Image Credit: Dr. Raowf Guirguis / National Cancer Institute / Wikimedia Commons. This image has been modified.

Cancer-Proofing Your Body

Lifestyle medicine pioneer Nathan Pritikin was an unlikely candidate to spark a nutrition revolution. He wasn’t a doctor or dietician but an engineer. As featured in my 2-min. video Engineering a Cure, he reversed his own heart disease with a plant-based diet and went on to help millions of others. He even saved the life of my own grandmother, which is what inspired me to go into medicine.

Pritikin’s work has continued though his research foundation. Once Dean Ornish proved that Our Number One Killer Can Be Stopped, the focus shifted from heart disease to cancer. In my 3-min. video Ex Vivo Cancer Proliferation Bioassay, I describe an elegant series of experiments in which people were placed on different diets and their blood was then dripped on cancer cells in a petri dish to see which diet was more effective at suppressing cancer growth.

As you can see in the video, even the blood of those on a standard American diet (S.A.D.) fights cancer, but the blood of those on vegan diets fights about 8 times better. The blood circulating within the bodies of vegans appears to have nearly 8 times the stopping power when it comes to cancer cell growth. That was after maintaining a plant-based diet for a year though. Subsequent studies against breast cancer showed the power of eating plants for just two weeks. Watch The Answer to the Pritikin Puzzle to see the remarkable results.

This dramatic strengthening of cancer defenses was after 14 days of a plant-based diet and exercise—they were out walking 30 to 60 minutes a day. Although Pritikin started out reversing chronic disease through diet alone, later—to his credit—he added an exercise component as well. That’s great for the patients, but scientifically it makes it hard to tease out which intervention is doing what. Maybe the only reason their blood started becoming so effective at suppressing cancer growth was because of the exercise—maybe the diet component had nothing to do with it. This had to be put to the test.

In my 4-min. video Is It the Diet, the Exercise, or Both? I describe the experiment. Three groups were compared: a plant-based diet and exercise group, an exercise only group, and a control group that did neither. The diet and exercise group had been on a plant-based diet for 14 years along with moderate exercise as simple as walking every day. The second group was exercise and hardcore exercise at that: 14 years of daily, strenuous, hour-long exercise like calisthenics, but they ate the standard American diet. Which group was better at fighting cancer?

The researchers took petri dishes brimming full of human prostate cancer cells and dripped blood from each of the three groups on different dishes to see whose blood killed off more cancer. Watch the diet vs. exercise video to see actual photomicrographs of the effects on cancer cells. Basically they found that strenuous exercise helped, but nothing appeared to kick more cancer butt than a healthy diet.

Even though diet appears more powerful than exercise in terms of rallying one’s cancer defenses it doesn’t mean we can’t do both. In fact eating certain plants may even improve athletic performance—check out my video series that starts with Doping With Beet Juice and ends with So Should We Drink Beet Juice Or Not?.

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my videos for free by clicking here and watch my full 2012 – 2015 presentations Uprooting the Leading Causes of Death, More than an Apple a Day, From Table to Able, and Food as Medicine.


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

14 responses to “Cancer-Proofing Your Body

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  1. I found out about Nathan Pritikin in the 80’s. My in-laws went to the Pritikin center when it was in Santa Monica. He was a pioneer and his books are still relevant today. We owe him so much. Because he was an engineer, he never got credits for his research but to me, he is my favorite hero. He has been proven right over and over again.

  2. Compared to the Standard American Diet, pretty much anything will come out on top. I’d like to see a comparison between vegan blood and that of someone eating a proper Paleo diet. (Paleo folks do eat a lot of meat and fat, but because they avoid grains and legumes, they end up often eating more vegetables than their vegan counterparts). Food for thought! ;-)

    1. That would be interesting to see if a Paleo diet could reverse heart disease as a plant-based diet has proven to do. On what basis do you say Paleo people eat more veggies than vegans?

    2. I wouldnt say “often”. I personally dont have vegan friends that arent mostly raw. The only vegans online I know that eat grains are in transition from eating meat. I think most people consider grains a meat-alternative at first, because its something they were already eating before (like pasta). So this is not the typical vegan by any stretch.

    3. Paleo diets tend to be low carb because such a high number of total calories come from meat. Harvard found of over 12,000 deaths that “A low-carbohydrate diet based on animal sources was associated with higher all-cause mortality in both men and women, whereas a vegetable-based low-carbohydrate diet was associated with lower all-cause and cardiovascular disease mortality rates.” See the “Plant-Based Atkins Diet” video where Dr. Greger reviews this study.

  3. I found Pritikin’s book in the 80s and it’s what helped me begin a very low fat, vegetarian/mostly-vegan, diet. I know he died of cancer, but staved it off in remission for decades with his diet and exercise, truly amazing. But Dr. G, my question is this, in a recent video you discuss the need to consume fats with veggies in order to get almost any benefit from them. But clearly Pritikin, Dr. McDougall, and their followers did pretty good long term–as did I–by keeping the fats and oils out of the diet. Do you have anything to add to clarify this. I now sometimes worry if I’m not having some fats with my veggies.

      1. I do now try to always eat some nuts or avocado with my veggies, ever since watching Dr G’s video about it. I’m just trying to understand it better since for so many years I followed a diet of as little fats and oils as possible.

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