Here in part two of my examination of green tea, I’ll look at the evidence for its use against gastrointestinal cancers and breast cancer. In each case, the news is good.
A large population study from China involved 931 colon, 884 rectum and 451 pancreatic cancer patients. Compared to about 1,550 healthy patients, it found that consuming green tea was linked with a lower risk of these tumors. This was stronger among women than men. Another study involved 185 esophagus, 893 stomach, 362 colon and 266 rectal cancer patients, compared against more than 21,000 healthy people. It proved that the risk of stomach cancer was lower among green tea drinkers. The best protection was in seven cups a day.
A recent review of world literature — with 25 studies in 11 countries — had three main conclusions:
1. Green tea reduced the risk of colorectal cancer by 18%;
2. Black tea showed some protective effect in women, but may promote colorectal cancer in men; and
3. More clinical studies are needed to confirm the above findings.
Several large population studies show that green tea could reduce the risk of breast cancer. One, in Los Angeles, showed that the risk of breast cancer was lowest in green tea drinkers, intermediate in green and black tea drinkers, and unchanged in black tea drinkers.
Another, from Japan, tested 472 breast cancer patients whose diseases were in stages I, II or III in terms of severity. They drank between two and eight cups of green tea a day. Among those in the first two stages, eight cups a day meant a lower cancer recurrence rate and a longer disease-free period (compared to two cups).
Another big review looked at 13 old studies from eight countries. It concluded that green tea is linked with a lower risk of breast cancer, while black tea may in fact promote such cancer.