Colon carcinogenesis, possible role

The possible role of dietary fat on colon carcinogenesis has received support from studies in animal models. In several earlier studies on dietary fat and colon cancer, interpretation of results between high- and low-fat diets was complicated by the use of diets of varying caloric density and confounded by different intakes of other nutrients. However, recent studies in which the intake of all nutrients and total calories were controlled between the high-fat and low-fat groups, indicated that the amount of dietary fat is an important factor in colon carcinogenesis (27). 

While there are no epidemiologic data available on lipotropic factors and colon cancer in human populations, results of animal studies suggest a possible role for this class of nutrients (choline, methionine, vitamin and folate) in colon carcinogenesis (69). Table XVI lists results typical of those observed when rats are fed a diet high in fat, low in lipotropes and exposed to a colon carcinogen. 

The diet is believed to play an important role in the onset of carcinogenesis, and there are a number of carcinogens present in food, including mycotoxins, polycyclic hydrocarbons, and pesticides. Associations have been made between dietary fat intake and morbidity and mortality from breast and colon cancer. Another possible mechanism for the proposed protective effects against cancer of olive oil compared with sunflower oil involves diet-induced alterations in host immune responses. Both the type and concentration of dietary fats have been reported to influence immune status in several animal models. The PUFA Cigtz is necessary for T-cell-mediated immunity, but high intakes will suppress immune function and may therefore increase the risk of cancer. Furthermore, comparisons between the effects of diets rich in Ci8 2 and those rich in Cig i on varying indicators of immune function in mice have shown that, while dietary Ci8 2 predisposed... 

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