The colon is another name for the large intestine, which makes up the second half of our digestive tract. Strong links have been found between the consumption of meats and other fatty foods and colon cancer. 73,74 When the past diets of cancer patients are studied, it is very clear that meat-based Western diets are linked to colon cancer. Comparisons of countries with different rates of colon cancer have supported this finding.
In order to absorb the fats we eat, our liver makes bile which it stores in the gallbladder. After a meal, the gallbladder squirts bile acids into the intestine, where they chemically modify the fats eaten so they can be absorbed. Unfortunately, bacteria in the intestine turn these bile acids into cancer-promoting substances called secondary bile acids. Meats not only contain a substantial amount of fat; they also foster the growth of bacteria that cause carcinogenic secondary bile acids to form. When meat is cooked, carcinogens can form on the surface of the food. As with breast cancer, frequent consumption of meat is associated with an increased risk of colon cancer,75 particularly that of red meat.76
High-fiber diets offer a measure of protection. 77 Fiber greatly speeds the passage of food through the colon, effectively removing carcinogens. And fiber actually changes the type of bacteria that are present in the intestine, so there is reduced production of carcinogenic secondary bile acids. Fiber also absorbs and dilutes bile acids.
Even people who are at particular risk for cancer can be helped by high-fiber diets. Jerome J. DeCosse, M.D., a surgeon at Cornell Medical Center, gave bran to patients with recurrent polyps of the colon. These are small growths that have a tendency to become cancerous. Dr. DeCosse found that within six months, the polyps became smaller and fewer in number. He believes that pentose fiber, which is plentiful in wheat, is the key to bran's power. 78
Vegetables, particularly cruciferous vegetables such as broccoli, cauliflower, Brussels sprouts, and cabbage, also lower the risk of colon cancer. 77
Two themes consistently emerge from studies of cancer from many sites: vegetables and fruits help to reduce risk, while animal products and other fatty foods are frequently found to increase risk.
When the terms "fiber" and "fat" are used, it is easy to forget the foods from which they come. When you hear about the dangers of fat, think meat-and-dairy-based diets, aided and abetted by oily foods. Fiber is found in whole grains, vegetables, fruits, and beans. There is no fiber in any product from an animal.
Surviving Colon Cancer
Colon cancer is encouraged by diets containing animal fat and discouraged by diets rich in vegetables. A low-fat, plant-based diet is important both for those seeking to prevent cancer and those who have already been treated for it.
Researchers at the University of Arizona found that people who have been treated for colon or rectal cancer have less risk of recurrence when their diets are rich in fiber. They found benefits from daily supplements of 13.5 grams of wheat bran fiber (the amount in a half-cup of bran cereal), but they speculate that other forms of fiber might have the same effect. A vegetarian diet can easily boost fiber intake by 10 to 29 grams per day. If you have bran cereal, topping it with soymilk rather than cow's milk allows you to avoid animal fat, cholesterol, lactose, and animal proteins.
Colon cancer typically develops from polyps in the colon wall. These polyps become smaller and fewer in number within six months on a high-fiber diet. 14
It is clear that much more needs to be learned about the power of foods to prevent cancer or to improve cancer survival. The good news is that the diet that helps protect against cancer is the same one that keeps cholesterol low and waistlines slim. Keeping animal products out of the diet, keeping oils to a minimum, and including generous amounts of vegetables, grains, beans, and fruits is a powerful prescription.