I don't know about you, but over the past several years I have heard a LOT about genetics and cancer [along with genetics and obesity, genetics and other disorders]. Genetics seems to be a really hot topic in these times; however, Dr. T. Colin Campbell's research in the famous China study [along with many other studies] showed that there is a much higher link to cancer when people eat protein from animal sources than from their genetics. His [and others'] research showed, for example, that rats and people who ate a diet high in animal protein [he compared, for example, rats given a 5% diet in casein protein and rats given a diet in 20% casein protein; casein is the primary protein in cow's milk] we much more likely to get many different forms of cancer than those who ate a low protein diet. Now, if you're like me, you might wonder how much of a difference rat diets and rat metabolism compared to human diets and metabolism there may be. Campbell reports that rats and humans have an almost identical need for protein, that protein operates the same way in rats as it does humans, and that the level of protein intake causing tumor growth is the same is the same level that humans consume (1, p. 65). Studies were also done with mice. And, from the China study, Campbell and his colleagues also found that people who ate higher levels of animal protein also had higher levels of different forms of cancer. Based on these and other studies, Campbell writes: "The results of these, and many other studies, showed nutrition to be far more important in controlling cancer promotion than the does of the initiating carcinogen (1, p. 66). Another pattern emerged from research on animal and plant-based proteins: "nutrients from animal-based foods increased tumor development while nutrients in plant-based foods decreased tumor development" (1, p. 66). The China study involved a rather homogenous group of people, called Han, so genetic influences were all but ruled out. Campbell's [and others'] conclusion from the various research studies on protein is that we should only get about 10% of our calories or energy from protein [or 50-60 grams]; the average American eats more along the lines of 15-16% [or 70-100 grams] (according to Campbelll at the time his book on the China Study was published in 2008; the amount of protein consumed by Americans may have increased since then).
There are about 12 grams of protein in 100 calories of spinach [15 ounces], 5 grams of protein in 100 calories of raw chick peas [about 2 tablespoons], and about 13 grams of prein in 100 calories of porterhouse steak (about 1 1/2 ounces).
Campbell and other researchers discovered that a low protein diet of 5% even reduced or eliminated certain markers [called foci] of cancer (1, p. 58-9)! Additional studies were conducted comparing plant and animal proteins, with the result being that plant protein did not promote cancer growth, even at higher levels of intake, as compared to casein (1, p. 59). Even wheat gluten did not produce cancer at 20% levels of intake. Thus, concludes Campbell, it is possible that cancer could be controlled through nutrition! Campbell, who had been raised on a dairy farm, and had believed, as many others of his time believed, that dairy was a superb protein source. As his research continued on for more decades, his belief about protein [and other notions about nutrition] was radically altered. Plant sources became a much more sound choice, and now he promotes a 'whole food plant based diet' (see his book Whole for more info, too). And, of course, Campbell is not alone in his attitude shift or belief about nutrition; many others have come to the same conclusion. Why many others, including intelligent scientists, refuse to act on the abundant research on a whole foods plant based diet is for another story!
So, when people ask you "Where do you get your protein?" you can say, "fortunately, I get mine from healthy plant sources, and am much less likely to develop horrible diseases such as cancer, heart disease, or other "diseases of affluence like diabetes!
1. Campbell, T.C. and Campbell, T. M. 2008. The China Study: Startling Implications for Diet, Weight Loss and Long-term Health.Benbella Books, Dallas, Tx.