Polyphenols in Green Tea and Oolong Tea by LiveStrong
Green tea contains unfermented mature tea leaves, while oolong
tea uses semi-fermented leaves. Both contain substances called
polyphenols in greater quantities than fully fermented black tea.
These polyphenols may contribute to a healthier body. Polyphenols
occur in different concentrations and in different forms in both
types of tea. Of the two, green tea appears to contain a higher
concentration of polyphenols and may have the most health-giving
Polyphenols work as antioxidants. That means they absorb
compounds in the body called free radicals. Left in the body, free
radicals can cause harm to living cells and even alter genetic
material within a cell. As experts from the University of Maryland
Medical Center point out, these free radicals are linked to
conditions such as heart disease and general ageing in the body.
Polyphenols also occur in foods such as berries, legumes and some
cereals. However, green and oolong tea offer some of the highest
doses of polyphenols in the diet.
Green tea contains a form of polyphenols known as catechins. In
a 1999 study published in the American Journal of Clinical
Nutrition, scientists from the University of Geneva established a
link between catechins and raised fat oxidization in the
body. This means that green tea polyphenols may temporarily
increase metabolism of body fat. Green tea is so rich in
polyphenols that many health food stores now stock green tea
extract in the form of pills.
Oolong tea contains a lower concentration of polyphenols than
green tea, but a higher concentration than traditional black leaf
tea. However, a 2005 study by Dr. David Shafer from the University
of Texas at Tyler suggests that oolong tea may contain some
polyphenols not found in green or black tea. He linked these oolong
polyphenols with lowered blood sugar, something that may help in
diabetes prevention and treatment, though the tests are not
Polyphenols from both green and oolong tea may help improve
overall health. However, polyphenols appear to have a particular
link with slightly reduced levels of cancer. Countries where people
drink a lot of green and oolong tea often have low cancer rates.
Research cited by the University of Maryland also points to lowered
risk of breast cancer in women, as well as reduced chance of the
disease spreading in affected women who drink green tea.
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