Almost 300 tea studies were completed last year. Tea is also hot among consumers: U.S. sales rose from $1.84 billion in 1990 to about $5.03 billion in 2002, says a trade group. Americans have long preferred coffee over tea. Coffee may be good, but it’s increasingly hard to ignore the evidence that tea is good for you.
Long seen simply as a reason to relax or a folk remedy for colds and digestive problems, tea may cut the risk of some serious illnesses, including heart disease, cancer and osteoporosis, mounting research suggests.
A healthier heart
Studies show the polyphenols in tea interfere with free-radical molecules that cause low-density lipoprotein (or “bad’) cholesterol to form plaque inside the heart’s arteries. Studies show polyphenols have anti-clotting effects and can relax blood vessels, so they function better.
Such findings suggest tea could cut heart-disease risk or help tea drinkers fare better after a heart attack. In a study last year in the journal Circulation, Kenneth J. Mukamal followed more than 1,900 people who’d had a heart attack. Heavy tea drinkers (14 or more cups a week) had a 44 percent reduced risk of dying compared with nondrinkers. Moderate tea drinkers showed some protection, too.
If the findings can be duplicated, and tea does indeed reduce heart-attack deaths, “that is a major public-health benefit,” Mukamal said.
A Dutch study published last year also found that tea drinkers had half the risk of heart attack, and one-third the risk of a fatal one, compared with nondrinkers.
Number of pounds of tea each person consumes on average each year, by country. Each pound equals about 200 servings.
United States 0.72
Source: International Tea Committee (figures from 1999-2001)
An important component of both the Mukamal and Dutch studies was that the participants, men and women mostly in their 60s, were similar in other ways age, education, income and exercise, smoking and drinking habits. Some researchers suggest it may not be tea that helps tea drinkers but other lifestyle aspects, such as diet and exercise.
“Maybe it isn’t just an artifact of healthier people drinking tea,” Mukamal said.
Possible cancer fighter
Various studies have suggested tea may reduce the risk of bladder, stomach, colorectal, esophageal and oral cancers.
Dr. Zuo Feng Zhang of the Jonsson Cancer Center at the University of California, Los Angeles, published a study in 2001 showing that drinking green tea can cut the risk of chronic gastritis by half. Chronic gastritis causes lesions which can progress to stomach cancer.
“This is a very promising area,” says Zhang. “Polyphenols can prevent cancer and also have vitamins C and E … very good for people’s health. We have very strong confidence that the effect we found with chronic gastritis is real.”
Zhang plans a randomized trial to see whether tea can prevent precancerous lesions in the stomach. And he and his UCLA colleagues have launched the largest clinical trial ever focusing on bladder cancer in smokers and former smokers. (Tobacco use is a major risk factor for bladder cancer.) Investigators will give the study participants a green-tea extract or an experimental drug called Iressa to gauge their effects at preventing cancer. Previous research at UCLA showed that green tea can cut growth of bladder cancer tumors in animals and humans.
Zhang’s work on stomach cancer is among several studies suggesting that tea has preventive properties. A 1994 study in the Journal of the National Cancer Institute found that drinking green tea reduced the risk of esophageal cancer by 60 percent, while a study presented at the Third International Symposium on Tea and Human Health last fall in Washington found that women who consumed high amounts of tea had a 60 percent reduced risk of rectal cancer. Researchers at Rutgers University have even identified a compound in black tea, called TF-2, that caused colorectal cancer cells to die in laboratory experiments leaving normal cells unaffected.
Taiwanese researchers last year announced that longtime tea use appears to strengthen bones. The study, published in the Archives of Internal Medicine, found hip-bone density 6.2 percent higher in people who drank tea habitually for 10 years or more, compared with nondrinkers. People who drank tea for six to 10 years had 2.3 percent higher density.
A British study, published in 2000 in the American Journal of Clinical Nutrition, also found higher bone density in women who drank at least one cup of tea a day.
Tea may confer a protective effect on bones because it contains both fluoride and phytoestrogens, which act like estrogen, which is known to strengthen bone.
Early research suggests that tea can inhibit the growth of bacteria on teeth and that a white tea-extract cream can protect against changes in the skin caused by the sun.
The most common therapeutic use for tea in the U.S. to ease cold symptoms is also getting a closer look. A particular compound found in green tea, methylated epigallocatechin gallate, can block the production of two substances in the body that cause sneezing, watery eyes and coughing.
There may be yet another reason to drink tea, says Jeffrey Blumberg, a tea researcher at Tufts Nutrition Center in Boston. He calls it the “substitution effect.”
“How do you go about making healthy food choices? … If you drink tea, you may not be having some of this stuff that’s not good for you.”
– Source: Los Angeles Times