Can Green Tea Help Prevent Cancer?

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Within 40 minutes of green tea consumption, we get a boost in antioxidant power in our bloodstream, and, within 60 minutes, an upregulation of DNA repair.

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

“[T]ea 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. 

Please consider volunteering to help out on the site.

Image credit: Humusak via pixabay. Image has been modified.

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

“[T]ea 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. 

Please consider volunteering to help out on the site.

Image credit: Humusak via pixabay. Image has been modified.

Doctor's Note

Sorry about the cliffhanger, but I wanted to give you a good background on its antioxidant and anti-inflammatory activities. Now that you’ve learned about green tea and the preventionof cancer, check out Can Green Tea Help Treat Cancer?.

What about prostate cancer? See my videos Preventing Prostate Cancer with Green Tea and Treating Prostate Cancer with Green Tea.

You may also be interested in these somewhat older videos:

How interesting was that information about wisdom teeth? Green tea can also be used as an anti-cavity mouth rinse, which I discuss in my video What’s the Best Mouthwash?.

For all our videos on the latest research on green tea, visit our Green Tea topic page.

Is Caffeinated Tea Dehydrating? Watch the video to find out.

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