Tea is an Important Part of a Healthy Diet

These days there are many more choices to select from, including organically grown teas, allowing for wider variety of flavors and aromas. It is believed that over 5,000 different teas exist in the world currently.
 
All tea comes from a single type of plant, the camellia sinensis, just as all wine comes from vitis vinifera. Within each of these plant families there are several varieties. In addition to the specific variety, the environment, weather, and of course the tea master (or wine maker) all play a role in making each tea different. Every country has its own nuances--just as the differences in a wine from France, Italy, or California are easily recognized, soon you will know if your tea is from Japan, China, Taiwan, India, or beyond. Experience and celebrate the differences within the world via a cup of tea.

Dietary polyphenols, nutrition and health

Even more than vitamins C and E, polyphenols are the most abundant antioxidants in our diet. The large number of scientific studies published to date show the wide diversity of biological effects from polyphenols, and suggests a protective role against a variety of diseases. However, few of the documented effects have been validated in a nutritional context. Most authors have used high polyphenol doses which could only be reached through drug administration.
 
The biological effects associated to food consumption could be very different from those observed in these studies. It is therefore essential to characterize precisely dietary intake, metabolism, and tissue exposure to polyphenols.  Researchers at the Linus Pauling Institute are currently constructing a comprehensive database and food composition table for polyphenols, based on the analysis of the scientific literature. More than 500 phenolic compounds are already included with over 40,000 content values. Such a database will allow estimating the dietary intake of all these compounds. Beyond intake, the bioavailability of several polyphenols representative of different classes found in food has been compared in animal and human experiments.
 
If you have read much about the health benefits of tea, you may have heard of EGCG, also known Epigallocatechin gallate. EGCG is the main active and water-soluble component of green tea - there is more EGCG found in green tea than any other type of catechin, and it is known for being the potent antioxidant of the catechin group.
 
EGCG accounts for 9-13% of green tea in net weight.  Because of its peculiar stereochemical structure, EGCG possesses much stronger anti-oxidant activities and plays an important role in preventing cancer and cardiovascular diseases.

Choosing the Right Tea by Time of Day

Not all teas are created equal, in terms of caffeine content.  In general, black tea has the most caffeine (40 grams per serving - half that of coffee at 80 grams per serving), followed by Oolong tea (30 grams per serving), green tea (20g/serving), white tea (15g/serving), decaf tea (2g/serving), and herbal tea (0g/serving).
 
It should come as no surprise, then that many people enjoy tea in part for the relief from fatigue it provides, and make their tea choices in no small part by how much caffeine a particular tea contains.  So, many people enjoy black teas in the early morning, oolong teas for lunch, green teas in the afternoon, and white or herbal teas in the evening.

Specific Health Benefits

The many health benefits of green tea, all of which have been demonstrated in way or another across many scientific studies, include:

• Cancer protection
• Cholesterol reduction
• Blood pressure reduction
• Antibacterial and antiviral activity
• Protection against radiation
• Reduction of body fat
• Reduction of blood sugar
• Polyphenols, highest in Green and White Teas

References

The Linus Pauling Institute, Oregon State University.