From the 1970s to the 1990s, epidemiological studies — the kind following large populations’ eating and disease patterns — found tea drinking might be associated with better health. But no clear cause-and-effect relationship between health and tea was established.
“More careful clinical and laboratory studies are needed,” said Johanna Dwyer, a professor at Tufts Medical School in Boston, at the fifth International Scientific Symposium on Tea and Human Health held Sept. 19 at the U.S. Agriculture Department.
But recent studies have been promising. What did they find? Just about every cell in the body could potentially benefit from tea — with virtually no downsides.
All true tea (white, green, oolong and black, as opposed to herbal varieties) comes from one plant: Camellia sinensis. The differences are in how they are processed, with white and green being the least processed, oolong in the middle and black the most processed. The processing changes the nutritional profile and some of the health effects. But no matter the process, all tea leaves are dense with flavonoids, health-promoting chemicals found in fruits, vegetables, whole grains and most plants.
“About one-third of the weight of a tea leaf is flavonoids, which is high, especially when you consider there are virtually no calories,” said Jeffrey Blumberg, professor of nutrition science and policy at Tufts University and chairman of the tea symposium. “A serving of tea is like adding a serving of fruits or vegetables to your diet.”
But can tea produce more health benefits than fruits or vegetables? Flavonoid research results are exciting but mixed, and there is still a lot to learn.
There are “small but possibly significant health effects, but study quality needs to improve. . . . The variety, geography, processing and brewing of tea must be considered since it will dramatically change flavonoid content and possibly associated health benefits,” Dwyer said, adding, “Tea is not a drug, and to expect a drug-like effect is unrealistic.”
So, while not a miracle cure-all, there is some exciting news about tea:
●It helps your heart by keeping blood vessels unclogged and flexible. Blood pressure and stroke risk were reduced in epidemiological and clinical studies (even with sugar added).
In a double-blind, randomized study in which hypertensive men drank one cup of black tea daily, both systolic and diastolic blood pressure were reduced. The blood-pressure-lowering effect was maintained even after a large intake of fatty, sugary food, which usually constricts blood vessels, showing that “cardiovascular protection can be achieved even without much sacrifice and with normal intakes,” said Claudio Ferri, a professor at Italy’sUniversity of L’Aquila School of Internal Medicine and co-author of the study.