[Dietary lipids and experimental colonic carcinogenesis. Critical review of the literature]

Colon cancer is one of the most common tumours observed in the western population for which the relationship between epidemiological and laboratory findings and an overall assessment of the influence of diet on carcinogenesis is not straightforward. The aim of this review is to evaluate critically the experimental data which suggest a positive modulating effect of dietary lipids. Although a great number of data are available on the relation between the nature of fat in diet and colon cancer, no clear conclusions can be drawn from their analysis. The lack of consistent findings is due to the discrepancy of the results which may have arisen from methodological differences between the studies. Concerning the influence of the amount of dietary fat on colon cancer, it has been demonstrated that a high fat diet could increase the incidence and the number of colonic tumours in rats. Nevertheless, this positive modulating effect could be seen provided the fat amount in the diet was at least 20% (w/w). This observation is of first importance for colon cancer prevention and must be confirmed for fat of various nature. Systematic dose-effect studies are necessary. The question whether the effect of dietary fat on carcinogenesis is due to the specific action of fat or to an associated caloric effect has been raised several times. Although the previous studies concerned the role of caloric intake versus fat intake in carcinogenesis, the observed effects might have been due to a change in body weight or to changes in other dietary components such as non nutritive fibre, protein and micronutrients.(ABSTRACT TRUNCATED AT 250 WORDS)