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:

How to Achieve Food Synergy

There are thousands of phytochemicals that will never make it onto the side of a cereal box but may play a role in reducing the risk of chronic diseases—and those are just the ones we know about. Whole plant foods have consistently been found to be protective, so it’s reasonable for scientists to try to find the “magic bullet” active ingredient that can be sold in a pill, but “[p]ills or tablets simply cannot mimic this balanced natural combination of phytochemicals present in fruits and vegetables.” When isolated out, the compound may lose its activity or behave differently. The antioxidant and anticancer activities of plant foods are thought to derive from the “additive and synergistic effects of phytochemicals in fruits and vegetables,” meaning the whole may be greater than the sum of its parts. This helps explain why a pill can’t replace the complex combination of phytochemicals present in whole plant foods.

As T. Colin Campbell has pointed out, more than a hundred trials “overwhelmingly show no long-term benefit for vitamin supplements, along with worrisome findings that certain vitamins may even increase disease occurrence for diabetes, heart disease, and cancer.” Supplementation with fish oil, for example, appears useless or, even worse, “posing increased risk for diabetes,” yet the science doesn’t seem to matter. People continue to buy them. “The public desire for quick fixes through pills…is overwhelming, especially when money can be made.”

Each plant has thousands of different phytochemicals, as well as entirely different phytonutrient profiles. So, there may be synergistic effects when eating different foods together, too. Eating beta-carotene in carrot form is more beneficial than in pill form. because of all the other compounds in the carrot that may synergize with the beta-carotene. Well, when we dip that carrot in hummus, we suddenly have the thousands of carrot compounds mixing with the thousands of chickpea compounds. So what happens if we mix different fruits with different vegetables or different beans?

As you can see in my video Food Synergy, combining foods across different categories increased the likelihood of synergy. For example, a study showed the antioxidant powers of raspberries and adzuki beans. If there were a strictly additive effect, the expected combined antioxidant power would simply be that of the raspberries plus that of the adzuki beans. However, the observed combined antioxidant power was actually greater than the sum of one plus the other.

What about cancer-fighting effects? The study was repeated, but, this time, different combinations of food were dripped on breast cancer cells growing in a petri dish. For some foods, the same synergistic effects were found. Grapes, for example, can suppress the growth of breast cancer cells about 30 percent, but onions worked even better, cutting breast cancer cell growth in half. One would assume that if we added half the grapes with half the onion, we’d get a result somewhere in the middle between the two. Instead, the researchers found that cancer cell growth was suppressed by up to 70 percent with that combination. The whole plus the whole was greater than the sum of the whole parts. Given these findings, did the researchers recommend people eat a variety of foods? Perhaps adding some raisins along with chopped red onions to our next salad? Where’s the money in that? No, the reason the researchers were investigating the different types of interactions was “to identify mixtures that hold synergistic interactions that can ultimately lead to the development of functional foods”—maybe something like grape-flavored Funyuns.


Why should we care about the antioxidant power of foods? See

If you’re not familiar with this concept of reductionism, be sure to check out some of these other videos: Industry Response to Plants Not Pills, Why Is Nutrition So Commercialized?, and Reductionism and the Deficiency Mentality.

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:

The Benefits of Sesame Seeds for Knee Osteoarthritis

Doctors have been injecting arthritis patients with gold since the 1920s. In fact, “[g]old-based medicines have been in use for thousands of years…and remarkably…are still in clinical use as DMARDs,” or disease-modifying anti-rheumatic drugs, meaning they can slow the progression of rheumatoid arthritis. Unfortunately, such drugs can be toxic and even fatal, causing conditions such as gold lung, a gold-induced lung disease. “Although its use can be limited by the incidence of serious toxicity,” injectable gold has been shown to be beneficial to patients with rheumatoid arthritis. But maybe, as some researchers have suspected, some of that benefit comes from the sesame oil that’s injected, which is used as the liquid carrier for the gold.

As I discuss in my video Sesame Seeds for Knee Osteoarthritis, sesame seeds contain anti-inflammatory compounds with names such as sesamin and sesamol, which researchers suggest “may serve as a potential treatment for various inflammatory diseases.” Those observations, however, came from in vitro (test tube) studies. First, we have to see if sesame seeds have an anti-inflammatory effect in people, not just in cells in a petri dish, but there haven’t been any studies on the effects of sesame seeds on inflammatory markers in people with arthritis, for example…until now.

The abstract states: “Considering the high prevalence of osteoarthritis (OA) and since until now there had not been any human studies to evaluate the effect of sesame in OA patients, this study was designed to assess the effect of administration of sesame on inflammation…” Indeed, researchers found a significant drop in inflammatory markers, but what effect did sesame seeds have on the patients’ actual disease?

Fifty patients with osteoarthritis of the knee were split into two groups. Both received standard treatment, but the sesame group also received about a quarter cup of sesame seeds a day for two months. Before they started, the patients described their pain as about nine out of ten, where zero is no pain and ten is the maximum tolerable pain. After two months, the control group felt a little better and reported their pain was down to seven, but the sesame group dropped down to three and a half, significantly lower than the control group. The researchers concluded that sesame appeared to have a “positive effect…improving clinical signs and symptoms in patients with knee OA…”

The main problem with the study, though, is that the control group hadn’t been given a placebo. It’s hard to come up with a fake sesame seed, but without a placebo, researchers basically compared doing nothing to doing something, and any time you have patients do something, you can’t discount the placebo effect. That said, what are the downsides? That’s the nice thing about using food as medicine—only good side effects. Though the results are mixed, there have been studies using placebo controls that found that adding sesame seeds to our diet may improve our cholesterol and antioxidant status, and the amount of sesamin found in as little as about one tablespoon of sesame seeds can modestly lower blood pressure a few points within a month, enough, perhaps, to lower fatal stroke and heart attack risk by about 5 percent, potentially saving thousands of lives.


What other dietary interventions can help with arthritis? Check out:

If the placebo effect is really that powerful, should doctors prescribe them? They already do! Check out The Lie That Heals: Should Doctors Give Placebos? for more on this.

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: