"The antioxidants in tea prevent the formation of hazardous products that occur in the body during normal metabolic reactions," Dr. Weisburger said. "The antioxidants in tea lower the formation of these dangerous oxidized form of chemicals that may cause cancer in the human body."

Antioxidants are certain nutrients in fruits, vegetables and in this case, tea, which appear to protect the body against oxygen-induced damage to tissues that occurs constantly as a result of normal metabolism. Antioxidants are thought to protect against cancers, especially those that appear to be related to diet.

"Initially such research was carried out in Japan and China because of their customs involving green tea. Now, a number of scientists in Europe and the US have investigations on black tea. Tea is one of the most widely consumed beverages, second only to water. It has been popular for over 4000 years," Weisburger added. The most common form of tea sold in the US is often labeled as orange pekoe, pekoe or cut black tea.

Dr. Junshi Chen from the Chinese Academy of Preventative Medicine in Beijing stated for the first time his research and clinical trials point to the protective effects of tea on humans with cancer. He used a liquid mixture of green and black tea which was rubbed on precancerous lesions. This treatment significantly reduced the growth of pre-cancerous cells. Dr. Chen's research showed tea slowed the development of lung tumors and colon cancer in mice.

"In the last five years, we have studied on a comparative manner, green tea and ordinary black tea that is available in any supermarket," Dr. Weisburger added. Black tea is just as effective in cancer prevention as is green tea. They are identical because they come from the same tea leaf."

Researchers at the conference agree further research is needed to determine the value of tea in preventing cancer of various types, to test tea's effectiveness in treating pre-cancerous conditions, and to better understand substances in tea that seem to be most beneficial.

Last year, professor Lenore Kohlmeier of the University of North Carolina at Chapel Hill published a study in Nutrition and Cancer stating, "The epidemiologic studies on tea drinking and stomach cancer do not justify claims of a cancer-protective effect. A protective effect of green tea on the development of colon cancer is suggested. The evidence regarding black tea is less clear, with some indication of a risk of colon or rectal cancer with regular use of black tea."

The ACS publication, Nutrition and Cancer Prevention states, "In animal studies, some teas have been shown to reduce cancer risk, but beneficial effects of tea on cancer risk in people are not yet proven."