Green tea tested
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
- reductions in systolic (top) and diastolic (bottom) blood pressure numbers,
- decreases in blood levels of glucose, tumor necrosis factor, CRP, triglycerides, and LDL cholesterol--so called "bad" cholesterol, and
- increases in antioxidant status and HDL, or "good" cholesterol.
Sipping, moving, and eating toward your best health
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.
- Sip, and sip again. One cup of green tea provides about 35 mg of the green tea antioxidant EGCG, so you'll need about six cups of green tea daily to match the EGCG levels used in the study. Try replacing some of your water and coffee with green tea. Iced green tea works well in summer. Even if you don't reach six cups, a couple of cups daily may still provide benefits.
- Walk, bike, swim. Physical activity is a cornerstone of heart health. Even if you don't lose a single pound, being physically active can improve health in many ways. Just 20 to 30 minutes of daily walking is enough to reap important benefits.
- Limit sitting. Prolonged sitting without breaks is particularly bad for heart health. If you work a desk job, get up to stretch and walk around for a few minutes at least once an hour.
- DASH to health. The DASH--Dietary Approaches to Stop Hypertension--diet is proven to help control high blood pressure. Key components of DASH include eating 4 to 5 servings of vegetables, 4 to 5 servings of fruit, 6 to 8 servings of high-fiber whole grains, and 2 to 3 servings of low-fat dairy daily. Also keep sodium (salt) intake below 2,400 mg per day, and include plenty potassium- and magnesium-rich foods.
(Nutr Res 2012; 32:421-7)