How Not to Die from Cancer

After Dr. Dean Ornish conquered our number-one killer, heart disease, he moved on to killer number-two. What happens if cancer is put on a plant-based diet? Ornish and colleagues found that the progression of early-stage prostate cancer could be reversed with a plant-based diet and other healthy lifestyle behaviors.

If the blood of those eating the Standard American Diet is dripped onto cancer cells growing in a petri dish, cancer growth is cut down about 9 percent. And if they’ve followed a plant-based diet for a year? Their blood can slash cancer growth by 70 percent. So the blood circulating thgouhout the bodies of those eating plant-based diets had nearly eight times the stopping power when it came to suppressing cancer cell growth.

That was for cell growth of prostate cancer, the leading cancer-killer specific to men. In younger women, breast cancer is the top cancer-killer. Researchers wanted to repeat the study with women using breast cancer cells, but they didn’t want to wait a whole year to get the results. Women are dying now. So they figured they’d see what a plant-based diet could do after just two weeks against three different types of human breast cancer.

As you can see in my video How Not to Die from Cancer, the study showed cancer growth started out at 100 percent, but then dropped after the subjects ate a plant-based diet for 14 days. A layer of breast cancer cells was laid down in a petri dish, and then blood from women eating the Standard American Diet was dripped on it. As you can see in the video, even the blood of women eating pretty poor diets had some ability to break down cancer. After just two weeks of eating healthfully, though, blood was drawn from those same women—so they effectively acted as their own controls—and was dripped on a new carpet of breast cancer cells. You can see for yourself that only a few individual cancer cells remained. Their bodies cleaned up. After only 14 days on a plant-based diet, their bloodstream became that much more hostile to cancer.

Slowing down the growth of cancer cells is nice, but getting rid of them all together is even better. This is what’s called apoptosis, programmed cell death. After eating healthfully, the women’s own bodies were able to somehow reprogram the cancer cells, forcing them into early retirement.

In my video, you can see what’s called TUNEL imaging, which allows researchers to measure DNA fragmentation, or cell death. With this technology, dying cancer cells appear as little white spots. From the start of the study, you can see one small white speck in the upper left of the image, showing that the blood of an average woman on a typical American diet can knock off a few breast cancer cells. After 14 days of healthy, plant-based living, however, her blood turned that one small white speck into a multitude of white spots. It’s as if she’s an entirely different woman inside! The same blood now coursing through these women’s bodies gained the power to significantly slow down and even stop breast cancer cell growth after just two weeks of eating a plant-based diet.

What kind of blood do we want in our body? What kind of immune system? Do we want blood that just rolls over when new cancer cells pop up, or do we want blood circulating to every nook and cranny of our body with the power to slow down and stop them?

The dramatic strengthening of cancer defenses shown in the study was after 14 days of a plant-based diet—and exercise.The researchers had the women walking 30 to 60 minutes a day. Given there were two factors, how do we know what role the diet played? Researchers decided to put it to the test.

In my video, you can see a chart that first shows how blood taken from those who ate a plant-based diet and had a routine of mild exercise, such as walking every day, over an average of 14 years, exhibited significant cancer cell clearance. The researchers then compared the substantial cancer-stopping power of plant eaters to that of an average sedentary American, which you can see is basically nonexistent.

The researchers also analyzed a third group. Instead of 14 years on a plant-based diet, they had 14 years on a Standard American Diet, but they also had 14 years of daily, strenuous, hour-long exercise, like calisthenics. They wanted to know if you exercised hard enough and long enough could you rival some strolling plant eaters.

The answer? There’s no question that exercise helped, but literally 5,000 hours in the gym was no match for a plant-based diet.

Once again using TUNEL imaging to analyze cancer cell death, the researchers found that even if you are a couch potato eating fried potatoes, your body isn’t totally defenseless. Your bloodstream can kill off some cancer cells, which you can see in my video as a couple white spots in the first image of that series. If you exercise for 5,000 hours, you can kill many more cancer cells, evidenced by the many more white specks appearing throughout that image. But nothing appears to kick more cancer tush than a plant-based diet, as that image is filled with white spots indicating cancer cells killed off.

Why is this the case? We think it’s because animal proteins, such as meat, egg white, and dairy protein, increase the level of insulin-like growth factor-1 (IGF-1), a cancer-promoting growth hormone involved in the “acquisition or progress of malignant tumors.”

In my video, you can see the results of a study that nailed IGF-1 as the villain. Just as in the previous studies, subjects went on a plant-based diet and cancer-cell growth dropped, while cancer-cell death shot up. This experiment, however, had a kicker: It added back to the cancer just the amount of IGF-1 that had been banished from your body as a result of eating and living healthier. In doing so, it effectively erased the “diet and exercise” effect. It’s as if the subjects had never started eating healthfully at all, with the cancer-cell growth rates and death rates returning to the same levels as before the plant-based diet intervention.

The reason one of the largest prospective studies on diet and cancer found “the incidence of all cancers combined was lower among vegetarians than among meat eaters” may be because they eat less animal protein, and thereby end up with less IGF-1, which means less cancer growth.

How much less cancer growth? A study found that middle-aged men and women with high protein intakes had a 75 percent increase in overall mortality and a fourfold increase in the risk of dying specifically from cancer. Does the protein source matter? Yes. It was specifically animal protein, which makes sense, given their higher IGF-1 levels.

The academic institution where the study was done sent out a press release with a memorable opening line: “That chicken wing you’re eating could be as deadly as a cigarette.” It went on to explain that “eating a diet rich in animal proteins during middle age makes you four times more likely to die from cancer…—a mortality risk factor comparable to smoking.”

What was the response to the revelation that diets high in meat, eggs, and dairy could be as harmful to health as smoking? One nutrition scientist replied it was “‘potentially even dangerous’ to compare the effects of smoking with the effect of meat and cheese,” but why? Because, they argued, a smoker might think “‘why bother quitting smoking if my cheese and ham sandwich is just as bad for me?’”

This reminds me of a famous Philip Morris cigarette ad that tried to downplay the risks of second-hand smoke. The ad included a chart with “everyday activities” and “reported relative risk,” in an attempt to say second-hand smoke wasn’t all that bad. The chart showed that while it increases the risk of lung cancer by 19 percent, drinking one or two glasses of milk every day may be three times as bad with a 62 percent higher risk of lung cancer. Lung cancer risk could be doubled if you frequently cook with oil, and heart disease risk tripled if you eat non-vegetarian or multiplied six-fold by eating lots of meat and dairy. Philip Morris’s conclusion? “Let’s keep a sense of perspective.” The “risk of lung cancer from second-hand tobacco smoke [was put] well below the risk reported by other studies for many everyday items and activities.”

That’s like saying, “Don’t worry about getting stabbed, because getting shot is so much worse.” Two risks don’t make a right.

Of course, you’ll note Philip Morris stopped throwing dairy under the bus once it purchased Kraft Foods.


The first time someone visits NutritionFacts.org can be overwhelming. With videos on more than 2,000 health topics, where do you even begin? Imagine stumbling onto the site not knowing what to expect and the new video-of-the-day is about how a particular spice can be effective in treating a particular form of arthritis. It would be easy to miss the forest for the trees, which is precisely why I created a series of overview videos that are essentially taken straight from my live, hour-long 2016 presentation How Not to Die: Preventing, Arresting, and Reversing Our Top 15 Killers.

The other videos in this overview series are:

Inspired to learn more about the role diet may play in preventing and treating cancer? Check out these other popular videos on the topic:

I’ve also produced an entire series on mammograms. You can find all of those videos here.

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:

How Can Animal Protein Intake Increase Childhood Obesity Risk?

If pregnant crickets are exposed to a predatory wolf spider, their babies will hatch, exhibiting increased antipredator behavior and, as a consequence, improved survival from wolf spider attack. The mother cricket appears to be able to forewarn her babies about the threat when they are still inside her, so they would be pre-adapted to their external environment. This even happens in plants. If you grow two genetically identical plants—one in the sun, one in the shade—the sun-grown plant will produce seeds that grow better in the sun, and the shaded plant will produce seeds that grow better in the shade—even though they’re genetically identical.

What’s happening is called epigenetics, external factors changing gene expression.

Vole pups born in the winter come out growing thicker coats. Vole mothers are able to communicate the season to their babies in utero and tell them to put a coat on even before they’re born. We’re no different. You know how some people have different temperature tolerances, resulting in “battles of the bedroom”? Do you turn the AC on or off? Open the windows? It’s not just genetics. Whether we’re born in the tropics or in a cold environment determines how many active sweat glands we have in our skin.

What does this have to do with diet? As I discuss in my video Animal Protein, Pregnancy, and Childhood Obesity, can what a pregnant woman eats—or doesn’t eat—permanently alter the biology of her children in terms of what genes are turned on or off throughout life?

What happened to the children born during the 1944 – 1945 Dutch famine imposed by the Nazis? They had higher rates of obesity 50 years later. The baby’s DNA gene expression was reprogrammed before birth to expect to be born into a world of famine and conserve calories at all cost. But when the war ended, this propensity to store fat became a disadvantage. What pregnant women eat and don’t eat doesn’t just help determine the birth weight of the child, but the future adult weight of the child.

For example, maternal protein intake during pregnancy may play a role in the obesity epidemic—but not just protein in general. “Protein from animal sources, primarily meat products, consumed during pregnancy may increase risk of overweight in offspring…” Originally, researchers thought it might be the IGF-1, a growth hormone boosted by animal product consumption, that may increase the production of fatty tissue, but weight gain was tied more to meat intake than dairy. Every daily portion of meat intake during the third trimester of pregnancy resulted in about an extra 1 percent of body fat mass in their children by their 16th birthday, potentially increasing their risk of becoming obese later in life, independent of how many calories they ate or how much they exercised.  But no such link was found with cow’s milk intake, which would presumably boost IGF-1 levels just as high.

Given that, perhaps instead of IGF-1, it’s the obesogens in meat, chemicals that stimulate the growth of fatty tissue. “[E]merging evidence demonstrates that environmental factors can predispose exposed individuals to gain weight, irrespective of diet and exercise.” After all, even our infants are fatter, and we can’t blame that on diet and exercise. Animals are fatter, too, and not just our pampered pets—even rats in laboratories and subways are bigger. “The likelihood of 24 animal populations from eight different species all showing a positive trend in weight over the past few decades by chance was estimated at about 1 in 10 million” so it appears something else is going on—something like obesogenic chemicals.

One such candidate is polycyclic aromatic hydrocarbons (PAHs), which are found in cigarette smoke, vehicle exhaust, and grilled meat. A nationwide study of thousands found that the more children were exposed to PAHs, the fatter they tended to be. The researchers could measure the level of these chemicals right out of their urine. Exposure can start in the womb. Indeed, prenatal exposure to these chemicals may cause increased fat mass gained during childhood and a higher risk of childhood obesity.

If these pollutants sound familiar, I’ve covered them before in relation to increasing breast cancer risk in the Long Island Breast Cancer Study Project. So, perhaps they aren’t just obesogens, but carcinogens, as well, which may help explain the 47 percent increase in breast cancer risk among older women in relation to a lifetime average of grilled and smoked foods.

If we look at one of the most common of these toxins, smokers get about half from food and half from cigarettes. For nonsmokers, however, 99 percent comes from diet. The highest levels of PAHs are found in meat, with pork apparently worse than beef. Even dark green leafies like kale can get contaminated by pollutants in the air, though, so don’t forage for dandelion greens next to the highway and make sure to wash your greens under running water.

These are fat-soluble pollutants, so they need lots of fat to be absorbed. It’s possible that even heavily contaminated plant-based sources may be safer, unless you pour lots of oil on your food, in which case the toxins would presumably become as readily absorbed as the toxins in meat.

The good news is they don’t build up in our body. As I show in my video, if we expose people to barbecued chicken, they get a big spike in these chemicals—up to a hundred-fold increase—but our body can get rid of them within about 20 hours. The problem, of course, is that people who eat these kinds of foods every day could be constantly exposing themselves, which may not only affect their health and their children’s health, but maybe even their grandchildren’s health.

Being pregnant during the Dutch famine of the mid-1940s didn’t just lead to an increase in diseases among their kids, but even apparently their grandkids. What a pregnant woman eats now may affect future generations. “The issue of generation-spanning effects of poor conditions during [pregnancy]…may shed light on the epidemic of diabetes, obesity and cardiovascular disease,” which is associated with the transition towards Western lifestyles.


Epigenetics is the science of altering the expression of our genes. No matter our family history, some genes can be effectively turned on and off by the lifestyle choices we make. See, for example:

For more on “obesogenic” chemicals, see:

I previously touched on PAHs in Meat Fumes: Dietary Secondhand Smoke.

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:

Dialing Down the Grim Reaper Gene

Only about 1 in 10,000 people live to be a 100 years old. What’s their secret? I discuss this in my video Animal Protein Compared to Cigarette Smoking.

In 1993, a major breakthrough in longevity research was published about a single genetic mutation that doubled the lifespan of a tiny roundworm. Instead of all worms being dead by 30 days, the mutants lived 60 days or longer. This lifespan extension was “the largest yet reported in any organism.” This methuselah worm, a “medical marvel,” is “the equivalent of a healthy 200-year-old human.” All because of a single mutation? That shouldn’t happen. Presumably, aging is caused by multiple processes, affected by many genes. How could knocking out a single gene double lifespan?

What is this aging gene—a gene that so speeds up aging that if it’s knocked out, the animals live twice as long? It’s been called the Grim Reaper gene and is the worm equivalent of the human insulin-like growth factor 1 (IGF-1) receptor. Mutations of that same receptor in humans may help explain why some people live to be a hundred and other people don’t.

So, is it just the luck of the draw whether we got good genes or bad ones? No, we can turn on and off the expression of these genes, depending on what we eat. Years ago I profiled a remarkable series of experiments about IGF-1, a cancer-promoting growth hormone released in excess amounts by our liver when we eat animal protein. Men and women who don’t eat meat, egg white, or dairy proteins have significantly lower levels of IGF-1 circulating within their bodies, and switching people to a plant-based diet can significantly lower IGF-1 levels within just 11 days, markedly improving the ability of women’s bloodstreams to suppress breast cancer cell growth and then kill off breast cancer cells.

Similarly, the blood serum of men on a plant-based diet suppresses prostate cancer cell growth about eight times better than before they changed their diet. However, this dramatic improvement in cancer defenses is abolished if just the amount of IGF-1 banished from their systems as a result of eating and living healthier is added back. This is one way to explain the low rates of cancer among plant-based populations: The drop in animal protein intake leads to a drop in IGF-1, which in turn leads to a drop in cancer growth. The effect is so powerful that Dr. Dean Ornish and colleagues appeared to be able to reverse the progression of early-stage prostate cancer without chemotherapy, surgery, or radiation—just a plant-based diet and lifestyle program.

When we’re kids, we need growth hormones to grow. There’s a rare genetic defect that causes severe IGF-1 deficiency, leading to a type of dwarfism. It also apparently makes you effectively cancer-proof. A study reported not a single death from cancer in about 100 individuals with IGF-1 deficiency. What about 200 individuals? None developed cancer. Most malignant tumors are covered in IGF-1 receptors, but if there’s no IGF-1 around, they may not be able to grow and spread.

This may help explain why lives appear to be cut short by eating low-carb diets. It’s not just any low-carb diet, though. Specifically, low-carb diets based on animal sources appear to be the problem, whereas vegetable-based low-carb diets were associated with a lower risk of death. But low-carb diets are high in animal fat as well as animal protein, so how do we know the saturated animal fat wasn’t killing off people and it had nothing to do with the protein? What we need is a study that follows a few thousand people and their protein intakes for 20 years or so, and sees who lives longest, who gets cancer, and who doesn’t. But, there had never been a study like that…until now.

Six thousand men and women over age 50 from across the United States were followed for 18 years, and those under age 65 with high protein intakes had a 75 percent increase in overall mortality and a fourfold increase in the risk of dying from cancer. Does it matter what type of protein? Yes. “These associations were either abolished or attenuated if the proteins were plant derived,” which makes sense given the higher IGF-1 levels in those eating excess protein.

The sponsoring university sent out a press release with a memorable opening line: “That chicken wing you’re eating could be as deadly as a cigarette.” It explained that “eating a diet rich in animal proteins during middle age makes you four times more likely to die of cancer than someone with a low-protein diet—a mortality risk factor comparable to smoking.” And when they say “low-protein diet,” what they actually mean is getting the recommended amount of protein.

“Almost everyone is going to have a cancer cell or pre-cancer cell in them at some point. The question is: Does it progress?” said one of the lead researchers. That may depend on what we eat.

“[T]he question is not whether a certain diet allows you to do well for three days,” a researcher noted, “but can it help you survive to be 100?” Excessive protein consumption isn’t only “linked to a dramatic rise in cancer mortality, but middle-aged people who eat lots of proteins from animal sources…are also more susceptible to early death in general.” Crucially, the same didn’t apply to plant proteins like beans, and it wasn’t the fat; the animal protein appeared to be the culprit.

What was the response to the revelation that diets high in meat, eggs, and dairy could be as harmful to health as smoking? One nutrition scientist replied that it was potentially dangerous because it could “damage the effectiveness of important public health messages.” Why? Because a smoker might think “why bother quitting smoking if my cheese and ham sandwich is just as bad for me?”

This reminds me of a famous Philip Morris cigarette ad that tried to downplay the risks of smoking by saying that if we think second-hand smoke is bad, increasing the risk of lung cancer 19 percent, drinking one or two glasses of milk every day may be three times as bad with a 62 percent higher risk of lung cancer. What’s more, doubling the risk is frequently cooking with oil, tripling our risk of heart disease is eating non-vegetarian, and multiplying our risk six-fold is eating lots of meat and dairy. So, they conclude, “Let’s keep a sense of perspective.” The ad goes on to say that the risk of cancer from second-hand smoke may be “well below the risk reported…for many everyday items and activities.” So, breathe deep!

That’s like saying we shouldn’t worry about getting stabbed because getting shot is so much worse. Or, if we don’t wear seatbelts, we might as well have unprotected sex. If we go bungee jumping, we might as well disconnect our smoke alarms at home. Two risks don’t make a right.

Of course, you’ll note Philip Morris stopped throwing dairy under the bus once they purchased Kraft Foods.


The IGF-1 story is so pivotal that it’s one of the first video series I ever produced for NutritionFacts.org. I’m so glad I was able to release this long-awaited update. If you want a blast from the past, watch the original series starting with Engineering a Cure.

For more parallels between the tobacco industry and the food industry, see:

What about the mobile phone industry? Does Cell Phone Radiation Cause Cancer?

For more on healthy aging and longevity, see:

It’s important to note the so-called low protein intake is actually the recommended protein intake, which is associated with a major reduction in cancer and overall mortality in middle age, under age 65. But did you notice that it says not among older individuals? All of this is covered in my video Increasing Protein Intake After Age 65.

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: