Green tea and cancer – What the research says December 16 2014

posted by Nick Schäferhoff

It is no secret that research in recent years has uncovered more and more health benefits of green tea. From reduced risk of diabetes to improved brain function and increased fat burning, it appears that the drink is a powerhouse for human health.

One thing that often gets cited in these circumstances is its role in cancer prevention. On every corner of the internet there are people shouting about green tea being the best thing one can consume in order to keep cancer at bay.

One of the reasons for this is the fact that there are much lower rates of certain cancers in Asia where the consumption of green tea is traditionally higher than in the western world. The theory goes that the drink is partially responsible for this.

It has also been established that oxidative damage contributes to cancer development and that antioxidants can have a protective effect. Green tea is nothing if not full of antioxidants and should therefore, at least theoretically, help in the prevention of cancer.

Since things only have to be repeated often enough to be accepted as facts, I wanted to know if that is actually true. Is the claim for green tea's positive effect on cancer development backed by research? Have we found clear link between drinking tea and cancer prevention?

Green tea – effective cancer prevention?

The short answer is: no. In humans, no clear link between green tea consumption and the prevention of cancer has been established. Trials have been inconclusive. We don't know for sure whether the drink can forestall or even cure cancer and if it can, we don't know how it does.

The long answer, however, is that a lot of things point to yes. More and more research comes out showing that green tea is in fact beneficial in the prevention of some cancers. For example:

  • Breast cancer: A meta-analysis of observational studies found a 22% lower risk of developing breast cancer in women who drank the most green tea. (1)
  • Prostate cancer: Another study found a 48% lower risk in the development of prostate cancer in men drinking the beverage. (2)
  • Colorectal cancer: The risk of developing cancer of the digestive tract was 57% lower among women who drank green tea regularly. The study looked at 69,710 Chinese women. (3)
  • Oral cancer: A double-blind interventional study found that consumption of tea extract had a positive effect on oral lesions which are thought to be precursors to oral cancer. (4).
  • Lung cancer: A study looking at smokers found that among those who drank green tea during the trial, there was a 31% decrease in cancer indicators. (5) This goes along with the so called Asian paradox: Asia has much lower rates of lung cancer than there should be given the prevalence of smoking in the population.
  • Liver cancer: In another trial, individuals at increased risk of liver cancer who consumed a daily green tea polyphenol supplement were reported to have reduced indicators of cancer risk (6).

While green tea is certainly not a wonder drug, there are promising results which show that it might have its place in cancer prevention. To me personally that is just another reason to indulge in the delicious drink.

**Side note: From a health point of view, putting milk in your tea might be a bad idea, because it can reduce the amount of antioxidants (7)