Health advocates and the popular press have been telling us that diet is a major risk factor for many kinds of cancer. One of the strongest cases for a relationship between diet and cancer is the case of meat consumption and colon cancer risk. Studies have shown that incidence of colon cancer is generally low in nations and in cultures where meat consumption is low, while in Europe and North America, where meat consumption is high, colon cancer incidence is also high. Moreover, people who move from a low incidence area, such as Japan, to a high incidence area, such as the United States, tend to acquire the high colon cancer incidence rate of the adopted country (B.E. Henderson, R.K. Ross, M.C. Pike : “Toward the primary prevention of cancer,” Science”, v.254, 1991).
One of the best studies that associated meat and animal fat consumption with colon cancer risk is known as the Nurses’ Health Study. It involved initially 121,700 female registered nurses in 1976, the beginning year of this prospective study. Subjects were surveyed using questionnaire on known and suspected risk factors for cancer. Then, all of these women were studied and followed over time. Women were eliminated from the study if they did not properly complete the dietary questionnaire, or if they had previously had cancer or other bowel disease. This left a group of 88,751 women who were closely followed until 1986. During the course of the study 150 women developed colon cancer, and this small group of patients was then compared to the other women in the study who did not develop cancer.
The study found that dietary consumption of animal fat was associated with an 89% increase in colon cancer risk. The relative risk of colon cancer risk was 2.5-fold higher in women who ate beef, pork, or lamb as a main dish every day, compared to women who reported eating these foods less than once a month. Processed meats (e.g. sausage, hot dogs, bacon, and sandwich meats) and liver were also associated with an increase cancer risk, but consumption of chicken without skin was actually found to be protective from colon cancer. Women who reported eating chicken without skin two or more times a week had half the risk of colon cancer of women who ate it less than once a month. These findings make a very convincing argument than it is worthwhile to reduce meat consumption