Can Green Tea Help Prevent Cancer?


Tea consumption is associated with a reduced risk of [heart disease], stroke,” and premature death in general, with each additional cup of green tea a day associated with a 4% lower mortality risk. So, maybe, “drinking several cups of tea daily can keep the doctor away”—as well as the mortician. But, what about cancer?

“There is growing evidence from laboratory, [population], and human intervention[al] studies that tea can exert beneficial disease-preventive effects,” and further, may actually “slow cancer progression.” Let’s review some of that evidence.

Not only do those who drink a lot of tea appear to live years longer than those who drink less; drinking lots of tea may delay the onset of cancer. Now, these are in Japanese tea cups, which only contain half a cup; so, the highest category here is greater than or equal to five full cups of tea, not ten. The women that did get cancer appeared to get it seven years later if they had been drinking lots of tea compared to those who consumed less, whereas men had a three-year delay, the difference male versus female due, potentially, to their smoking habits.

Green tea may be able to interfere with each of the stages of cancer formation: the initiation of the first cancer cell, promotion into a tumor, and then, the subsequent progression and spread. Cancer is often initiated when a free radical oxidizes our DNA, causing a mutation. But within 40 minutes of drinking green tea, you can get a nice “spike” in the antioxidant power of your bloodstream. “This increase…, in turn, [may] lower oxidative damage to DNA and so decrease [the] risk of cancer.”

Furthermore, in terms of “genoprotective effects”—protecting our genes—”pre-existing oxidation-induced DNA damage was…lower” after drinking green tea, suggesting that it can boost DNA repair as well. But, we didn’t know for sure, until now.

There’s a DNA-repair enzyme in our body called OGG1, and within one hour of drinking a single cup of green tea, we can boost its activity—though after a week of tea drinking, we can boost it even higher. So, “regular intake of green tea [may have] additional benefits in the prevention and/or repair of DNA damage.” Tea is so DNA-protective, it can be used for sperm storage for fresh samples until they can be properly refrigerated.

And so anti-inflammatory, it can be used for pain control as a mouthwash after wisdom tooth surgery. And, in terms of controlling cancer growth, at a dose of green tea compounds that would make it into someone’s organs after drinking six cups of tea, it can cause cancer cells to commit suicide—apoptosis (programmed cell death)—while leaving normal cells alone.

There’s lots of chemo agents that can kill cancer through brute force. But, that can make normal cells vulnerable too. So, “green tea appears to be potentially an ideal agent” for cancer prevention: “little or no adverse side effects,” efficacious for multiple cancers “at achievable dose levels,” and can be taken orally.

We have a sense of how it works: by stopping cancer cells from growing and causing them to off themselves. It’s cheap and has a history of safe, acceptable use. But this was all based on in vitro studies in a test tube. It needs to be evaluated in human trials: give people with cancer green tea to see if it helps—which we’ll explore, next.

Doctor’s Note

Sorry about the cliffhanger! I just wanted to offer a good backgrounder on the antioxidant and anti-inflammatory activities. Stay tuned for Can Green Tea Help Treat Cancer?

You don’t have to wait for info on prostate cancer, though. See my recent videos: Preventing Prostate Cancer with Green Tea and Treating Prostate Cancer with Green Tea.

I also have a few older videos:

That wisdom tooth thing is so interesting. It can also just be used as an anticavity mouth rinse (see What’s the Best Mouthwash?).

Is Caffeinated Tea Dehydrating? Watch the video!

If you haven’t yet, you can subscribe to my videos for free by clicking here.

In health,

Michael Greger, M.D.

Michael Greger, M.D., is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous “meat defamation” trial. Currently Dr. Greger proudly serves as the Director of Public Health and Animal Agriculture at the Humane Society of the United

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