Tea: a health drink?

Recent research indicates that drinking tea can prevent cancer and heart diseases. However, not everyone is buying this idea

Published: Monday 31 July 2000

Wonder beverage of the new mil it is available anywhere in the world, is inexpensive, easy to prepare and stimulating too. Now, research shows that apart from being a refreshing beverage, tea is also a health drink. At the recently-held India International Millennium Tea Conference in New Delhi, scientists and planters from across the world gathered to, one, exchange their findings on the medicinal value of tea and, two, to promote the cuppa as a health drink in this millennium.

Among other things, tea holds the promise of preventing many other types of cancer including breast and prostrate, says John Weisburger of the American Health Foundation, a non-profit research centre. Weisburger and his colleagues believe that the potential benefit is due to its polyphenols -- the major component of the soluble constituent of tea. Polyphenols affect certain enzyme activity and slow the conversion of normal cells to tumour cells, they say.

Another researcher at the Rutgers University, usa , C S Yang, says that his studies on mice and rats showed that green tea and black tea inhibit cancer formation. "I think it is a healthy beverage but more research is needed before we can conclude that it prevents certain types of cancer," he says.

"Abundant experimental and epidemiological data accumulated mainly in the last decade, from several laboratories worldwide, provides convincing evidence that polyphenolic anti-oxidants present in green as well as in black tea are capable of affording protection against cancer in a variety of animal tumour bioassay systems," says Hasan Mukhtar, research director at the Case Western Reserve University (cwru ), Cleveland, usa .

Initial studies in this area of research reported from cwru showed that the consumption of tea and its polyphenolic fraction afforded protection against chemical carcinogen or ultra violet radiation-induced skin cancer in mouse model. This work laid the foundation for many subsequent studies from several laboratories around the world.

Mukhtar says that collectively, these studies showed that tea consumption affords protection against chemical-carcinogen induced lung, fore-stomach, pancreas, liver, breast and colon cancer in mice, rats and hamsters.

"The studies have shown that green as well as black tea may also prevent prostrate cancer," he says. These findings may also explain the geographical difference in prostrate cancer incidence. It is important to note that people in Japan and China, who traditionally consume a diet having low fat and several cups of tea, have one of the lowest rates of prostrate cancer in the world. The incidence of prostrate cancer in India, a population that consumes tea regularly, is lower than in the western countries," Mukhtar says.

Tea has been shown to strengthen blood vessels and to decrease the cholesterol level in the bloodstream. Epidemiological studies have shown the preventive effect of green tea consumption against atherosclerosis and coronary heart disease. In some studies, tea consumption has been shown to afford protection against high cholesterol levels and high blood pressure.

"We believe that along with the inherent goodness of tea, with the new developments in the areas of health, tea is set to be the "wonder beverage of the new millennium," says R S Jhawar, chairperson, Consultative Committee of Plantation Associations, Calcutta.

However, some scientists are not too sure about the results. Barbara Howard, vice-chairperson of the nutrition committee for the American Heart Association says that although some studies have shown tea to be beneficial for heart disease, yet there is no long-term, large randomised trials on human to prove its effectiveness. She adds: "We think tea can be a part of a healthy diet," she says but there is no conclusive evidence that it has beneficial effects on heart disease. "We don't want people to think that by drinking large amounts of tea they can ignore what's proven to be beneficial for heart diseases -- lowering cholestrol, for instance."

Adds Colleen Doyle, director of nutrition and physical activity for the American Cancer Society: "The science isn't there yet. It looks really promising but in terms if human data, the jury is still out. I usually tell people, If you like tea, drink it, but keep eating your fruits and vegetables. We know for sure that fruits and vegetables are protective against cancer. We can't say that at this time about tea.

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