The role of biotransformation in dietary (anti)carcinogenesis

The fact that dietary compounds influence the susceptibility of human being s to cancer, is widely accepted. One of the possible mechanisms that is res ponsible for these (anti)carcinogenic effects is that dietary constituents may modulate biotransformation enzymes, thereby affecting the (anti)carcino genic potential of other compounds. This ambiguous theme is the basis for t he present paper. The possible effects of enzymatic bioactivation and detox ification of dietary constituents are discussed using two representative ex amples of phase I and phase II biotransformation enzymes i.e., cytochrome P 450 and glutathione S-transferase. Furthermore, the impact of genetic polym orphisms of these two enzyme systems is considered. Although it is very dif ficult on the basis of the enzyme inducing or inhibiting properties of diet ary compounds, especially to characterize them as anticarcinogenic, for cer tain constituents it is acknowledged that they have anticarcinogenic proper ties. As such, this provides for an important mechanistic substantiation of the established cancer chemopreventive effect of a diet rich in fruits and vegetables. (C) 1999 Elsevier Science B.V. All rights reserved.