 mg of a green tea antioxidant called EGCG (epigallocatechin gallate).
Study participants were advised to follow their usual diet and exercise routines, and several measures of cardiovascular disease risk were assessed at the beginning and end of the three-month study period. These measures included blood pressure and blood levels of cholesterol, triglycerides, glucose, creatinine, tumor necrosis factor, C-reactive protein (CRP), and total antioxidant status. (Creatinine gives an indication of kidney function. Tumor necrosis factor and CRP are linked with inflammation; higher levels mean more inflammation.)
After three months, compared with the placebo group, the green tea group experienced significant
This study showed green tea extract improves blood pressure, insulin resistance, inflammation, oxidative stress, and cholesterol and triglyceride levels in obese people with high blood pressure. These are markers of heart health, but the study did not consider long-term outcomes, such as heart attack or new diabetes cases. Still, the results are impressive and suggest green tea has a role to play in keeping hearts happy. Our tips can help you fine-tune your heart health plan.
(Nutr Res 2012; 32:421-7)