I don't think major studies show any great advantage to vegetarianism. Shouldn't they show a 90% drop in cancer deaths? Also 90% drop in diabetes? And a 90% drop in heart disease, leading to a HUGE increase in life expectancy.... Nope, I just don't see it.
I am currently reading this book. I would note that through the book so far, campbell is slowly building his case starting with his early work with mice and liver cancer through to the exhaustive and massive China study. When he ventures off the path into speculation I have found that he notes that is what he is doing and says why he is doing so. He is also very careful to note the level of statistical significance in correlations, which is very very refreshing in a book that people might (mis)label as a 'diet book'.
As mentioned above. You should see 90% drop in diabetes, cancer, and heart disease incidence among people who eat little no no meat, which is exactly the case. I am not really the typical read of this book, because I started with the actually data from the china study itself, looked at the patterns that I could see and then heard there was a book on the subject. It is quite obvious that there are two sets of diseases in our world: Diseases of affluence that effect the western world and diseases of poverty that effect the 'third' world. The diseases of affluence: cancer, diabetes (type one and two) and heart disease are virtually absent in populations where the people eat a predominantly plant based diet.
He claims that high cholesterol is the cause of cancer (specifically, liver and colorectal cancer). He claims that cancer is caused by by-product of protein metabolism; specifically of animal protein..
That's not what I read. Campbell mentions cholesterol as a contributing factor in these diseases, but to say that he says that it's the 'cause of cancer' seems to me to be deliberately misrepresenting his argument. He also does not say that cancer is 'caused' by animal protein at all. He says that (and this is a dumbed down over simplified version) having animal protein in your body makes it easier for cancer causing agents such as radiation or chemicals to cause lasting damage to cells further that protein then feeds those cancer cells, making the promotion stage of cancer growth far more efficient... in essence: Eating animals doesn't cause cancer, it just aids and abets it.
That said, the critiques I have read so far suggest that campbell does not present an iron clad case for veganism per se. The leap from very little meat (which are the populations the china study finds to have the lowest rates of affluence diseases eat less than 5% animal foods, but still eat some) to ZERO animal products is not as trivial as Campbell supposedly makes it seem. I have not made it that far in the book yet, but I am interested to know how he makes that case.
I personally, am a Vegan, becoming one mostly because my wife did about a year and a half ago. I am not an activist or a commie. I am a male American in my 30s and my cholesterol is 70 according to a test about 2 weeks ago. Unfortunately I don't know what it was before I became a vegan, but I can say that both my mother and my father are taking cholesterol lowering medication to (hopefully) lower their risk of heart attack and stroke. I do not include this to convince you my fellow skeptics, as it is anecdotal, merely so you understand why I became acutely interested knowing about the relative health of a vegan diet and any literature on what effect it might have on me... I also wanted to know if a 70 cholesterol was going to hurt me, as my doctor immediately wanted to put me on cholesterol raising drugs. From what I have read so far, I am glad I decided against it.
In end I am beginning to simply see meat eating as a natural selection mechanism. Let the rest of them eat their meat and cheese and icecream and get cancer and diabetes and have heart attacks and strokes. If only the insurance actuaries took my diet into account, I wouldn't even have to pay for everyone else's slow self-induced deaths.