A plant-based diet is a powerful way to substantially cut your risk of colon cancer. It’s long been known that vegetarians have a very significantly reduced risk of colon cancer. Several studies have shown that vegetarians reduce their risk of colon cancer by 46%-88%, they have a 54% reduced risk of polyps, and a 200% reduced risk of advanced polyps which can become malignant. Since colon cancer is the second leading cause of cancer death, these percentages are very important. While we’ve known this for quite a while, we didn’t know why until recently – now we do!

First, processed meat such as hot dogs, bacon, and salami have been declared as carcinogenic (cancer causing) by the World Health Organization, placing them in the same category as tobacco. Even ordinary red meat, such as steaks and burgers, has recently been classified as probably carcinogenic. While the nitrites are the biggest culprits in processed meat, there are also chemicals called polyaromatic hydrocarbons (PAHs) and heterocyclic amines (HCAs), which are formed when meat is cooked. These have been shown to cause colon cancer, and so are a major factor in the increased risk of colon cancer that meat eaters experience. By following a meat-free diet vegetarians lower their exposure to all these carcinogens, thus lowering their risk of colon cancer.

Secondly, we are all familiar with the fact that our colons, or large intestines, have a lot of bacteria living in them. When some of the bacteria encounter red meat they produce two carcinogens, called nitroso amine and hydrogen sulfide, adding to the cancer risk. In addition, studies show that vegetarians have a very different mix of bacteria in their gut compared to meat-eaters. It turns out that the bacterial mix, or profile, that results from a meat-laden diet also causes inflammation. Inflammation can contribute to causing colon cancer. However, the bacterial profile that comes from following a plant-based diet not only doesn’t produce nitroso amines and hydrogen sulfides, but produces butyrate, a biochemical that actually reduces inflammation.

Thirdly, certain other diseases, such as prediabetes and Crohn’s disease, raise the risk of getting colon cancer. Since vegetarians have a lower risk of getting these diseases, this also helps reduce their risk for colon cancer.

Fourthly, vegetarians consume more foods that have a cancer preventing action. For instance, sulforaphane is a cancer fighting nutrient found in foods such as broccoli and other members of the cruciferous family. The cancer protective properties of sulforaphane have been observed in every stage of cancer formation. Since vegetarians tend to eat more of these vegetables than meat-eaters, they benefit more from the protective properties of sulforaphane. Naturally occurring salicylates, an aspirin-like biochemical found in a several different fruits and vegetables, have also been shown to fight colon cancer. And, of course, plant foods have plenty of colon-health-promoting fiber.

Fifth, if you’ve already had colon cancer, you can reduce your risk of recurrence by 85% by avoiding processed meat. However, certain plant foods, in particular beans and tree nuts, have been shown to be especially good at preventing colon cancer recurrence. Those colon cancer patients who ate the most beans, peas, green beans and nuts, substantially reduced their risk of cancer recurrence.

What about a colonoscopy? By having a colonoscopy, doctors can find and remove a polyp once it has formed, but they can’t keep it from happening in the first place. It’s therefore a form of secondary prevention. Following a plant-based diet actually reduces the risk of polyps forming and the colon cancer that may arise from them. It prevents the disease process in the first place. This is known as primary prevention. A plant-based diet may not remove the necessity for having a colonoscopy completely, but many more colonoscopy patients will receive a clean bill of health as a result.

See our professional level report on Colon Cancer.