It is the constituent polyphenols, a type of flavonoid-containing catechin and proanthocyanidins that have earned tea such a reputation for imbuing good health. Of the three most common types of tea–black, green, and oolong–green tea contains the most polyphenols, at about 15 to 30 percent by weight. About half of that is epigallocatechin gallate (EGCC). But black and oolong teas are not far behind. Tea’s polyphenols, especially EGCG, are recognised as an antioxidant. They prevent free-radical damage and have even been found to lower levels of free radicals produced by the environmental toxin paraquat. EGCG has been found to be twenty times stronger than vitamin E in protecting brain lipids, which are very susceptible to oxidative stress. Polyphenols are also anticarcinogenic.
Surveys of Japanese tea drinkers show that those consuming four to six cups daily have lower rates of breast, oesophagal, liver, lung, and skin cancers than those who drink less or none at all. Other studies support these findings, indicating that drinking green tea can reduce the occurrence of a broad range of cancers. Green tea prevents blood platelet aggregation, the “clumping together” of blood that can lead to blood clots, heart attacks, and stroke. Tea’s polyphenols, along with its vitamin C content, also help strengthen blood vessel walls. In fact, the consumption of green tea with meals has been shown to reduce the occurrence of arterial disease, while a study of six thousand Japanese women who were nondrinkers and nonsmokers over the age of 40 found that those who drank about five cups of green tea daily had a 50 percent decrease in the risk of stroke.
Teestrauch, Kamelie (German); théier, Rose du Japon, Camelia (French); Camelia té (Italian); Camelia (Spanish); An Hua Ch’A, Assam Tea, Cay, Ch’A, Green Tea, Hsueh Ch’A, Lo Chieh Ch’A, Ming, P’U Erh Ch’A, P’U T’O Ch’A, Shui Sha Lien Ch’A, Wu I Ch’A
Tea has long been a popular beverage. The processing of and amount of essential oils and tannins in tea leaves, which varies depending on where and how the tea was cultivated, create a variety of flavour nuances. In general, green tea has a milder flavour than black tea. Drinking tea after a meal aids in the digestion of fats, reducing the risk of arterial disease. Tea flowers are edible; they are often battered and deep fried. An oil obtained from the seeds is also edible.
CNS stimulant, mild diuretic, cardiac stimulant, antioxidant, cholesterol reducing, cancer preventive (green tea is stronger). It also exerts “vitamin P”-like effect (= helps in normalising an increased microvascular permeability and fragility), in which black tea is stronger.
Allergies, arteriosclerosis, asthma, cancer, catarrh, cholera, high cholesterol, colds, congestion, coughs, depression, diarrhea, digestive tract infection, dysentery, external viral conditions (black tea), fatigue, fever, flu, hangover, hepatitis, influenza (green tea), migraines, obesity, tooth decay, typhus, and tumors.
Theophylline, a chemical found in both green and black tea, is extracted from the leaf of the tea plant. Theophylline relaxes the smooth muscles supporting the bronchial tubes, reducing the severity of asthma and bronchitis. Drinking either green or black tea provides theophylline in small doses (0.02 to 0.04 percent), which may not be large enough to affect asthma.
Atherosclerosis and high cholesterol
Green tea lowers total blood cholesterol and low-density lipoprotein (LDL, or “bad”) cholesterol without side effects. Clinical studies have shown that green tea slows the oxidation of LDL cholesterol into forms that can cause atherosclerotic plaques, although researchers describe this effect as mild. Black tea has a similar effect. In one study, people who drank five or more cups of green tea compared to those who drank one or fewer had a 42 percent less chance of death due to stroke. Even those who drank one cup a day got some benefit, and the benefit increased according to the number of cups consumed.
Breast cancer, endometriosis, fibrocystic breasts
The polyphenols in green tea occupy many of the sites on the exteriors of cells that otherwise would receive oestrogen. This keeps the cells from receiving oestrogen, reducing the effects of oestrogen on the body. This stops oestrogen from stimulating the growth of cells in breast, ovarian, and uterine cancer. In one study, women in Japan who had long-term high intakes (five cups a day) of green tea had improved prognosis if they developed breast cancer.
Some animal studies have shown that the polyphenols in green tea may offer significant protection against cancers of the pancreas, prostate, urinary tract, head and neck, colon, stomach, lung, and small intestine.
Colorectal cancer and food poisoning
Green tea catechins kill many types of foodborne bacteria, especially Clostridium bacteria, which are associated with colon cancer. Laboratory studies with animals have found that regular consumption of green tea catechins prevents the growth of colorectal tumours.
A couple of human studies have shown that those who consume three cups or more of green tea a day have a 33 percent reduced risk of type 2 diabetes compared to those who drink less than one per day. Even green tea extracts containing 544 milligrams of polyphenols a day lowered insulin levels in patients with borderline diabetes or diabetes over two months. Other parameters such as blood sugar, inflammatory markers, and insulin resistance did not change.
In two studies involving 1,000 people, green tea was applied as an ointment three times a day, and 54 percent of the people had their warts cleared by week sixteen compared to only 35 percent in the placebo group.
Liver disease and gout
Researchers have found that components in green tea are able to protect liver cells in rats when they are exposed to hepatotoxic agents. These compounds help to safeguard the linings of liver cells from damage from oxygen free radicals released by toxins. Also, green tea may be helpful for gout, as its polyphenols inhibit the enzyme xanthine oxidase, which is responsible for the buildup of uric acid in the blood. This is how the conventional treatment, allopurinol, works.
Green tea catechins prevent Streptococcus mutans from forming dental plaque. (This may explain why early Asians cleaned their teeth with whisks of green tea leaves—before the invention of toothpaste.)
Green tea has a fat-burning capability that promotes fat loss and weight loss and prevents or limits weight regain. In one study, subjects took 90 milligrams of green tea polyphenols and 50 milligrams of caffeine three times a day and fat burning increased by 41 percent, and the amount of calories burned by the body increased as well. These benefits were not seen with caffeine alone, so there is something else in green tea that promotes fat burning and hypermetabolism.
Green tea may protect the skin from the effects of harmful free radicals that can lead to wrinkling. In one study, women who used a 10 percent green tea cream and 300 milligrams of an extract twice a day for eight weeks had improvement in the elasticity of the skin, but so did the women in the placebo group.
Dosage (Divided Daily)
• Dried Powder: 1,500 – 3,000 mg
• Powder Extract: 500 – 1,500 mg (50% EGCG)
Caffeine content may cause CNS stimulation and diuresis if consumed in large amounts.
Interactions with other drugs
Tannins can bind to iron, thus reducing absorption. Separate intake by at least 2 hrs.
Balch, P. A., & Bell, S. J. (2012). Prescription for herbal healing (2nd ed.). New York, N.Y.: Avery.
- Herbalpedia (2013)
- Mars, B. (2007). The desktop guide to herbal medicine: the ultimate multidisciplinary reference to the amazing realm of healing plants, in a quick-study, one-stop guide. Laguna Beach, CA: Basic Health Pub.
Skenderi, G. (2003). Herbal vade mecum: 800 herbs, spices, essential oils, lipids, etc., constituents, properties, uses, and caution. Rutherford, N.J.: Herbacy Press.
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