Vegans consuming 7-18 servings of soy foods a day may end up with circulating IGF-1 levels comparable to those who eat meat.
Too Much Soy May Neutralize Benefits,
We know what happens when men with active prostate cancer start eating a vegan diet, the progression of their cancer appears to reverse, to get better—no drugs, no surgery, no radiation, just a vegan diet and other healthy lifestyle behaviors. Cancer markers in the control standard American diet group tend to get worse, and in the vegan diet group they tend to get better, the blood of those on a plant-based diet suppresses cancer growth about 8 times better. We're talkin' change on a genetic level diet and lifestyle changes switching on and off gene expression, delaying or avoiding the need for surgery and conventional chemo/radiation altogether.
I've already gone through that in videos past, but what if you did the same thing, men with prostate cancer, but this time—half in the control group and half in not just a vegan diet group, but in a heavily soy-based vegan diet group. How much soy are we talking about? 7-18 servings a day, for an entire year. That’s like entire blocks of tofu, or 7-18 glasses of soymilk—that’s like 4 quarts a day, all year round. What do you think happened to their IGF levels at the end?
The IGF-1 levels of the control group in the study didn’t drop at all, started high, stayed high. In a varied vegan diet—protein from multiple plant sources, all different kinds of benas, whole grains, etc—after years you can see IGF levels drop like this from baseline.
What happened to the drowning in soy vegan group. Did their levels drop too? With that much added soy, the vegans in the study got literally pounds of more protein in their diets than the meat-eating controls, but it was all added plant protein. Soy, however, one of those rare plants that mimics the protein profile of meat. So with that much more animal-type protein in their diet were they even worse?
Surprisingly, they ended up with values about same as the meateaters. But wait a second, in Asian countries, where they eat the most soy, they’ve traditionally just had a fraction of our breast and prostate cancer rates. Well the researchers found something interesting, the isoflavones, the phytoesterons in soy, may actually bump up production of IGF binding protein. So even though they had similar levels of IGF in their blood, in those eating vegan more of it may be bound up and unavailable to stimulate as much cancer growth.
Also, even in China and Japan, they don’t eat 7-18 servings of soy a day.
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 Kerry Skinner.
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The allusion to stopping cancer progression through diet is a reference to Dr. Ornish's remarkable work featured in my video Cancer Reversal Through Diet. The eight-fold higher cancer cell growth suppression documented in those eating plant-based diets can be found in Developing an Ex Vivo Cancer Proliferation Bioassay. It's important to remember in this discussion that soy food consumption is associated with an array of health benefits. See, for example,Breast Cancer Survival and Soy, The Effect of Soy On Precocious Puberty, andSoy Foods & Menopause. The question really just comes down to the topic of tomorrow's video, How Much Soy Is Too Much?
For some context, please check out my associated blog post: How Much Soy Is Too Much?
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