Green tea and cancer prevention

One thing you hear a lot about in relation to green tea is its potential to prevent, or reduce the risk of, cancer. A lot of sites you stumble across refer to this like it's a fact, but I thought I'd search around the internet for some information on what studies have actually been carried out and whether they support the claim that green tea reduces the risk of cancer. 

Overall, in a nutshell, it looks as though the answer of actual studies into this claim is "maybe, but more research is required". One study that reached such a conclusion (if you can call it a conclusion) was carried out by "The Cochrane Collaboration" and can be found here. 

The study starts out with a good background of why these claims about green tea's cancer prevention properties are made. Basically the tea plant called "'camellia sinensis" has in it an active ingredient polyphenol, which contains catechins (which are potent antioxidants). So this has led to people suggesting that green tea polyphenol may prevent cell proliferation. Observational studies have also led people to believe that green tea could have cancer preventative effects.

Their research considered 51 studies with more than 1.6 million participants. 27 studies attempted to find a connection between green tea consumption and cancer of the digestive tract, primarily of the upper gastrointestinal tract, 5 with breast cancer, 5 with prostate cancer, 3 with lung cancer, two with ovarian cancer, 2 with urinary bladder cancer one with oral cancer, 3 further studies included people with different cancer diagnoses.

Some highlights include: 

• limited evidence that green tea reduces the occurrence of liver cancer;
• limited to moderate evidence that green tea reduces the risk of lung cancer; and
• limited moderate to strong evidence for pancreatic, lung, and colorectal cancer.

Overall the study concluded that "there is insufficient and conflicting evidence to give any firm recommendations regarding green tea consumption for cancer prevention". The study noted that any trends found needed to be treated with caution because the majority of studies were conducted in Asia where culturally it's more common to drink tea. Nonetheless they say that if you don't exceed the daily recommended limit (which they say is 3 to 5 cups a day), those people who like drinking green tea should keep drinking it and that it seems to be safe.

So if you're looking for answers on green tea and cancer prevention, I'll be blunt and say I don't think the answers you want are out there (yet, anyway). But if you enjoy drinking green tea then overall the studies suggest you should just go on drinking it. I personally believe if you don't like it you shouldn't take it up just in the hope it might prevent cancer. But if you enjoy it anyway, it may end up being a nice bonus!