Treating Prostate Cancer with Green Tea

Green tea has been called nature’s defense against cancer. Population studies linking green tea consumption with lower cancer risk have led some to advocate for the incorporation of green tea into the diet “so as to fully benefit from its anticarcinogenic properties.” What, after all, is the downside?

But, population studies can’t prove cause and effect. Indeed, “it is not possible to determine from these population-based studies whether green tea actually prevents cancer in people”…until it is put to the test.

Prostate cancer is preceded by a precancerous condition known as intraepithelial neoplasia. You can see a graphic of the progression at 0:41 in my video Treating Prostate Cancer with Green Tea. Within one year, about 30 percent of such lesions turn into cancer. Because no treatment is given to patients until cancer is diagnosed, this presents a perfect opportunity to try green tea. In the study, 60 men with precancerous prostate intraepithelial neoplasia were randomized into either a green tea group or a placebo group. Since it’s hard to make a convincing placebo tea, the researchers used green tea pills that were roughly equivalent to about six cups of green tea a day and compared them to sugar pills. Six months into the study, they took biopsies from everyone. In the placebo group, 6 of the 30 men developed cancer by the halfway point and 3 of the remaining 24 developed it by the end of the year. So, 9 out of 30 in the placebo group, about 30 percent, developed cancer within the first year, which is what normally happens without any treatment. In the green tea group, however, none of the 30 men developed cancer within the first six months and only one developed it by the end of the year. Only 1 out of 30 is nearly ten times less than the placebo group. This marked the first demonstration that green tea compounds could be “very effective for treating premalignant lesions before [prostate cancer] develops.” Even a year later, after the subjects stopped the green tea, nearly 90 percent of the original green tea group remained cancer-free, while more than half of the placebo group developed cancer, as you can see at 2:09 in my video. This suggests that the benefits of the green tea may be “long-lasting,” with an overall nearly 80 percent reduction in prostate cancer.

What if you already have prostate cancer? A proprietary green tea extract supplement was given to 26 men with confirmed prostate cancer for an average of about a month before they had their prostates removed, and there was a significant reduction in a number of cancer biomarkers such as PSA levels, suggesting a shrinkage of the tumor. However, there was no control group, and the study was funded by the supplement company itself. When an independent group of researchers tried to replicate the results in a randomized, double-blind, placebo-controlled trial, they failed to find any statistically significant improvement. Perhaps green tea is only effective in the precancerous state and not powerful enough “to meaningfully impact overt prostate cancer”?

It certainly didn’t seem to help for advanced metastatic cancer in the two studies that tried it. What’s more, doubt has recently been cast on the precancerous results. When researchers tried to replicate it, the green tea extract group only seemed to cut prostate cancer development about in half, which very well may have happened just by chance, given the small number of people in the study. So where does that leave us?

Unfortunately, green tea extract pills are not without risk. There have been about a dozen case reports of liver damage associated with their use. Until there’s more solid evidence of benefit, I’d stick with just drinking the tea. Green or black? A recent study that randomized about a hundred men with prostate cancer to consume six cups a day of green tea or black tea found a significant drop in PSA levels and NF-kB in the green tea group, but not in either the black tea or control groups, as you can see at 4:12 in my video. NF-kB is thought to be a prognostic marker for prostate cancer progression, so the green tea did appear to work better than the black tea.


What happens if we pack our diet with all sorts of plant foods? See my Cancer Reversal Through Diet? video.

Before and after: Learn about Preventing Prostate Cancer with Green Tea and Changing a Man’s Diet After a Prostate Cancer Diagnosis.

Similar studies were done with pomegranates. I discuss the results in Pomegranate vs. Placebo for Prostate Cancer.

Interested in other ways to prevent or treat prostate cancer? See:

What about green tea and other types of cancer? Check out:

For more on some of green tea’s other benefits, see:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:

Does Green Tea Help Prevent Prostate Cancer?

“Prostate cancer is a leading cause of illness and death among men in the United States and Western Europe,” but rates in Asia can be as much as ten times lower. Perhaps Asians are genetically less likely to get prostate cancer? No. Japanese Americans and Chinese Americans have high prostate cancer rates as well, as you can see at 0:22 in my video Preventing Prostate Cancer with Green Tea. In the United States, up to nearly one in three men in their 30s already has small prostate cancers brewing and that grows to nearly two thirds of American men by their 60s. On autopsy, most older men were found to have unknown cancerous tumors in their prostates. What’s remarkable is that Asian men seem to have the same prevalence of these hidden, latent prostate cancers on autopsy, but they don’t tend to grow enough to cause problems. In Japan, men tend to die with their tumors rather than from their tumors. Of course, that’s changing as Asian populations continue to Westernize their diets.

What is it about Western diets that fuels cancer growth? It could be carcinogens in the diet accelerating the growth of cancer. Indeed, the typical American diet is rich in animal fats and meats, but it could also be something protective in Asian diets that is slowing the cancer growth, such as fruits, vegetables, soy foods, or green tea.

How might we determine if there is a link between tea consumption and the risk and progression of prostate cancer? Dozens of studies have examined whether tea drinkers tend to get less cancer in the future and if cancer victims tend to have drank less tea in the past. Although the results have been mixed, overall, tea consumption was associated with a lower risk of prostate cancer. So, tea consumption might indeed play a protective role. However, just because tea drinkers get less cancer doesn’t mean it’s necessarily because of the tea. Perhaps drinking tea is just a sign of a more traditional lifestyle and maybe tea drinkers are less likely to be patrons of the thousand KFC fast-food restaurants now in Japan.

In vitro studies performed in a lab allow for as many factors to be controlled as possible. When everything is removed from the equation except for green tea and prostate cancer, dripping green tea compounds directly on prostate cancer cells in a petri dish can cause them to self-destruct, as you can see at 2:31 in my video. But we do not appear to absorb enough green tea compounds into our bloodstream to reach those kinds of levels. This may explain why some studies failed to find an association between tea drinking and cancer. Maybe we’re not drinking enough? In the United States, for example, the “high” tea-drinking group may be defined as more than five cups of tea a week. In Japan, however, the “high” tea-drinking group can consume five or more cups a day, which was associated with about halving the risk of aggressive prostate cancer. How? Apparently, it was not by preventing the formation of the cancer in the first place, but perhaps by slowing or stopping the cancer’s growth. If green tea can stop the growth of prostate cancer, why not try giving green tea to prostate cancer patients to see if it will help? Green tea is actually put to the test in cancer patients in my video Treating Prostate Cancer with Green Tea.


For more on men’s health, check out:

Interested in more on tea? See:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:

Pomegranates Put to the Test for Prostate Cancer

The pomegranate “has been revered through the ages for its medicinal properties”––so much so that it’s been used as a symbol for some medical organizations. A fruit seems to me a better representation of health than the American Medical Association’s snake on a stick.

The pomegranate is thought to be beneficial for a wide range of diseases, including several types of cancer, cardiovascular disease, and rheumatoid arthritis. Evidently even the cannibals love it as it improves the color of “kid meat.” The researchers were talking about baby goats, but the title of their study did make me do a double-take!

Most of the attention over the last decade has focused on pomegranates and prostate cancer. In vitro studies have shown that pomegranate extract can suppress the growth of prostate cancer cells in a petri dish by up to 95 percent. As you can see in my video Pomegranate vs. Placebo for Prostate Cancer, there is no real difference between what normal prostate cells look like under a microscope with a little or a lot of pomegranate extract; it doesn’t seem to have much of an effect on healthy cells. However, prostate cancer cells are decimated by pomegranate extract—at least in a petri dish, but what about in a person? If these results translated to the clinic, it could be dramatic, but we first need to try it out in people.

“Primary management of prostate cancer…consists of either radical surgery or radiation therapy.” Despite this, “a significant number of patients relapse and ultimately develop metastatic disease.” Even after radical prostatectomy, the cancer comes back in about one-third of the patients, as evidenced by rising prostate-specific antigen (PSA) levels. At that point, the treatment options are limited as the prostate has already been removed. The next step is essentially chemical castration, or hormonal ablation. Just like breast cancer can thrive on estrogen, prostate cancer can thrive on testosterone. We can try to wipe out testosterone, but that can have such negative side effects that anything we can do to delay that would be good. 

So, what about plants? Men in Asia appear to have the lowest prostate cancer rates in the world, up to ten times lower than men in North America. Is this simply because of genetics? No. When Japanese individuals move to the United States and start living and eating like us, their breast and prostate cancer rates shoot right up toward ours. It could be because of what they start eating more of: animal products, which are the strongest risk factor for prostate cancer worldwide on a country-by-country basis. Or, it could be because of what they’re eating less of in the United States, namely their traditional low-fat, high-fiber, generally plant-rich diet with soy products and green tea. So, did the researchers put the cancer patients on a plant-based diet? No, they just had them drink a cup of pomegranate juice every day. Why? Because the study was funded by a pomegranate juice company.

In the three years leading up to the study, participants’ cancer was steadily growing, as measured by the increase in their average PSA levels. Once they started the juice, their tumors continued to grow, but it looked like they were growing slower. In contrast, Dean Ornish and his colleagues got an apparent reversal in early prostate cancer growth with a plant-based diet and other healthy lifestyle changes. Indeed, PSA didn’t just go up slower—it trended down. And, when dripping the blood of the men on prostate cancer cells growing in a lab, the blood serum of those eating healthfully suppressed cancer growth nearly eight times better, whereas the blood of the men on the pomegranate juice suppressed cancer growth by only about 12 percent. Still, to see any effect from drinking a cup of juice a day is pretty impressive.

The problem is that there was no control group in the pomegranate juice study. We could say the patients acted as their own controls, before and after. It’s probably not just a coincidence that their tumors started growing slower right when they started the juice. But, a drug trial tried to do the same thing—treat men with recurring prostate cancer after surgery or radiation. In the drug group, tumor growth slowed in 55 percent of the men. A pretty effective drug, right? Well, the sugar pill worked 73 percent of the time. The placebo effect can be so powerful that it may slow cancer growth. This is why we need placebo-controlled trials. Maybe tricking people into drinking pomegranate-flavored Kool-Aid would have had the same effect. We don’t know until we put it to the test.

Finally, researchers did a randomized, controlled trial of pomegranate juice for prostate cancer, and the daily pomegranate intake had no impact. What do they mean, no impact? Twenty-five percent of the cancer patients appeared to shrink their tumors as soon as they started drinking the pomegranate juice, but 35 percent shrunk their tumors not drinking pomegranate juice. So, any effect appears just to be a placebo. It’s the same story with pomegranate extract pills: They seemed to work until they went head to head with sugar pills and fell flat on their face.


I love pomegranates! Unfortunately, the juice and extracts look no more promising today than when I produced my video Is Pomegranate Juice That Wonderful?.

For some foods that may actually affect prostate cancer progression, see:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations: