Cancer and the Animal-to-Plant Protein Ratio

Eating More Meat Than Veggies? For Prostate Cancer, it Matters

It is now eight years since the famous Ornish study was published, suggesting that 12 months on a strictly plant-based diet could reverse the progression of prostate cancer. For those unfamiliar with that landmark Ornish study, see Cancer Reversal Through Diet?, which the Pritikin Foundation followed up on with Ex Vivo Cancer Proliferation Bioassay.

Wait a second. How were they able to get a group of older men to go vegan for a year? They home delivered prepared meals to their doors, I guess figuring men are so lazy they’ll just eat whatever is put in front of them.

But what about out in the real world? Realizing that we can’t even get most men with cancer to eat a measly five servings of fruits and veggies, in a study profiled in my video, Prostate Cancer Survival: The A/V Ratio, researchers settled on just trying to change their A to V ratio—the ratio of animal to vegetable proteins—and indeed were successful in cutting this ratio by at least half, from about two to one animal to plant, to kind of half vegan, one to one.

How’d the men do? Their cancer appeared to slow down. The average PSA doubling time (an estimate of how fast the tumor may be doubling in size) in the “half vegan” group slowed from 21 months to 58 months. So the cancer kept growing, but with a part-time plant-based diet they were able to slow down the tumor’s expansion. What Ornish got, though, was an apparent reversal in cancer growth—the PSA didn’t just rise slower, it trended down, which could be an indication of tumor shrinkage. So the ideal A to V ratio may be closer to zero.

If there’s just no way grandpa’s going vegan, and we just have half-measures, which might be the worst A and the best V? Eggs and poultry may be the worst, respectively doubling and potentially quadrupling the risk of cancer progression in a study out of Harvard. Twice the risk eating less than a single egg a day and up to quadruple the risk eating less than a single daily serving of chicken or turkey.

And if we could only add one thing to our diet, what would it be? Cruciferous vegetables. Less than a single serving a day of either broccoli, Brussels sprouts, cabbage, cauliflower, or kale may cut the risk of cancer progression (defined as the cancer coming back, spreading to the bone, or death) by more than half.

The animal to plant ratio might be useful for cancer prevention as well. For example, in the largest study ever performed on diet and bladder cancer, just a 3% increase in the consumption of animal protein was associated with a 15% higher risk of bladder cancer, whereas a 2% increase in plant protein intake was associated with a 23% lower risk. Even little changes in our diets can have significant effects.

What else might help men with prostate cancer? See Flaxseed vs. Prostate Cancer and Saturated Fat & Cancer Progression. What about preventing it in the first place? See:

Poultry and eggs may be related to cancer risk in a variety of ways:

Crucifers may also help with other cancers. See:

Breast cancer is highlighted in my video Breast Cancer Survival Vegetable.

-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.

Image Credit: Greg Habermann / Flickr

  • I dislike being a nitpicker here, because I know what Dr. Greger is saying, but calling someone a “half vegan” is like calling someone a “half racist” or, to be more apropos, a “half slaver”. Being that a vegan is one who stands up against the exploitation of others and thus there is no room for half measures. Now, saying someone is half plant-powered, plant-based, etcetera is much more fitting. :-)

    • Justice0501

      WOW. Way to combine the most fanatical components of veganism and political correctness. Get a fucking life.

    • Ben

      I agree “half-vegan” is probably a bad term. I would go with “half-plant-based”, but that is a mouth-full!

    • Taargus Taargus

      oh get over yourself it was an effective way of communicating an idea

  • El

    I’m assuming that the eggs and poultry mentioned in paragraph 5 were not organic?

    I wonder if eating eggs from your own chickens and poultry that is free-range with non-soy feed would have the same negative effects?

  • Kitsy Hahn

    I always look for broccoli with buds that are deep green, not yellowish like in the above photo. That broccoli looks kinda elderly. Oh, right, it was the lighting. :-)

  • Anonymous

    Imagine the irony of reading this in your urologist’s office for your very first biopsy 2.5 years after going full on plants because the new PHI test says you might have PCa – here’s hoping Dr. Greger is right and my body just had the good sense to balk at the dimbulb tests!

    • Thea

      Good luck! Eating healthy is not a guarantee, but it does improve your risks dramatically. I’ll think good thoughts for you.

      • Anonymous

        Thanks Thea. Really mixed feelings at this point. In one sense There is no way to avoid embarrassment here – either I undertook this very painful test for no reason (distrusting the program), or went vegan for no apparent health benefit. On the other hand, it will be awesome to learn it was nothing, or a comfort knowing that it probably would have been much worse.

  • jim

    any idea how much flax you should take if you have prostate cancer?

    • DanielFaster

      In the cited study it was 3 tablespoons of ground flax per day. Cruciferous veggies and allium (onion garlic etc) and fenugreek also looked helpful. Orange bell peppers and lutein as in tomatoes and green tea and whole soy (tofu is good isolate is not) and mushrooms and pecans walnuts and peanuts have also been mentioned.

  • Dommy
  • JC

    Dr Greger,Please respond to this.

    • JC

      It does not look like the evidence is very strong for flax as prostate cancer inhibitor.

  • bruxe

    Great article, some of the questions I have been interested in were answered, but very explicitly.

    >> the PSA didn’t just rise slower, it trended down, which could be an indication of tumor shrinkage. So the ideal A to V ratio may be closer to zero.

    What is “PSA”, I don’t see it defined anywhere in the article?

    Are there any studies that qualify how many veggies of what sort OR how little animal products of what sort to eat to get this effect?

    The cruciferous veggies are specifically mentioned, but at what dose. For a regular diet it seems really odd to mention eating 3 tablespoons of flax and things like that for an otherwise healthy person, I don’t think many will do that, and it is expensive and time consuming.

    One other thing is why are only certain cancers mentioned of studies … are we expected to eat some new kind of weird stuff to reduce the
    chances of getting every different kind of cancer is there an “anti-Cancer diet” that will help with all cancers?

    • PSA stands for prostate specific antigen which is produced by both normal and cancerous prostate cells. Although the cancerous cells produce twice as much per cell… hence the stated “usefulness” in using the test to screen for the disease. Unfortunately inflammation and infection in the prostate can cause elevation and the % of men with the disease is quite high. I would suggest you read Dr. Greger’s post…

      and more specifically to answer your question about vegetable selection see video: #1 Anticancer Vegetable… or

      At this point it seems that the best “anticancer” diet would be a whole food vegan diet with adequate intake of Vitamin B12. You should consume a variety of vegetables.

      The risk of cancer with consumption of animal products seems to be linear such that less is always better. Of course most of our exposure to carcinogens especially dioxin like compounds comes from meat, dairy and fish. By going to browse all topics you can view any of the 58 video’s on carcinogens. You need to keep tuned in to NutritionFacts as the science keeps coming. Good luck.

  • FrFong

    Ornish is OK with egg whites, dairy, fish oil, and fish consumption.

    • When I have heard Dr. Ornish speak in the last 2 years he seems to be sticking with fish oil despite the lack of science supporting its use. I am not aware of any studies which support the use of egg whites, dairy and fish for improving your odds of avoiding early death or disability.

      • FrFong

        I highly doubt Dr. Ornish would make a recommendation to consume fish oil, egg whites, or some dairy without referencing studies and science supporting the benefits.

        As far as avoiding early death….How do you explain this from Dr. Greger himself? He admits vegans don’t live longer than meat eaters.

        • There are always exceptions. One reported case was a patient born with abnormalities in their coronary arteries which predisposed him to an early heart attack. By consuming the correct diet you improve the odds for delaying death and avoiding chronic diseases. The original studies by Ornish and Esselstyn were done in the early 1990’s and we have learned alot since those studies. The best results have now been shown by Dr. Esselstyn in his recent report on long term follow up of almost 200 patients. If you view the videos on this website re: fish oil, dairy and eggs and come to the conclusion that they are healthy foods then we will just be in disagreement. That said if you can find good scientific studies that show the benefits of fish oil, dairy, etc. I would be glad to read them. Since the science keeps changing we should be ready to shift our beliefs. So you need to keep tuned to

          • Frong

            I am more focused at the 5:19 mark of Dr. Greger’s video where he referenced the Harvard Study on Vegetarian mortality. 8,000 people over 18 years. Found no difference vs. meat eaters. His jaw dropped as mine did when I first watched this video.

          • Plantstrongdoc M.D.

            Vegetarian is definitely not the same as eating a carefully planned Whole Foods Plant based Diet. Probably even most vegans dont. So it is difficult to conclude on a WFPD from studies where people claim to be vegetarian.

          • fruitbat

            Other studies have shown that vegetarians live 7 years longer than meat eaters, and vegans live longer than vegetarians. The minority of studies that show vegetarianism in a negative light are always the ones that gain the most publicity.