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Animal Protein, Cancer, and the Optimal Diet

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  • Animal Protein, Cancer, and the Optimal Diet

    Hi everyone,

    Let me start by saying that I am new to this forum, but find the advice given in The Primal Blueprint fascinating. It makes so much sense that the optimal diet (and lifestyle) for us should be close to the one that we evolved on.

    However, I recently heard about research done by a Cornell professor by the name of T. Colin Campbell that gives convincing evidence that animal protein in excess of very minimal amounts is highly carcinogenic. Now I'm confused: maybe we shouldn't be eating animals?

    Here is a video where he explains the research that he has done over the past 40+ years and why he has come to his conclusions. It's an hour long, but worth the watch.

    I would really appreciate feedback on what you guys think.



  • #2

    I just researched the china study. It was a wonderful study, but it's my view that Campbell's failure was that he never made distinctions of quality. Americans eat more meat, but we are eating industrial garbage meat. We eat less carbs, but we are eating non whole grain carbs.

    Also, the china study only focused on one ethnic group. The work of weston a price and others clearly shows that humans are able to thrive on a variety of diets. Therefore I can't trust any one size fits all diets.

    I just wrote a report on this, I threw it on my blog if you want to check it out.


    • #3


      maybe we shouldn't be eating animals?

      What do you think we have been eating for the last few million years?

      I think it was Taubes who proposes that we actually get cancerous cells all the time. If we are in good shape and eating correctly, the body fights the cells off.

      All meat diets certainly work well for a lot of hunter gatherers and they don&#39;t get cancer!

      The "Seven Deadly Sins"

      Grains (wheat/rice/oats etc) . . . . . Dairy (milk/yogurt/butter/cheese etc) . . . . . Nightshades (peppers/tomato/eggplant etc)
      Tubers (potato/arrowroot etc) . . . Modernly palatable (cashews/olives etc) . . . Refined foods (salt/sugars etc )
      Legumes (soy/beans/peas etc)


      • #4


        Thanks for your reply! I just read your report:

        I agree that when you analyze populations&#39; diets you are encompassing a variety of variables, not just the one you are trying to test. Is it the animal protein that is causing cancer, or the quality of the animal protein, or maybe that the protein is denatured (via cooking), or the presence of toxic chemicals, etc, etc. But in the video I linked Campbell also mentions controlled laboratory studies, like where he feeds rats milk protein in different amounts, and observes a correlation between milk protein and cancer. The point is that it&#39;s not just the china study that offers evidence to the relationship between animal protein and cancer.


        • #5


          First of all, let&#39;s clear up a little confusion. Campbell&#39;s research does not say that animal protein causes cancer. It says that EXCESS animal protein causes cancer. In the rat study, when the rats&#39; diet consisted of only 5% animal protein, the link between the animal protein and cancer wasn&#39;t there. It&#39;s not clear how much meat our hunter-gathering ancestors actually ate. Maybe the bulk of their diet was fruits and veggies, just like our closest living relatives, the Common and Bonobo Chimpanzees (they eat mostly fruit, and rarely hunt game. In fact the Bonobo never hunts.) Maybe in the U.S., we just go way overboard with the amount of meat we eat?

          But I agree with your sentiment. This is why I am actually troubled, and why I posted. It makes SENSE to eat meat if we assume that we evolved as HUNTER-gatherers. But if it turns out that animal protein is the single most carcinogenic substance that we can put into our bodies, then I may have to rethink my love of meat. Like everybody else I just want to know the truth of what I should be putting into my body.


          • #6

            I agree with him about the development of policy and the importance of nutrition information for the public.

            I didn&#39;t not follow his leap from Milk protein finding to condemning all animal protein.

            Regarding the china study, he seemed to say that the lack of plant foods was a problem and that animal fat was not a problem and PUFA rich oils were. He does not seem to mention carbs at all.

            So I conclude for myself, I am doing the right thing. Eat an omnivore diet. Eat a lot of different stuff and eat good fats and don&#39;t sweat the amount of protein I get.

            It's grandma, but you can call me sir.


            • #7

              granny, you may recall I did a thread recently asking how much protein we really need. A lot of enlightening responses, and I&#39;ve continued my internet research on the topic. The answer is:

              Nobody knows for sure. Not even factoring in the variable of rebuilding lean body mass from its normal sluffing of cells, or body building or other hard work, everyone has an opinion w/o much science.

              I even went to vegetarian/vegan sites to see what they say. Sort of the same as the carnivore/omnivore sites.

              Without becoming psychotic about it, it seems .5 gram per pound of Ideal Body Weight is a working minimum. "More", whatever that is, for athletes. Count all types of amino acids in that total.

              As good a hunch as anything, I guess. Right back where I started from, in a sense.


              • #8

                vkh - the milk protein is casein right? this is a particularly difficult to digest protein and seems to be the crux of why some people don&#39;t like campbell&#39;s points. i dont know anything about it though.


                • #9

                  Has anyone researched the connection amongst animal protein + acid/alkaline imbalance + cancer? I&#39;m very vague on it, but it seems I&#39;ve read somewhere that meat is acidic and that cancer cannot grow in an alkaline environment--thus meaning that meat consumption should be accompanied by lots of good fruits and veggies. Anyone know more about it, or have I been slapped with junk science again? Did any of these studies look at what these folks were eating along with the protein?


                  • #10

                    But where does this leave the healthy Inuit on their traditional diet of mostly all animal protien and fat? The cancer rate among such people is almost nonexistent.

                    Start weight: 250 - 06/2009
                    Current weight: 199
                    Goal: 145


                    • #11

                      Okay, so, let&#39;s hold up for a second here. Dr. Campbell&#39;s experiments with rats were looking at 5% casein diet vs. 20% casein diet in rats. First of all, casein causes significant release of IGF1, which is of course going to promote tumor growth. The reason casein has that effect on mammals is because it&#39;s what they&#39;re intended to eat when nursing -- of course it&#39;s going to release growth factor.

                      The elephant in the room is the other 95% or 80% of that diet. Research diets for rodents always tend to make up the balance with soybean oil, corn starch, and sucrose. It&#39;s not surprising how easy it is for mice and rats to get cancer on that diet.

                      I would guess that what his research observed -- and again, it&#39;s ridiculous to extrapolate from casein to all animal proteins -- is that on a high sugar, high omega-6 diet, if you starve an animal of protein it doesn&#39;t have sufficient protein to sustain tumor growth.

                      If you take a look at another study of China, you&#39;ll see that as income and education go up (similar to the higher income folks in the Philippines getting more cancer that Campbell observed), people switch from rice to wheat, and more refined carbs:



                      That study didn&#39;t look at cancer rates, but it&#39;s not inaccurate to say that heart disease, obesity, diabetes, and cancer all tend to show up at the same time when your society&#39;s diet changes to promote the "diseases of civilization".

                      Bottom line, Campbell&#39;s a militant vegan and has books to sell, accuracy of his research be damned.


                      • #12

                        cat, katt - inuits certainly lived on diets of 90% meat. could any of us three adapt to that easily? maybe, but probably not. biochemical individuality, metabolic typing.. everyone is different, and a smart nutrition program should reconcile for that. anyway, in some people high levels of meat consumption will lead to acidic bacterial flora leading to a disposition for cancer. other people can handle it.


                        • #13

                          90%? Try 100%. All that "metabolic typing" and "biochemical individuality" stuff is not a hypothesis -- it&#39;s just a tricky way to say "I have no idea how to explain those data."

                          Proper human dietary theory will encompass and explain all humans and all diets and their health consequences in a satisfactory way, and neither the Inuit or the Kitavan will be unexplained edge cases.

                          Let&#39;s have no more discussion of the Inuit diet until we&#39;ve all read the experiences of one Vilhjalmur Stefansson:


                          Tarlach, if you haven&#39;t read it already, I imagine you&#39;ll like the part about salt.


                          • #14

                            That Stefansson article was really interesting. About the only "downside" I could see from an all-fish diet (perhaps an all-meat diet) was the increased metabolic rate that it may cause, a side-effect of which is premature aging.

                            One big problem for us in the 21st century is that our waterways are now so polluted that you cannot eat an arbitrary amount of arbitrary fish without ingesting harmful amounts of mercury and PCBs (see for example for a list of safer fish).


                            • #15

                              Yes, everyone is exposed to high amounts of carcinogens every minute of every day, but we have the ability to fight it off. The study may be "skewed". Read this: