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Friday, October 10, 2008

White Tea Versus Green Tea

by dr.AY

In a daily life, green tea is well known has several health benefits such as acting as an antiviral, contributing to oral health by inhibiting bacterial plaque, acting as an anti-inflammatory, maintaining a healthy, active metabolism and circulatory system. In European Journal of Cardiovascular Prevention and Rehabilitation, it found that found that the consumption of green tea rapidly improves the function of (endothelial) cells lining the circulatory system; endothelial dysfunction is a key event in the progression of atherosclerosis. Results showed that endothelium-dependent brachial artery dilatation increased significantly after drinking green tea, with a peak increase of 3.9 per cent 30 minutes after consumption. The effect of caffeine consumption (or hot water) was not significant. While black tea has been associated with improved short and long-term endothelial performance, this is the first time that green tea has been shown to have a short-term beneficial effect on the large arteries. Another study has already shown that green tea reverses endothelial dysfunction in smokers. What about white tea?

There are several major categories of tea, which are distinguished by different processing methods and, consequently, different concentrations of specific tea polyphenols. Fresh tea leaves are rich in polyphenolic compounds known as catechins. When tea leaves are intentionally broken or rolled during processing, catechins become oxidized through the action of polyphenol oxidase enzymes present in the tea leaves. The oxidation of catechins, known as fermentation in the tea industry, causes them to polymerize and to form larger, more complex polyphenols known as theaflavins and thearubigins.

White teas are unfermented teas made from very young tea leaves or buds that are steamed immediately after harvest to inactivate polyphenol oxidase and then dried. Consequently, white teas usually contain higher concentrations of catechins than other teas. Tea leaves that are destined to become green teas are withered by air drying prior to heat inactivation of polyphenol oxidase. Although still rich in catechins, green teas may have slightly lower catechin concentrations than white teas. During the processing of black teas, tea leaves are rolled and allowed to oxidize or ferment fully, resulting in high concentrations of theaflavins and thearubigins and relatively low catechin concentrations. Oolong teas are only partially fermented—they are allowed to oxidize for shorter periods than black teas. Consequently, oolong teas fall between green and black teas with respect to their catechin concentrations. Since different categories of tea contain different amounts of catechins, theaflavins, and thearubigins, it is important to distinguish between the consumption of different categories of tea when examining studies of tea consumption and chronic disease risk. White tea do not go through any oxidation. As a result, white teas contain the highest level of antioxidants of any tea variety.

What are the benefits of white tea?

With a higher level of antioxidants compared to to green tea, white tea has proven to have greater cancer-fighting ability. White tea is known to boost the immune system and can help to fight viruses and infection-causing bacteria. Studies have also demonstratedd that white tea is fluoride-rich and can prevent the growth of dental plaque, the chief cause of tooth decay. The polyphenols in white tea have also been shown to lower cholesterol, reduce blood pressure and fight fatigue. White tea also contains much less caffeine per cup than green, oolong, or black tea. If consumed properly, white tea can relieve stress as well.

New studies conducted at Pace University have indicated that White Tea Extract (WTE) may have prophylactic applications in retarding growth of bacteria that cause Staphylococcus infections, Streptococcus infections, pneumonia and dental caries. Researchers present their findings today at the 104th General Meeting of the American Society for Microbiology. White tea was more effective than green tea at inactivating bacterial viruses. Results obtained with the bacterial virus, a model system; suggest that WTE may have an anti-viral effect on human pathogenic viruses. The addition of White Tea Extract to various toothpastes enhanced the anti-microbial effect of these oral agents. Studies have also indicated that WTE has an anti-fungal effect on Penicillium chrysogenum and Saccharomyces cerevisiae. In other study, Scientists say they have proven ingredients in white tea are effective in boosting the immune function of skin cells and protecting them against the damaging effects of the sun. Researchers believe that white tea extract's anti-oxidant properties are the reason the extract was effective; if so, it also suggests that the agent may provide anti-aging benefits. The same process of oxidative stress in skin cells that leads to immune system damage can also promote skin cancer and photo damage, such as wrinkling or mottled pigmentation.

Related sources:

Tea Health Research Journal of Chinese Medicine

Potential effects of tea on health - Wikipedia, the free encyclopedia

White tea - Wikipedia, the free encyclopedia

The benefits of green tea in reducing an important risk factor for heart disease

Health Benefits of Green Tea - Journal Watch (General)

Mary Ann Liebert, Inc_ - The Journal of Alternative and Complementary Medicine - 11(3)521

White Tea Beats Green Tea In Fighting Germs. ScienceDaily

Tea and Chronic Disease Prevention

White Tea Extract Protects Skin from Sun.SeniorJournal.com

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