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Studies showing cancer risk with vegan diet

Posted by tinako on December 5, 2009

As an aside to my China Study postings, I’m going to pop into this posting any scientific studies I find over time that look into differences in cancer rates on a vegan diet.  I promise I will include any I find that show veganism increases cancer.  I am not going to include any studies that only look at vegetarians or do not differentiate between vegetarians and vegans, because a vegetarian diet is not good enough.  Linda McCartney makes a good example of this.  This publication makes the point that lumping “vegetarians” together may not be yielding helpful analysis.   Unfortunately, most of the big studies in the U.S. don’t seem to have figured out this important difference, and so their results are not always conclusive.  I think this refusal to even consider dairy as a possible bad-guy is the single biggest impediment to seeing the dramatic difference that animal products make in our health.  The logic goes like this: somebody switches from meat to dairy and their health doesn’t improve; therefore don’t bother giving up meat.

Further discussion of unhelpful studies.  And this is a post I wrote about soy and cancer.

Studies showing cancer risk with vegan diet:

  • This link is a blog, not a published, peer-reviewed study, but I welcome comments that question The China Study.  I’m vegan for other reasons; if The China Study skews the truth, then out with it: “A Closer Look at the China Study.”  I have not yet come across criticism of the rat studies.

Vegans who get cancer:

( I looked into Kris Carr of Crazy Sexy Cancer and she was not vegan before she was diagnosed.)

  • Bif Naked, Canadian raw vegan 10 years before diagnosed with breast cancer 2008 (thanks, Janet)
  • 11/12/10 – relative of a friend, vegan 10 years, developed adenocarcinoma cancer in mouth, rare and has no risk factors
  • Also see comments below

People who get cancer, then switch to a vegan diet and their cancer keeps growing:

  • See below

42 Responses to “Studies showing cancer risk with vegan diet”

  1. Janet said

    Bif Naked is a vegan musician who was diagnosed with breast cancer in 2008.

  2. moi said

    According to the Physicians Committee for Responsible Medicine, and the scientific evidence is clear: “Vegetarians are about 40 percent less likely to get cancer than nonvegetarians, regardless of other risks such as smoking, body size, and socioeconomic status.”

    This doesn’t mean that vegetarians (or vegans) will not get cancer… it means there is a significant decrease of risk involved in this dietary approach. Genetics and environmental factors would play a role also.

    • tinako said

      This doesn’t quite answer my question. Again with the vegetarian/vegan issue; the PCRM says “vegetarians.” Now, PCRM is pro-vegan and so may really mean no animal products at all, but it’s unclear, and vegetarian usually includes dairy and eggs. There is a bigger difference between vegetarian and vegan diets than those two little ingredients imply, because vegetarians tend to overdo it on them, and I would not expect the percentage reduction in risk to be very close for the two diets.

      So even though, as you say, this statement clearly doesn’t explicitly mean vegetarians (or vegans) will not get cancer, it also doesn’t say vegans could. It doesn’t answer the question I am asking, which is based on the dramatic results of rat and mice studies described in The China Study: “For two different organs, four different carcinogens, and two different species, casein promotes cancer growth while using a highly integrated system of mechanisms” [p.65]. The rats and mice who got low animal protein diets did not get cancer, none of them, and the one who got higher (but still reasonable) amounts of animal protein got cancer, all of them.

      So my question is, does this translate to humans? And so far we have one example (above) of a vegan who got cancer. So maybe not.

      Maybe the PCRM knows the answer to my question, but the quote above doesn’t seem to be it.

      Thanks for the comment.

  3. Deborah said

    A couple of days ago I heard a scientist (did not catch his name) who is conducting a study where animal and humans have participated on how to influence DNA. Not the sequence of DNA but the structure of it. Very interesting. The study was in favor of Vegan diet as a not only cancer preventative but a possible cancer cure. I am going to google and see if I can find him. I believe there is a book.

  4. Juni said

    “over 4,000,000 are vegans, and if veganism no difference, 23%, or over 900,000 of them should die of cancer every year.”
    Don’t get that sentence. 23% of people die of cancer every year… huh, what…?

    Wild herbivore animals get cancer too (if they survive long enough..), so it’s obviously not diet alone.
    But logically meat eaters must take up more toxins over time than herbivores, as all the crap gets concentrated in meat…

    • tinako said

      I left out the word “makes.” I just meant that finding vegans whose cancer grows would look bad for Dr. Campbell’s conclusions. Not a disproof, but would weaken the argument. And indeed I have found a few, and so I am letting go of the hypothesis that veganism would stop cancer. But as you say, it probably helps.

  5. Dr. Mevalonate said

    I’ve studied the Mevalonate pathway, due to the problems and serious side effects of extensive long-term statin usage. Veganism would closely resemble a HmG-CoA inhibitor–eliminating cholesterol. (However, I am unsure how the Vegan body recycles cholesterol.) I would be concerned that long-term Veganism would mimic long-term statin usage due to the compromised cellular bilayer–cholesterol is in integral part of every cell and required for adequate hormone production. Also, does ingestion of Vitamin D2 from plants (irridated mushrooms) enable the biosynthesis of 7-dehydrocholesterol in the skin–the precursor to Vitamin D3?
    Important questions!

    • tinako said

      Animals (including humans) manufacture cholesterol. That is how cows get it from grass. You would know better than me as to whether statins affect manufacture of blood cholesterol or, upstream, digestion of dietary cholesterol. While there is a relationship between consumption of dietary cholesterol and level of blood cholesterol, they are not the same thing, and cholesterol consumption is not even the leading cause of high blood cholesterol, according to Campbell anyway.

      There is a lot of controversy about vitamin D right now. I’m waiting for the dust to settle. I try not to get all worked up about the latest findings, Campbell included.

  6. Meena said

    Bif Naked was a heroin addict and heavy drinker longer than she has been vegan. Her diet was not what I would call healthy either. That may have something to do with her health.

  7. Lorelei said

    Hi, My sister-in-law, a devout Buddist, has followed a strict vegan diet for years (in addition to avoiding garlic, onions, and leeks for reasons unknown to me) was diagnosed with breast cancer two years ago. The cancer has spread to her lungs, and she was recently given only 6 months to live. I am not sure if the vegan diet she followed was balanced in receiving proper nutrients because she told me that she was not consuming much fruit (she does not like fruit) but ate lots of white rice and noodles (and not the whole grain type). I am wondering if her unbalanced diet might have contributed to perhaps lowering her immune system (antibodies, after all, are proteins)…

  8. Trish said

    Hi Lorelei,

    In the book ‘Healing Cancer From the Inside’ (and on the DVD of the same name) the diet recommended and shown to reverse cancer worked best if vegetables and particularly green and other colourful vegetables were eaten the most. Nuts should be kept at small amounts and NO added oils. Most importantly they recommend a whole food plant based diet. So white rice and noodles would be off the agenda and definitely no sugar – sugar feeds cancer.

    They recommend half raw (salads mostly – only a few nuts) and all organic. They also say that the diet works best the sooner you start it after diagnosis and if you don’t have any surgery or chemo, but people have still reversed cancer after conventional cancer ‘treatments’. Those that don’t survive have their pain levels decreased substantially and often live months or years longer than expected at a much higher quality of life.

    My son (a meat eater) has been diagnosed. I am doing the anti-cancer diet to try to encourage him to do it. I would encourage your sister in law to not give up hope and to change her diet to a whole food plant diet. It is absolutely possible to have a bad vegan diet – which is another reason why the studies need to look at the quality of the diet and not just whether someone is vegan.

    Some info on the RAVE Diet and its healing powers with regards to cancer can be found here :

  9. Dveg said

    I now know two vegans with cancer. I don’t know the details of their vegan diets (how much whole foods vs vegan junk foods), but being vegan and not knowing very many other vegans, this is of concern! Actually, now that I think of it, they are the only two people I know with cancer right now (and I know a lot more folks who eat the Standard American Diet). I wish, hope, and pray that a whole foods plant based diet is the answer, but it is hard for me to ignore these two healthy vegans who now have cancer. Hmmm. 😦

  10. Jessie said

    Bif Naked never did heroin… she actually led a pretty healthy life. According to her wiki page, “She also has X’s tattooed on her hands, which represent the X’s drawn on the hands of minors in bars to prevent them from ordering drinks. Bif identifies as straight-edge.”

    • Ashleigh said

      Ahh yeah..because wikipedia is a great reliable source of information.

    • Meena said

      Sorry Jessie. Bif is straight edge now, but I witnessed her drinking a lot of booze and shooting up heroin and nodding out in the 80’s and 90’s.

  11. Judy said

    Vegan 2 years here. Skin cancer started growing in two spots on my scalp a year ago, which now I have to have removed. It’s only basal cell carcinoma, but still embarrassing. Cancer and heart disease prevention were a big part of why I started eating vegan and now I have to admit to others, who I tried to convince to try the diet, that it didn’t work. I don’t have great cholesterol levels either. Beginning to doubt claims about veganism being so healthy. Also, I am not a junk food vegan. Maybe I’m not perfect but I get my leafy greens in every day and eat a good rainbow of veggies and fruit.

    • tinako said

      I think if we tell people that veganism is the cure for everything, all the time, we are setting ourselves up to be wrong at least sometimes. There are people with very bad health habits that live to 100, and people who do everything right who get Western diseases early. I believe statistics show that on average, people will be much healthier on a plant-based diet. I know mine improved just going from vegetarian to vegan.

      The China Study has a lot of 100% correlations in it (like the rat studies). That perfect score clearly doesn’t translate to humans, as your case shows. I never touted these studies as a reason to go vegan, since even the disease-free people and other animals in the studies weren’t completely vegan, but I find myself distancing myself even more from the “miracle cure” aspect as I hear more stories like yours.

      I’m sorry that on top of the fear and discomfort of your skin cancer, you have the public embarrassment of having been wrong when you were only trying to help others. Yours isn’t the first case I’ve heard like that. I wouldn’t let that embarrassment embitter you towards plant-based diets. Maybe we just need to temper our expectations.

      Thanks for writing. Best wishes, get well soon.

      • Jasmine said

        Also, Judy, that was skin cancer. You can’t protect your outer skin so much. Skin is vulnerable all the time. Fortunately, you may have prevented an internal cancer thanks to veganism. I wouldn’t stop trying to convince people that the vegan diet decreases the risk, but that’s more about internal risk.

    • Marie said

      I converted to a plant-based whole foods diet a little over a year ago (Forks over Knives/Drs. Campbell and Esselstein) mostly to ward off heart disease that runs in my family. I also increased exercise to 5 times per week. Prior to that I ate meat about once a week and exercised more moderately. The diet worked to shed 25 lbs and significantly reduce cholesterol. I am now at the very low side of a healthy weight. But almost exactly 1 year after starting the diet I was diagnosed with breast cancer (no family history). 6 months ago I has a suspicious mammogram (determined at the time not to be cancer, I am only 42) and in a follow up mammogram six months later it had grown and was diagnosed as cancer. I had been following a very healthy whole foods vegan diet the whole time. I plan to continue the diet as a general health measure, but I am very suspicious of claims that the diet can, by itself, prevent or cure cancer. I don’t know if the cancer would have been worse without it, but it certainly didn’t stop it. And I certainly would not forgo conventional treatments and rely on diet alone as a cure. I truly wish the answer were that simple, but at least in my case it is not.

      • tinako said

        Thanks for your helpful story. I’ve heard enough like yours to be suspicious, as you are. Best of luck with your health.

      • Monica Peg said


        What about contraceptives? If only women our age knew that it greatly increased the risk of breast cancer. Not just words…the Mayo clinic did a meta-analysis of studies concerning the subject and gave the conclusion that OCPs do indeed increase the risk of breast cancer. Here is a little info on where to find the study……

        The journal of the Mayo Clinic (Mayo Clinic Proceedings) has published a key
        article in it’s October 2006 issue entitled “Oral Contraceptive Use as a Risk
        Factor for Pre-menopausal Breast Cancer: A Meta-analysis”, authored by Chris
        Kahlenborn, M.D., (Internal Medicine, Altoona Hospital, PA), Francesmary
        Modugno, Ph.D., (Epidemiology), Douglas M. Potter, Ph.D. (Biostatistics) both
        from the University of Pittsburgh, and Walter B. Severs, Ph.D., Professor
        Emeritus of Pharmacology at the Penn State College of Medicine.

      • Jen said

        I read recently that anti-persperants may also cause a significant increase in breast cancer because of the chemicals used in them, and because of the fact that it is applied so close to the breasts and that there are many glands in that area. The article gave some clinical studies that showed a chemical commonly found in anti-perspirants was also found in 80-90% of all breast cancers…… just something to think about…. because our skin is our largest organ, and the chemicals we put on it do get absorbed……

    • Scott said

      Hi Judy,
      Might it be that your skin cancer resulted from not one year, but a lifetime of eating whatever you ate before going vegan? Perhaps it is a mild case thanks in part to your relatively recent transition to vegan eating? I wouldn’t rule these possibilities out, as it is well known that cancers require long-term existence of causal factors. Cheers

  12. Bob Rutledge said

    Study the science and follow the money on the studies you read about. Cancer prevention is the answer. Go to . 10 years to put this book together – “The Hidden Story of Cancer”. Follow the science not opinions and hype.

  13. charra said

    People seem to overlook the chemicals in their foods, vegan or no…and I’m not necessarily referring to applied pesticides. Speaking on rice and noodles, for example: rice (even brown, even organic) has been shown to retain high levels of arsenic (known carcinogen), based on the lead arsenate used years ago as pesticide. Arsenic, evidently, has a tendency to just sit on the soil. For years. Just try to find a “healthy” snack bar that doesn’t include rice puffs and (concentrated) rice syrup. Apples, grapes and pears (and their concentrated juices) are also at risk for high arsenic levels. There go all the juices (even if they’re flavored otherwise…I’m sticking to lemonade). Cadmium, now proven to be linked to breast cancer, is found in its highest dietary levels to be in grains (noodles, etc., whole grain, organic, or no), as well as root veggies. So really, there is no safety in agribiz foods at all, regardless of your chosen menu. Now with Fukushima fallout still being found in measurable amounts in west coast dairy and in some seaweeds and fish, well…there you have it. I believe we are entering an era of decreased life expectancy across the board and across diets.

    • tinako said

      So what do you suggest we do?

      • Rebecca Winter said

        Eat vegetables and beans and fruit with seeds ( like sunflower, pumpkin) and nuts (like walnuts and almonds). A tablespoon of ground flaxseed for your Omega 3 essential fatty acid; and a B12 supplement and a Vitamin D supplement. Avoid everything else- including any animal product. We eat fresh, raw and organic as much as we can ; we cook very simply without oil. We add turmeric, minced garlic and lemon juice and balsamic vinegar as salad dressing. We love our new diet- we enjoy delicious meals with every vegetable, bean and fruit under the sun. We abandoned our wine/cheese/bread and a lifetime of cappucinos in cafes with only a little effort and dropped sugar as the toxic drug that it is. We immediately started losing weight and yet we are never hungry. We always have something delicious and nutritious that makes us feel great. We could never go back to our old way of eating. We are just so happy with our new way of life. AND I am sleeping so well! Just try it and see.

    • Bob said

      Pesticides and residual chemicals was a point I was about to comment on. I think a vegan diet is absolutely great for the body, but it’s the all the nasty man-made stuff (in addition to natural levels of arsenic in the soil) that plants can absorb that get passed directly to humans. The bad stuff completely offsets the good stuff. Plants have no organs so they cannot flush out the toxins as opposed to cows that have livers. The most effective thing to do to prevent bad vegatables and fruits from getting into the food supply is to conduct random testing on crop growers and levy a fine. This would hopefully give an incentive to farmers to buy a simple soil testing kit and do their own testing as well as make a greater effort to reduce their pesticide use.

  14. *********I think maybe the key is pesticides *********

    • Madamegato said

      I think you are absolutely right. Pesticides and all the chemical garbage we put in our bodies and on it. Plastics, petroleum… the issue goes so far beyond food.

  15. aaron said

    Here’s my take on the issue. I believe the research is conclusive that red meat and all animal products (to a lesser degree) contribute to cancer and heart disease. However, those of us who have been diagnosed with cancer, or want a dramatic risk reduction, should do more than just eating a whole foods vegan diet. Plant foods differ dramatically in their ability to fight disease and increase health. In fact certain vegetables have been shown to be far more effective than others for fighting certain cancers. But cruciferous and allium vegetables have been successful in fighting virtually any cancer cells put to the test. If there were only two vegetables I could eat, I would choose broccoli sprouts and garlic. The cruciferous sprouts have been shown to be about 50% more potent than the mature plant. I try to eat two raw cloves of garlic and two cups of cruciferous sprouts every day. I just swallow the chopped garlic with water, and I blend the sprouts with fruits and leafy greens.

  16. Bella said

    I believe most vegans are healthier because they usually eat healthier overall once becoming vegan. Although studies have shown that when people have breast cancer (knowing or unknowing) and consume soy, the soy creates a false estrogen and speeds up the cancer growth. More research needs to be done on soy.

    • Jen said

      Soy has gotten a bad rep about the estrogen thing, but soy can be VERY healthy for you as long as it is FERMENTED (like Tempeh). The “bad” soy is what is found in fake meat products – you’ll see them on the label as “soy protein isolates” these are bad for you. Organic tofu and tempeh are good for you, whether you have cancer or not. Please do your research!

  17. Lillie said

    I bet those raw vegans who are getting cancer are eating a lot of soybeans. Soybean turns to estrogen when digested, and there are a lot of estrogen related cancers, such as cervical cancer. Also, although they did not have risk factors per se, we cannot rule out whether their partners are chain smokers. Second hand smoke and environment factors put us at huge risk. Sweeteners in teas like aspartame and NutraSweet feed cancer as well. Raw vegans think they are not at risk but are due to these sneaky, underlying, high risk factors. I only eat fruits, vegetables, nuts and seeds (salmon and tuna sparingly). And I feel back to normal, praise God. No sweeteners, not even Stevia. Sweeteners overwork your pancreas, which releases insulin every time it senses something sweet. Why overwork your pancreas like that? That’s how you get pancreatic cancer. Stay away from breads, because breads, even wheat breads, can be high in glucose, and high glucose levels feed cancer. The only anti-cancer diet is a high alkaline diet that is a strict vegan diet– no meat and dairy. Period.

    • Laura said

      Most unorganic soy grown is genetically modified. There is absolutely no good reason for genetically modifying apart from putting even more money in the pockets of evil companies such as Monsanto. Naturally grown soybeans eaten in moderation are not the problem.
      I notice someone mentioned Linda McCartney, but there is no way I would have touched anything she marketed, because most of her recipes either contained high fat levels or required to be fried.
      The body is not designed to be sick. Given the right nutrients and a clean environment, I believe we are able to fight off most diseases. Sometimes when a person switches to a vegan diet, diseases which have been lying dormant from the past are uncovered and the body starts to deal with them because now it can while it’s not being continuously poisoned any more. I hope the vegans who have been diagnosed with cancer decide to treat it naturally – I personally would go on to the Gerson therapy – because what an insult it would be to the body to start consuming deadly chemicals (chemo) when it is trying to fight the cancer itself.
      Lillie, please don’t eat salmon (most of which is GM) or tuna (very high in mercury). All seafood should be avoided by anyone wishing to stay healthy.

  18. desiree said

    I agree with Lillie and Bella, soy needs to be looked at more. Most soy in the US is genetically modified (99%, GMOs have been around since 1996) and on top of that, phytoestrogen. I am vegan but I do not eat soy. Many of my vegan friends live on “fake” meat, while KINDER, is not healthy. Organic is also important.

  19. Jean Myers said

    Cancer begins as a single cell and can take years or decades to grow to a detectable size. If a person switches to a whole foods vegan diet and discovers cancer one year later, that cancer was growing a long time before the switch to the healthier diet. To really prevent disease healthy diets need to begin much, much earlier. However, some who change to a whole foods vegan diet after diagnosis do much better than they would otherwise.

  20. Loui said

    Organic vegan is the way to go free range eggs for B12 would be the the exception for consuming animal products preferably from your own happy healthy organically fed chooks:)

  21. Sabine said

    Since you mention the China study, it might be helpful to separate vegan diets from plant-based, or nutritarian diets. I have met many so called vegans who consume processed foods, sugars and oils every day and they are not healthy, nor are they slim. I think when it comes to health, you really have to cut out more than just meat and dairy – you have to go full scale plant based, meaning – 90% or more of your diet must consist of fresh raw vegetables, raw fruits, beans, raw nuts and seeds. So when you look at these studies with those so-called vegans, you have to be really careful not to mud the waters. Even moderation can kill you sometimes, especially if genetics or other exceptions play a role.

  22. kruemmel said

    In medical terms, you will not find guarantees. You can only predict a certain risk factor, such as smoking will increase your risk for lung cancer. But I might smoke all my life and never get any cancer at all. We humans are all different and there will always be some diseases that we can not control 100%. Cancer is such a disease.

    Also, being a vegetarian or vegan does not mean you are healthy! A vegan may consumer sugars, fats and processed food-like items that have as much nutrition as the box they came in. it is the micro nutrients that your body uses for optimum

    Thousands of studies clearly show that a diet consisting of mainly plant based foods, such as raw vegetables, fruits, legumes, beans, nuts and seeds will drastically reduce your risk of cancer.

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