Botanical name: Camellia sinensis Common name: Green tea, black tea ("regular"), Oolong tea
For centuries, numerous cultures have used tea, not only as the preferred beverage, but also for its medicinal properties. (the earliest recorded use dates back to around 2700 B.C). Even in today's cultures, tea is a key component in ceremonies and celebrations, and can be found on the table at meal time in most parts of the world. There are, however, a few countries, such as the United States, where coffee has become the more popular beverage. Green, black, and Oolong teas are all made from the leaves of the same plant, (Camellia sinensis), but have a different chemical make-up and taste dependent upon the fermentation process used. While Oolong tea is partially fermented and black tea is fully fermented, green tea leaves are allowed to wither in the hot air and are then pan-fried to halt the fermentation process, (also known as oxidation), allowing green tea to retain more of the medicinal chemicals found in the leaves.
GREEN TEA FOR A HEALTHY BRAIN
Scientists are toasting both black and green teas as a growing body of research suggests that their components may offer cognitive health benefits. A new study by researchers at Douglas Hospital Research Centre (DHRC) in Quebec, published in a recent issue of the European Journal of Neuroscience, reports that regular consumption of either tea may reduce the risk of age-related degenerative brain disorders such as Alzheimer's disease. "Our findings showed that administration of both black and green tea extracts and catechins strongly blocked death of neurons," says Remi Quiron, scientific director of the DHRC. "This is the first study to show this beneficial effect of both black and green tea."
Also supporting the potential role of green tea in preventing and treating Alzheimer's disease is a study by University of South Florida researchers, published last fall in the Journal of Neuroscience. The scientists used extracts of epigallocatechin-3-gallate (EGCG), an antioxidant polyphenol found in green tea that has also been studied for anticancer effects. Mice that received daily EGCG injections had lower buildups of beta-amyloid, a protein that can lead to nerve damage and memory loss like that of Alzheimer's disease.
Researchers also reported that supplements may be the best way to achieve this result, since other substances present in green tea may hinder the EGCG from providing a beneficial effect.
Finally, a study published in the April 2006 issue of the Journal of Nutrition suggests that green tea catechins may help boost learning ability related to reference and working memory. Japanese researchers studied the effects of green tea extracts on the cognitive learning ability of rats, using a concentration of catechins classified as 63% EGCG, 11 % epicatechin, 6% epigallocatechin, and 6% 'epic ate chin gallate.
Actions And Properties
Lowers total cholesterol
Raises HDL ("good" cholestorol)
Nervous system related pain
Green Tea for HEALTHY WEIGHT LOSS
Green tea catechins, a class of polyphenols, are known to promote weight loss by increasing the metabolism of fats by the liver (thermogenic effect), inhibiting lipase (fat absorption enzyme) in the digestive tract, and providing a feeling of satiety and fullness. Catechins do not function as a stimulant.
Green Tea Weight Loss Research
Five independent clinical trials with at total of 500 subjects have documented that green tea catechins have reduced body weight, especially abdominal body fat. These results were even more dramatic in obese subject, who observed a greater reduction. In one particular double-blind study involving 80 subjects, the Green Tea treatment group received 588 catechins daily and showed a significant (P<0.01) weight loss of 1.7kg in 12 weeks.
A separate study conducted in Switzerland supported these results (Dullo , et.al 1999). This study found that green tea weight loss programs can raise metabolic rates and speed up fat oxidation. Compared with placebo and caffeine alone, subjects taking green tea extracts have a significant increase in daily energy expenditure. The study noted that: green is superior to stimulant diet drugs, which can have adverse cardiac effects, especially in obese individual’s with hypertension and other cardiovascular complications.
GREEN TEA DECREASES ABDOMINAL FAT
Excess abdominal fat is associated with high cholesterol an increased risk of heart disease and stroke. In another Green Tea study, healthy male and female subjects were given 500-600mg per day of Green Tea Catechins 12 weeks without any dietary restriction. Green Tea Catecheins significantly (P<0.01) reduced abdominal fat, measured by CT scan.
Other studies support these findings. In a study of 1200 Taiwanese adults, adults who consumed tea more than once a week for six months had 19.6% less body fat and 2.1% reduction in waist to hip ration compared to non-tea drinkers (Wu, 2003). Another study found a significant decrease in body weight, body mass index, waist circumference, body fat ratio, abdominal fat, glucose, insulin and total cholesterol in a group of 23 healthy adult males who took 483mg catechins per day over a twelve week period (Hase 2001). In those who took 118mg daily only weight, body mass index and insulin changed.