This is an old study but it was a big deal at the time. Still is. It analyzed data from the Nurses Health Study 2 cohort, over 88,000 women, and found that the more red meat and animal fat the women ate, the more likely they were to develop colon cancer. The risks were big – those eating the most animal fat were almost twice as likely to develop colon cancer as those eating the least. And “women who ate beef, pork, or lamb as a main dish every day” were two and a half times more likely to develop colon cancer as those who ate them once a month:
Relation Of Meat, Fat, And Fiber Intake To The Risk Of Colon Cancer In A Prospective Study Among Women, New England Journal of Medicine, 1990
The lead researcher, Dr. Walter Willett of Harvard, said at the time:
“If you step back and look at the data, the optimum amount of red meat you eat should be zero.”
I was looking around for recent work addressing this link, a link that has no dearth for support in the literature, and discovered this:
Colorectal Carcinoma: Why Is There a Lower Incidence in Nigerians When Compared to Caucasians?, Journal of Cancer Epidemiology, December 2011
“Cancer prevention and cancer-protective factors are deemed to lie in the starchy, high-fiber, spicy, peppery foodstuff low in animal protein which many West African nations consume.”
In more depth:
This is one area that has been extensively researched in the epidemiology of colorectal carcinoma. Appreciation of the environmental dependence of bowel cancer was noticed from migration studies as one can see the contrast between American blacks, who now have an incidence comparable to Caucasians, and that of native Africans. This is because these migrants have adopted the dietary customs of their new country .
Indeed, the idea that colon cancer is linked to diet is usually credited to Dennis Burkitt who reported that colorectal cancer was rare among rural Africans. This, he suggested, was because Africans had little meat in their diet and instead ate a lot of fibre from fruits, grains, and vegetables .
Colonic adenocarcinoma is the 3rd commonest malignant neoplasm in societies with western type lifestyle as diet rich in red meat and fat, lacking in vegetables, fruit, and fibre is implicated in colonic carcinogenesis [3, 4, 8]. It is without doubt that countries that consume a lot of meat and animal fat have the highest rates of colon cancer, and this inversely correlates with the consumption of dietary fiber [32–34].”
Here’s a bit of mechanism. I’ve discussed this at length over the years, how resistant starch lowers cancer risk through production of short-chain fatty acids:
“The carbohydrate-based diet of Nigerians had been mentioned earlier, and this has been shown to be protective against the development of colon cancer. The human colonic bacteria ferment starch and nonstarch polysaccharides to short-chain fatty acids, mainly acetate, proprionate, and butyrate . Butyrate has been found to be a preferred substrate for colonocytes and appears to promote a normal phenotype in these cells [44, 45]. Resistant starch fermentation favours butyrate production and may be more protective against colorectal cancer than nonstarch polysaccharides which are the major components of dietary fiber [44–48].”
We’re back to the starchy, high-carb diet that a growing number of medical professionals are advocating – a diet low in animal food, low in fat generally.
Low-carb, Paleo, Wheat Belly, Grain Brain, and other Atkins-type diets fail to show good for a spectrum of diseases. They can assist with initial weight loss. But it is that weight loss, no matter how it is achieved, which benefits health … which lowers blood pressure and blood glucose, which improves sleep apnea and pain from arthritis … not necessarily the low-carb diet. Unfortunately, diets high in animal foods have been shown, in many types of studies, in animals and in humans, to increase the risk for cancers.
Why not choose a diet that doesn’t have you trading one disease for another? A whole food, plant-based diet gives you that.