Doctor's Note

This is the third of a 15-part video series exploring this phenomenon, which I attempted to summarize in Uprooting the Leading Causes of Death. Be sure to see Ex Vivo Cancer Proliferation Bioassay, which describes the experimental protocol in more detail. 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 can improve athletic performance—check out my video series that begins with Doping With Beet Juice, and ends with So Should We Drink Beet Juice Or Not? 

Exercise itself may be protective against breast cancer (see Exercise & Breast Cancer), and be instrumental in Reversing Cognitive Decline.

If a healthy diet can slow down the abnormal growth of prostate cancer cells, how about the abnormal growth of normal prostate cells? Find out in Some Prostates Are Larger Than Others.

For further context, check out my associated blog posts: Top 10 Most Popular Videos of the YearCancer-Proofing Your BodyHow Do Plant-Based Diets Fight Cancer?Vegan Men: More Testosterone But Less CancerTreadmill Desks: Stand Up For Health; and Flax Seeds for Prostate Cancer.

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  • This is the third of a 15 video series exploring this phenomenon, which I attempted to summarize in Uprooting the Leading Causes of Death. Make sure to see yesterday’s video-of-the-day Developing an Ex Vivo Cancer Proliferation Bioassay, which describes the experimental protocol in more detail. 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 can 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?. Exercise itself may be protective against breast cancer, and be instrumental in Reversing Cognitive Decline. If a healthy diet can slow down the abnormal growth of prostate cancer cells, how about the abnormal growth of normal prostate cells? Find out in tomorrow’s video-of-the-day Some Prostates Are Larger Than Others

    If you haven’t yet, you can subscribe to my videos for free by clicking here.

    • HemoDynamic, M.D.

      I like the Johnny Paycheck reference: Take your programed cell death and shove it!.
      I sing this verse to the same tune: 
      Take this cancer and shove it, I ain’t eatin’ meat no more
      My women just cooked me a plant based meal
      It’s what I’ve been lookin for.

  • martin

    it is a pity they didn’t have a fourth group with both strenuous exercise and plant-based food, now we don’t know how a plant based body reacts on exercise compared to a body on a s.a.d.
    (Does a plant-based body responds even better to strenuous training or or is the immune system is already working max speed just by eating the right diet and moderate exercise?)

    • DT

      The Barnard et at 2003 study is invalid for making the conclusion that diet+exercise is superior to just exercise as this is not a randomized trial (the 3 groups are unrelated and not selected randomly at baseline).


      • donmatesz

         What do you mean by “invalid”?  Are you saying it supplies no valuable information?

        IMO, saying it is invalid is like saying that Thomas Edison’s first 9,999 attempts at making a light bulb were invalid because they didn’t produce a light bulb.  In reality, every one of those ‘mistakes’ provided Edison with valuable information that led him to the invention of the light bulb. 

        Just so, most pieces of research, though flawed, provide some valuable clues.  These clues lead to further research, which provides more information.  In this case, this piece of research suggests that diet+exercise is superior to exercise alone.  Since we have good evidence that diet affects hormone and immune status their conclusion is not “invalid.” 

        You seem to believe that only “conclusive” studies are valid, which is not what scientists believe.  Rather, they look at the trend of research and evaluate each study in relation to other research that may support or not the conclusions.  They look for the preponderance of evidence, not a single “conclusive” study.

        • Doug R

           I agree; invalid is too harsh a word. DT seems to be saying that there might be some self-selection bias. The diet and light exercise group might choose these activities because they’re more health-conscious and  they may already be doing other unrelated things which actually result in greater apoptosis such as taking supplements that fight cancer. The heavy exercise group may be taking only steroids which might partly block the cancer-fighting effects of cancer since they act as growth promoters.

        • Veganrunner

          I agree. These arguments just crack me up. 

          Dr. Barnard is a disciplined researcher and professor at UCLA. (talk about pier review!) Having not read the original piece and only the abstract I can’t comment specifically on the research. But I am sure he was after something. Invalid? Doubt it. He researches how diet and exercise affects the health of the body and more specifically the cardiovascular system, and he has been doing it forever. He was my professor 30 years ago. 

          • DT

             My critique is on the misuse of the study by Dr. Greger, which he presents as a decisive proof that the difference was due to the diet,
            Moreover, even if the difference is indeed due to the diet, we do not know which aspect of the diet had the effect. Maybe it was the elimination of vegetable oil? Maybe it was the elimination of refined carbohydrates?

          • Roberta Peck

            Good points

    • DT

       Few other minor points:
      Beside the difference in diet there were other differences between the groups. The diet+exercise group was very thin (BMI 21.5), the exercise group was overweight (26.5), and the “control” group was obese (38). The people in the diet+exercise group were also 7 years younger on average. Maybe these differences explain the different rates of apoptosis. Other difference may exists between the groups (smoking, ethnicity) but no information is given in the paper.

      Dr Greger continues to be misleading about the Pritikin diet which does include animal products. This time he even calls the people vegan, which they are not.

      Dr Greger gives an inaccurate description of the physical activity of the diet+exercise group, which he describes as “strolling”.  The people in this group did (initially) aerobic exercise 4-5 times per week with target heart rate of 70%-85% which is clearly not “strolling”.

      • Doug R

         Thanks for pointing out the details, DT. We need to keep the facts straight and not be given a slanted opinion. Great job and keep it up. I wouldn’t have known otherwise.

      • Veganrunner

        Definitely not strolling. Pritikin is not vegan–low fat plant based.

        You obviously read the entire article. What was the purpose of the research?

  • I take issue with your comment about the folks who killed themselves in the gym with high BMIs being unfit.  A BMI that is considered “overweight” or “obese” could be easily achieved with muscle mass and low body fat.  BMI is useless without more data.

    • Veganrunner

      So true. Rick look at those muscles in your picture! 

  • Veganrunner

    Here’s to plant strong diet and exercise!

    Off for my run!

  • impkokay

    I would be curious to see the results of a plant based diet with little to no exercise. 

  • Domeonmoutain

    Have to agree . Missing the most important comparison. Exercise and plant based , Vs  
    plant based only.

    • HemoDynamic, M.D.

      The problem is that when people are plant based vegan (Not oil based) they can’t sit still.  They have so much energy that they will spontaneously be doing more activities.  They want to move.  Maybe you could chain the plant based Vegans to a chair so they can’t exercise.
      Compare and contrast this to the Pizza the Hutt diet from Space Balls.

      • Frasier Linde

        Generalize much? There are some plant-based vegans who aren’t that energetic, and some omnivores who are. It’s a matter of achieving a diet and lifestyle that is effective for the individual—plant-based or otherwise.

        • Kim

          My own experience (I know, anecdotal) has been that as a regular ol’ vegan, eating whatever junk food I wanted in the context of a pretty high-fat diet, my energy levels varied. I’m a lazy person by nature, and have spent most of my life quite sedentary, with spurts of exercise here and there, some hiking. I’ve been a serious couch potato. I kept losing all the excess weight I needed to get rid of while consuming a junk food vegan diet and being sedentary. Dairy kept me fat for so many years…

          I gradually shifted my vegan diet more and more to whole foods including lots of nuts and other high-fat foods, with little shift in energy levels (again, they varied). Always found switching to lower-fat left me with less energy on account of not getting enough calories (as a vegan I have my super metabolism of my childhood days back: I’m 5’5″ and 106-108 lbs.), so I’d always migrate back over to more nuts, coconut, etc. again. Or junk food.

          Lately, though, I’m finding that the more I stick with lower-fat, and specifically higher-carb food (so lots more fruit and grains, alongside my veggies, legumes, and smaller amounts of nuts, coconut, etc.), I’m finding that I’m getting used to the higher volume of fiber-rich food and feeling the best I’ve ever felt in my life, and even though I’m still quite sedentary, I know very well the feeling HemoDynamic is describing. After a little while, I want to get up and move. I’m no athlete, but I find myself doing more housecleaning and random tasks around the yard, or doing yoga and some squats, crunches, push-ups. I don’t consider myself active enough by current health standards, but I’m doing better than I was. :)

          So I’d say, based on my own experience, that if you’re high-carb, whole foods plant-based, you’ll definitely notice a surge in your energy and you’ll want to move around more, as well as a host of other benefits. Switching from vegetarian to vegan was amazing, but switching from high-fat, whole foods vegan to high-carb, whole foods vegan has been just as profound, for me. :)

          • Frasier Linde

            I think you can get (and I have experienced) that effect from a high-carb (or moderate-carb, depending on where you draw the line), whole foods diet, regardless of whether you exclude animal foods you are not individually sensitive to (e.g. dairy for a lot of people). Some have also reported that effect upon adapting to a high-fat, low-carb (ketogenic) diet. There are many factors that come into play—for example, some suggest that we tend to do better eating more carbs during the summer, and less during the winter. Thriving on a high-carb, low-fat diet requires a well established gut flora, which actually converts many of those carbs and fibers to fats and other nutrients in your gut. On the other hand, if your gut flora is deranged, you may need to limit carbs and fiber, and rely more on dietary fat and protein for caloric needs until you’re able to normalize your gut flora.

  • I’m all for a healthy diet, exercise, and chemo / radiation for cancer patients. Attack damn cancer with everything you can find!

  • elias masri

    mehh vegan propaganda…

  • this study doesn’t seem to me very convincing! To be meaningful, I believe, the groups needed to be omogeneous at the beginnin, then put on three different treatments…isn’t it?

  • henry2403

    Dr. Greger,

    Thank you for this amazing site and your continued hard work.

    It has helped change my life and has become a go to reference for my patients.

  • Theresa A.

    Hooray for the plant based diet.  Does PBD mean vegan  
    however?  If so, I wonder what a Nutritarian vegan diet would yield in the petri dish.
    You know..GOMBBS (Super Immunity) Greens, Onions, Mushrooms, Beans, Berries, Seeds (and nuts). 
    Thank you!  

  • There’s two thing’s I never get about the videos in this series.

    1. Why the conclusion is always that it’s the fact that a diet is “plant-based” that is being peddled, when the diets aren’t even equivalent in terms of nutrition and allow for daily consumption of animal products. I don’t see how one can say that it’s the plant content that matters without doing a study using a diet that is similar to the Pritikin diet, but containing more lean animal products.

    2. Why Bruce Friedrich keeps posting links to these videos on Twitter touting the cancer fighting benefits of a “vegan” diet.

  • Dar

    I would have liked to see two more groups included in this study…sedentary plant-based vegans and strenuously exercising plant-based vegans.

  • Kevin

    Thanks Doc!  I am a cancer survivor and have been cancer free for over 10 years.  I have been following a WFPB diet and exercise since my diagnosis.  I now teach others to do the same at my gyms.  Check us out  The MBG-3 

  • Trisha M

    Thank you for listing the sources! Such a great resource thank you!

  • Can you make a food list of foods you recommend to eat. With a simple meal list. And any supplements you might consider people to take. Plus how much exercise to do and what types? Like a little article or three part videos on it… or something. :-)

  • naama

    Hi Dr.Greger, I have a question:
    I’m 20 years old and exercise daily, (aerobic and anaerobic sports) I need to eat 2400 calories everyday in order to maintain my weight. I would like your advice for a daily plant-based diet for me.
    Thank you,

    • Your daily diet will depend alot on your tastes. Most of my patients have a habit where they eat they have a regular rotation of menu items… maybe 1-2 for breakfast, 3-4 for lunch and 6-10 for dinner. It is a question of what works for you and those around you. A good starter is the Vegetarian Starter Kit which can be found free on the Physicians Committee for Responsible website. Other resources available for free is Dr. John McDougall’s website which contains alot of recipes as well. The basic whole food plant based diet with Vitamin B12 supplementation is the foundation but needs to be varied depending on the goals of the patient and any clinical issues such as family history or diagnosis. Congrats on starting to eat healthy at such a young age. Keep tuned to for the latest in science. Good luck.

    • Toxins

      If by weight, you mean maintaining your muscle mass, then as long as you are eating whole plant foods when your hungry till your full, you will not experience muscle wasting. I prefer the complex carbohydrate approach of consuming whole grains like rice, oats and whole pasta, beans as well as potatoes and any other complex starches that I missed mentioning. these foods are highly satiating, nutritious and more calorie dense then plain veggies.Of course you would want to mix veggies with these starches for an optimally healthy meal.

  • Roberta Peck

    Thank you for the information . I would think that the age difference and body fat differences would as well impact the graph, aside from that that not all Pritican “vegans” were 100 percent vegans

  • tinyR

    This is such great information. It would help if you would accompany your videos with the research citations for those of us who want to learn more about the studies.

    • Thea

      tinyR: Already done! Under every video is a section called “Sources Cited”. Just click the link to expand that section.

  • Frasier Linde

    By the wording you quote, eating poultry or grass-fed bison once a week and fish or shellfish on other days qualifies as “optimal.” It does not explicitly suggest complete avoidance of animal protein. Furthermore, what the approach “encourages” (by your interpretation or otherwise) is not the same as what people on the diet actually eat—which is what is matters when interpreting these studies.

  • Arne Jan Bjermeland

    While I find Dr. Greger’s articles very useful, there are times, such as this video, where it would have been highly desirable for him to comment on some of the objections or comments made. I find it peculiar that a dedicated professional like him does not address some of these comments, since they represent an integral part of his overall blog and forum.

  • chris milligan

    In the book “Spark: The Revolutionary New Science of Exercise and the Brain” by John Ratey, MD, I read that exercise increases IGF-1 levels in the body. Dr. Ratey’s description of this increase gave me the impression that it was a good thing. All the evidence suggest exercise is really good for us as well as diet. Is there an explanation for this conflicting information?

    • Thea

      chris milligan: I’m not an expert, but here is my guess: Exercise may increase IGF-1 levels, but only to a healthy degree. And it works well to get some extra IGF-1 when we exercise because we need to build back up tissues that we broke down during exercise. Animal proteins on the other hand, appear to increase IGF-1 levels too much/to an unhealthy degree and what if there’s nothing to repair? Maybe our bodies would then start growing cancer cells since you have to grow something…??? I am guessing that it is like the cholesterol situation: our bodies naturally make all the cholesterol we need when we eat a whole plant food diet. However, when we eat added cholesterol and saturated fat, then we start to get too much cholesterol in our bodies and it causes a series of problems. It’s my guess that the IGF-1 situation is the same – ie, that getting IGF-1 naturally through exercise gives us the healthy right amount, but …
      What do you think?

      • chris milligan

        Great response Thea. I watched a Ted talk last night by Dr. William Li along the same lines about angiogenesis. Too little and you get lots of problems, too much and you get cancer growing out of control. No surprise to nutritionfacts fans many plants are anti-angiogenic, but not too much. Dr. Li is currently working on a top list of anti-angiogenic foods as well as a study with Dr. Ornish. to show efficacy in humans. I’m sure Dr. Greger will tell us all about them in a future video.

        Hopefully some day I can see some data on IGF-1 from exercise compared to food to see if your hunch is correct. Thank you for the input.

  • GeminiRat

    The Economist summarized a study entitled “Cancer: A run a day keeps the tumour at bay” on February 27, 2016. Conducted in Denmark, they injected rats with three types of cancers and provided one group with an opportunity to run on a wheel while the other group was not. In short they concluded it was “epinephrine, a hormone also commonly known as adrenaline, that has the potential to mobilize natural killer cells.” Epinephrine “levels in the blood rise during periods of physical exertion.” Levels of interleukin-6 also spike during exercise and it was shown to help immune cells home in on tumors as well.

  • david

    if I only eat vegetables & beans/ lentils all day, what would you recommend eating post workout?

    • VegEater

      I’m a girl who doesn’t want big muscles, but mine are visibly growing anyway. I eat a normal breakfast post workout–1/2 cup black beans, 1/2 cup wholegrain barley, an orange, 1-2 T ground flaxseed. It works.

  • Anne

    Hi, I’m not sure this is the most relevant video/posting, but I read in the book, How not to die, that you recommend significant exercise every day. What are your thoughts on HIIT, would that reduce the amount of daily cardio you would recommend?