If you want a beverage that is delicious, nutritious and provides a plethora of health benefits, you can’t beat green tea. It’s a great source of antioxidants that can help prevent cardiovascular disease, protect your brain from Alzheimer’s disease, and even keep certain cancers at bay, like colorectal and breast cancer. The predominant antioxidants in green tea are the polyphenols EGCG ad EGC, which protect your cells from the ravages of free radicals.
While green tea’s heart benefits have been proven in numerous studies, its effect on high blood pressure is less clear. Since green tea has such a positive effect on overall heart health, you would think that would translate to blood pressure benefits. But the problem is that green tea’s caffeine content could potentially reverse those benefits, and some studies have indicated that caffeine may even increase blood pressure.
So researchers in Korea conducted a new study to learn more about green tea’s effect on blood pressure, as well as insulin resistance — two of the biggest predictors of metabolic syndrome. Given caffeine’s potential to increase blood pressure, they specifically studied decaffeinated green tea extract.
Twenty 13-week-old rats were randomly assigned to either the treatment group, which received oral decaffeinated green tea extract, or the control group. Prior to the administration of the green tea researchers measured the body weight, blood pressure, heart rate and blood glucose of all the rats after they fasted for 12 hours. They performed the tests again at the end of the study, when the rats were 25 weeks old.
After analyzing and comparing results, researchers found that the rats that received the decaffeinated green tea extract had significantly lower blood pressure, plasma glucose and insulin levels, which is potentially great news for those who suffer from metabolic syndrome. Researchers also noticed an improvement in endothelial function, which translates to better platelet adhesion, immune function and electrolyte balance.
Since this study was conducted with rats, human studies obviously need to be conducted to further validate these preliminary findings. But without a doubt, green tea is proving itself to be a health tonic of sorts.
Between the heart, cancer and brain-protective effects, and now its potential to lower blood pressure and insulin levels, you really can’t go wrong by drinking a cup of freshly brewed green tea once or twice a day. If you’re looking specifically for blood pressure-lowering benefits, though, stick with the decaffeinated form to avoid the potentially negative effects of caffeine.
If you don’t like the taste of green tea, you can take green tea extract in supplement form. These can be found at most health food stores or vitamin retailers.
 Ihm S-H et al. Decaffeinated green tea extract improves hypertension and insulin resistance in a rat model of metabolic syndrome. Atherosclerosis. 2012. doi: 10.1016/j.atherosclerosis.2012.07.006.