Protein and Liver Cancer?

I think you’re misunderstanding me. I had read the referenced study and the point of it and others was not to demonstrate whether or not casein causes cancer. Rather, it was to see if a high protein diet exacerbated or inhibited the carcinogenic effects of aflatoxin. As I said before, you can’t draw conclusions about a second compound (casein) based upon its’ effects after exposure to one (aflatoxin) that inherently causes the end result (hepatic tumors). This is a very basic principle. It’s making too large of a leap to then deduce that casein will cause hepatic cancer.

Again, the point of those studies as they were published was to evaluate what would exacerbate and what would inhibit the effects of acute aflatoxin exposure in rodents. It in no way indicates that it’s a causal factor. An example of what I mean would be the following:

Let’s say we find that rodents bathing in the sun and using baby oil experience significantly more skin cancer than those that don’t.

With the same reasoning that casein causes cancer, we would then conclude that baby oil causes skin cancer. Obviously that is not the case, rather, UV radiation acts as an initiator.

Now, a better argument to be made would be that we are exposed to large amounts of aflatoxin and thus we should avoid casein. But again, that still involves a number of leaps being taken as I pointed out in the previous post.

If the argument being made is that casein is a promoter, then one needs to establish that all of our livers are being exposed to large amounts of compounds which exceed the threshold thought to exist within the multiple hit model. Of course, sufficient data to suggest that it is a promoter in humans would be needed as well.

[quote]BmacG wrote:
Cy, the study did vary the amounts of casein in the rat and mice diet, one group receiving about 5-6%, the other receiving about 20-22%. The issue tested was not whether aflatoxin initiates and promotes cancerous tumor growth, that is known (to be conservative, in mice and rats at least, whether in humans we don’t know one could argue, but the argument is put forth that protein metabolism and requirements in rats is very similar to humans). The resulting incidence of liver tumor growth was much (significantly) higher in the higher casein group than the lower casein group. The equivalent high gluten group (20-22% gluten fed diet) was also low, roughly equivalent to the 5-6% casein.

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Cy, I just want to say you’ve put up some great posts. And please let me clarify my intent, as I feel that perhaps one might infer that I’m attempting to knock casein protein consumption. Rather, after reading about these studies it got me thinking, and I’ve been attempting to find good counterarguments, as I’d very much like to continue using casein in products such as Grow!. I feel a point counterpoint approach, especially when making important decisions that have potential impacts on my health, is invaluable. Having said that…

I think perhaps we’ve misunderstood eachother. We’re both arguing the same point but assuming we’re arguing the alternative, that casein was the cause of cancer. Rather we know that it would exacerbate the effects of a carcinogenic compound, aflatoxin, and allow an increased rate of promotion of liver tumors (the second, “better” argument you mentioned in your post) in rodents. There are a number of leaps to be made for humans, but nonetheless it’s an intriguing connection. I’m sorry if I wasn’t clear enough.

Using your rat’s sunbathing with and without baby oil analogy (I got a good laugh out of that one), I completely agree that it would be fallacious to infer that the baby oil (casein) was the cause of increased rates of skin cancer. UV radiation (aflatoxin) is indeed the cause, yet baby oil no doubt accelerates the rate.

I think one of the main leaps that would need to be made in the argument is that aflatoxin is a good proxy for the effects of other environmental toxins on promotion of liver tumors. But isn’t a lot of nutritional research and advice based on similar types of animal studies, whose results are accepted as approximating or even duplicating similar effects in humans?

This has been a really informative discussion, thanks so much for putting up some awesome posts that’re allowing me to understand the issue more clearly. I’m really just trying to justify buying Grow! :wink: