Green tea is known to reduce hypertension and has been used as a medicine in China for at least 4,000 years. How does green tea lower high blood pressure?
Why is it effective
The secret of lies in the fact green tea is rich in catechin polyphenols, particularly epigallocatechin gallate, which is a powerful anti-oxidant.
It is made from the leaves of the Camellia Sinensis plant. The leaves are steamed, which prevents the EGCG compound from being oxidized. By contrast, black and oolong teas, which come from the same plant, are made from fermented leaves, which results in the EGCG being converted into other compounds that are not as effective in preventing and fighting various diseases.
How Does It Lower High Blood Pressure (BP)?
It enables blood vessels to relax. Tea has caffeine but, unlike coffee, it actually relaxes you and your blood vessels and lowers BP naturally without side effects.
ACE, one cause of high blood pressure, is inhibited
Studies show that green tea catechins, especially EGCG, inhibit ACE (angiotensin converting enzyme), that causes the tiny muscles surrounding the arteries to clamp down, making the arteries smaller, which forces your BP to rise. (source: Actis-Goretta L, et al: Inhibition of angiotensin converting enzyme activity by flavanol-rich foods. J Agric Food Chem. Jan 2006; 54: 229-34). If green tea can do this naturally, why take an artificial ACE inhibitor such as ramipril.
Salt uptake is blocked
Laboratory tests have shown that green tea blocks salt uptake in the intestine leading to lowered BP readings. Also theanine, a protein from the tea, lowered blood pressure in genetically hypertensive rats but not in normal ones. (Source: Kreydiyyeh SI, et al: Tea Extract Inhibits Intestinal Absorption of Glucose and Sodium in Rats. Comp Biochem Physiol Pharm Tox Endocrin. July 1994; 108: 359-365). That is good news for those of us who are genetically predisposed to hypertension.
Reduced risk of hypertension for middle-aged people
Recent research, following an eight year study, has shown that middle-aged people who drank more than 600ml of green tea each day have a 65% lower risk of developing hypertension. People who drank between 110ml and 600ml of it daily for more than a year showed 46% lower risk of high blood pressure.
People who did not drink it or who drank less than 110 ml daily had no protection from hypertension.
This protection from the development of hypertension by drinking the tea did not show up statistically until after one year of daily use. Short-term human trials were inconclusive.
Given all the evidence, green tea is most effective at reducing hypertension if we drink four or five cups of green tea each day. “It is Better to be deprived of food for three days, than tea for one” (Ancient Chinese Proverb). Making green tea part of your daily diet can help lower your high blood pressure naturally.