Dietary fat and experimental carcinogenesis: a summary of recent in vivo studies

Diets high in fat have been demonstrated to enhance carcinogenesis in numerous models. Studies on the relationship between dietary fat and cancer in experimental animals have improved with the evolution in our knowledge of the carcinogenic process and with our ability to formulate better controlled diets. This paper summarizes studies conducted during the past 15-20 years on the effects of dietary fat on in vivo carcinogenesis. Relationships between skin carcinogenesis and dietary fat have received little attention during this time, but tremendous progress has been made in our understanding of mammary and colon carcinogenesis. Studies have been conducted of mammary carcinogenesis induced in various rat strains by several chemical carcinogens or by X-irradiation. Several colon carcinogenesis models have also been used to evaluate dietary fat effects. Recent studies in the lung, liver, and pancreas have shown relationships between the carcinogenic process at these sites and dietary fat; however, further studies are needed. The confounding between high fat intakes and low carbohydrate intakes and the difficulties of separating high fat intake from high caloric intake must be addressed in future research. The mechanism of the observed effects of dietary fat is unknown.