In a bid to keep cancer at bay, more and more people are turning to green tea. However, a new review of studies on the effect of green tea on cancer prevention has yielded conflicting results.
Researchers looked at 51 medium-to-high-quality studies, conducted from 1985 through 2008, that covered more than 1.6 million participants.
The studies focused on the relationship between green tea consumption and a variety of cancers, including of breast, lung, digestive tract, urological prostate, and gynecological and oral cancers.
Many of the reviewed studies took place in Asia, where tea drinking is widespread and part of the daily routine for many.
"Despite the large number of included studies, the jury still seems to be out on the question of whether green tea can in fact prevent the development of various cancer types," said lead study author Katja Boehm.
Since people drink varying amounts of green tea, and different types of cancers vary in how they grow, it is impossible to state definitively that green tea is "good" for cancer prevention.
"One thing is certain: green tea consumption can never account for cancer prevention alone," said Boehm.
The review found that green tea had limited benefits for liver cancer, but found conflicting evidence for other gastrointestinal cancers, such as cancer of the esophagus, colon or pancreas.
One study found a decreased risk of prostate cancer for men who consumed higher quantities of green tea or its extracts, said a release of the Oncology Study Group.
The review did not find any benefit for preventing death from gastric cancer, and found that green tea might even increase the risk of urinary bladder cancer.
Despite conflicting findings, there was "limited, moderate to strong evidence" of a benefit for lung, pancreatic and colorectal cancer.
The review appeared in a recent issue of The Cochrane Library.