DIETARY FATS AND CANCER

Dietary fat may be a promoter, not an initiator of carcinogenesis. Animal studies suggest that the fat:carcinogenesis link is dominated by increased energy intakes and growth rates on high fat diets. Energy restriction reduces the effect. Restricting food intakes and growth rates in humans is unrealistic but low fat, high nutrient diets may reduce overweight and prevent cancer. Polyunsaturated fatty acids promote cancer up to a dietary concentration of 5%; further increases have little effect. Free radical damage to DNA by carcinogens is reduced by scavengers and modulated by dietary factors. Cross cultural associations, time trend and migrant studies are compatible with a link between fat intake and cancers of colon, breast, ovary, endometrium and prostate. Fat increases often involve the reciprocal fall in complex carbohydrates and their associated antioxidants and non-nutritive modulators of carcinogenesis, which are increasingly recognized as important. New tests can assess DNA damage.