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 the Egg Industry Tried to Bury the TMAO Risk

“Metabolomics is a term used to describe the measurement of multiple small-molecule metabolites in biological specimens, including bodily fluids,” with the goal of “[i]dentifying the molecular signatures.” For example, if we compared the metabolic profile of those with severe heart disease to those with clean arteries, we might be able to come up with a cheap, simple, and noninvasive way to screen people. If heart patients happened to have something in their blood that healthy people didn’t, we could test for that. What’s more, perhaps it would even help us understand the mechanisms of disease. “To refer to metabolomics as a new field is injustice to ancient doctors who used ants to diagnose the patients of diabetes” (because the ants could detect the sugar in the diabetics’ urine).

The first modern foray discovered hundreds of substances in a single breath, thanks to the development of computer technology that made it possible to handle large amounts of information—and that was in 1971, when a computer took up nearly an entire room. “[N]ew metabolomics technologies [have] allowed researchers to measure hundreds or even thousands of metabolites at a time,” which is good since more than 25,000 compounds may be entering our body through our diet alone.

Researchers can use computers to turn metabolic data into maps that allow them to try to piece together connections. You can see sample data and a map at 1:28 in my video Egg Industry Response to Choline and TMAO. Metabolomics is where the story of TMAO started. “Everyone knows that a ‘bad diet’ can lead to heart disease. But which dietary components are the most harmful?” Researchers at the Cleveland Clinic “screened blood from patients who had experienced a heart attack or stroke and compared the results with those from blood of people who had not.”

Using an array of different technology, the researchers identified a compound called TMAO, which stands for trimethylamine N-oxide. The more TMAO people had in their blood, the greater the odds they had heart disease and the worse their heart disease was.

Where does TMAO come from? At 2:19 in my video, you can see a graphic showing that our liver turns TMA into TMAO—but where does TMA come from? Certain bacteria in our gut turn the choline in our diet into TMA. Where is the highest concentration of choline found? Eggs, milk, and meats, including poultry and fish. So, when we eat these foods, our gut bacteria may make TMA, which is absorbed into our system and oxidized by our liver into TMAO, which may then increase our risk of heart attack, stroke, and death.

However, simply because people with heart disease tend to have higher TMAO levels at a snapshot in time doesn’t mean having high TMAO levels necessarily leads to bad outcomes. We’d really want to follow people over time, which is what researchers did next. Four thousand people were followed for three years, and, as you can see in the graph at 3:10 in my video, those with the highest TMAO levels went on to have significantly more heart attacks, strokes, or death.

Let’s back up for a moment. If high TMAO levels come from eating lots of meat, dairy, and eggs, then maybe the only reason people with high TMAO levels have lots of heart attacks is that they’re eating lots of meat, dairy, and eggs. Perhaps having high TMAO levels is just a marker of a diet high in “red meat, eggs, milk, and chicken”—a diet that’s killing people by raising cholesterol levels, for example, and has nothing to do with TMAO at all. Conversely, the reason a low TMAO level seems so protective may just be that it’s indicative of a more plant-based diet.

One reason we think TMAO is directly responsible is that TMAO levels predict the risk of heart attacks, strokes, or death “independently of traditional cardiovascular risk factors.” Put another way, regardless of whether or not you had high cholesterol or low cholesterol, or high blood pressure or low blood pressure, having high TMAO levels appeared to be bad news. This has since been replicated in other studies. Participants were found to have up to nine times the odds of heart disease at high TMAO blood levels even after “controll[ing] for meat, fish, and cholesterol (surrogate for egg) intake.”

What about the rest of the sequence, though? How can we be certain that our gut bacteria can take the choline we eat and turn it into trimethylamine in the first place? It’s easy. Just administer a simple dietary choline challenge by giving participants some eggs.

Within about an hour of eating two hard-boiled eggs, there is a bump of TMAO in the blood, as you can see at 4:51 in my video. What if the subjects are then given antibiotics to wipe out their gut flora? After the antibiotics, nothing happens after they eat more eggs. In fact, their TMAO levels are down at zero. This shows that our gut bacteria play a critical role. But, if we wait a month and give their guts some time to recover from the antibiotics, TMAO levels creep back up.

These findings did not thrill the egg industry. Imagine working for the American Egg Board and being tasked with designing a study to show there is no effect of eating nearly an egg a day. How could a study be rigged to show no difference? If we look at the effect of an egg meal (see 5:32 in my video), we see it gives a bump in TMAO levels. However, our kidneys are so good at getting rid of TMAO, by hours four, six, and eight, we’re back to baseline. So, the way to rig the study is just make sure the subjects hadn’t eaten those eggs in the last 12 hours. Then, you can show “no effect,” get your study published in the Journal of the Academy of Nutrition and Dietetics, and collect your paycheck.


Unfortunately, this appears to be part for the course for the egg industry. For more on their suspect activities, see:

For more on the TMAO story, 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:

The Foods With the Highest Aspirin Content

The results of a recent aspirin meta-analyses suggesting a reduction of cancer mortality by about one-third in subjects taking daily low-dose aspirin “can justly be called astounding.” Yet the protection from “Western” cancers enjoyed by those eating more traditional plant-centered diets, such as the Japanese, “is even more dramatic.” I examine this in my video Plants with Aspirin Aspirations.

Before the Westernization of their diets, animal products made up only about 5 percent or less of the Japanese diet. At 0:37 in my video, you can see the difference in cancer mortality of U.S. men and women compared with Japanese men and women. “[A]ge-adjusted death rates from cancers of the colon, prostate, breast, and ovary were on the order of 5–10-fold lower in Japan than in the US at that time; mortality from pancreatic cancer, leukemias, and lymphomas was 3–4-fold lower in Japan. But this phenomenon was by no means isolated to Japan; Western cancers were likewise comparatively rare in other societies where “people ate plant-based diets.”

“The cancer protection afforded by lifelong consumption of a plant-based diet, in conjunction with leanness and insulin sensitivity (which tend to be promoted by low-fat plant-based diets)…may be very substantial indeed.” Therefore, a “lifestyle protocol for minimizing cancer risk” may include a whole-food plant-based diet.

If part of this cancer protection arises out of the aspirin phytonutrients in plants, are there any plants in particular that are packed with salicylates? Though salicylic acid, the main active ingredient in aspirin, is “ubiquitously present in fruits and vegetables,” the highest concentrations are found in herbs and spices.

Red chili powder, paprika, and turmeric contain a lot of salicylates, but cumin is about 1 percent aspirin by weight. Eating a teaspoon of cumin is like taking a baby aspirin. (See the table at 1:54 in my video for details on other herbs and spices, and their salicylate content.) “Consequently, populations that incorporate substantial amounts of spices in foods may have markedly higher daily intakes of salicylates. Indeed, it has been suggested that the low incidence of colorectal cancer among Indian populations may be ascribed in part to high exposure to dietary salicylates throughout life from spice consumption.”

“The population of rural India, with an incidence of colorectal cancer which is one of the lowest in the world, has a diet that could be extremely rich in salicylic acid. It contains substantial amounts of fruits, vegetables, and cereals flavored with large quantities of herbs and spices.” Some have proposed it’s the curcumin in the spice turmeric (which I discuss in detail in my video Turmeric Curcumin and Colon Cancer), but it may be the salicylic acid in cumin—and the spicier the better.

A spicy vegetable vindaloo may have four times the salicylates of a milder Madras-style veggie dish. As you can see from the chart at 2:55 in my video, after just one meal, we get an aspirin spike in our bloodstream like we just took an aspirin. So, eating flavor-filled vegetarian meals, with herbs and spices, may be more chemoprotective—that is, more protective against cancer—than regular, blander vegetarian meals.

We may also want to eat organic produce. “Because salicylic acid is a defense hormone of plants, the concentration…is increased when plants become stressed,” like when they are bitten by bugs (unlike pesticide-laden plants). Indeed, soups made from organic vegetables were found to have nearly six times more salicylic acid than soups prepared from conventionally grown ingredients.

We should also choose whole foods. Whole-grain breads, which are high in salicylic acid, contain about 100 times more phytochemicals than white bread: 800 phytochemicals compared to 8.

“Interest in the potential beneficial effects of dietary salicylates has arisen, in part, because of the extensive literature on the disease-preventative effects of Aspirin™. However, it should not be forgotten that plant products found to contain salicylic acid are generally rich sources of other phenolic acids…[and many] also have a marked anti-inflammatory and redox-related bioactivity [that is, antioxidant activity] in mammalian cells. Their potential protective effects should not be overlooked. In this context, the importance of dietary salicylic acid should not perhaps be over emphasised…Indeed, some believe that ‘salicylic acid deficiency’ has important public health implications and that it should be classed as an essential vitamin, namely ‘Vitamin S’.”

What they’re saying is that we should all eat a lot of plants.


If you missed the first two videos in this series, see Should We All Take Aspirin to Prevent Heart Disease? and Should We All Take Aspirin to Prevent Cancer?.

The drug-like anti-inflammatory power of certain plant foods may make them a risky proposition during pregnancy. See Caution: Anti-Inflammatory Foods in the Third Trimester.

Herbs and spices not only have some of the most anti-inflammatory properties, but they also are well-rounded protectants. 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: