Green Tea and Blood Pressure
The Effect of Green Tea on Blood Pressure
The major risk factor for stroke and cardiovascular disease is hypertension.
In a cross-sectional study of 1507 Chinese subjects, the role of regular green tea consumption was investigated.
After adjustment for confounding factors, including BMI, lifestyle and diet, it was observed that daily consumption of 120–599ml of green tea per day for at least one year reduced the risk of developing hypertension by 46%, compared to those subjects consuming less than 120 ml per day.
Consuming more than 600 ml per day reduced the risk by 65%.
These results provide one possible explanation for the reduced mortality from cardiovascular disease associated with regular green tea consumption.
Russian scientists, after prolific studies on patients, praise tea's ability to delay atherosclerosis, strengthen capillaries, thin the blood, lower blood pressure and "exert a favorable regulatory effect on every vital component of human metabolism".
For example, Mikhail A. Bokucha, at the Bakh Institute of Biochemistry in Moscow, reported that tea in Russian patients had been shown to relieve high blood pressure, headaches, prevent thrombosis and strengthen blood vessels.
He called tea catechins "superior to every known capillary-strengthening drug".
Sedative Action
California investigators in 1984 reported that decaffeinated green tea had a sedative action in mice.
According to James P. Henry, M.D., a professor of psychiatry at Loma Linda University School of Medicine, the tea, stripped of its caffeine, seemed to relax the animals by affecting the central nervous and neuroendocrine system.
The tea definitely also lowered the animals' blood pressure. What's more, the mice getting the tea lived longer. Dr Henry credits so-called bioflavonoids in tea.
French scientists have found the same thing in rats eating two specific flavonoid compounds; their blood pressure dropped significantly.
The French concluded that the bioflavonoids probably lower blood pressure by performing like beta blocker drugs.
Other related studies have indicated that the rare amino acid called, L-theanine (found in abundance in Japanese green tea), while effecting the chemical state of the brain, also positively effects the peripheral nervous system, diminishing hypertension and contribute to normalizing blood pressure.
The amazing thing is that even green tea with caffeine has the same calming and relaxing effect.
The L-theanine present in green tea seems to counterbalance the effect of caffeine. This amino acid actually acts antagonistically against the stimulatory effects of caffeine on the nervous system.
Research on human volunteers has demonstrated that L-theanine creates a sense of relaxation in approximately 30-40 minutes after ingestion via at least two different mechanisms.
First, this amino acid directly stimulates the production of alpha brain waves, creating a state of deep relaxation and mental alertness similar to what is achieved through meditation.
Second, L-theanine is involved in the formation of the inhibitory neurotransmitter, gamma amino butyric acid (GABA).
GABA influences the levels of two other neurotransmitters, dopamine and serotonin, producing the key relaxation effect.
What Are ACE Inhibitors?
Another type of drugs used for heart disease are ACE inhibitors.
As it turns out, green tea has more ACE-inhibiting compounds than any other herb that can be used for heart disease (as well as at least 10 beta-blockers, 7 calcium channel blockers and 16 diuretics).
One of the reasons for high blood pressure can be put down to overproduction of an enzyme (angiotensin converting enzyme or ACE) which causes angiotensin I to be converted into angiotensin II.
Angiotensin II is a hormone which causes constriction of blood vessels and an increase in blood pressure.
ACE inhibitors, as the word suggests, inhibit this conversion allowing the blood vessels to dilate causing a decrease in blood pressure.
Dr Y. Hara, from the Japan Society for Bioscience and Biotechnology, has shown that green tea catechin impedes the action of ACE and suppresses production of angiotensin II.
He has also demonstrated that the administration of catechin to mice with Spontaneously Hypertensive Rate (SHR) can reduce high blood pressure.
Results of his experiments indicate that daily consumption of green tea catechins have the ability to prevent a rise in blood pressure.
These studies demonstrate the wonderful effect of green tea on blood pressure and that consuming a moderate amount of green tea, on a regular daily basis, can reduce blood pressure levels, improving overall heath.
These studies demonstrate the wonderful effect of green tea on blood pressure and that consuming a moderate amount of green tea, on a regular daily basis, can reduce blood pressure levels, improving overall heath.
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