Tea is the most consumed beverage in the world after water and has been used by man for millennia. Modern medical research continues to highlight the special health benefits of a specific tea - green tea, a drink made from the leaves of the tea plant (Camellia sinensis).
This same plant produces green tea, black tea and oolong teas, but green tea is truly unique. The vast differences arise largely from the time of harvesting and how the leaves are treated and processed after they are reaped. As soon as the leaves are picked, they are heated by steaming to lock in their bright, green character. This provides green tea's high polyphenol content and uplifting flavour, described as fresh and grassy.
Much of its many health benefits have been attributed to potent antioxidants found in the tea leaves called polyphenols. These substances are also found in smaller amounts in other plant foods, like cocoa.
The polyphenols in green tea play critical roles as antioxidants in neutralising free radicals, controlling inflammation, and supporting cellular health. Bacteria in the colon break down polyphenols into more simple compounds, called phenols. These and other polyphenol-derived molecules are transported to the liver, where they are further transformed and delivered to all the tissues of the body.
Cardiovascular disease remains the number one killer on the planet. Chinese scientists investigating men and women diagnosed with high blood pressure found that those who consumed one to five cups daily had a 46 per cent reduced risk of developing hypertension, compared to those consuming less than one cup daily. And those who took over five cups daily were 65 per cent less likely to develop hypertension.
Data from stroke research showed that those who drank three or more cups of green tea daily had a 21 per cent lower risk of stroke, compared to those who drank less than a cup of tea daily.
Cancer is the second-leading cause of death. Green tea polyphenols have been shown in multiple studies to suppress the development and aggressiveness of several different cancers, especially breast, colon and prostate cancers.
Research suggests that drinking green tea may reduce the risk of several human malignancies. By regulating multiple pathways, green tea polyphenols can inhibit the growth of new blood vessels that feed the cancer, discouraging spread, while controlling growth and promoting apoptosis (cancer cell death).
In Japan, where green tea is very popular, surveys showed that regular green tea drinkers had a much lower incidence of breast, prostate, liver, pancreatic, lung, esophageal and stomach cancers.
A recent review suggested that green tea could be a very promising agent in the search for an effective anti-Alzheimer's medication. And in another compelling study, consuming green tea for just two months was found to improve cognitive function in patients with severe Alzheimer's.
Other research found that green tea improves cognition and memory, and suggested that these benefits should not be attributed to just one constituent, but rather to green tea itself as a beverage.
Recently, however, researchers have identified another substance that is found only in the tea plant. It is a special amino acid called theanine that accounts for the ability of tea to create relaxation while energising the drinker. Theanine is the predominant amino acid in green tea leaves and gives tea its characteristic taste, while contributing to many of its other medicinal benefits.
Although green tea contains small quantities of natural caffeine, the calming effect of the theanine in it balances the stimulating effects of caffeine on the nervous system.
Researchers have demonstrated that theanine creates this sense of relaxation about half an hour after ingestion by two separate actions:
First, it stimulates the electrical activity of the brain to produce a state of relaxation and mental alertness similar to that achieved through meditation. Second, theanine causes the brain to increase its levels of two neurotransmitters, dopamine and serotonin. These important brain chemicals produce feelings of well-being and relaxation.
Theanine is particularly useful for people under stress as it helps to alleviate the negative effects without producing sedation or drowsiness.
In order to get all the benefits from green tea listed above, the research suggests that one would need to drink several cups of green tea daily. Modern technology has resolved this problem by creating a patented green tea concentrate in powder form. Half of a teaspoonful of this powder (Herbal Tea Concentrate) makes a cup of tea (hot or cold) that provides the benefits of several cups made from regular green tea leaves. I use this green tea concentrate myself and recommend it to all my patients. It is an ideal, healthy breakfast beverage.
- You may email Dr Vendryes at tonyvendryes@gmail.com [3] or listen to 'An Ounce of Prevention' on POWER 106 FM on Fridays at 9:10 pm. Visit www.tonyvendryes.com [4] for details on his books and articles.