Lack of colon promoting carcinogenesis by beef in the rat model

The possibility that eating red meat might cause colon cancer has received much attention by the popular press. An article in Time magazine carried the headline "Red Alert on Red Meat" (Toulexis, 1990). Additionally, a cartoon accompanying a New York Times column showed a man using a saw to cut away the section of a dining table that held a platter of steak. When articles and pictures such as these are appearing in major newspapers and magazines, it is understandable that people have become concerned or even fiightened about eating red meat and rightly so as cancer is second only to heart disease as the leading cause of death in the United States (American Cancer Society, 1992). Colorectal cancer is the third leading cancer in both men and women (Figures 1 and 2) and accounted for 11% of all cancer deaths in males and 13% in females in 1992(Anonymous, 1992).

Recent epidemiological studies have implicated red meat consumption as a risk factor for colon cancer in both men and women. A recent analysis of mortality data has identified animal fat in particular as the factor most strongly correlated with the risk for colon cancer (McKeon-Eyssen et al., 1984). The association between animal fat and colon cancer was said to be largely due to red meat consumption. However, a comparative study by Kinlin (1982) of strict religious orders in Britain showed that colon cancer mortality was not lower in religious orders that consumed no meat as compared to orders that regularly consumed meat as part of their dietary intake. Furthermore, it has been difficult to separate the effects of meat as a protein source from the accompanying fat content of the diets analyzed in these studies. Very little information has been published on the dietary effects of beef consumption on experimental colon cancer, so the issue still remains controversial. Therefore, the goal of this study was to rigorously study the effects of beef as a protein source, and the effects of fat source (beef tallow and com oil) at fat levels of 5 and 20%> and their contributions as dietary factors, as either promoters that increase the risk or protectors that reduce the risk, for colon carcinogenesis.