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Slowing the Growth of Cancer

Researchers discovered a dietary intervention that may slow the progression of cancer.

August 20, 2007 |
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Supplementary Info

Sources Cited



Every year hundreds of the top cancer scientists from countries around the world converge to discuss the latest on diet and cancer. I'd like to share what I found to be the most interesting hi-light from this year's conference. First some background. One cancer cell never hurt anyone, two cancer cells never hurt anyone but a billion cancer cells, that's when we start getting into trouble, so we have to slow and reverse the division of cancer cells. We all have cells that could grow into tumors but if we slow them down our immune systems might be able to clean them up before they spell trouble. Take breast cancer for example, the most common cancer among American women. Like all cancers it starts with just one cell. This is a photo micro-graph  a photo taken under a microscope of an actual breast cancer cell, which then divides and becomes two cells and then four, eight and so on. Every time the cells divide the tiny tumor doubles in size. The tumor need only double about 30 times and we're up to a billion cancer cells which is a tumor just large enough to be picked up by mammography. Even though it only has to double 30 times, it takes between 25 and 1000 days for cancer cells to double just once. So that means, from the time that first cell gets mutated it takes between two and a 100 years before it shows up as a little tumor that we can see. The shortest known interval between exposure to a carcinogen and cancer is about 18 months which is when the first leukemia cases started appearing after Hiroshima. Cancers need time to grow and for most solid tumors, meaning non-blood tumors like breast cancer, cancer can take decades to develop. Many breast cancers may start in the teen years. Some think we may actually start developing breast cancer in the womb before we are even born and that depends in part on what our mom ate. This is what's called the promotion stage of cancer. Twenty years ago I ate meat, a lot of meat. I may very well have mutated one of the cells in my prostate, liver, colon but you know, I don't mind if I get cancer in a hundred years. I don't expect to be around to worry about it. The cancer may have been initiated by a DNA mutation but if we don't promote it, if we keep it dormant, if we slow it down we may even be able to reverse it's growth. According to autopsy studies in Japan, they've got just as much prostate cancer as we do but the rate of Japanese men dying from prostate cancer is one tenth that of American mens, till they start eating like us. Japan has the number one longest life expectancy of any nation. The US falls around 19th. When Japanese men finally do die though, many have tiny prostate tumors but they died with their cancer instead of from their cancer. By age 80 the majority of men have tiny prostate cancer tumors and by age 40, one third of women have microscopic cancerous breast tumors. It's like atherosclerosis about half of your Americans in theirs twenties already have atherosclerotic plaques, hardening of their arteries. Many of us right now will have tumors growing inside of us, so we can't wait until later to start eating healthier. We have to start now. How can we slow down and reverse cancer while it's still microscopic. Well, for prostate and breast cancers, these tissues tend to be sensitive to growth supporting steroid hormones like estrogen, so one way to decrease our levels of these steroid hormones may be to stop eating and drinking them by avoiding eggs, meat and dairy. Ok, let's get to the new research. UCLA scientists placed women on a plant based diet with exercise and the levels of all measured growth hormones in their blood dropped dramatically. That's not new news. It's what they did next that made this one of the most exciting papers to come from that conference. Before and after the dietary change was initiated researchers drew blood from the women and dripped it on live human breast cancer cells growing in a petri dish. After just two weeks the blood of the women on the plant based diet reduced the cancer growth rate by 20%. This is before, just packed with cancer. This is after, just two weeks on a plant based diet and the blood circulating in their entire bodies was that inhospitable to cancer. Again, many of us right now have tumors growing inside of us so we can't wait until we're older to start eating healthier, we have to start now, tonight.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring watch the above video. This is just an approximation of the audio contributed by veganmontreal.

To help out on the site please email

Dr. Michael Greger

Doctor's Note

Please feel free to post any ask-the-doctor type questions here in the comments section and I’d be happy to try to answer them. And check out theother videos on cancer. Also, there are 1,449 other subjects covered in the rest of my videos--please feel free to explore them as well!

For more context, check out my associated blog posts: Stool Size and Breast Cancer RiskEating To Extend Our Lifespan, Gerson Therapy for Cancer?, and Flaxseeds for Prostate Cancer

  • Michael Greger M.D.

    Please feel free to post any ask-the-doctor type questions here in the comments section and I’d be happy to try to answer them. And check out the other videos on cancer. Also, there are 1,449 other subjects covered in the rest of my videos–please feel free to explore them as well!

    • forever-ru

      Could you please comment on programs like the one run by Dr. Nicholas Gonzalez who does nutrition therapy for cancers. For most cancers he recommends plant based diets, however, for cancers like Non-Hodgkins Lymphoma he recommends a diet high in red meats. My dad would love to think he could treat his cancer with a steak, but I am hesitant on the whole idea and keep pushing the spinach his way instead. Reputable programs like McDougall, Ornish, and Gerson go the plant direction…Mercola goes with some meat. ?!?!? Who do I believe?

      • Toxins

        Hello forever!

        The fact of the matter is, whole plants are the most nutrient dense sources of food we can come across
        If one is to eat a diet high in meat, putting all health detriments and contamination aside, meat is a relatively nutrient poor food and does not promote the immune system unlike plant sources, which are the only foods that contain phytochemicals and the great majority of the antioxidants. To consider meat a health food is laughable simply looking at its micro nutrient load, which is very small. Looking at its macro nutrients, red meat and dairy are the only natural sources of trans fats, which are recommended to be at 0 grams per day The protein itself, as discussed commonly with T. Colin Campbell has been shown to promote cancer growth as well as the clear link between meat consumption and mortality and lastly, looking at fiber, it is no where to be found in any meat source. I encourage you to also view this video that discusses DNA repair mechanisms (DNA brakes linked with cancer) which are enabled by the phytochemicals and antioxidants in plant foods.

        Please excuse the brashness in my response. It is more to what was suggested by that doctor in your comment rather than your comment as a whole that struck me. Continue your quest for nutritional truth and view all the videos Dr. Greger has to offer for a very complete understanding of the health promoting properties of plants over meat. Whats so great is that you can view the studies yourself to see if you agree too!

    • HemoDynamic, M.D.

      Just came across this vid today. . . Just fantastic!  I just had to give news to a patient today about a new diagnosis of Barretts Esophagus (the first one I have ever seen personally).  Guess who’s is going to get this information forwarded to them.  I already got her on a plant based diet but this is the Vegan icing on the vegan cake!
      I’m just bummed I hadn’t come across it sooner.
      Great job on this video.  I kinda like the longer length of this video as well.

  • Jacqueline Cassavoy

    I just became a vegan 14 months ago. I wish I knew how great it is a long time ago.

  • Mike Quinoa

    Wow…that’s powerful stuff. All these videos are incredibly informative, but this one is a must-see.

    • Michael Greger M.D.

      If you didn’t already, please rate the video (click on the stars) so it will bump up in the “Highest Rated” category and more people will be able to discover it–I’m glad you did! For more videos on cancer, please click here.

  • Kaye Carpenter

    I am a 4th generation vegan. My Great grandmother had breast cancer at 50. The second gen vegan got breast cancer at 78. The 3rd and fourth who added soy have no breast cancer. I am sharing this at Weimar Center of Health and Education, Weimar, CA to our residential patients. They love it.

    • Jeff Hicks

      Dr. McDougall would agree. Apparently soy increases IGF-1 more than milk.

      • DebbieSLP

        It’s only the processed soy that increases IGF-1. Whole or minimally processed soy foods, like edamame beans, soy milk, and tofu, do not raise IGF-1.

        • Falon Wells Jordan

          Soy milk is heavily processed.

  • berggren73

    Great site and videos. But what about vitamin B12 ? As I understand it B12 can only be found in meat. Or am I wrong Michael Greger? And aren’t there also other benfits than protein, from eating beef from grass fed animals? Thanks /Hakan from Sweden

  • Marc Slavin

    Great stuff! You’ve changed my life for the better.

  • duchaspa

    Hi.Last week I got a yearly visit from a 40 yearold patient who had had ulcerative colitisfor 20 years. I told him to stop dairy and readyour 2001 paper got milk. He thanked me for his colitis stopped forthwith and since he cut all dairy. In chap 1 of China study the’error’ with alpha f protein in Philippino kids and the reproduction in rat studies,I interpret as “Cancer cells need animal protein to grow” If u stop it,they shrink.Ok i am not a scientist but I proposed this to 7 advanced cancer patients 2 of whom were in “palliative stage> All 6 are doing VERY WELL,the oncologists do not understand it.I tell them “plant based diet,no cheating”. It has worked for now,and I am flabbergated. For the record,I got about 4 hrs of nutrition in med school,A whole semester in pharmacology,and 8 lectures on surgery of thyroid cancer this was 1963-1967. I stopped smoking in 1988,stopped meat and dairy in 2005(yr influence Sir),do not worry about future hope to live to 80 but take one day at a time. Thank you for bringing the fun back into my medical practice.

    • Michael Greger M.D.

      I’m so glad you wrote in–you’ve certainly made my day! As much as I love lecturing to medical students and the general public (largely via Rotary), my most fulfilling presentations are grand rounds in hospitals for clinicians. My goal is to reignite that spark they all had when they started medical school to help people, to cure people, to make people better. As you know, too much in medicine these days is just palliation, just covering up symptoms and slowing their downward spiral into disease and disability. When I start going through the case series showing that many of the chronic diseases that make up the bulk of their practices can be reversed, that people can be restored to health, you can see their faces light up. There are powerful tools at their disposal that no one ever taught them about. Please let me know if there is ever anything I can do to help further..

      In terms of some of your individual points, the latest review on the theory that a farm animal pathogen in meat and dairy may be triggering inflammatory bowel disease is worth the read: Ulcerative colitis and Crohn’s disease: is Mycobacterium avium subspecies paratuberculosis the common villain? If indeed these diseases are related to diet, then the good news the review concludes with is that “We can end the public health tragedy of Crohn’s disease, and ulcerative colitis, in our lifetimes.”

      And I continue to be as excited as you at the possibility that certain cancers can be stopped and reversed through diet as well. I’ll keep bringing everyone the latest building off the preliminary results presented here: Cancer reversal through diet?

    • World’s Worst Diet

      duchaspa – hi. I’m writing a book on the risks of high-protein diets. May I interview you, by phone or email, about what you’ve posted here?

      Please email me at dave at

      Or call me at +61432814888

      I’d be obliged. I need great true stories like yours to make it easier for readers to understand the statistics and research I’m writing about.


  • DrDons

    I can’t add much to Dr. Greger’s excellent response. I too enjoy speaking with physicians. It is rewarding to make patients better but I would suggest you redefine your goal to live a quality life well beyond 80. We need all the physicians who are well versed in primary and secondary preventive strategies. Maybe you could give some presentations locally to other health care professionals.

  • mcarsonbreber

    Thank you so much for your incredibly informative videos! I have been forwarding your links to my family and friends. I found this one especially helpful.

    After listening to this and reading the above comments, I find myself confused about soy intake. Could you clarify if soy milk is helpful or harmful? It is my main source of liquid for smoothies, oatmeal, etc. since not having any dairy.

    Thank you!

    • Michael Greger M.D.

      Soy milk is a great choice for nondairy milk! I have 20 videos on soy if you want to check them out:

  • Carolyn

    Hi Dr. Greger,
    I know you from T.McQuirter’s EatSmart class. My mother has stage 4 lung cancer. She started radiation treatment today for 6 weeks.  I know that diet changes will help her however she is not  ready to embrace a vegan/lifestyle completely.  I started giving her wheatgrass this morning and after radiation treatment.  She will eat some vegan meals that I make from Tracye’s book.  Any other suggestions?

  • Daren

    A very convincing explanation about something we should all be concerned about. 
    Thank you

  • Jordan

    How does a 20% reduction in the growth RATE, and not the growth itself make it possible to show the before and after pictures that are so different?

    Wouldn’t the cancer cells continue to grow, but just at a slower rate?

  • Lauren Benitez Urbino

    knowledge is power…

  • CJ

    Do vegans get cancer?

    • CJ

      I realise that my question is very grey-area. I specifically meant, those on a non-processed, plant-based, low-fat diet. And if a plant-based diet slows cancer so substantially, is Gerson right?

      • Toxins

         Yes, vegans can get cancer but the risk is much much lower and if one is vegan their entire life, then the possibility of getting cancer is even more slim. Other factors may contribute such as air pollution, pesticides and the like.

  • bellybuttonblue

    I have a skin tag in my armpit. I’m not a doctor, but on the internet I read that it’s a benign tumor. When I started to eat vegan, one of the first things I noticed was that the skin tag was shrinking. I’m on a vegan diet for about 4 months and the skin tag is half the size now. 

  • Magdaleno81

    So does this really work? I don’t Doubt it, but I have a family member who doesn’t believe in this. I would love to hear from somone who has reverse their cancer.I’m trying to get my aunt to follow this. She has stage 4 cancer in the stomach. Any info would be appreciated

  • Joseph Denman MD

    Dear Dr. Greger
    I have developed ALS and am losing weight partly due to swallowing difficulties and reaction to Rilutek. I now have a PEG tube and would like to change my diet to that of a vegan, but do not see how this will provide me with the caloric intake required to replace the 10 pounds i recently lost. I wonder if you could comment on this and point me to any information which might support a dietary approach to management of this disease.
    Eye MD

    • Jan

      Read the research on ketogenic diet for ALS.

  • Sporter

    My dad was diagnosed with secondary brain cancer last year – told he’d be dead within a year and that they would focus on pain management. He decided to forgo radiation and chemo since they’re not effective in trigeminal nerve pain and the cavernous sinus area… decided instead on a strict vegan diet with supplements (based on Dr. Coldwell – The only answer to cancer). So vegan, along with no sugar, no soy unless non-gmo, no vinegar, etc…. that was over a year ago. Since then doctor’s at the cancer clinic have indicated that the MRI’s show the tumor has shrunk and that the blood flow seems to be almost no-existent to the site. Do you have any experience with this? Would love to hear your thoughts..

  • Joanne Dunn

    Thank you very much for sharing this informative post.

    • Michael Greger M.D.

      You are absolutely welcome–so glad I can help!

  • Sue OKeefe

    First of all TY for your informative videos (we bought the complete set) they have taught me so much. I made the mistake of having a 5mm. cancerous tumor removed from my breast 2 mos. ago. I have only been on a strict vegan and juicing, with wheat grass also, diet for 3 mos. My onco. Dr. STRONGLY recommends Femara in case of recurrance in the breast and if it got in my bloodstream through surgery. I’ve said no to radiation but am i making a mistake thinking my diet will prevent the cancer from returning? I would truly appreciate your thoughts on this. TY

  • Catrina Scicchitano

    I have stage 1 C.I.N.. I hear soursop juice is a natural way to prevent 12 cancers. I don’t know what the real facts are. Do you think drinking this would help to prevent my C.I.N. from turning into cancer. I read some things that say its 10,000 times more powerful then a component in chemo.  Other things I read say that soursop can be dangerous if you drink too much. You find all the facts, so I wanted to contact you to see what if anything you might have to share with me about the benefits or hazards of soursop juice for my situation. If I wind up with uterine cancer, I would want to try natural ways to cure it over chemo. I hope to hear back from you. 

  • Agumadu Ifeanyi

    My dad had a prostrate cancer surgery around October 2012, recently he is having heavy blood in his urine and feels weak most of the time. Kindly educate me on what to

    • Don Forrester MD

      I would have your father get evaluated by his physician as soon as possible. There are many causes for blood in the urine and weakness. His urologist and primary care physician should be able to pin point the cause of his bleeding. As relates to his prostate cancer… the best diet is a whole food plant based diet although some foods seem to be better then others as relates to prostate cancer. You can find out information about that by going to the video’s on prostate cancer on However it is important for your father to contact his physicians to be seen. Good luck.

      • Ramdath Dhanassar

        Hi My father was diagnosed with stage 2 gallbladder cancer in May, they removed the gallbladder but caused a spill on the liver, he took 6 treatments of chemo and no improvement , I wanted to go all natural , does anyone have a good diet plan that I should follow? Thanks

  • Mary Lynn

    I watched your video on “Slowing the Growth of Cancer” and you discussed how breast and prostate are sensitive to estrogen. By eating less meat, eggs and dairy we can eliminate some of the estrogen. what about cancers that do not rely on estrogen. How does a plant based diet stack up?

    • vegan31

      Mary Lynn, did you ever get an answer to ” what about cancers that do not rely on estrogen. How does a plant based diet stack up”? I would like to know the answer, as well.

  • Jackie Thomas

    I am confused by tamoxifen; I understand how it works, but why does a post menopausal woman have so much estrogen floating around? Are there studies that show plant-based diet is as effective in further cancer as tamoxifen? I think estrogen is carried by the fat cells, so if you are thinner, do you have less estrogen? (post menopausal)? Can you help clear up the confusion?