Tea
BREWING TEA to get the most EGCG: Brewing green tea starting in boiling water for 4 to 5 minutes dissolves the most EGCG, nearly 3x as much as 1 minute in 80oC water.
FROM JAMA 2006 To investigate the associations between green tea consumption and all-cause and cause-specific mortality. Hazard ratios of mortality due to all causes associated with different green tea consumption frequencies for men were 1.00 (reference) for less than 1 cup/d, 0.93 for 1 to 2 cups/d, 0.95 for 3 to 4 cups/d, and 0.88 for 5 or more cups/d, respectively. The corresponding data for women were 1.00, 0.98, 0.82, and 0.77, respectively. So benefit rises even to 5 cups daily.
FROM LINUS PAULING DIET AND OPTIMAL HEALTH MEETING MAY 18-22, 2005
For those with patience, here are my notes from one of the best professional meetings for M.D. and Ph.D. professionals involved in nutrition professionally. They have not been edited, and are slowly moving on to the appropriate web pages of Nutrition Investigator. Any mistakes are my own, but I have done my best to capture relevant exciting information I learned at this conference.
Remarks on flavanols – Dr. Katan
Effect of tea flavanols on risk of second heart attack
Cups per day024Relative risk of 2nd heart attack100% (control)80%55%
Green tea catechins absorbed mainly in large intestine; one main component of red wine and green tea is gallic acid
Tea effect causing prevention of cancer is EGCG, 0.26 uM in humans from 2-3 cups per day. Better without a meal; increased EGCG lasts 12 hours. 20 known enzyme effects already, like activation of demethylation genes to activate oncogene reverting cancer cells to normal!!
Just chewing tea leaves is great.
Green tea blocks prostate cancer.
TEA HELPS PREVENT COLON CANCER
“Research shows that epigallocatechin-3-gallate (EGCG), an antioxidative polyphenol in tea, can inhibit the activity of the §-catenin/Tcf signaling pathway in vitro. More than 80% of human colon cancers have a mutation in the APC gene, and those that do not have mutations in §-catenin. ”
update: A cup of tea may delay onset of Alzheimer’s disease. Effects of green tea last a week, while black tea works only a day. Tea inhibits brain enzymes linked to the disease. Newcastle Univ. Study, Phytotherapy Research Online, Oct. 2004
TEA is currently unique as something one can consume. At the American Aging Association meetings during the summer of 2003, I heard many presentations with comments about tea. One study reported that animals who received the human equivalent of 4 cups of green tea per day lived 10% longer. This is the first legitimate report I have heard of anything we can eat that will prolong life span. Antioxidants like vitamin C and E reduce risk of disease, and genetic manipulation of DNA will extend life of creatures, but green tea is the only thing likely to conveniently extend life. This may relate to the fact that Chinese have been consuming green tea for thousands of years.
In this essay, I highlight Proceedings of the Third International Scientific Symposium on Tea and Human Health, as published in The Journal of Nutrition 133:3242S-3318S (October, 2003). The key ingredient in tea is a class of compounds called flavonoids.
Tea has been consumed since the beginning of its history 5,000 years ago. The polyphenolic flavonoids include catechins associated with antiangiogenic, antibacterial, anticarcinogenic, antiinflammatory, antithrombotic, antiviral, hypocholesterolemic, hypoglycemic and vasodilatory effects. Brief definitions:
antiangiogenic – prevents growth of new blood vessels required by cancer tumors
antibacterial – kills bacterial infections
anticarcinogenic – blocks cancer formation
antiinflammatory – prevents inflammation, which is currently held to be a key factor causing heart attacks
antithrombotic – prevents blood clots, which leads to heart attacks and strokes
antiviral – kills viruses
hypocholesterolemic – reduces cholesterol
hypoglycemic – reduces blood sugar levels. High blood sugar levels leads to adult-onset diabetes
vasodilatory – relaxes blood vessels lowering blood pressure
Tea may reduce the risk for cancer and heart disease. Medical costs of these are $157 billion per year, productivity costs are $352 billion per year.
Type of Tea. flavonoid concentration (micrograms/mL)
brewed hot tea. 541-692
instant tea 90-100
decaffeinated tea. 10-20% less than regular
THREE KINDS OF TEA – All real tea comes from Camellia sinensis. Other than water, it is the most widely consumed beverage in the world [how about substituting it for coke and pepsi when one is thirsty?].
Black is made via a postharvest “fermentation”, an auto-oxidation catalyzed by polyphenol oxidase.
Green tea is steamed shortly after picking to deactivate the polyphenol oxidase.
Oolong tea is allowed to partially oxidize, half way between green and black.
There is no evidence to suggest any adverse consequences from tea consumption..
Bioavailability and antioxidant activity of tea flavanols after consumption of green tea, black tea, or a green tea extract supplement Susanne M Henning et al Am. J. Clinical Nutrition, Dec 2004; 80: 1558 – 1564. Conclusions: Our observations suggest that green tea extract supplements retain the beneficial effects of green and black tea and may be used in future chemoprevention studies to provide a large dose of tea polyphenols without the side effects of caffeine associated with green and black tea beverages.
Food. Flavonols. . proanthocyanidins. . range of these Rank
good molecules
apple with peel. 19. 147. . 166. 4
blueberries. 4.. 131. . 230. 2
broccoli raw 3.. not determined(nd). . nd. nd
chocolate, dark. 24.. 165. . 189. 3
chocolate, milk. 6. . 88. . 94. 7
orange juice. 29.. nd. . nd. nd
tea, black. 16. . nd. . 132. 5
tea, green. 316. . nd. . 319. 1
wine, red. 30-40. . 85-145. . 130. 6
wine, white. 2-3. . 2-3. . 5. 8
As all of these contain different compounds, it is useful to consume some of all of them on a regular basis. But as a general rule of thumb, darker things (blueberries, tea, red wine, dark chocolate) are better for your health than lighter (white) things – white potatoes, white rice, white bread, white pasta.
Other papers in this symposium describe the following:
Mechanisms of cancer prevention by tea constituents – “the scientific evidence is strongest for the potection of DNA from oxidative damage” from antioxidants in tea.
Black Tea Consumption reduces total and LDL cholesterol in mildly hypercholesterolemic adults.- it appears tea does reduce LDL levels
The epidemiology of tea consumption and colorectal cancer – unfortunately, it does not presently appear protective.
For likely mechanism of green tea action via EGCG, see J Biol Chem 277 (34): 30574-80 (Aug. 23, 2002)
