Tea Bush

Tea plants can grow into trees of 30 feet if left at peace, but on tea plantations tea plants are pruned to about 3 feet. Tea plants grow only in warm climates at altitudes ranging from sea level to 7,000 feet. The best teas, grow at higher altitudes where the leaves mature more slowly. A tea plant may take from 2 to 5 years to be ready for picking, but once productive, it can provide tea leaves for close to a century. Only the smallest and youngest leaves are picked for tea, the two leaves and bud at the top of each young shoot.


Kinds of tea

Kinds of tea differ only in the amount of fermentation. Green tea leaves are steamed, black tea is fermented, oolong is partially fermented. Unfermented leaves contain the highest concentration of polyphenols, chemicals that act as powerful antioxidants. Steaming prevents the loss of polyphenols, which is why there are so many more benefits to green tea.

Growing conditions like altitude, climate and soils vary, this results in a multitude of distinctive teas. The way the leaves are processed, is also important in developing the individual characteristics of a tea.

Green Tea caffeine

Green tea caffeine is one half or a third as much as in coffee. That means you can drink twice to three times as much. The most caffeine is found in black tea. Caffeine is stronger the smaller the tea leaf. A higher caffeine content is in the tea leaves that are fermented longer. Fresh tea leaves contain about 4% caffeine.

If you do not want green tea caffeine, you can try decaffeinated green tea, but it still has some caffeine. Not all of the green tea caffeine can be taken out by the decaffeinating process only most of it. There is debate about how much of the benefits are lost by the decaffeinating process. Some say the health benefits are ruined.


Green Tea health benefits

There are a wide variety of green tea health benefits. Some of these claims have not been validated by scientific evidence but some claims have been validated. One example is the Ohsaki study. the Ohsaki study. The study looked at green tea consumption and mortality due to cardiovascular disease, cancer, and all causes in Japan:

The Ohsaki National Health Insurance Cohort Study, a population-based, prospective cohort study initiated in 1994 among 40,530 Japanese adults aged 40 to 79 years without history of stroke, coronary heart disease, or cancer at baseline. Participants were followed up for up to 11 years (1995-2005) for all-cause mortality and for up to 7 years (1995-2001) for cause-specific mortality.

CONCLUSION: Green tea consumption is associated with reduced mortality due to all causes and due to cardiovascular disease but not with reduced mortality due to cancer.


Green Tea and weight loss

The combination of green tea's anti-oxidants (polyphenols) with caffeine appears to have an effect that neither substance can have on its own. Green tea's caffeine does not appear to raise the heart rate or blood pressure the way that other forms of caffeine do, but it does seem to raise the metabolic rate. Polyphenols seem to work with the body to intensify fat burning.


Green Tea and cancer

There have been several studies that suggest that green tea helps protect against a range of cancers, including lung, prostate and breast cancer. This has been attributed to flavonoid phytochemicals called polyphenols. The polyphenols in tea mainly belong to the type called catechins. The major catechins in green tea leaves are epigallocatechin gallate (EGCG), epicatechin gallate (ECG), epigallocatechin (EGC) and epicatechin (EC). Of the catechins, EGCG is the most abundant one in green tea leaves. White tea is almost as rich in catechins as green tea but is different in composition and less well studied. Black tea leaves have a much lower content of these catechins. EGCG is brain permeable.


EGCG inhibits tumour cell growth by binding to a receptor on cells.
A paper in the April, 2004 issue of Nature Structural & Molecular Biology by researchers at Kyushu University in Japan led by Hirofumi Tachibana, has shown that EGCG inhibits tumour cell growth by binding to a receptor on cells called 67 LR, a cell surface protein. Several tumours produce abnormally high levels of 67 LR, and the receptor is thought to be involved in the spread of cancers through the body. The team showed that the growth of human lung cancer cells that have the receptor slows significantly when they are exposed to EGCG at the concentrations equivalent to those in the body after drinking only two or three cups of green tea. Many other chemicals in green tea, including caffeine, did not influence cancer cell growth. Nature Structural & Molecular Biology 11, 380 - 381 (01 Apr 2004)

Lifelong tea drinkers have lower incidences of heart disease, high cholesterol and some forms of cancer, they are less likely to suffer from diabetes or be overweight. Fluoride in green tea is great for your teeth and gums. Green tea may even have potential to prevent diseases like Parkinson’s and Alzheimer’s

Seed bearing fruits of Camellia sinensis by Shizhao