Beef Tallow Increases Apoptosis and Decreases Aberrant Crypt Foci Formation Relative to Soybean Oil in Rat Colon

Abstract

Although epidemiological studies have implicated red meat as increasing colon cancer risk, animal studies have generally not been supportive of such an effect. This study examined red meat components, such as beef protein and tallow, on markers of colon cancer risk. Rats administered dimethylhydrazine were fed either casein or beef protein as the protein source and soybean oil or tallow as the fat source in a 2 2 factorial design for 9 wk. There were fewer preneoplastic lesions [aberrant crypt foci (ACF)] and a greater apoptotic labeling index (P < 0.05) in the distal colonic mucosa of rats fed tallow compared with soybean oil. Fecal bile acid concentrations were significantly lower in rats fed tallow compared with soybean oil. There were no significant differences in mucosal cell proliferation. No significant effects were found due to protein source or to interactions between fat and protein sources for ACF, cell proliferation labeling indexes, or bile acid concentrations. However, there was a significant protein by fat source interaction for the apoptotic labeling index. The decreased number of ACF, decreased fecal bile acid concentration, and increased mucosal apoptosis with tallow consumption are not consistent with a role for this fat in increasing risk of colon cancer.

Processed Meat and Colorectal Cancer: A Review of Epidemiologic and Experimental Evidence

“…No difference in epithelial cell proliferation rate was observed in rats fed diet with 10%, 25% or 40% of the energy derived from fat (38). Beef tallow diet (14%) reduces the number of aberrant crypt foci and increases apoptosis in the colon of DMH-initiated rats, compared with soybean oil diet controls (39). A metaanalysis of rat studies can explain these puzzling discrepancies: saturated and n-6 polyunsaturated fats are promoters in F344 rats, but SD rats resist to high-fat diet promotion (40).…”

“…However, the hypothesis that saturated fat intake enhances fecal BA excretion was not supported by several studies in rats and in volunteers. Compared with soybean oil diet, beef tallow reduces fecal BA in DMH-induced rats (39). Another Gallaher's study shows that low-fiber diets rich in beef tallow (20%) decreases BA concentration in the colon and do not increase colon carcinogenesis in rats (42).…”

Meat and Colorectal Cancer: Associations and Issues

“…These include total iron, heme iron, saturated fatty acids, and protein fermentation products. However, there is little experimental support for a role of non-heme iron [18,19] or for fat from meat [20,21] in colon carcinogenesis. Although protein fermentation products appear to be toxic to the colonic epithelium, their role in promoting colon cancer remains uncertain [22].…”